Tesis: "Frequency Reconfigurable Antennas"

1

Borda, Fortuny C. "New frequency reconfigurable antennas for wide frequency range tuning". Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1544686/.

Texto completo

Resumen

Frequency reconfigurable antennas are becoming a compelling solution for the increasing demand of higher antenna capabilities, since they can operate at tunable narrow frequency bands while rejecting the undesirable signals from other bands. The aim of this project is to develop new designs for frequency reconfigurable antennas that can work across a wide frequency range (from 1 GHz up to 6 GHz) while maintaining stable radiation pattern and polarisation as required by the industry sponsors. A Vivaldi antenna is considered as the basis for a frequency reconfigurable design as it maintains the radiation characteristics in its operating band. Dual-band, tri-band and quad-band switched reconfigurable designs are proposed and analysed. These antennas are electronically-tuned using RF switches which adjust the impedance to reconfigure the operating band of the antenna. A prototype is tested in an anechoic chamber obtaining good performance. However, as the switches lead to several challenges, such as the effect of bias lines and the excessive insertion losses, a new approach is taken. State-of-the-art technologies are studied and fluid antennas are introduced. Current developments show that liquid antennas can have radiation efficiencies up to 90 % and conductivities close to copper, which makes them a good candidate to fulfil the requirements of this project. A hybrid Vivaldi antenna with an ionised water switch is proposed and a prototype tested. By introducing ionised water into a specific point of the feed line the operating frequency of the antenna is adjusted. The replacement of RF switches for electronically-controlled fluids brings high flexibility, suppression of the bias lines impact, dynamic adjustment and continuous frequency tuning compared to conventional antenna systems.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Sun, Xiaolei y 孙肖磊. "Dual-band and frequency-reconfigurable monopole antennas". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50899880.

Texto completo

Resumen

The designs of three compact dual-band monopole antennas for wireless-local-area-network (WLAN)applications are presented. In these designs, an L-or U-shaped monopole element with microstrip-fed is used to generate a high-frequency band at around 5.5 GHz to cover the high WLAN bands at 5.2/5.8GHz for the IEEE 802.11a standard. An E-shaped element, loop element or meander-microstrip ground stub element with coupled-fed through the monopole element is used to generate a low-frequency band at around 2.4 GHz to cover the low WLAN band for the IEEE 802.11b/g standards. With such arrangements, the three antenna shave very compact radiators of only 11.3×8 mm2,12.6×9 mm2and11.8×9.4 mm2. To investigate the performances for practical uses, these antennas are also designed on a mobile-phone printed-circuit board and studied using computer simulation and measurement. Dual-band antennas with reconfigurable Dual-band antennas with reconfigurable lower band, higher band and dual-band are designed in this thesis. The dual-band antenna consists of two radiating branches generating the frequency bands at around 2.4 GHz and 3.5 GHz for the WiMAX system. Varactors are placed on the corresponding branches for continuously tuning of the operating bands for different WiMAX standards. For frequency tuning of the lower band or higher band, simple and novel DC biasing circuits without requiring any soldering wire are proposed to bias the varactor on a radiating element. While for simultaneous frequency tuning of the two individual bands, simple and novel DC biasing circuits requiring two soldering wires are proposed to bias the varactors on the radiating elements. Both simulation and measurement results show that the DC biasing circuits designed have very little affects on the antennas performances. The design of a monopole ultra-wide band (UWB)antenna with a reconfigurable notch band is presented. The antenna employs a vertical-ellipse radiator to achieve an UWB. A compact defected-ground structure (DGS)is used to create a notch band for the antenna. To frequency tune the notch band, a varactor is placed on the DGS to control the resonance frequency. The tuning performance, in terms of reflection coefficient, radiation pattern, efficiency and gain, of the antennais studied using simulation and measurement. Results show that the notch band can be tuned continuously from 5.2 to 6.32 GHz for the WLAN bands. In the measurement of a monopole antenna with a small ground plane, the feeding cable used to connect the antenna to the measurement equipment Satimo Starlab system causes discrepancies between the simulated and measured radiation patterns, efficiencies and peak gains at lower frequencies. In the designs of antennas in this thesis, the cable effects are studied by modeling the feeding cable using the EM simulation tool CST. Results show that, by using the cable model, the simulated and measured results agree very well.
published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Desjardins, Jason. "Reconfigurable Dielectric Resonator Antennas". Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19838.

Texto completo

Resumen

With the increasing demand for high performance communication networks and the proliferation of mobile devices, significant advances in antenna design are essential. In recent years the rising demands of the mobile wireless communication industry have forced antennas to have increased performance while being limited to an ever decreasing footprint. Such design constraints have forced antenna designers to consider frequency agile antennas so that their behavior can adapt with changing system requirements or environmental conditions. Frequency agile antennas used for mobile handset applications must also be inexpensive, robust, and make use of electronic switching with reasonable DC power consumption. Previous works have addressed a number of these requirements but relatively little work has been performed on frequency agile dielectric resonator antennas (DRAs). The objective of this thesis is to investigate the use of DRAs for frequency reconfigurability. DRAs are an attractive option due to their compactness, very low losses leading to high radiation efficiencies (better than 95%) and fairly wide bandwidths compared to alternatives. DRA’s are also well suited for mobile communications since they can be placed on a ground plane and are by nature low gain antennas whose radiation patterns typically resemble those of short electric or magnetic dipoles. One way to electronically reconfigure a DRA, in the sense of altering the frequency band over which the input reflection coefficient of the antenna is below some threshold, is to partially load one face of the DRA with a conducting surface. By altering the way in which this surface connects to the groundplane on which the DRA is mounted, the DRA can be reconfigured due to changes in its mode structure. This connection was first made using several conducting tabs which resulted in a tuning range of 69% while having poor cross polarization performance. In order to address the poor cross polarization performance a second conducting surface was placed on the opposing DRA wall. This technique significantly reduced the cross polarization levels while obtaining a tuning range of 83%. The dual-wall conductively loaded DRA was then extended to include a full electronic implementation using PIN diodes and varactor diodes in order to achieve discrete and continuous tuning respectively. The two techniques both achieved discrete tuning ranges of 95% while the varactor implementation also had a continuous tuning range of 59% while both maintaining an acceptable cross polarization level.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Tang, Ming-Chun, Zheng Wen, Hao Wang, Mei Li y Richard W. Ziolkowski. "Compact, Frequency-Reconfigurable Filtenna With Sharply Defined Wideband and Continuously Tunable Narrowband States". IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017. http://hdl.handle.net/10150/626120.

Texto completo

Resumen

A compact, frequency-reconfigurable filtenna with sharp out-of-band rejection in both its wideband and continuously tunable narrowband states is presented. It is intended for use in cognitive radio applications. The wideband state is the sensing state and operationally covers 2.35-4.98 GHz. The narrowband states are intended to cover communications within the 3.05-4.39 GHz range, which completely covers the Worldwide Interoperability for Microwave Access (WiMAX) band and the satellite communications C-band. A p-i-n diode is employed to switch between these wide and narrowband operational states. Two varactor diodes are used to shift the operational frequencies continuously among the narrowband states. The filtenna consists of a funnel-shaped monopole augmented with a reconfigurable filter; it has a compact electrical size: 0.235 lambda(L) x 0.392 lambda(L), where the wavelength lambda(L) corresponds to the lower bound of its operational frequencies. The measured reflection coefficients, radiation patterns, and realized gains for both operational states are in good agreement with their simulated values.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Li, Hui. "Decoupling and Evaluation of Multiple Antenna Systems in Compact MIMO Terminals". Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96239.

Texto completo

Resumen

Research on multiple antenna systems has been a hot topic in recent years due to the demands for higher transmission rate and more reliable link in rich scattering environment in wireless communications. Using multiple antennas at both the transmitter side and the receiver side increases the channel capacity without additional frequency spectrum and transmitted power. However, due to the limited space at the size-limited terminal devices, the most critical problem in designing multiple antennas is the severe mutual coupling among them. The aim of this thesis is to provide compact, decoupled and efficient multiple antenna designs for terminal devices. At the same time, we propose a simple and cost effective method in multiple antenna measurement. All these efforts contribute to the development of terminal devices for the fourth generation wireless communication. The background and theory of multiple antenna systems are introduced first, in which three operating schemes of multiple antenna systems are discussed. Critical factors influencing the performance of multiple antenna systems are also analyzed in details. To design efficient multiple antenna systems in compact terminals, several decoupling methods, including defected ground plane, current localization, orthogonal polarization and decoupling networks, are proposed. The working mechanism and design procedure of each method are introduced, and their effectiveness is compared. Those methods can be applied to most of the terminal antennas, reducing the mutual coupling by at least 6dB. In some special cases, especially for low frequency bands below 1GHz, the chassis of the device itself radiates like an antenna, which complicates the antenna decoupling. Thus, we extend the general decoupling methods to the cases when the chassis is excited. Based on the characteristic mode analysis, three different solutions are provided, i.e., optimizing antenna locations, localizing antenna currents and creating orthogonal modes. These methods are applied to mobile phones, providing a more reliable link and a higher transmission rate, which are evaluated by diversity gain and channel capacity, respectively. In order to measure the performance of multiple antenna systems, it is necessary to obtain the correlation coefficients. However, the traditional measurement technique, which requires the phase and polarization information of the radiation patterns, is very expensive and time consuming. In this thesis, a more practical and convenient method is proposed. Fairly good accuracy is achieved when it is applied to various kinds of antennas. To design a compact and efficient multiple antenna system, besides the reduction of mutual coupling, the performance of each single antenna is also important. The techniques for antenna reconfiguration are demonstrated. Frequency and pattern reconfigurable antennas are constructed, providing more flexibility to multiple antenna systems.
QC 20120604

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Gokalp, Nihan. "Beam Steerable Meanderline Antenna Using Varactor Diodes And Reconfigurable Antenna Designs By Mems Switches". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609982/index.pdf.

Texto completo

Resumen

Recently, reconfigurable antennas have attracted significant interest due to their high adaptation with changing system requirements and environmental conditions. Reconfigurable antennas have the ability to change their radiation pattern, frequency or polarization independently according to the application requirements. In this thesis, three different reconfigurable antenna structures have been designed
beam-steerable meanderline antenna, dual circularly polarized meanderline antenna and dual-frequency slot-dipole array. Traveling wave meanderline antenna arrays are investigated in detail and a beam-steerable traveling wave meanderline antenna array has been introduced for X-band applications. Beam-steering capability of the antenna array has been achieved by loading the antenna elements with varactor diodes. Theoretical analysis and computer simulations of the proposed antenna have been verified with experimental results. Radiation direction of the 8-element meanderline array can be rotated 10°
by changing the varactor diode&rsquo
s bias voltage from 0V up to 20V. Also, a polarization-agile meanderline antenna array has been designed and simulated. Polarization of the circularly polarized meanderline array can be altered between right hand circularly polarized and left hand circularly polarized by using RF MEMS switches. The third type of reconfigurable antenna investigated in this thesis is a dual frequency slot-dipole array operating at X- and Ka-band. Electrical length of the slot dipoles has been tuned by using RF MEMS switches. Antenna prototypes have been manufactured for &lsquo
on&rsquo
and &lsquo
off&rsquo
states of RF MEMS switches and it has been shown that the operating frequency can be changed between 10 GHz and 15.4 GHz.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Mopidevi, Hema Swaroop. "Micro Electro Mechanical Systems Integrated Frequency Reconfigurable Antennas for Public Safety Applications". DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/744.

Texto completo

Resumen

This thesis work builds on the concept of reconfiguring the antenna properties (frequency, polarization, radiation pattern) using Radio Frequency (RF) Micro Electro Mechanical Systems (MEMS). This is a part of the overall research performed at the RF Micro/Nano Electro Mechanical Systems (uNeMS) Laboratory at Utah State University, which includes design, microfabrication, test, and characterization of uNeMS integrated cognitive wireless communication systems (Appendix A). In the first step, a compact and broadband Planar Inverted F Antenna (PIFA) is designed with a goal to accommodate reconfigurability at a later stage. Then, a Frequency Reconfigurable Antenna (FRA) is designed using MEMS switches to switch between the Public Safety (PS) bands, 152-162 MHz and 406-512 MHz, while maintaining the integrity of radiation pattern for each band. Finally, robust mechanical designs of the RF MEMS switches accompanied by different analyses have been performed. These analyses are instrumental in obtaining high yield, reliable, robust microfabrication processes including thin film metal deposition and patterning.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Cure, David. "Reconfigurable Low Profile Antennas Using Tunable High Impedance Surfaces". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4659.

Texto completo

Resumen

This dissertation shows a detailed investigation on reconfigurable low profile antennas using tunable high impedance surfaces (HIS). The specific class of HIS used in this dissertation is called a frequency selective surface (FSS). This type of periodic structure is fabricated to create artificial magnetic conductors (AMCs) that exhibit properties similar to perfect magnetic conductors (PMCs). The antennas are intended for radiometric sensing applications in the biomedical field. For the particular sensing application of interest in this dissertation, the performance of the antenna sub-system is the most critical aspect of the radiometer design where characteristics such as small size, light weight, conformability, simple integration, adjustment in response to adverse environmental loading, and the ability to block external radio frequency interference to maximize the detection sensitivity are desirable. The antenna designs in this dissertation are based on broadband dipole antennas over a tunable FSS to extend the usable frequency range. The main features of these antennas are the use of an FSS that does not include via connections to ground, their low profile and potentially conformal nature, high front-to-back radiation pattern ratio, and the ability to dynamically adjust the center frequency. The reduction of interlayer wiring on the tunable FSS minimizes the fabrication complexity and facilitates the use of flexible substrates. This dissertation aims to advance the state of the art in low profile tunable planar antennas. It shows a qualitative comparison between antennas backed with different unit cell geometries. It demonstrates the feasibility to use either semiconductor or ferroelectric thin film varactor-based tunable FSS to allow adjustment in the antenna frequency in response to environment loading in the near-field. Additionally, it illustrates how the coupling between antenna and HIS, and the impact of the varactor losses affect the antenna performance and it shows solutions to compensate these adverse effects. Novel hybrid manufacturing approaches to achieve flexibility on electrically thick antennas that could be transitioned to thin-film microelectronics are also presented. The semiconductor and ferroelectric varactor-based tunable low profile antennas demonstrated tunability from 2.2 GHz to 2.65 GHz with instantaneous bandwidths greater than 50 MHz within the tuning range. The antennas had maximum thicknesses of λ/45 at the central frequency and front to back-lobe radiation ratios of approximately 15dB. They also showed impedance match improvement in the presence of a Human Core Model (HCM) phantom at close proximity distances of the order of 10-20 mm. In addition, the use of thin film ferroelectric Barium Strontium Titanate (BST) varactors in the FSS layer enabled an antenna that had smaller size, lower cost and less weight compared to the commercially available options. The challenging problems of fabricating robust flexible antennas are also addressed and novel solutions are proposed. Two different types of flexible antennas were designed and built. A series of flexible microstrip antennas with slotted grounds which demonstrated to be robust and have 42% less mass than typically used technologies (e.g., microstrip antennas fabricated on Rogers® RT6010, RT/duroid® 5880, etc.); and flexible ferroelectric based tunable low profile antennas that showed tunability from 2.42 GHz to 2.66 GHz using overlapping metallic plates instead of a continuous ground plane. The bending test results demonstrated that, by placing cuts on the ground plane or using overlapping metallic layers that resemble fish scales, it was possible to create highly conductive surfaces that were extremely flexible even when attached to other solid materials. These new approaches were used to overcome limitations commonly encountered in the design of antennas that are intended for use on non-flat surfaces. The material presented in this dissertation represents the first investigation of reconfigurable low profile antennas using tunable high impedance surfaces where the desired electromagnetic performance as well as additional relevant features such as robustness, low weight, low cost and low complexity were demonstrated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Erdil, Emre. "Tunable Frequency Microstrip Antennas By Rf-mems Technology". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606022/index.pdf.

Texto completo

Resumen

This thesis presents the design, fabrication, and measurement of tunable frequency microstrip antennas using RF MEMS (Microelectromechanical Systems) technology. The integration of RF MEMS components with radiators enable to implement tunable systems due to the adjustable characteristics of RF MEMS components. In the frame of this thesis, different types of structures have been investigated and designed. The first structure consists of a microstrip patch antenna which is loaded with a microstrip stub whose length is controlled by RF MEMS switches. In the other structure, the length of a microstrip patch antenna is changed by connecting a metal plate using RF MEMS switches. The third structure is composed of a microstrip patch antenna and a microstrip stub on which RF MEMS variable capacitors are placed periodically to control the resonant frequency. In order to maintain an easier integration with RF MEMS capacitors, another structure consisting of a microstrip patch antenna and a coplanar waveguide (CPW) stub which is loaded with variable RF MEMS capacitors is designed. The final structure is a dual frequency CPW-fed rectangular slot antenna whose resonant frequencies are shifted by RF MEMS variable capacitors placed on a short circuited stub inserted inwards the antenna. The fabrication of CPW-fed rectangular slot antenna is completed in the MEMS fabrication facilities of METU using RF MEMS process based on electroforming on glass substrate. The measurement results show that RF MEMS components might be a proper solution to obtain tunable frequency antenna structures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Guclu, Caner. "Dual Frequency Reconfigurable Reflectarray Antenna Of Split Ring Elements With Rf Mems Switches". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612449/index.pdf.

Texto completo

Resumen

Dual band (K and Ka) electronically scanning reflectarray with RF MEMS switches is designed, implemented and measured. Unit cell of the reflect array is composed of conductor backed split-ring elements. In order to steer the beam, the phase of the incident circularly polarized wave is controlled by RF MEMS switches that modify the angular orientation of split-rings individually. Reflectarray is designed using unit cell approach with periodic boundary conditions. The antenna is fabricated by using surface micromachining process developed in METU MEMS Center. Radiation patterns of the antenna are measured and compared with the simulations. It has been shown that the reflectarray is capable of beam switching to 35°
in Ka band, 24°
in K band.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Wolcott, Paul Joseph. "Toward Load Bearing Reconfigurable Radio Frequency Antenna Devices Using Ultrasonic Additive Manufacturing". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338385633.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Elfergani, Issa T. "Investigation, design and implementation of frequency tuneable antennas for mobile handset and UWB applications : simulation and measurement of tunable antennas for handheld mobile handsets and UWB system, investigations of frequency tuneable range, antenna radiation performance and antenna design optimisation using parametric studies". Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/13761.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Dey, Abhishek. "Frequency Tunable Antennas and Surface Microwave Imaging System Using Microfluidic Reconfiguration Techniques". Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6491.

Texto completo

Resumen

Reconfigurable radio frequency (RF) devices are attractive for miniaturization of wireless components and systems by handling functionality of multiple distinct devices. Existing reconfiguration techniques rely on device loadings with semiconductor diodes, ferrite/ferroelectric materials, and microelectromechanical system (MEMS) switches and capacitors. However, it is well-recognized that these techniques cannot fully address important system metrics such as high efficiency, wide frequency tuning range, high power handling capability and cost. Therefore, novel alternative techniques are highly desirable to advance the state of the art in reconfigurable RF devices. The aim of this dissertation is to investigate the novel concept of microfluidically loaded reconfigurability within the context of RF antennas and imaging systems. The proposed devices operate based on continuously movable microfluidic loads consisting of metal (liquid/solid) and dielectric solutions. Microfluidics and microfabrication techniques are utilized with flexible/rigid multilayered substrates to maximize the reconfigurable loading effect on the devices and enable highly reconfigurable antennas and imaging array realizations. Specifically, a wideband frequency tunable monopole antenna is introduced by utilizing continuously movable liquid metal within the microfluidic channel as a length varying conductor. By resorting to ultra-thin channel walls, the liquid metal volume overlapping with the microstrip line feed is utilized as a non-radiating capacitive excitation point to achieve the realized 4:1 (1.29GHz – 5.17GHz) frequency tuning range. Subsequently, an alternative design that replaces liquid metal volume with a microfluidically movable metallized plate is introduced. This novel liquid-metal-free implementation alleviates the liquid metal associated drawbacks of reliability, long-term device operation, and efficiency. The antenna is shown to provide 2:1 (1.6GHz – 3.5GHz) frequency tuning range with > 87 % radiation efficient. Due to the high radiation efficiency, the antenna is also capable of handling 15 W of RF power which is 10 W more than its liquid metal counterpart. This metallized plate approach is also suitable for reconfiguration of miniature antennas, and this is demonstrated with the design/implementation of a microfluidically reconfigurable top loaded monopole antenna. It is also suitable for reconfiguration of other structures such as textile antennas – and this is demonstrated with a 0.8GHz to 1.4GHz frequency reconfigurable textile antenna realization. The last section of the dissertation introduces a novel surface imaging array realization by utilizing the microfluidically reconfigurable metallized plate as an RF read-out circuit component. Specifically, a 24 element imaging array is designed and validated to operate within 6 – 12 GHz band with subwavelength resonators to demonstrate the possibility of constructing low-cost high-resolution microwave surface imaging arrays by utilizing the microfluidics based reconfiguration techniques. The presented work emphasizes system level implementation of the proposed devices by integrating them with micropump units, controller boards, and investigating their reliability performances under higher power RF excitations.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Zheng, Guizhen. "Low Power Reconfigurable Microwave Circuts Using RF MEMS Switches for Wireless Systems". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/11656.

Texto completo

Resumen

This dissertation presents the research on several different projects. The first project is a via-less CPW RF probe pad to microstrip transition; The second, the third, and the fourth one are reconfigurable microwave circuits using RF MEMS switches: an X-band reconfigurable bandstop filter for wireless RF frontends, an X-band reconfigurable impedance tuner for a class-E high efficiency power amplifier using RF MEMS switches, and a reconfigurable self-similar antenna using RF MEMS switches. The first project was developed in order to facilitate the on-wafer measurement for the second and the third project, since both of them are microstrip transmission line based microwave circuits. A thorough study of the via-less CPW RF probe pad to microstrip transition on silicon substrates was performed and general design rules are derived to provide design guidelines. This research work is then expanded to W-band via-less transition up to 110 GHz. The second project is to develop a low power reconfigurable monolithic bandstop filter operating at 8, 10, 13, and 15 GHz with cantilever beam capacitive MEMS switches. The filter contains microstrip lines and radial stubs that provide different reactances at different frequencies. By electrically actuating different MEMS switches, the different reactances from different radial stubs connecting to these switches will be selected, thus, the filter will resonate at different frequencies. The third project is to develop a monolithic reconfigurable impedance tuner at 10 GHz with the cantilever DC contact MEMS switch. The impedance tuner is a two port network based on a 3bit-3bit digital design, and uses 6 radial shunt stubs that can be selected via integrated DC contact MEMS switches. By selecting different states of the switches, there will be a total of 2^6 = 64 states, which means 64 different impedances will be generated at the output port of the tuner. This will provide a sufficient tuning range for the output port of the power amplifier to maximize the power efficiency. The last project is to integrate the DC contact RF MEMS switches with self-similar planar antennas, to provide a reconfigurable antenna system that radiates with similar patterns over a wide range of frequencies.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Zheng, Guizhen. "Low power reconfigurable microwave circuits using RF MEMS switches for wireless systems". Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-05242005-135940/.

Texto completo

Resumen

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.
John Papapolymerou, Committee Chair ; Joy Laskar, Committee Member ; John Cressler, Committee Member ; Alan Doolittle, Committee Member ; Clifford Henderson, Committee Member.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Hage-Ali, Sami. "Antennes et dispositifs hyperfréquences millimétriques ultrasouples reconfigurables à base de Microsystèmes Magnéto-Electro-Mécaniques (MMEMS) : conception, réalisation, mesures". Phd thesis, Ecole Centrale de Lille, 2011. http://tel.archives-ouvertes.fr/tel-00638181.

Texto completo

Resumen

Il y a à l'heure actuelle un grand besoin d'antennes reconfigurables dans la bande des 60 GHz pour des applications de télédétection et de télécommunications sans fil très hauts débits. Les solutions traditionnelles de reconfiguration sont basées sur des semiconducteurs ou des composants RF-MEMS, qui connaissent un coût, une complexité et des pertes croissantes en bande millimétrique. Dans cette thèse, une approche originale a été développée : elle est basée sur la reconfiguration mécanique d'antennes et dispositifs millimétriques microrubans sur substrat élastomère ultrasouple PDMS grâce à des actionneurs MEMS grands déplacements. Premièrement, les choix de conception, la technique de simulation éléments finis (HFSS), et surtout la microfabrication d'antennes sur membrane PDMS ainsi que les techniques de mesure en impédance et rayonnement sont abordés.Deux axes ont ensuite été étudiés : les antennes accordables en fréquence, et les antennes et composants pour le balayage angulaire (déphaseurs et antennes à balayage mécanique de type scanner). Des procédés technologiques innovants ont été développés (reports de métallisations épaisses biocompatibles et d'aimants permanents en couches minces sur membrane PDMS) et différentes techniques d'actionnement (pneumatique, magnétique, par électromouillage) ont été mises en œuvre. Les performances en terme d'accord en fréquence (8,2 %) et de balayage angulaire (-90/+100°) dépassent l'état de l'art des antennes du même type en bande millimétrique, et ceci en utilisant une technologie peu complexe, ultra bas-coût et prometteuse pour la montée en fréquence.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Lockyer, David S. "Reconfigurable and closely coupled frequency selective surfaces". Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/6828.

Texto completo

Resumen

The performance of a planar Frequency Selective Surface (FSS) cannot be changed or adapted once the manufacturing process has been completed. In practice, however, it would be advantageous to be able to do so, in order to increase flexibility of performance in multiband systems for example. This thesis examines a novel electromagnetict echniquet hat has beend eveloped,w hereby the frequencya nd/or the angular response of FSS's can be tuned in situ over a wide range of frequencies and/or steering angles. The technique employed is passive and relies upon the displacemento f closely separated( and therefore closely coupled) arrays with respect to each other. A global loading of the array results so that the reconfigurable FSS (RFSS) will produce a broadband and/or multibeam response without altering the individual array design. The experience and understanding gained during this work was subsequently used to produce FSS responses of extreme angular stability. In this case a static, double layer structure has been used to make use of the high coupling between the layers i.e. two FSS's printed on a single dielectric substrate to form a close coupled FSS (CCFSS). It was found that the coupling between the two layers was highly dependent on the relative displacement between arrays. This displacement is introduced statically during the manufacture of the FSS. The cases described use two identical layers. A further development of this concept makes use of complementary conducting and aperture elements giving rise to a complementary FSS (CFSS). The CFSS is also manufactured on a common dielectric and produces ultra stable resonant frequencies for both TE and TM oblique incidences. Theoretical verification of the measured results has been achieved, and the measured and predicted results agreed very closely. Modal analysis, using a novel coupled integral equation technique, has been used to predict the response of the RFSS and CFSS. The correlation between the predicted and measured transmission response of the RFSS was very good and it was discovered that operational stability of the bandwidths and band spacing ratios were significantly improved over conventional static FSS.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Jung, Chang won, Ming-jer Lee, Sunan Liu, G. P. Li y Flaviis Franco De. "RECONFIGURABLE PATCH ANTENNA FOR FREQUENCY DIVERSITY WITH HIGH FREQUENCY RATIO (1.6:1)". International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/605028.

Texto completo

Resumen

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada
Reconfigurable patch antenna integrated with RF mircoelectromechanical system (MEMS) switches is presented in this paper. The proposed antenna radiates circularly polarized wave at selectable dual frequencies (4.7 GHz and 7.5GHz) of high frequency ratio (1.6:1). The switches are incorporated into the diagonally-fed square patch for controlling the operation frequency, and a rectangular stub attached to the edge of the patch acts as the perturbation to produce the circular polarization. Gain of proposed antenna is 5 - 6dBi, and axial ratio satisfies 3dB criterion at both operating frequencies. The switches are monolithically integrated on quartz substrate. The antenna can be used in applications requiring frequency diversity of remarkable high frequency ratio.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Zohur, Abdul. "Micro-Electro-Mechanical Systems (MEMS) Integrated Frequency Reconfigurable Antenna". DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1731.

Texto completo

Resumen

In this paper, the design, analysis, and characterization of reconfigurable antennas based on radio frequency micro-electro-mechanical systems (RF MEMS) operating in the United States' public safety (PS) bands are presented. The design methodology of these antennas, which are different from the normal antenna design, is also reported. In this thesis, two electrically small reconfigurable antenna designs have been presented, with two and three modes of operation, and central frequencies of 718 and 4960 MHz and of 857,809 and 4960 MHz, respectively. The maximum frequency tunable ratio achieved in these designs is 7. The recongurability between the modes is achieved by one and three RF MEMS switches in all three designs. These switches enable a change in the length of the current flow path, thereby changing the resonance frequencies. The measurement results for impedance and radiation characteristics of the fabricated antennas prototypes are also presented, and agree reasonably well with the simulations results from An-soft HFSS.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Chauloux, Antoine. "Contribution à l’étude d’antennes de puissance à efficacité optimisée : application aux réseaux large bande et reconfigurables en diagrammes de rayonnement". Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S179.

Texto completo

Resumen

L'émergence depuis ces dernières années de nouvelles capacités technologiques permettant la mise en œuvre de dispositifs d'agression électromagnétique, imposent d'étudier la faisabilité de ces potentielles Armes à Energie Dirigée ÉlectroMagnétiques (AED EM). Parmi les différentes briques technologiques qui composent ces systèmes, l'aérien est l'élément déterminant de la formation du faisceau d'ondes rayonnées et nécessite donc d'être évalué. C'est dans ce contexte que le Centre de Gramat du Commissariat à l'Énergie Atomique et aux Énergies Alternatives s'est associé à la Direction Générale de l'Armement afin de proposer cette thèse réalisée en collaboration avec l'Institut d'Électronique et de Télécommunications de Rennes. Le sujet propose l'étude complète de trois solutions antennaires susceptibles d'être intégrées sur un système de type AED EM. Chaque type d'antenne répond à une problématique qui lui est propre : Il s'agit en premier lieu de réaliser une antenne fonctionnant à fréquence fixe et possédant un gain maximisé ; Dans un second temps l'étude est menée afin de concevoir et réaliser une antenne à diagramme de rayonnement variable dans un plan et stable dans l'autre plan ; Enfin une antenne large bande fonctionnant sur une octave est développée dans le but de maintenir un diagramme de rayonnement possédant des ouvertures à mi-puissance constantes. Chacune de ces études est gouvernée par deux contraintes difficiles que sont d'une part le maintien d'une tenue en puissance élevée (niveau injecté de l'ordre du kilowatt pulsé) et d'autre part un encombrement réduit en vue d'une intégration sur porteur par exemple. Chaque antenne est élaborée à l'aide d'un logiciel de calcul électromagnétique puis réalisée afin d'être validée expérimentalement
It is true that during the last past years, High Power Microwave (HPM) weapons threat has grown up. One way to prevent from this kind of system is to study every part of it. Among them, the antenna is the element that influences the most the electromagnetic waves behavior then it has to be evaluated. This is the reason why the Centre de Gramat du Commissariat à l’Energie Atomique et aux Energies Alternatives has teamed up with the Direction Générale de l’Armement in order to propose this thesis in collaboration with the Institut d’Electronique et de Télécommunications de Rennes. The subject provides the full study of three antennas that can be integrated on an HPM weapon. Each type of antenna is developed to address a problem: The first antenna operates at a fixed frequency and is designed to provide a maximized gain; The second one is manufactured to have a variable radiation pattern in one plane and a stable radiation pattern in the other plane; Finally, a broadband antenna operating between 2 and 4 GHz is developed in order to maintain a stable radiation pattern. Each study is led by taking into consideration high input power (around 1 kW pulsed power) and also dimensional constraints in order to be integrated on a mobile device for instance. Each antenna is designed using electromagnetic software then validated by measurements

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Orlic, Yovan. "Dispositifs flexibles de communication à 60 GHz reconfigurables mécaniquement". Thesis, Ecole centrale de Lille, 2014. http://www.theses.fr/2014ECLI0002/document.

Texto completo

Resumen

Il y a à l’heure actuelle un grand besoin d’antennes reconfigurables dans la bande des 60 GHz pour des applications de télédétection et de télécommunication sans fil. Les solutions traditionnelles de reconfiguration sont basées sur des semi-conducteurs ou des composants RF-MEMS conventionnels dont le coût, la complexité et les pertes croissent avec la fréquence.Dans cette thèse une approche originale a été développée : elle est basée sur la reconfiguration mécanique d’antennes et de dispositifs sur substrat élastomère souple PDMS et l’utilisation d’actionneurs MEMS grand déplacement.L’histoire et le contexte de la télécommunication sont abordés pour faire comprendre l’intérêt récent pour la communication à 60 GHz ainsi que la nécessité de la reconfiguration et l’avantage de la reconfiguration mécanique à cette fréquence. Le PDMS, polymère ultra-souple de choix est ensuite étudié en détail. Il est caractérisé mécaniquement et diélectriquement. Sont ensuite présenté les applications développées par cette approche : des antennes accordables en fréquence ainsi que des dispositifs permettant un balayage de l’espace. Différents mode d’actionnement (pneumatique, magnétique, interaction électro-fluidique) sont explorés
There is an increasing need for tunable antennas in the 60 GHz band for remote sensing application and wireless communication. Traditional tuning solutions are based on semiconductor or conventional RF-MEMS but these component face cost, complexity and losses issues at millimeter waves. In this thesis, an original approach was developed: it is based on the mechanical reconfiguration of millimeter wave microstrip antennas and devices printed on ultrasoft elastomeric PDMS substrate, thanks to large displacement MEMS actuators.First, a quick history and context on the telecommunication explain the recent interest toward the 60 GHz band for telecommunication and the need for tenability and advantage of mechanical tenability at this frequencies. The ultrasoft polymeric PDMS is then studied. It is caracterised both mechanically and dielectrially. Then the different applications developed during this thesis are presented: frequency tunable antenna and beam steering systems. Different actuation solution (pneumatic, magnetic, electro-fluidic interaction) are explored

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Yee, Steven C. (Steven Christopher) 1989. "A frequency reconfigurable circularly polarized microstrip patch antenna using liquid metal microswitches". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82359.

Texto completo

Resumen

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 78-80).
Reconfigurable antennas with adaptable frequency, pattern, and polarization offer flexibility and size reduction for wireless systems that must increasingly execute multiple missions with less volume. These antennas will also complement anticipated cognitive radio systems, which promise more efficient use of the electromagnetic spectrum. Microscale liquid metal switches are proposed to overcome the series loss, mechanical fatigue, and limited power handling reliability of common methods of antenna reconfiguration such as semiconductor diodes and microelectromechanical switches. The proposed microswitches consist of mercury droplets that selectively connect solid metal traces. Both fluidic and electrostatic switch actuation mechanisms are investigated, and an electrostatic switch is demonstrated. Electrostatically actuated switches are designed into a compact single-feed patch antenna configurable between two communication frequency bands and a GPS band with different circular polarizations. The antenna topology is based on a corner truncated square patch with switched sets of extensions to achieve resonant frequency and axial ratio control. Measurements of reconfigurable prototypes demonstrate frequency and polarization configurability in good agreement with full-wave simulations. The proposed reconfiguration mechanism is compared to other methods, and future directions for the integration of microfluidics in reconfigurable radio frequency systems are proposed.
by Steven Christopher Yee.
S.M.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Nguyen, Viet Hung. "Antennes miniatures et reconfigurables utilisant des matériaux diélectriques et ferroélectriques oxydes et oxynitrures en couches minces". Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00866988.

Texto completo

Resumen

Face à la volonté d'intégrer une quantité toujours plus importante de nouveaux services au sein des terminaux mobiles de nouvelle génération et afin de répondre à leurs contraintes d'encombrement, des nouveaux concepts d'antennes intelligentes font l'objet de nombreuses recherches. Parmi les solutions proposées dans la littérature, la technique consistant à charger l'antenne par un matériau aux propriétés commandables apparaît particulièrement intéressante puisque elle cumule les effets de miniaturisation et d'agilité. Le travail de cette thèse concerne l'intégration des films minces La-Ti-O-N et BST dans des antennes miniatures et agiles en fréquence. Pour cela, une étude systématique des propriétés diélectriques (constante, tangente de pertes et accordabilité) des films La-Ti-O-N a été réalisée en basses et hautes fréquences. Ces propriétés sont fonction des caractéristiques structurales des films, elles-mêmes issues de la nature du substrat utilisé et des conditions de dépôt. En parallèle, une étude sur l'intégration de ces matériaux dans des structures rayonnantes pour atteindre l'agilité souhaitée a été menée. De premiers démonstrateurs d'antennes miniatures et reconfigurables à base des films minces La-Ti-O-N et BST ont été réalisés et caractérisés.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Dufour, Gaëtan. "Dispositifs hyperfréquences reconfigurables par des mécanismes micro-mécaniques et micro-fluidiques : conception, réalisation, mesures". Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0008/document.

Texto completo

Resumen

Il y a à l'heure actuelle un grand besoin en systèmes et composants agiles pour les dispositifs front-end RF. Dans cette thèse, deux approches innovantes sont développées pour la conception de tels dispositifs RF. Dans un premier temps, un mécanisme de reconfiguration micro-mécanique est développé. Cette approche vise à contrôler la hauteur d'un gap d'air inséré dans le substrat de composants microrubans afin d'en modifier les dimensions électriques. Les choix de conception et la fabrication d'un déphaseur à ligne micro-ruban ainsi que d'une antenne accordable en fréquence sont discutés. Une solution d'actionnement piézoélectrique basse tension (+/- 30 V) est retenue. La figure de mérite obtenue dans le cas du déphaseur atteint jusqu'à 313 °/dB ce qui dépasse l'état de l'art en matière de déphasage analogique. Dans le cas de l'antenne, le potentiel d'agilité en fréquence atteint 35 % autour d'une fréquence centrale de 55 GHz. Contrairement aux solutions classiques à base de semiconducteurs ou de RF-MEMS, ce mécanisme de reconfiguration n'impacte pas les performances de l'antenne dont l'efficacité de rayonnement est proche de 94 %. Dans un second temps, c'est un mécanisme micro-fluidique qui est étudié. L'agilité en fréquence d'antennes est créée par l'écoulement successif de liquides de permittivités différentes dans des micro-canaux intégrés au substrat. L'accord en fréquence atteint alors la très large ampleur de 51 % pour une fréquence centrale de 22 GHz. Cette étude s'accompagne de la recherche et caractérisation diélectrique de plusieurs fluides dans l'optique d'augmenter aussi bien la plage d'accord en fréquence que les performances de rayonnement des antennes
As wireless networks evolve, the frequency bands they exploit multiply. Frequency multiplexing, beamforming and tracking, networks interoperability, those mutations increase the need for agility and tunability in the RF-front end systems. In this thesis, two innovative approaches for the design of tunable RF components are studied. First, a micro-mechanical reconfiguration mechanism is developed. This approach means to control the height of an air gap within the substrate of microstrip components in order to control their electrical dimensions. Considerations for the design and fabrication of a phase-shifter and a frequency tunable patch antenna are made and a low voltage piezoelectric actuation (+/- 30 V) is chosen. The phase-shifter figure of merit reaches up to 312 °/dB which is beyond the state of the art in terms of analogic phase-shifting. Regarding the antenna, the frequency tuning potentially reaches up to 35 \% of a central frequency of 55 GHz. Unlike the classic solidstate or RF-MEMS based solutions, this reconfiguration mechanism does not impact the radiation performance of the antenna whose radiation efficiency is 94 \%. In a second approach, a micro-fluidic solution is studied. Frequency tuning capability is created in different antennas by the flow of successive liquids with different permittivities in integrated micro-channels. A large frequency tuning of 51 \% for a central frequency of 22 GHz is achieved. This study goes along with the search and characterization of several fluids with the objective of increasing both the frequency shift and the radiation performance of those antennas

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Pan, Kuan-Chang. "Vanadium Dioxide Based Radio Frequency Tunable Devices". University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton154341840843132.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Papantonis, Dimitrios Papantonis. "Tightly-Coupled Arrays with Reconfigurable Bandwidth". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503046689468305.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Cissé, Fatou. "Dispositifs hyperfréquences et antennes périodiques reconfigurables à base de films minces ferroélectriques des systèmes KTN-KNN". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S028/document.

Texto completo

Resumen

Ce travail concerne la réalisation et la caractérisation de dispositifs hyperfréquences agiles en fréquence à base du matériau ferroélectrique KTa1-xNbxO3 (KTN) déposé en couche mince. Doté d'une permittivité diélectrique élevée (er = 700 à 10 GHz et Ebias = 0 kV/cm), KTN est un candidat prometteur pour la reconfigurabilité et la miniaturisation des dispositifs hyperfréquences. Ses pertes restent néanmoins conséquentes (tanδr = 0,3 à 10 GHz et Ebias = 0 kV/cm) et sont en partie à l'origine des pertes globales des dispositifs hyperfréquences réalisés. Afin de limiter ces pertes, une double approche a été engagée : (1) réduction des pertes diélectriques par le dopage du matériau KTN par un oxyde à faibles pertes : MgO à 3% et 6% en moles et (2) réduction des pertes globales par le confinement du matériau KTN dopé dans les zones actives des dispositifs hyperfréquences. Les couches minces de KTN non dopé et dopé d'épaisseur ~ 600 nm ont été déposées sur substrats de saphir orienté R par ablation laser pulsé (PLD). Deux compositions différentes (KTa0,5Nb0,5O3 et KTa0,65Nb0,35O3) ont été sélectionnées pour cette étude. Des dispositifs coplanaires imprimés sur les films ferroélectriques ont été réalisés et caractérisés dans la bande d'intérêt 1 GHz-20 GHz. Le dopage à 6% assure le meilleur compromis pertes / agilité avec une réduction significative des pertes globales de 0,73 à 0,20 (facteur ~ 4) du dispositif résonant imprimé sur KTa0,5Nb0,5O3 après son confinement par microgravure laser. Une agilité en fréquence de 8% est obtenue sous Ebias ≈ 75 kV/cm. L'étude d'une antenne à ondes de fuite reconfigurable en bande Ku a ensuite été mise en oeuvre. Les couches minces de KTa0,5Nb0,5O3 d'épaisseur ~ 600 nm ont été déposées par PLD sur substrats de saphir R, puis le matériau ferroélectrique a été localisé par microgravure laser dans les 6 zones actives de l'antenne (constituée de 6 tronçons). L’évolution du coefficient de réflexion sous Ebias ≈ 85 kV/cm montre une agilité en fréquence égale à 2%. Un gain maximal de 6,7 dBi a été mesuré à f = 17 GHz et Ebias = 0 kV/cm, conformément aux résultats de simulation
This work deals with the fabrication and characterization of frequency tunable microwave devices based on ferroelectric KTa1-xNbxO3 (KTN) thin films. KTN material is a promising candidate for the tunability and miniaturization of microwave devices, due to its high dielectric permittivity (er= 700 at 10 GHz and Ebias= 0 kV/cm). Nevertheless its intrinsic loss (tanδr= 0.3 at 10 GHz and Ebias= 0 kV/cm) strongly impacts the global loss of the tunable microwave devices. To reduce this, a twofold solution has been investigated: (1) reduction of the loss tangent by doping KTN material with a low loss oxide, namely MgO (3% and 6% in mol.) and (2) confinement of the doped KTN film in efficient regions of the microwave devices and removal in noncritical areas by laser microetching. The ~ 600 nm-thick undoped and doped KTN films have been grown by Pulsed Laser Deposition (PLD) on R-plane sapphire substrates. Two different compositions (KTa0.5Nb0.5O3 and KTa0.65Nb0.35O3) were specifically selected for this study. Microwave measurements have been performed on KTN-based coplanar devices from 1 GHz to 20 GHz. Stub resonator printed on confined 6% doped KTa0.5Nb0.5O3 film exhibits the best loss/agility trade-off with a significant global loss reduction from 0.73 to 0.20 (factor ~ 4) with a 8% frequency tunability under Ebias≈ 75 kV/cm.Thereafter, the study of a reconfigurable Ku-band leaky-wave antenna has been carried out. A ~600 nm-thick KTa0.5Nb0.5O3 film was deposited by PLD on R-plane sapphire substrate. The ferroelectric material was localized by laser microetching on 6 specific areas of the antenna (consisted of 6 sections). The variation of the reflection coefficient under biasing (Ebias≈ 85 kV/cm) demonstrates a frequency tunability of 2%. A gain equal to 6.7 dBi has been measured at f= 17 GHz and Ebias= 0 kV/cm, in accordance with the numerical results

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Yoon, Youngchang. "Reconfigurable CMOS RF power amplifiers for advanced mobile terminals". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48987.

Texto completo

Resumen

In recent years, tremendous growth of the wireless market can be defined through the following words: smartphone and high-data rate wireless communication. This situation gives new challenges to RF power amplifier design, which includes high-efficiency, multi-band operation, and robustness to antenna mismatch conditions. In addition to these issues, the industry and consumers demand a low-cost small-sized wireless device. A fully integrated single-chip CMOS transceiver is the best solution in terms of cost and level of integration with other functional blocks. Therefore, the effective approaches in a CMOS process for the abovementioned hurdles are highly desirable. In this dissertation, the new challenges are overcome by introducing adaptability to a CMOS power amplifier. Meaningful achievements are summarized as follows. First, a new CMOS switched capacitor structure for high power applications is proposed. Second, a dual-mode CMOS PA with an integrated tunable matching network is proposed to extend battery lifetime. Third, a switchless dual-band matching structure is proposed, and the effectiveness of dual-band matching is demonstrated with a fully-integrated CMOS PA. Lastly, a reconfigurable CMOS PA with an automatic antenna mismatch recovery system is presented, which can maintain its original designed performance even under various antenna mismatch conditions. Conclusively, the research in this dissertation provides various solutions for new challenges of advanced mobile terminals.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Asif, Rameez. "Design and Implementation of System Components for Radio Frequency Based Asset Tracking Devices to Enhance Location Based Services. Study of angle of arrival techniques, effects of mutual coupling, design of an angle of arrival algorithm, design of a novel miniature reconfigurable antenna optimised for wireless communication systems". Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/17143.

Texto completo

Resumen

The angle of arrival estimation of multiple sources plays a vital role in the field of array signal processing as MIMO systems can be employed at both the transmitter and the receiver end and the system capacity, reliability and throughput can be significantly increased by using array signal processing. Almost all applications require accurate direction of arrival (DOA) estimation to localize the sources of the signals. Another important parameter of localization systems is the array geometry and sensor design which can be application specific and is used to estimate the DOA. In this work, various array geometries and arrival estimation algorithms are studied and then a new scheme for multiple source estimation is proposed and evaluated based on the performance of subspace and non-subspace decomposition methods. The proposed scheme has shown to outperform the conventional Multiple Signal Classification (MUSIC) estimation and Bartlett estimation techniques. The new scheme has a better performance advantage at low and high signal to noise ratio values (SNRs). The research work also studies different array geometries for both single and multiple incident sources and proposes a geometry which is cost effective and efficient for 3, 4, and 5 antenna array elements. This research also considers the shape of the ground plane and its effects on the angle of arrival estimation and in addition it shows how the mutual couplings between the elements effect the overall estimation and how this error can be minimised by using a decoupling matrix. At the end, a novel miniaturised multi element reconfigurable antenna to represent the receiver base station is designed and tested. The antenna radiation patterns in the azimuth angle are almost omni-directional with linear polarisation. The antenna geometry is uniplanar printed logspiral with striplines feeding network and biased components to improve the impedance bandwidth. The antenna provides the benefit of small size, and re-configurability and is very well suited for the asset tracking applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Ali, Ammar H. A. "Design and Implementation of Radio Frequency Power Feeding Networks for Antenna Array Applications: Simulation and Measurements of Multiport, Equal and Unequal, Fixed and Reconfigurable Radio Frequency Power Feeding Networks for Narrow and Ultra-Wideband Applications". Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17447.

Texto completo

Resumen

Power dividers are vital components and widely used in radio technology, such as antenna arrays, power amplifiers, multiplexers and mixers. A good example is the well-known Wilkinson power divider with its distinctive feeding network characteristics. A comprehensive review indicated that limited research is carried out in the area of planar multiport and reconfigurable power dividers in terms of the power levels between output ports. The main objectives of this work were to develop a small size power divider, a planer multi-output ports power divider and a power divider with a reconfigurable power division ratio. These power dividers were designed to operate over either an ultra-wideband frequency (3.1-10.6 GHz) or WLAN bands (2.4 or 5.2 GHz). A novel multi-layered topology solved the complexity of interconnecting isolation resistors by introducing an additional layer below the ground layer. The prototype was fabricated and tested to validate the results. The measurements and simulation were in good agreement. Finally, a novel uniplanar power divider with reconfigurable output power level difference was developed. The configurability feature was achieved by tuning the quarter wave transformer using one varactor diode. The power divider was applied to improve a full duplex system cancellation performance at the receiver element caused by interference from in-site transmitting antennas. This study investigated fixed power dividers, multi-output power dividers and reconfigurable power dividers. The measurements validated by the simulation results and applications proved the designed power dividers could be used in practical applications.
Higher Committee for Education Development (HCED), Iraq

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Chen, Tseng-Yuan y 陳贈元. "Frequency-Reconfigurable Microstrip Patch Antennas Using Ferroelectric Varactors". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/78521734492517559596.

Texto completo

Resumen

碩士
國立中央大學
電機工程學系
105
The operating frequency of an antenna can be made reconfigurable by incorporating tuning elements. In this thesis, microstrip patch antennas are loaded with variable capacitors (varactors) to acquire frequency tunability. We design and fabricate two kinds of frequency-reconfigurable microstrip patch antennas, both of which use ferroelectric varactors with barium strontium titinate (BSTO) as the dielectric material for the capacitive loading. One of the microstrip patch antennas uses benzocyclobutene (BCB) as its dielectric whereas the other patch antenna uses high-resistivity silicon substrate. The operating frequency of the frequency-reconfigurable patch antenna with BCB as its dielectric is set at around 15 GHz. The ferroelectric capacitors and the patch are connected using the BCB stacked via process developed by our lab. Measurement results show that, when the bias voltage of the varactor is tuned from 0 V to 25 V, the operating frequency of the antenna varies from 13.8 GHz to 14.3 GHz, which translates into a 3.5% frequency tuning range (FTR). The operating frequency of the microstrip patch antenna with high-resistivity silicon as its dielectric is also designed to be around 15 GHz. The ferroelectric varactors are connected to the ground plane on the backside of the silicon substrate by through substrate vias (TSVs). Measurement results of this antenna show that the operating frequency is fixed at 9.7 GHz. No frequency tunability is observed. We find that the reason why the antenna is not tunable is because the annealing temperature for the BSTO thin film is too low for this sample. As for the large frequency shift, it is due to a mistake in layout. The layout mistake results in an unexpected silicon-nitride capacitor with a large capacitance, which becomes part of the capacitive loading. In this thesis, we successfully realize a frequency-reconfigurable microstrip patch antenna with BCB as its dielectric and with ferroelectric varactors as its capacitive loading. On the other hand, we successfully fabricate a capacitively loaded microstrip patch antenna using the TSV process we develop. Though the measured operating frequency has deviated from the designed value and cannot be tuned, we have discovered the reasons that result in these problems. We believe that the expected performance can be obtained after these issues are resolved.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Jhao, Sheng-Ci y 趙聖齊. "Reconfigurable Frequency Band MIMO Antennas Designed for LTE". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/44975667793739588493.

Texto completo

Resumen

碩士
龍華科技大學
電子工程系碩士班
104
In this thesis, the reconfigurable frequencies of MIMO antennas are proposed for long-term evolution LTE band; MIMO antennas consist of two meander-line monopole antennas and the decoupling devices at 0.9 GHz. The design antenna size is 100 x 69 mm2.proposed MIMO antennas were designed double sides printed circuit board (PCB) FR4 substrate with permittivity εr=4.4, loss tangent tanδ=0.0245, and thickness h=0.8 mm. The decoupling devices are connected with the MIMO antennas, eliminating the coupling effects to achieve a good isolation conditions. The isolation is greater than -21dB for LTE Band 19 (832.4MHz ~ 842.6MHz)and -23dB for LTE Band 28(703MHz ~ 748MHz).The results for S-parameter (S11, S21, and S22), far-field H- and E-plane radiation patterns of the proposed antennas are presented and discussed. The measured results show a good agreement with the simulated results.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Tsai, Jia-Fu y 蔡佳甫. "Designs of Frequency Reconfigurable Antennas with Omnidirectional Radiation". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/80817366916600586807.

Texto completo

Resumen

碩士
國立彰化師範大學
電機工程學系
99
A study for frequency reconfigurable antennas is presented in the thesis, and two different designs with a wide tuning range as well as an omnidirectional radiation pattern are proposed. The first design is based on a center-fed circular microstrip antenna operating at its TM0n mode. By adding a tunable capacitor into the input port of the antenna, the capacitance cancels out the inductive reactance of the antenna at a specified frequency, and thus the antenna resonant frequency can be changed. Then, the remaining resonant resistance can be matched to 50 Ω with a traditional impedance transformer. From the measured results, the antenna operating frequency is ranged between 4.97 GHz and 6.17 GHz (21.3 %) while the capacitors with various capacitances are used; moreover, symmetrical conical radiation patterns are observed across the available operating bandwidth. The other design is using the structure composed of a top-loaded monopole and a parasitic shorted square-ring patch which is introduced to enhance the resonant resistance. Like the first design, the resonant frequency of the antenna is switched with a tunable capacitor. To achieve a more broadband impedance match, a microstrip exponential tapered line is adopted. According the experimental results, the design can provide a frequency tunable range of 52.6 % as the capacitance is ranged between 0.5 pF and 20 pF; in addition, stable omnidirectional patterns are obtained within the tunable range. The designs integrating a varactor diode are also successfully implemented. Details of the experimental data are given along with the simulated results carried out with HFSS (High Frequency Structure Simulator).

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Yeh, Che-ting y 葉哲廷. "Frequency-Reconfigurable Antennas Using Ferroelectric Varactors and PIN Diodes". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/82187010793721711517.

Texto completo

Resumen

碩士
國立中央大學
電機工程學系
104
In this thesis, by loading the antennas with either tuning elements or switches, the operating frequency is made reconfigurable. Two antennas are presented: a frequency-reconfigurable slot-loop antenna with ferroelectric varactors and a switchable patch antenna for 2.45-GHz and 5.8-GHz ISM bands. First, a frequency-reconfigurable slot-loop antenna with a tunable matching network is designed, fabricated, and measured. The frequency-reconfigurable antenna is implemented by loading ferroelectric varactors along a slot loop. CPW (coplanar waveguide) feed is used to preserve the advantage of being uniplanar. However, it is usually difficult to provide a good matching over wide frequency by a direct CPW feed. To solve this problem, a tunable matching network is added. The tunable matching network is implemented using a varactor in series, which does not increase the area of the antenna. Measurement results show that, when the bias voltage of the ferroelectric varactors is increased from 0 V to 15 V, the operating frequency of the antenna can be tuned from 6.71 GHz to 9.14 GHz, equivalent to a 30.6% bandwidth. When biased at 15 V, the antenna gain is −3.1 dBi. Over the entire frequency tuning range, the return loss is greater than 20 dB, validating the effectiveness of the tunable matching network. Second, a patch antenna that can be switched between 2.45-GHz ad 5.8-GHz ISM bands is designed, fabricated, and measured. The antenna is designed by connecting two patches with five equally spaced PIN diodes, which act as switches. When the switches are off, only one patch is connected to the feed and the operating frequency is designed to be 5.8 GHz. On the other hand, when the switches are turned on, the two patches are electrically connected, resulting in an increase in electrical length and lowering the operating frequency to 2.45 GHz. The switchable patch antenna is fed using a coaxial probe feed. The position of the feed is adjusted so that good matching is observed for both frequencies. Measurement results show that, when the bias voltage of the PIN diodes is −10 V, i.e., when operated in the off state, the resonant frequency of the patch antenna is 5.75 GHz and its gain is 6 dBi. On the other hand, when the overall bias current is 250 mA, when operated in the on state, the resonant frequency of the patch antenna is 2.53 GHz with a gain of −0.8 dBi. At both frequency bands, the return loss is greater than 15 dB. In this thesis, two frequency-reconfigurable antennas using either ferroelectric varactors or PIN diodes are successfully designed and implemented. The tunable slot-loop antenna achieves the widest effective bandwidth when compared with other ferroelectric-based tunable antennas in the literature.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Ko, Chih-Hsiang y 柯智祥. "Novel Dual-Band Pattern Reconfigurable Reflector Antennas Using Switching Frequency Selective Surfaces". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/23325456335805321137.

Texto completo

Resumen

碩士
國立交通大學
電信工程系所
97
With the development of the wireless communication, more and more devices share the limited bandwidth for communication. Therefore, how to reduce the interference from other devices and environment and use the limited bandwidth efficiently is one of the important subjects. A smart antenna which can change radiation patterns and focus the patterns is a good candidate to solve those problems. In this thesis, a novel dual-band smart antenna is developed. By the switching frequency selective surface, the principle of a right angle corner reflector antenna, and the operation of switches, three dual-band pattern reconfigurable antennas are investigated. The operating frequencies in our design are 2.45 GHz and 5.25 GHz. Through combinations of switches on reflecting walls, multiple radiation patterns can be obtained. Each reflecting wall of the first proposed pattern reconfigurable antenna operates only at one frequency; therefore, Two-layer reflecting walls are needed here. However, the volume of the completed antenna is about one-wavelength of 2.45 GHz square due to the principle of the corner reflector antenna. In the second proposed antenna, a reflecting wall can operate at two frequencies. As a result, the size of the antenna can be reduced, and the amount of switches can be decreased too. Finally, a dual-band pattern reconfigurable antenna with a simpler structure such as a rectangular loop is developed without the damages to the original properties belonging to the second antenna. Since omni-directional and directional patterns are the most important in application, we mostly focus on those two patterns in our design.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Wang, You-Jiun y 王宥竣. "A Study of Frequency Reconfigurable Active Integrated Antennas Using Metamaterial Combination with Switching Diode". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dccg2m.

Texto completo

Resumen

碩士
國立臺灣科技大學
電機工程系
106
This study focuses on designing two types of frequency reconfigurable active integrated antenna. This novel idea is based on using switching pin diode with metamaterial in order to realize frequency reconfigurable metamaterial resonator. Two metamaterials are successfully integrated on single antenna structure. By only adjusting the voltage of pin diode to control left-handed shunt inductor and keep the bias voltage of transistor as the same, the active antenna can operate between negative μ resonator (MNG) mode and composite right/left handed (CRLH) mode. Firstly, frequency reconfigurable active integrated antenna is proposed. This novel layout is based on the feedback oscillator network using frequency reconfigurable metamaterial resonator integrated with single transistor. By controlling the switching diode, the oscillation steadily appears at two distinct frequencies corresponding to +1 mode of MNG resonator and CRLH resonator. Secondly, with the characteristic of metamaterial that the size and operating frequency are not unrelated, frequency reconfigurable metamaterial resonator in cross couple pair oscillator is studied. As long as adjusting the voltage to control the status of pin diode in order to achieve the condition of zeroth-order oscillator, the active antenna can operate at two distinct frequencies corresponding to the +1 mode of MNG resonator and zeroth-order mode of CRLH resonator. In the second study, the other frequency reconfigurable active integrated antenna is successfully realized.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Wu, Cheng-Hsun y 吳政勳. "A Study of Quasi-Isotropic and Reconfigurable Self-Oscillating Active Integrated Antennas with Frequency and Pattern Agility". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/64263559275183787629.

Texto completo

Resumen

博士
國立臺灣科技大學
電機工程系
103
Using a new simulation scheme for fully integrated active antennas, in this dissertation, innovative self-oscillating active integrated antennas (AIAs) with a variety of distinct radiation characteristics are proposed and demonstrated for wireless power transmission and radio frequency identification (RFID) applications. The new simulation scheme relies on alternative uses of the full-wave simulator HFSS and circuit emulator ADS, and is capable of accurately predicting the radiation characteristics and oscillation behaviors of a fully integrated self-oscillating AIA even if its size is electrically small compared to the wavelength. The simulation method is verified using a dual-ring AIA whose size and radiation characteristics are comparable to those of a traditional rectangular patch. By placing a loop radiator over a truncated ground plane, a miniaturized self-oscillating AIA with quasi-isotropic radiation is then proposed. The AIA directly integrates a loop radiator and an unstable transistor. As the radiator is partially shielded by the ground plane, equivalent electric and magnetic dipole moments are generated simultaneously, therefore giving rise to nearly uniform radiation in terms of the total electric field. Benefitting from slow-wave loadings connected to the loop radiator, the proposed AIA shows the smallest footprint among the state-of-the-art designs in open literature, but still features acceptable effective isotropic radiated power (EIRP). Thirdly, a compact frequency-agile self-oscillating semi-ring AIA is presented and investigated. The AIA can be operated at two distinct oscillation states by utilizing a PIN diode and a varactor diode. For each state, the oscillation frequency can be controlled by the reverse bias of the varactor to satisfy the spectrum regulation in real deployment scenarios. A pattern-reconfigurable self-oscillating AIA with frequency agility is proposed. By embedding two PIN diodes into the radiator, the antenna can be switched in four states, each associated with a unique radiation pattern and polarization. Additionally, for each state the oscillation frequency can be controlled by means of a varactor diode within a reasonable range. This design could be a pioneering work which combines two reconfigurable techniques into a single AIA. Finally, experiments are performed for the sake of exploring the potential applications of AIAs to wireless charging and multi-carrier RFID systems. The dual-ring AIA is used to verify the concept of wireless charging. A newly developed metamaterial AIA is then applied to demonstrate the applicability of self-oscillating AIAs for extending the coverage of a commercial interrogator.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Hung, Sheng-Chao y 洪聖超. "Frequency Reconfigurable Antennas Using a PIN Diode Switch for Penta-Band and Hepta-Band For Mobile Phones". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/54757864678305284654.

Texto completo

Resumen

碩士
國立交通大學
電信工程研究所
98
In this thesis, a frequency reconfigurable antenna design for WWAN-band and LTE-band mobile phones is developed. This structure utilizes a loop antenna and the switching circuit of PIN diode. Through the operation of switch, three different loop lengths are switched so that the lower band is reconfigurable, and the higher band maintains its performance. As a result, this antenna can achieve much more bands. In this concept, we design two frequency reconfigurable antennas for penta-band mobile phones and a frequency reconfigurable antenna for seven-band mobile phones. The first proposed antenna has the capability of switching the lower band between the GSM850 and GSM900 frequency ranges with only a minor impact on the upper band. The upper band covers the frequency ranges of the GSM1800, DCS1900 and UMTS2100 communication standards. With the need of market, a complete ground is needed under the antenna to provide more area to lay out circuits. The second proposed antenna with the complete ground also has the capability of switching the lower band between the GSM850 and GSM900 frequency ranges and the upper band maintains GSM1800/GSM1900/UMTS2100. As mentioned above, we achieve two frequency reconfigurable antennas for penta-band mobile phones . With the development of LTE, The third proposed antenna has the capability of switching the lower band between the LTE700/GSM850 and GSM850/GSM900 frequency ranges. The upper band covers the frequency ranges of the GSM1800, DCS1900, UMTS2100 and WLAN2.4G. Consequently, we achieve a frequency reconfigurable antenna for seven-band mobile phones.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Hussaini, Abubakar S., Yasir I. Abdulraheem, Konstantinos N. Voudouris, Buhari A. Mohammed, Raed A. Abd-Alhameed, Husham J. Mohammed, Issa T. Elfergani et al. "Green flexible RF for 5G". 2015. http://hdl.handle.net/10454/9163.

Texto completo

Resumen

No
5th Generation mobile networks (5G) and mobile communications technologies beyond 2020 will need to be energy aware so as to support services that are likely to be intelligent and bandwidth hungry, as well as to support multi-mode operation (LTE, LTE+, HSDPA, 3G among others) in a HetNet environment. This imposes stringent design requirements on the RF transceiver, a key consumer of power in networks today. This chapter will investigate the key RF subsystems forming part of the 5G RF transceiver, where energy efficiency and full radio flexibility are at the forefront of system design. In particular, we target advanced designs on antenna systems, RF power amplifiers and the challenges facing cross-talk in MIMO architectures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Chen, Keng-Hsien y 陳耿賢. "Multiple Polarization and Multiple Frequency Reconfigurable Antenna". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/33716507740250385936.

Texto completo

Resumen

碩士
國立交通大學
電信工程研究所
98
A novel multiple-ear patch antenna for polarization and frequency diversities is proposed. The proposed antenna uses the PIN diodes and adjacent ears, which are small adjacent patches, to achieve the diversities purposes. By connecting or disconnecting the ears and main patch, both of the resonant frequency and transverse magnetic (TM) of proposed antenna are changed to achieve the diversities. The proposed antenna has a compact size and simple structure, which comprises of a main patch antenna, four adjacent patches and four PIN diodes. With suitable arrangement of the bias network, the proposed antenna demonstrates either switching frequency in 3.2, 3.35 or 3.6GHz with the linear polarization (LP); or switching polarization in linear, right hand circular or left hand circular polarization (RHCP/ LHCP) in the same frequency. The simulated and measured results reveal good impedance bandwidth, axial ratio, and radiation patterns; hence the proposed reconfigurable mechanism is well suited for wireless communication applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Hsieh, Tsung-Hsun y 謝宗勳. "Frequency Reconfigurable Circularly-Polarized Slot Antenna Design". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/78966112774513460804.

Texto completo

Resumen

碩士
國立彰化師範大學
電機工程學系
97
Reconfigurable designs for a circularly-polarized ring-slot antenna with switchable frequency are presented in the thesis. The contents of the thesis are mainly divided into three topics. In Chapter I, a compact design method for the circularly-polarized ring-slot antenna is first proposed and investigated. By using an L-shape microstrip feed line, an annular-ring slot antenna can generate circular polarization radiation. To compact the antenna size, four parasitic strips are placed symmetrically beneath the annular-ring slot. Because the addition of the parasitic strip can increase the effective permittivity in the slot, the resonant frequency of the ring-slot antenna is thus decreased. The effects of varying the dimensions of the parasitic strips on antenna performances are also studied in detail. The obtained results show that a reduction of more than 50 % on antenna size can be reached. In Chapter II, a design of frequency reconfigurable slot antennas for the applications of the dual-band global position system is proposed. According to the results given in Chapter I, the required dimensions of the parasitic strips which correspond to L1 and L2 frequency bands are first determined. Then, by embedding PIN diodes into the parasitic strips and L-shaped coupling strip, their electrical dimensions can be varied by DC bias. As a result, the resonant frequency of the ring-slot antenna can be electrically switched between L1 and L2 frequency bands. In Chapter III, a circularly-polarized ring-slot antenna with frequent agility is presented. It is first proved that the resonant frequency of the ring-slot antenna can also be decreased by using a chip capacitor instead of the parasitic strip, and the more the capacitor value, the lower the resonant frequency. Several antenna prototypes with various chip-capacitor values are implemented to investigate their effects on the antenna performances. For obtaining a tunable capacitor value, a varactor diode is used to replace the chip capacitor, and the operating frequency of the circularly-polarized ring-slot antenna can be adjusting via DC bias. Moreover, a metal plane is added below the slot antenna as a reflector to increase the antenna gain and reduce back radiation. From the obtained results, it is found that the frequency reconfigurable reflector-backed slot antenna has a tuning circularly-polarized frequency rang of about 180 MHz, which is four times that of its counterpart without using varctors.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Ojaroudi, Parchin Naser, Yasir Al-Yasir, Ahmed M. Abdulkhaleq, Issa T. Elfergani, A. Rayit, James M. Noras, Jonathan Rodriguez y Raed A. Abd-Alhameed. "Frequency Reconfigurable Antenna Array for MM-Wave 5G Mobile Handsets". 2018. http://hdl.handle.net/10454/16680.

Texto completo

Resumen

Yes
This study proposes a compact design of frequency-reconfigurable antenna array for fifth generation (5G) cellular networks. Eight compact discrete- fed slot antennas are placed on the top portion of a mobile phone printedcircuit- board (PCB) to form a beam-steerable array. The frequency response of the antenna can be reconfigured to operate at either 28 GHz or 38 GHz, two of the candidate frequency bands for millimeter-wave (MM-Wave) 5G communications. The reconfigurability function of the proposed design can be achieved by implementing and biasing a pair of diodes across each T-shaped slot antenna element. Rogers RT 5880 with thickness of 0.508 mm and properties of ε = 2.2 and δ = 0.0009 has been used as the antenna substrate. The antenna element is very compact in size with a good end-fire radiation pattern in the frequency bands of interest. The proposed beam-steerable array provides very good 3D coverage. The simulation results show that the proposed design provides some good characteristics fitting the need of the 5G cellular communications.
Innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424, UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

TUAN, WEI-YING y 段蔚瑩. "Reconfigurable Antenna with Multi-polarization and Continuous Frequency Band". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/xqx99s.

Texto completo

Resumen

碩士
國立臺北科技大學
電子工程系研究所
105
This thesis presents a reconfigurable antenna based on a circular patch antenna with diode switches. By turning on or off the diode switches, the polarization of the antenna can be changed, such that a single antenna can receive incoming signals of different polarizations. The change of diode switch states can also change operating frequencies. We hope that these operating frequencies can cover from 700 MHz to 3 GHz, satisfying major mobile communication frequency bands and providing future expanse of more frequency bands. The structure of the antenna is based on a circular patch antenna with a ring slot on it. On the ring slot, a total of 24 diodes are placed at an equal interval of 15°. A 0.2-mm wide slit is added on the circular patch from the ring slot to the outer edge at a 15° interval, so that the circular patch is equally divided into 24 blocks. By using circuit theory, a Matlab program is employed to simulate all combination of diode states to find the highest return loss value at each frequency and the corresponding diode configuration. Finally, even though the proposed antenna does not meet the bandwidth goal, it still satisfies part of the bandwidth.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Lin, Fong-Yi y 林鳳儀. "Study of Frequency Reconfigurable Antenna on VHF Two Ways Radio". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/38267374607960836191.

Texto completo

Resumen

碩士
亞東技術學院
資訊與通訊工程研究所
101
The two way radio usually used the helix antenna, has narrow band characteristic and it can't cover the The two way radio band 132MHz to 174MHz. The SDR system can tunable antenna working frequency, but In addition to the impedance of the resonant frequency, the other bands doesn't have impedance matching, and the efficiency will be down, and influence intercom the channel quality. So that the two way radio need a single tunable antenna and that can operate in various frequency bands. This paper is study of used the microstrip antenna to design high efficiency meander line monopole antenna, it's using the microstrip line of characteristic can equivalent the LC circuit to matching Impedance, and upgrade the antenna efficiency, and last is using PIN diode switch to change the antenna resonant structure, and thus make the antennas has the frequency reconfigurable operated for three-band.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Huang, Chia-Ping y 黃嘉平. "Frequency Reconfigurable Antenna for Two Ways Radio at VHF Band". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/22106444416992829570.

Texto completo

Resumen

碩士
亞東技術學院
資訊與通訊工程研究所
103
Two ways radio is often used traditional helical antenna on market, but the weakness is narrow band that can’t cover very high frequency (VHF). In order to achieve frequency switching, it has to change the antenna for each band. Frequency Reconfigurable Antenna can switch frequency by use single-antenna. This paper continues study with “Study of Frequency Reconfigurable Antenna on VHF Two Ways Radio” by Fong-Yi Lin. In “Study of Frequency Reconfigurable Antenna on VHF Two Ways Radio”, Author use FR4 (0.8mm) for material to design meander line antenna, and use FR4 (0.4mm) for material to design voltage control. The purpose is change electric current to resonant frequency. The structure is complex, the production is more difficult and antenna characteristic is poor. This paper purpose is structure simplify and switching frequency by change electric current. It uses P-intrinsic-N Diode for electronic switch. That is open circuit when voltage is 0V. That is short circuit when voltage is 0.7V. It controls inductance to achieve needs frequency for very high frequency. This paper use Advanced Design System (ADS) and GEMS to verify electric circuit and impedance. Last, verifying it in 7 x 4 x 3 anechoic chamber. In this paper, the measurement for low band bandwidth is 131MHz to 145MHz and gain is -12dBi; The measurement for mid band bandwidth is 145MHz to 161MHz and gain is -10dBi; The measurement for high band bandwidth is 158MHz to 175MHz and gain is -9dBi, The bandwidth is conform 132MHz to 174MHz for very high frequency. Finally, this paper wills its simulation and experimental results to collate and make conclusions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Sun, Chia-Shan y 孫嘉杉. "A 2.45GHz Miniaturized Smart MIMO Antenna Using Reconfigurable Frequency Selective Reflectors". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/97e96v.

Texto completo

Resumen

碩士
國立交通大學
電信工程研究所
105
In this thesis, a miniaturized smart MIMO antenna using reconfigurable frequency selective reflectors is proposed. This antenna can be applied to Wireless Access Point. The operating frequency is 2.4GHz to 2.5GHz in Wi-Fi band and the radiation efficiency is 40% ~ 70%. The size of substrate is 120mm x 120mm x 0.8mm, and the actual antenna size is 120mm x 120mm x 12.3mm, compared to the center frequency of 2.45GHz, is 0.98λx 0.98λx 0.1λ. The combination of the reconfigurable frequency selective reflector’s characteristics between reflection and radiation is designed to reduce the occupied area of the smart antenna unit and the performance of smart antenna unit is not affected by each other. In addition, this antenna can display different radiation patterns by using one to multipath switching feeding network to change each reconfigurable frequency selective reflector’s characteristic, and offer the best signal strength according to the position of the user in different directions. In this thesis, the design of the MIMO antenna structure is also proposed. The smart MIMO antenna can judge the best switching combination of the reconfigurable frequency selective reflectors with algorithm in communication, if the antenna is installed at indoor environment existing big obstacles like pillars, furniture, etc. With this advantage, the smart MIMO antenna has higher abilities about adaptability and flexibility.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Abdulraheem, Yasir I., George A. Oguntala, Abdulkareem S. Abdullah, Husham J. Mohammed, R. A. Ali, Raed A. Abd-Alhameed y James M. Noras. "Design of Frequency Reconfigurable Multiband Compact Antenna using two PIN diodes for WLAN/WiMAX Applications". 2017. http://hdl.handle.net/10454/11484.

Texto completo

Resumen

Yes
In this paper, we present a simple reconfigurable multiband antenna with two PIN diode switches for WiMAX/WLAN applications. The antenna permits reconfigurable switching in up to ten frequency bands between 2.2 GHz and 6 GHz, with relative impedance bandwidths of around 2.5% and 8%. The proposed antenna has been simulated using CST microwave studio software and fabricated on an FR-4 substrate. It is compact, with an area of 50 × 45 mm2, and has a slotted ground substrate. Both measured and simulated return loss characteristics of the optimized antenna show that it satisfies the requirement of 2.4/5.8 GHz WLAN and 3.5 GHz WiMAX antenna applications. Moreover, there is good agreement between the measured and simulated result in terms of radiation pattern and gain.
Engineering and Physical Science Research Council through Grant EP/E022936A.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Wang, Ping-Yuan y 王品淵. "Reconfigurable Antenna with Continuous Frequency Bands and Multi-polarization Optimized by Genetic Algorithm". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/68333k.

Texto completo

Resumen

碩士
國立臺北科技大學
電子工程系
107
This thesis presents a reconfigurable antenna based on a circular patch antenna with a ring slot on which a total of 16 diodes are placed at an equal interval of 22.5°. By manipulating the on-off states of the diodes, the antenna can operate at different frequencies and receive incoming signals at different polarizations. The design process features the use of genetic algorithm to find the appropriate antenna geometrical parameters and Matlab program to find the suitable diode states at each frequency. Our goal is to cover all frequencies from 0.7 - 3 GHz with return loss greater than 6 dB and radiation efficiency greater than 40 %. Although the measured return loss of the realized antenna does not meet the target, still 79 % of the frequencies satisfy the 6 dB return loss criteria.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Luo, Jun-Yan y 羅俊彥. "Design of Dual-Band Frequency Reconfigurable Antenna for GPS and S Band Radar Applications". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/28409184437663282158.

Texto completo

Resumen

碩士
國立中央大學
電機工程學系
105
In the thesis, designs of a dual-band frequency reconfigurable antenna which covers the GPS band (1.227 GHz ~ 1.575 GHz) for Global Positioning System applications and the S band (2.45 GHz) for radar system applications are presented. Striplines are mainly used in the antenna structure as radiators. Inductive feed is used with the capacitor elements to generate resonant modes. By changing the value of the capacitor, the antenna center frequency can be adjusted, and the antenna size can be reduced. We first design the single-frequency antenna structure. We then use the same resonance mechanism to develop dual-frequency and multi-frequency antennas. The similar frequencies of the two resonant modes are combined into a broadband response by an appropriate design. The S-band (2.45 GHz) bandwidth is increased from 120 MHz to 205 MHz. We later replace the capacitor with a variable capacitor, and apply the bias circuit to give the DC voltage as the tunable structure. The dual-band frequency reconfigurable antenna can be switched between the GPS L1, L2 and L3 bands (1.227 GHz, 1.381 GHz and 1.575 GHz). In the case, the performance of the S band (2.45 GHz) is not affected. Finally, through the implementation and measurement the proposed designs are all validated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Tsai, Chia-Heng y 蔡佳衡. "Frequency Reconfigurable MIMO Antenna with Wideband Sensing Capability and High Isolation for Cognitive Radio Applications". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/74136266858845501011.

Texto completo

Resumen

碩士
國立中山大學
電機工程學系研究所
104
In recent years, the development of wireless communication system has grown rapidly, efficient utilization of the available spectrum has become a more important feature for broadband communication system. Therefore, the cognitive radio (CR) concept has been proposed. A CR technology can provide better spectrum utilization by sensing the occupied frequency band and switching to another frequency. With the trend toward higher data rate, MIMO (Multi-Input Multi-Output) technology plays an essential role for the future wireless communication. Thus, the concept of CR system combination with MIMO technology is a potential solution. 　　In this thesis, a frequency reconfigurable MIMO antenna with high isolation is proposed for CR applications. This structure is composed of two planar reconfigurable monopole antennas and a wideband sensing antenna on the single substrate. For MIMO antenna system, mutual coupling is a considerable problem. The wideband sensing antenna at the center of the substrate is used to enhance the isolation between two reconfigurable antennas. The dual-element MIMO antenna can cover a wide range frequency band from 2.18~6.19 GHz by tuning varactor diodes. The frequency reconfigurable ratio that can be achieved is 2.85. The wideband sensing antenna is capable of sweeping the frequency band over 2.17~6.15 GHz. The proposed antenna structure can be applied to cognitive radio system applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Frequency Reconfigurable Antennas"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros