Dissertations / Theses on the topic 'Planar antenna'

Made available in DSpace on 2015-03-03T15:07:32Z (GMT). No. of bitstreams: 1 AdaildoGDAJ_DISSERT.pdf: 911535 bytes, checksum: 85d35a0c8d60343a1313312b827ff4af (MD5) Previous issue date: 2007-02-22<br>Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico<br>The great interest observed in wireless communication systems has required the development of new configurations of microstrip antennas, because they are easily built and integrated to other microwave circuit components, which is suitable for the construction and development of planar antenna arrays and microwave integrated circuits. This work presents a new configuration of tapered microstrip antenna, which is obtained by impressing U-slots on the conducting patch combined with a transmission line matching circuit that uses an inset length. It is shown that the use of U-slots in the microstrip antenna conducting patch excites new resonating modes, that gives a multiband characteristic for the slotted microstrip antenna, that is suitable for applications in communication systems that operates several frequencies simultaneously. Up to this date, the works reported in the literature deals with the use of Uslotted microstrip rectangular antennas fed by a coaxial probe. The properties of a linear array of microstrip patch tapered antennas are also investigated. The main parameters of the U slotted tapered microstrip antennas are investigated for different sizes and locations of the slots impressed on the conducting patch. The analysis of the proposed antenna is performed by using the resonant cavity and equivalent transmission line methods, in combination with a parametric study, that is conducted by the use of the Ansoft Designer, a commercial computer aided microwave software well known by its accuracy and efficiency. The mentioned methods are used to evaluate the effect in the antennas parameters, like resonant frequency and return loss, produced by variations of the antenna structural parameters, accomplished separately or simultaneously. An experimental investigation is also developed, that consists of the design, construction and measurement of several U slotted microstrip antenna prototypes. Finally, theoretical and simulated results are presented that are in agreement with the measured ones. These results are related to the resonating modes identification and to the determination of the main characteristics of the investigated antennas, such as resonant frequency, return loss, and radiation pattern<br>A demanda por novos sistemas de comunica??es sem fio (wireless communication systems) tem requerido o desenvolvimento de novas configura??es de antenas de microfita, pois estas antenas apresentam uma grande facilidade de integra??o com outros componentes de circuito que facilitam a constru??o de arranjos planares e de circuitos integrados em freq??ncias de microondas. Neste trabalho ? analisada uma nova configura??o de antena de microfita afilada, na qual s?o introduzidas fendas em U (U-slots), no patch condutor, al?m de uma reentr?ncia (inset), atrav?s de uma se??o de linha de microfita, para fins de casamento da imped?ncia de entrada. A introdu??o de uma ou v?rias fendas no patch condutor da antena de microfita excita novos modos de resson?ncia, dando ? estrutura fendida uma caracter?stica de opera??o em multibanda, que possibilita a sua utiliza??o em sistemas com freq??ncias de opera??es distintas. Os trabalhos publicados com a impress?o de fendas em U dizem respeito ? utiliza??o de patches retangulares de microfita alimentados por cabo coaxial. Tamb?m ? investigada a associa??o de antenas afiladas na composi??o de arranjos lineares. S?o examinados e discutidos diversos aspectos relacionados com as dimens?es dessa fenda e o seu posicionamento no patch da antena considerada em termos do efeito produzido nas suas principais caracter?sticas de radia??o. A an?lise da antena proposta ? efetuada atrav?s dos m?todos da cavidade ressonante e da linha de transmiss?o modificados, em combina??o com um estudo param?trico, que ? realizado atrav?s do software comercial Ansoft Designer. Estes m?todos s?o empregados para avaliar as modifica??es produzidas nas caracter?sticas eletromagn?ticas, como a freq??ncia de resson?ncia e a perda de retorno, da antena em resposta ?s varia??es introduzidas em alguns dos seus par?metros estruturais. Al?m da investiga??o te?rica, ? inclu?da uma parte experimental que consistiu no projeto, constru??o e medi??o de v?rios prot?tipos configura??o de antena considerada. Finalmente, s?o apresentados resultados te?ricos (m?todos aproximados) e simulados (Ansoft Designer), que apresentam boa concord?ncia com os das medi??es efetuadas. Estes resultados consistem principalmente na identifica??o dos modos de resson?ncia e na determina??o das caracter?sticas principais das antenas consideradas, como a freq??ncia de resson?ncia, a perda de retorno e o diagrama de radia??o

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.<br>The design of an electrically small planar antenna for compact circular polarization is presented. After an in-depth study of the performance limitations on electrically small antennas and an investigation into the working of various existing electrically small antennas, the design, simulation and measurement of the proposed antenna element is presented in detail.

Thesis (M.S. in Electrical and Computer Engineering)--Naval Postgraduate School, June 2009.<br>Thesis Advisor(s): Janaswamy, Ramakrishna. Second Reader: Neta, Beny. "June 1990." Description based on title screen as viewed on 19 October 2009. DTIC Identifier(s): Planar antennas, antenna arrays, millimeter waves, integrated circuits. Author(s) subject terms: Thesis, word processing, Script, GML, text processing. Includes bibliographical references (p. 124-125). Also available online.

Els serveis de telecomunicacions i sistemes radar estan migrant a freqüències mil•limètriques (MMW), on es disposa d 'una major amplada de banda i conseqüentment d'una major velocitat de transmissió de dades. Aquesta migració requereix de l'ús de diferents tecnologies amb capacitat d'operar a la banda de freqüències mil•limètriques (30 a 300 Ghz), i més concretament en les bandes Ka (26,5 - 40GHz), V (50 – 75GHz) i W (75 – 110GHz). En moltes aplicacions i sobretot en aquelles on l'antena forma part d'un dispositiu mòbil, es cerca poder utilitzar antenes planes, caracteritzades per tenir unes dimensions reduïdes i un baix cost de fabricació. El conjunt de requeriments es pot resumir en obtenir una antena amb capacitat de reconfigurabilitat i amb un baix nivell de pèrdues en cada una de les bandes de freqüència. Per tal d'afrontar aquests reptes, les dimensions de les antenes mil•limètriques, juntament amb els tipus de materials, toleràncies de fabricació i la capacitat de reconfigurabilitat ens porten a l'ús de processos de microfabricació. L'objectiu d'aquesta tesis doctoral és l'anàlisi dels conceptes mencionats, tipus de materials, geometries de línia de transmissió i interruptors, en el context de les freqüències mil•limètriques, així com la seva aplicació final en dissenys d'antenes compatibles amb els processos de microfabricació. Finalment, com a demostració s'han presentat dissenys específics utilitzables en tres aplicacions a freqüències mil•limètriques: Sistemes de Comunicació per Satèl•lit (SCS) a la banda Ka, Xarxes d'àrea personal inalàmbriques (WPAN) a la banda V i sistemes radar per l'automoció a la banda W. La primera part d'aquesta tesis consisteix en l'anàlisi d'algunes tecnologies circuitals a freqüències mil•limètriques. S'han presentat els materials més utilitzats a altes freqüències (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) i Low Temperature Co-fired Ceramic (LTCC)) i s'han comparat en termes de permitivitat i tangent de pèrdues. També s'inclou un estudi de pèrdues a altes freqüències en les principals línies de transmissió (microstrip, stripline i CPW). Finalment, es presenta un resum dels interruptors RF-MEMS i es comparen amb els PIN diodes i els FET. En la segona part, es presenten diferents agrupacions d'antenes amb la capacitat de reconfigurar la polarització i la direcció d'apuntament. S'han dissenyat dos elements base reconfigurables en polarització: CPW Patch antena i 4-Qdime antena. La primera antena consisteix en un element singular amb interruptors RF-MEMS, dissenyada per operar a les bandes Ka i V. La segona antena consisteix en una arquitectura composta on la reconfigurabilitat en polarització s'obté mitjançant variant la fase d'alimentació de cada un dels quatre elements lineals. La fase és controlada mitjançant interruptors RF-MEMS ubicats en la xarxa de distribució. L'antena 4-Qdime s'ha dissenyat per operar en les bandes V i W. Ambdós elements base s'han utilitzat posteriorment pel disseny de dues agrupacions d'antenes amb capacitat de reconfigurar l'apuntament del feix principal. La reconfigurabilitat es dur a terme utilitzant desfasadors de fase d'1 bit. La part final de la tesis es centra en les toleràncies de fabricació i en els processo de microfabricació d'agrupacions d'antenes mil•limètriques. Les toleràncies de fabricació s'han estudiat en funció dels error d'amplitud i fase en cada element de l'agrupació, fixant-se en les pèrdues de guany, error d'apuntament, error en l'amplada de feix, errors en el nivell de lòbul secundari i en l'error en la relació axial. El procés de microfabricació de les diferents antenes dissenyades es presenta en detall. Els dissenys de l'antena CPW Patch reconfigurable en polarització i apuntament operant a les bandes Ka i V, s'han fabricat en la sala blanca del Cornell NanoScale Science & Technology Facility (CNF). Posteriorment, s'han caracteritzat l'aïllament i el temps de resposta dels interruptors RF-MEMS, i finalment, el coeficient de reflexió, el diagrama de radiació i la relació axial s'han mesurat a les bandes Ka i V per les antenes configurades en polarització lineal (LP) i circular (CP).<br>Telecommunication services and radar systems are migrating to Millimeter-wave (MMW) frequencies, where wider bandwidths are available. Such migration requires the use of different technologies with the capability to operate at the MMW frequency band (30 to 300GHz), and more specifically at Ka- (26.5 to 40GHz), V- (50 to 75GHz) and W-band (75 to 110GHz). For many applications and more concretely those where the antenna is part of a mobile device, it is targeted the use of planar antennas for their low profile and low fabrication cost. A wide variety of requirements is translated into a reconfiguration capability and low losses within each application frequency bandwidth. To deal with the mentioned challenges, the MMW antenna dimensions, together with the materials, fabrication tolerances and reconfigurability capability lead to microfabrication processes. The aim of this thesis is the analysis of the mentioned concepts, materials, transmission lines geometries and switches in the MMW frequencies context and their final application in antenna designs compatible with microfabrication. Finally, specific designs are presented as a demonstration for three MMW applications: Satellite Communication Systems (SCS) at Ka-band, Wireless Personal Area Network (WPAN) at V-band and Automotive Radar at W-band. The first part of this thesis consist to analyze some MMW circuit technologies. The four most used materials at MMW frequencies (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) and Low Temperature Co-fired Ceramic (LTCC)) have been presented and compared in terms of permittivity (εr) and loss tangent (tanδ). An study of the main transmission lines attenuation (microstrip, stripline and CPW) at high frequencies is included. Finally, an overview of the RF-MEMS switches is presented in comparison with PIN diodes and FETS switches. The second part presents different polarization and beam pointing reconfigurable array antennas. Two polarization-reconfigurable base-elements have been designed: CPW Patch antenna and 4-Qdime antenna. The first consists of a single reconfigurable element with integrated RF-MEMS switches, designed to operate at Ka- and V-band. The second antenna presented in this thesis has a composed architecture where the polarization reconfigurability is obtained by switching the phase feeding for each of the four linear polarized elements in the feed network with RF-MEMS switches. The 4-Qdime antenna has been designed to operate at V- and W-band. The two base-elements have been used to design two beam pointing reconfigurable antenna arrays. Using phased array techniques, beamsteering is computed and implemented with 1-bit discrete phase-shifter. The final part of the thesis is focused into the fabrication tolerances and microfabrication process of Millimeter-wave antenna arrays. The fabrication tolerances have been studied as a function of the amplitude and phase errors presented at each elements array, focusing on the gain loss, beam pointing error, Half-Power Beamwidth (HPBW) error, sidelobe level error and axial ratio error. The microfabrication process for the designed antennas is presented in detail. Polarization- and pointing- reconfigurable CPW Patch antenna operating at Ka- and V- band have been fabricated in a clean-room facility at Cornell NanoScale Science & Technology Facility (CNF). The RF-MEMS switches isolation and time response have been characterized. Finally, the reflection coefficient, radiation pattern and axial ratio have been measured at Ka- and V-band for the fabricated antennas configured in Linear Polarization (LP) and Circular Polarization (CP).

Planar holographic antennas composed of printed dipole or conducting ring elements offer the promise of both low-profile and freedom from the losses associated with conventional printed beamforming networks at Ka-band frequencies and above. While some advances have been made, the aperture efficiencies achieved thus far have been unexpectedly low. These antennas are electrically quite large and materially inhomogeneous, which has prevented their rigorous analysis using computational electromagnetic (CEM). In this thesis we use CEM to study their operation, and point to several (and possibly unavoidable) reasons for the above-mentioned low aperture efficiency.

Neste trabalho é apresentado o projeto de uma antena planar de formato de F-invertido (PIFA) com ranhura-T para aplicação nos sistemas de comunicações sem fio GSM/UMTS/WCDMA. As larguras de banda da antena são aumentadas em função do aproveitamento dos modos ressonantes implícitos no plano de terra. Uma análise paramétrica é feita visando a obtenção de desempenho equilibrado na antena. As diversas simulações do desempenho da antena são realizadas com o software SEMCAD, que utiliza o método das diferenças finitas no domínio do tempo (FDTD). No trabalho é avaliada a diferença de desempenho da antena com e sem a presença do aparelho celular e também próximo à cabeça do usuário. Deste modo, é observada uma influência negativa sobre o desempenho da antena causada pela presença da cabeça do usuário. Adicionalmente, boa concordância é observada entre os dados do modelo simulado e os resultados medidos do protótipo.<br>This work presents the design and implementation of a planar inverted F-type antenna (PIFA) slot-T for wireless mobile communications GSM/UMTS/WCDMA. The excitation of the ground plane modes is used to increase the antenna bandwidth. A parametric analysis is done to obtain a balanced performance of the antenna. The several antenna performance simulations are performed with the SEMCAD software, which use the finite difference time domain (FDTD) method. In addition the differences in performance of the antenna are evaluated with and without the presence of the cell phone housing and the user's head, thus, negative influence on the antenna performance caused by the presence of the user's head is observed. Finally a prototype is implemented to get an idea of the real behavior of the proposed antenna. Good agreement is observed between data of the simulated model and measured results of the prototype.

碩士<br>國立臺北科技大學<br>電腦通訊與控制研究所<br>92<br>In this thesis, the design and measurement of novel antennas and broadband transition are separately proposed in three sections, including the impedance matching technique, the broadband antennas and, antenna application of metamaterial. The specific properties of the radiated structure composing metamaterial elements and series-fed printed-strip dipole pair is investigated. The composite circuits can support the beam-scanning characteristic. We proposed three broadband antennas, which are linearly tapered slot antenna, series-fed printed dipole array and ultra wide-band (UWB) planar tapered loop antenna. On the basis of careful design and optimization, these antennas feature a very broad bandwidth. The planar transition transforming from the unbalanced conductor-backed coplanar waveguide (CBCPW) to balanced coplanar stripline (CPS) is applicable to the 180° feed networks for balanced antenna applications. Compared to other traditional transitions, this configuration is compact in size and no need for vias. Therefore, the transition is suitable for various broadband antennas and mixers applications. These proposed antennas have the advantages of uniplanar configuration, allowing it to be readily integrated with other microwave devices. These structures are useful in practical broadband and compact applications.

No<br>A miniaturized modified planar inverted-F antenna (PIFA) is presented and experimentally studied. This antenna consists of a planar rectangular monopole top-loaded with a rectangular patch attached to two rectangular plates, one shorted to the ground and the other suspended, both placed at the optimum distance on each side of the planar monopole. The fabricated antenna prototype had a measured impedance bandwidth of 125%, covering 3 to 13GHz for reflection coefficient better than -10 dB. The radiator size was 20 x 10 x 7.5 mm(3), making it electrically small over most of the band and suitable for incorporation in mobile devices. The radiation patterns and gains of this antenna have been cross-validated numerically and experimentally and confirm that this antenna has adequate characteristics for short range ultra-wideband wireless applications.

碩士<br>義守大學<br>電子工程學系碩士班<br>94<br>Microstripe antennas have the advantage of lightweight, small size and low profile and had found wide application in various wireless communication areas in this two decades. Microstripe antennas can radiate in broadside and act in resonant mode; hence, they usually have limited impedance bandwith. Increasing the bandwith of microstrip antenna has been the major thrust of research in this field. In this paper, the radiation characteristics of the microstripe dual-band monopole antenna are investigated in detail and designed to operate on the transceiver of the Bluetooth, WLAN for the 2.45GHz and 5.2GHz ISM bands. Numerical results show that dual-band antenna has a good simulation performance is agree with the practical and is applicable for the wireless communication device.

碩士<br>元智大學<br>通訊工程學系<br>105<br>This thesis presents an design approach for planar multiband antennas. It is shown that the multiband operations can be attained by introducing band-notched structures in a broadband antenna. In this thesis, the triangular patch and slot are employed to synthesize notches in the wide operation band of a self-complementary bow-tie antenna. Also, the open stubs are adopted for impedance matching design. The approach is experimentally verified. The presented antenna has three operation bands: 0.7-0.96GHz (LTE700, LTE800, GSM850, GSM900), 1.7-2.7GHz (DCS1800, PCS1800, UMTS, LTE2300, LTE2500), and 3.4-3.8GHz (LTE3500, LTE3700). As for the radiation characteristics, the antenna has nearly omni-directional transmitting / receiving capability along with a high efficiency at all bands.

碩士<br>國立高雄應用科技大學<br>光電與通訊研究所<br>95<br>This thesis is based on planar antenna, apply the fractal to the antenna, utilize the characteristic of its size reduction and wideband to design different types of antenna and used in different band. Including a “Dual Band Wide-slot Antenna Fed by CPW, ” design with a wide-slot antenna with Hilbert Curve apply to IEEE 802.11 a/b/g, “UWB Monopole Antenna with Sierpinski Carpet, ” design a monopole antenna performance 2.26-11.23 GHz by a changing direction Sierpinski Carpet, and “Fractal Dipole Antenna for WiMAX Communication , ” design by a loop shape dipole antenna including Hilbert Curve to make it accord with the standard of international FWA(3.4-3.7 GHz). Observe each above-mentioned antenna, analysis and discuss the change under the different iteration about fractal.

碩士<br>大葉大學<br>電機工程研究所<br>90<br>In this thesis, an amplifier-type active microstrip antenna to be operated in the frequency range of 1.53GHz to 1.62GHz is proposed. This amplifier-type active microstrip antenna consists of an active element and a passive element. The active element is a power amplifier or a low noise amplifier and the passive element is a microstrip antenna. First, we design a low noise amplifier and a 3-dB, 90-degree coupler to construct a semi-balance type amplifier. Next, we design a circularly polarized rectangular microstrip antenna with dual feeds. Finally, we integrate the semi-balance type amplifier with the rectangular microstrip antenna. The fabricated amplifier-type active microstrip antenna exhibits an antenna gain of 10dBi to 14dBi and an axial-ratio lower than 2dB over the frequency range of interest, whose bandwidth is about 90MHz. Such performance is well suited to GPS related application.

碩士<br>大葉大學<br>電機工程學系<br>106<br>This paper is based on Multi-input Multi-output (MIMO). It utilizes the multiple transmit antennas and multiple antennas to improve the spectral efficiency of wireless communication systems by the spatial degree of freedom. This foundation designs a five-band MIMO antenna that covers a personal wireless communication system. The antenna generates low frequency frequencies by two symmetric inverted L-shaped monopole antennas, and then it adds a capacitively coupled rectangular circular helix structure. And it introduces two protruding ground branches and M-type structures to improve bandwidth and isolation, respectively that it generate frequency bands covering GSM 1800, LTE 2300, LTE 2500, WiMAX and WLAN. The antenna is fabricated on a common 0.8 mm FR4 fiberglass substrate.The HFSS (High Frequency Structure Simulator) simulate and test the data of each structure and modify it. The antenna changes the structure to achieve the requirements of each frequency band.And it use the simulation program to verify and test the feature that can

碩士<br>淡江大學<br>電機工程學系碩士班<br>106<br>In this thesis, an asymmetrically fed directional antenna is proposed first. The structure of this antenna is thin and simple, half wavelength resonant mode like a dipole antenna can be generated by feeding a metallic strip with a slightly offset from its center. By adding two parasitic elements, planar Yagi antenna with directional radiation pattern can be formed. This antenna is designed to resonant at 2.45GHz, thinks to the novel feeding technique of the driven element, the Yagi antenna is more easily to be integrated with circuit components and to be used for IOT or wireless sensor network. In the second part of this thesis, two directional beam switchable antenna designs are proposed. The first one is a planar beam forming antenna with eight printed dipoles around the ground plane. By exciting three of the eight dipoles with appropriate phase delay contributed by the delay line of the feeding network, the radiation pattern can be focused on one direction. The second design is similar, but the eight dipoles are perpendicular to the ground plane. In this design, only one dipole is activated each time and the other seven dipoles act as reflectors, achieving beam forming characteristic. This two antenna design not only can be used for MIMO system to increase channel capacity, but also can be used for indoor locating system, which have great contributions on practical applications and academic research.

碩士<br>明新科技大學<br>電機工程系碩士班<br>105<br>In this thesis, FR4 substrate and IE3D software are used to design multi-band antennas, including comb shaped with rectangular arm dipole antenna which can be applied to 1.8GHz,2.4GHz,2.45GHz and 2.6GHz frequency bands, comb shaped with needle arm dipole antenna which can be applied to 1.8GHz,2.4GHz,2.45GHz and 2.6GHz frequency bands, comb shaped with unequal rectangular arm dipole antenna which can be applied to 1.8GHz,2.4GHz,2.45GHz and 2.6GHz frequency bands , and comb shaped slot antenna which can be applied to 0.7GHz 0.9GHz and 1.8GH frequency bands. In this study, the size parameters of comb shaped planar dipole antenna are changed to observe the impacts on antenna characteristics. After simulation, the better parameter values of dipole antenna are obtained and can be used in GPS,RFID,WLAN and LTE frequency bands. The suitable size parameter L5=26.75mm of the comb shaped with uequal rectangular arm dipole antenna is obtained from simulated results. The proposed antenna can be used in RFID, WLAN and LTE frequency bands. The comb arm size parameters of the dipole slot antenna are adjusted to observe the variations with respect to the bandwidth, resonant frequency and gain of the proposed antenna. The better size parameters L5=29mm and L6=15mm are obtained to fabricate the comb dipole slot antenna which can be used in LTE 0.7GHz, LTE 0.9GHz and LTE 1.8GHz frequency bands. The proposed multiband dipole antennas by changing size parameters can be applied to GPS, WLAN, RFID and LTE frequency bands, respectively. Key words：planar dipole antenna、comb shaped rectangular arm、needle arm、WLAN、LTE

碩士<br>國立臺灣科技大學<br>電機工程系<br>97<br>Point-to-point communications requires high gain and high directivity antennas. Besides the conventional dish antenna solution, the array antenna, which has planar structure and low profile, is an usual alternative. However, the gain performance of large scale array antenna is often limited by the loss on the feeding network. A traditional feeding network comprises cascaded one-to-two power dividers, which usually results in long branches and many corners. Substantial losses are therefore accumulated. In this work, a dipole array was devised with a novel antenna feed scheme. The dipole elements are connected in a serial fashion with a straight pair wire transmission line to form a dipole branch. Although the power delivered to each dipole elements are not equal, the dipole array still yields a boresite pattern since dipole branches are arranged in a symmetric fashion. The measurement results show that due to the simple feeding structure, the proposed array antenna retains a higher gain comparing to arrays with convention branching feeds. A four patch array antenna with reconfigurable polarization feature is proposed in this work. The antenna comes with two sets of feeding network made of microstrip lines. Instead of awkwardly laying out two feeding networks on the same plane, they occupy the top on bottom surfaces of the ground to avoid collision. Such a feeding scheme helps reduce losses on transmission lines. Each patch antenna element is excited by two slots on the ground plane placed perpendicularly. A hybrid coupler controlled by RF switches is connected to the two feed sets. By adjusting the RF switch settings, the phase difference of two feeds can be 0, 90, or 180 degrees. According to the phase difference value, the array antenna polarization can be either RHCP, LHCP, vertical LP or horizontal LP. The proposed antenna configuration can therefore achieve polarization diversity. Performance validations are provided by simulation and measurement results. Finally, a dual band array antenna is presented in this work to operate in 2.4 GHz and 5 GHz bands of WLAN application. A slot array for 2.4 GHz and a dipole array for 5 GHz operation are combined in the same space to deliver dual band operation while maintaining decent isolation performance. Measurement results show high gain performance is achieved for both bands.

碩士<br>國立中正大學<br>電機工程所<br>97<br>In this thesis, the planar antenna for receiving digital television signals from terrestrial broadcasting is developed to have an ultra-wide band, omni-directional radiation, small size and low cost. This planar antenna built by the double-dipole structure is implemented by the printed circuit board. Rather than the inverted-F structure, multiple loops are constructed in the proposed antenna for the purpose of size reduction. Since each loop corresponds to a specific frequency response, multiple loops can yield the integrated frequency response from coupling all frequency responses of multiple loops to reach an ultra-wide band. Particularly, the relationship between the loop’s length and frequency resonance point is formulated. The High-Frequency Structure Simulator (HFSS) was employed to design the proposed planar antenna based on the double-dipole structure. The performance of the fabricated planar antenna is very consistent with that of the simulated one. The proposed planar antenna can have S11 below -10dBm in the Ultra-High Frequency (UHF), ranging from 470MHz to 860MHz, an average gain of 2.78dBi and an omni-directional radiation pattern like a monopole antenna.

碩士<br>國立臺灣科技大學<br>電子工程系<br>96<br>The aim of this thesis is to design the triple-bands mono-pole antenna, which was made by common material named FR4 board purchased from the market. Literature survey studied from dual-bands and triple-bands’ papers and these as the fundamental structure; the implementation performed by electromagnetic analysis program named IE3D to do fine tuning antenna and come out simulation results. The optimized parameters had been resolved for making actual antenna product. The proposed planar mono-pole antenna has excellent function upon WiMAX and WLAN frequency bands (2500-2690/3400-3690/ 5250-5850 MHz for WiMAX) and (2.4-2.484 GHz and 5.15-5.35 GHz、5.725-5.825 GHz for WLAN); This antenna also could support frequency bands for PCS(1.85 ~ 1.99 GHz) and UMTS (1.92 ~ 2.17 GHz) with acceptable performances. It should be a good product applying to industrial enterprise.

碩士<br>國立交通大學<br>電信工程系<br>88<br>In the thesis,a 38.5GHz planar cassegrain antenna is developed.the planar cassegrain antenna consist with fed antenna、polarizer and twisting polarization reflectarray. Using the polarizer to reflect the power from fed antenna and then the power will fall in twisting polarization reflectarray. The reflectarray will change the polarization about 90 degree. Using the tunning stub to focus the every reflect element and then the power through the polarizer and low loss. furture,may be we can achieve the beam scanning refer to Rotman lens structure or rotating by mechanical designed. This structure can popularly use in military or commercial communication. final,the 38.5GHz planar cassegrain property: 3.4 degree beamwidth、22 dBi antenna gain 、main lob and side lob ratio is 15 dB and co-polarization and cross-polarization ratio is 10 dB.

碩士<br>龍華科技大學<br>電子工程系碩士班<br>102<br>This thesis presents a compact multiband planar MIMO antenna that covers the standards of the Global System for Mobile (GSM), Long Term Evolution (LTE) and Ultra-Wideband (UWB). The MIMO antenna contains two printed back-to-back multiband monopole elements with a closed distance of one-tenth wavelength of 900MHz. The element in the MIMO antenna is structured by merging an UWB antenna and a parasitic multi-loaded winding line monopole that is capable of providing the broadband coverage for the standards of the GSM, LTE and UWB. The size of the antenna element without ground plane was 30mm x 28mm. Because of the asymmetric element radiation pattern and, thus the MIMO antenna exhibits the desirable low mutual coupling effect at 900MHz frequency band. Further, a pair of meta-material resonator is constructed and placed between antenna elements in order to improve the correlation coefficient at 1.8GHz and 2.2GHz bands. The measured isolations of the prototype are less than -20 dB in all operating frequency bands.

碩士<br>龍華科技大學<br>電子工程研究所<br>99<br>In order to follow with the popularity of the applications of the mobile wireless broadband radio access systems, two type of planar broadband antennas are designed and presented in this thesis. Both two antennas are tuned from very simple rectangular planar structures by applying the principle of self-resonance design. The first one is considered to operate at the frequency bands of GSM, DCS, and WiFi 2.4 GHz, where the meander line is constructed to achieve the lower operating band of 900MHz for GSM, while the other two bands are formed by using conventional inverted F planar antenna. By applying the same design principle, the second planar antenna is constructed by using meander slot to obtain the 2.4GHz frequency bands for the WiFi application. Two proposed antennas are successfully manufactured with the FR4 print circuit board, and measurement show the desirable characteristics and performance issued in the mobile wireless broadband radio access systems.

碩士<br>國立臺灣科技大學<br>電機工程系<br>98<br>This thesis investigates two antenna related topics. Conventionally, because the automobiles use omni-directional antenna for communication systems, which may suffer limited communication distance and interference. A Planar one-to-four beam switching antenna is proposed to solve these issues. Two periodic leaky wave antennas are arranged in a cross configuration. In order to improve the isolation performance of the cross leaky wave antenna, we reshape square patches into rectangular ones. Fillisters are also added between patches to increase isolation. The leaky wave antenna comprises four driven patch elements, which are connected via a one-to-four RF switch and five parasitically coupled patch elements. By selecting a specific through path, RF power is fed to one of the driven patch elements to produce a directive beam. The proposed beam switching antenna can help increase spatial diversity. Due to the growing popularity of personnel mobile communication devices, antenna designs are in great demands. In mass production, it is expensive to evaluate the reflection coefficient of antennas using a traditional network analyzer. Therefore, this research attempts to develop a new antenna impedance measurement apparatus composed of a VCO, a power detector and a circulator. A curacy in the magnitude of measured reflection coefficient is estimated by comparing results of three different types of antennas with network analyzer measurement results. A more sophisticated system, which in dudes a phase shifter, a voltage controlled attenuator and a rat-race hybrid, is proposed to measure the phases of reflection coefficients.

碩士<br>淡江大學<br>電機工程學系<br>92<br>In this thesis, the author propose reduced-size T-shape slot antenna and Notch planar antenna fed by a microstrip line on a FR4 board. The tradeoff between the size reduction and the bandwidth is found. A center frequency tuning scheme is developed to overcome the tradeoff. Reduced-size T-shape slot antenna fed by microstrip line comprises a T-shape slot in the plane of a grounded substrate. The T-shape slot has the characteristics of open circuit at one end and short circuit at the other. Such that the slot length is smaller than half a wavelength. The T-shape slot is further reduced by adding a microstrip stub across the slot near the open circuit end. The microstrip stub provides additional capacitance such that the small T-shape slot antenna about 0.125 wavelength can be achieved. The concept of designing reduced-size notch slot antenna is similar to that for the T-shape slot antenna. Compared with the T-shape slot antennas, the size of notch antenna is smaller (0.0735 wavelength), and the bandwidth is broader. It is found that the center frequency of the above antennas drifts when the thickness of FR4 board substrate varies. A technique to tune the center frequency is proposed to overcome the frequency drift such that the fabricated antennas can properly operate on the designed frequency range.

碩士<br>國立交通大學<br>電機學院通訊與網路科技產業專班<br>96<br>This thesis focuses on the use of antenna in thin laptop applications. Based on slot antenna theory, we extend the fabrication to broadband, dual-band, and five-band applications. The five-band antenna is able to be operated on the GSM850/GSM900/PCS/DCS/UMTS. We use printed circuit broad (PCB) to realize this five-band antenna. The planar property is suitable for thin laptop cases. At the same time, using PCB could reduce the cost of manufacture. Then, we further address the possible conditions for laptop applications with antenna. The antenna average gain is about 0 dBi, and radiation patterns are similar at different resonances. All together, it shows good adaptability to antenna position and ground effects.

碩士<br>國立高雄師範大學<br>物理學系<br>97<br>Designs of planar antenna for PCMCIA cards are presented in this dissertation. Three antenna designs have been proposed. These antennas have advantages of low profile, light weight, easy construction and also can be printed on dielectric substrates integrated with associated circuitry on the same substrates, which not only reduces the manufacturing cost but also decreases the required size of the complete system. In this thesis, three advanced design concepts for further studies are presented. Firstly, the design of CPW-fed slot antenna using chip capacitors-loading for operating at the 5.2 and 5.8 GHz WLAN band is presented. Secondly, the design of triple-band monopole antenna using inverted-L structure for operating in the 2.5, 3.5 and 5.5 GHz WiMAX band is presented. Finally, a novel printed monopole antenna is shown. In this design, the open-ended of a rectangular ring obtained multiband to satisfy the dual-network WLAN/WiMAX services.

碩士<br>國立臺灣海洋大學<br>電機工程學系<br>97<br>The purpose of this thesis is on the design and research of a high gain antenna. The main body of the radiation structure is a circular disk monopole antenna that has a wideband with a fairly all-directional radiation pattern and simple shapes characteristics, which can satisfy a frequency band of 2.4 GHz ~ 2.48 GHz for Bluetooth/WLAN application and 3.1 GHz ~ 10.6 GHz for Ultra-wideband ( UWB ) application. The antenna was printed on a FR4 substrate which has a thickness of 0.4 mm and relative permittivity of 4.4. The proposed monopole antenna has the advantage of simplicity of construction and low cost. In additions, the characteristics of this antenna were studied by tuning the radiating disk element and the distance from the radiation structure to ground and the ground size. A comparison of the simulation results with that of the actual measurements enables us to explore and identify the physical origin of the discrepancies in the designed parameters of the antenna system. Finally, through adding several Fresnel plate lens structures, the combined structure exhibits an enhanced gain. The relevant parameters of the Fresnel lens, such as lens radii, gap width and the number of lens, on the radiation characteristics of the monopole antenna were studied and discussed.

碩士<br>長庚大學<br>電子工程學研究所<br>96<br>Because the volume of wireless communication device becomes more mini than before, smaller antennas are going to be future trend. The problem is that the efficiency of antenna might decrease while the size of antenna is becoming smaller. For that reason, the efficiency of antenna is a very important issue to designing antenna besides matching and resonance frequency. The thesis is discussing how to utilize Planar Inverter-F antenna (PIFA) technology to design an applicable antenna for Worldwide Interoperability for Microwave Access (WiMAX) in 2.5-2.69GHz. PIFA is a kind of antenna utilizing transmission line technology. The feature of PIFA is that it has a short end and a open end and the equivalent circuit is they are in parallel. Inductive reactance and capacitive reactance caused by the short end and the open end will cancel out through appropriate turning and real impedance remains finally. The PIFA antenna with better efficiency will be designed by this method and it is applicable to WiMAX. After PIFA implementation and measurement, results exhibit operating frequency from 2.45GHz to 3.43GHz, and frequency bandwidth of 0.87 GHz.

碩士<br>元智大學<br>通訊工程學系<br>95<br>This thesis presents a design of the modified bow-tie slot antenna fed by CPW for WiMAX systems, and then extends this antenna to the dual-band operation for both WiMAX and WiFi applications. For the automotive environments of wireless usages, the bow-tie slot active antenna is presented with the integrations of the proposed antenna and the low noise amplifier for improving the receive noise figure. The influences of the antenna performances for integrating the active device are also examined.

博士<br>國立中山大學<br>電機工程學系研究所<br>94<br>The studies in this dissertation mainly utilize planar antennas for ultra-wideband antenna designs not only on the investigation of antenna performance but also towards exploiting attractive features of ultra-wideband antennas for practical applications, such as WMAN access-point antennas, omnidirectional WiMAX access-point antennas, band-notched UWB (Ultra-wideband, 3.1 ~ 10.6 GHz) antennas, and so on. To begin with, the effects of the ground-plane size and the asymmetrical ground plane on ultra-wideband antennas are studied in Chapter 2. Following up, from the conclusive results, an antenna for WMAN operation in access-point applications and an omnidirectional monopole for USB wireless network card device are proposed and analyzed. Characteristics of ultra-wideband antenna radiation in relation to the antenna''s width for obtaining omnidirectional radiation are addressed. In Chapter 3, several ultra-wideband access-point antennas are presented for achieving good omnidirectional radiation in the azimuthal plane across the bandwidth. Furthermore, in Chapter 4, band-notching techniques are applied to ultra-wideband antennas for avoiding the interference between the UWB and the WLAN systems.

碩士<br>國防大學中正理工學院<br>電子工程研究所<br>91<br>In this thesis, several designs of low-profile monopole antennas with omni-directional patterns, multiple operating bands for some special standards or specifications, and a reduced antenna height are presented. The proposed antennas with a largely lowered antenna height are basically constructed by a metallic strip composed of a straight-line section and a ring-shaped section with a tail-slit of 0.5 mm width. Dual-band or tri-band planar monopole antennas are achieved by adding one or two ring-shaped metallic strip(s) with a tail-slit in the inner space of a metallic strip with the same shape and different radii. The total length of each metallic strip, associated with the quarter wavelength of a resonant frequency excited by the metallic strip, can be calculated in the beginning of antenna design process. And, by embedding a suitably selected chip resistor at an appropriate place among ring-shaped metallic strips or adding a properly designed outer arc-shaped metallic strip, impedance matching and bandwidth enhancement of some band mismatched when the chip resistor or the outer arc-shaped metallic strip is absent can be simultaneously obtained. Thus, novel antenna designs for multi-band operation, which are the combinations between GSM and DCS, PCS bands or that between ISM and UNII bands, can be easily implemented.

碩士<br>明新科技大學<br>電機工程系碩士班<br>103<br>In this thesis, FR4 substrate and IE3D software are used to design multi-band antennas, including dipole antenna which can be applied to 1.8GHz, 2.6GHz, and 5GHz frequency bands, meander dipole antenna which can be applied to 0.7GHz and 1.8GHz frequency bands, and planar antenna which can be applied to 0.9GHz and 2.6GH frequency bands. In this study, the size parameters L1, L3 and W2 of planar antenna are changed to observe the impacts on antenna characteristics. After simulation process, the better parameter values L1=20.5mm, L3=15.5mm and W2=2mm are obtained to fabricate the triple band dipole antenna that can be used in GSM, WLAN and LTE frequency bands. The suitable size parameters L2=34mm, S=4 and W7=2mm of the meander dipole antenna are also obtained after simulation process. The proposed meander dipole antenna can be used in LTE 0.7GHz and LTE 1.8GHz frequency bands. The arm size parameters L3, L4, and L5 are adjusted to observe the variations with respect to the bandwidth, resonant frequency and gain of the proposed planar antenna. The better size parameters L3=28mm, L4=49.5mm and L5=21.5mm are obtained to fabricate the planar antenna which can be used in LTE 0.9GHz and LTE 2.6GHz frequency bands. The LTE antennas including triple band dipole antenna, planar meander dipole antenna and planar antenna are implemented in this thesis. The proposed multiband antennas by changing size parameters can be applied to GSM, WLAN, RFID and LTE frequency bands respectively. Key words：Triple band planar dipole antenna、meander planar dipole antenna、WLAN、LTE

碩士<br>國立中正大學<br>通訊工程學系<br>98<br>In this thesis, two types of planar microstrip Yagi-Uda antenna fabricated on a FR4 substrate are investigated. The design is based on the planar half wavelngth dipole antenna with directing elements to form the high gain antenna. The first planar microstrip Yagi-Uda antenna was designed at 2.4 GHz for IEEE 802.11 b/g/n WLAN which has the return loss of 13.3 dB and antenna gain of 9.36 dBi and the bandwidth of 500 MHz. The second Yagi-Uda antenna has the bandwidth extention for IEEE 802.11 b/g/n WLAN, IEEE802.16 WiMAX , and 3GPP LTE applications, there measured return loss is 16 dB in 2.3-2.7 GHz and antenna gain is 8.99 dBi at 2.5GHz. The experimental results show good agreement with the simulated data.

碩士<br>明志科技大學<br>電機工程研究所<br>100<br>The three antennas which are applied to different applications are proposed in this paper. The first antenna, asymmetric dipole antenna, used a flexible maternal with dielectric constant of 2.8, and suited to Digital Video Broadcasting(470-862MHz) applications. Its advantage of the substrate material is pliant and it can freely adjust the usage of space limitations. The second antenna is a coupling monopole antenna with a size of 50(W)*100(L)*0.8(H) mm^3, which is printed on a inexpensive FR4 substrate with 0.8mm-thick. This antenna is suited to eight-band operation involving LTE(700/2300/2500),GSM(850/900/1800/1900),and UMTS(1920-2170MHz). Two antennas, as mentioned above, the return losses of them can fully reach the generally commercial. The third antenna is a planar monopole antenna which is applied to wireless communication protocol WLAN(2.4/5.2/5.8GHz) bands and WiMAX (2.5/5GHz) bands. The antenna is occupied 20(W)*450(L)*0.8(H) mm^3 and printed on a 0.8 mm-thick FR4 substrate. The return loss of the antenna is totally below -10dB and its operation bands are achieved 2.4-2.58GHz and 5-6GHz. The three antennas are measured by network analyzer and experimented in the anechoic laboratory. The return loss and the simulation results are reached good agreements. And the radiation pattern can meet the requirements of the omni-directional. So, they can become the good candidates for different areas of wireless communications antenna.

碩士<br>國立中央大學<br>通訊工程學系在職專班<br>101<br>In this thesis, a planar miniaturized antenna(83mm x 10mm) which covered eight bands of Long-term Evolution(LTE700 / 2300 / 2500) and Wireless Wide Area Network(GSM850 / GSM900 / DCS1800 / PCS1900 / UMTS2100) for embedded application in the Laptop and Tablet PCs is presented. Nowadays, the trend of Laptop and Tablet PC products design are slim and light-based, therefore, the proposed antenna in this thesis is base on a planar antenna structure and using a gap-coupled structure in the loop antenna to achieve the miniaturization antenna demand. The proposed antenna can be realized by mature printed circuit board technology easily since its structure is very simple, and do not need additional assembly and processing which means the antenna characteristics have a high degree of consistency and production cost advantages for mass production. For the low-band portion(LTE700 / GSM850 / GSM900) of antenna, the proposed antenna was using a gap-coupled structure for increasing antenna bandwidth and two parasitic strips for tuning the antenna matching as well. For the high-band portion(DCS1800 / PCS1900 / UMTS2100 / LTE2300 / LTE2500) of antenna, the proposed antenna was added two parasitic strips for tuning the high-band matching to achieve up to 1 GHz bandwidth demand. Detailed antenna designs and measured results are introduced in this thesis.

碩士<br>國立臺灣海洋大學<br>電機工程學系<br>101<br>In this thesis, the design of an ultra broadband standard log-periodic dipole antenna (LPDA) is considered. The frequency-independent characteristics of LPDA enabled the realization of wide bandwidth with stable gain and desired radiation pattern. Based on the operation principles of LPDA, several design consideration for LPDAs have been fabricated on printed circuit board. The first design operated as endfire array which required a larger space requirement for practical applications. To downsize the effective space requirement, we have modified our design for the planar LPDA to that of the broadside array. However, the planar broadside array LPDA has inherent difficulty in achieving good impedance matching. To solve this problem, we have implemented a three-dimensional microstrip line impedance converter to improve the impedance match. Nevertheless, the process can be quite complicated and the 3D feed generally resulted in a large effective volume for practical application. Finally, we have devised a simple modified LPDA such that a planar microstrip line impedance converter can be incorporated to improve the impedance matching of the LPDA. Our modified planar LPDA can operate satisfactorily within the bandwidth from 1.7 GHz to 6.5 GHz with return loss of below -10 dB and a maximum gain of 6.2 dBi.

碩士<br>北台灣科學技術學院<br>機電整合研究所<br>96<br>The Compact Designs of Planar Loop Antenna with Circular Polarization(CP) have been investigated in this dissertion. The study of serpentine construction to increase current path and reduce dimension arrive at Circular Polarization. There are two designs in this dissertation.The single layer compact is designed by Coplanar Waveguide and the double layer compact is designed by Microstrip-Line. To compare oringinal size antenna with compact size antenna to analysis and discussion. The input impedance of planar loop antenna can be matched by serpentine meander line and serpentine microstrip patch to save antenna area.The antennas operation frequency designs can be used to 802.11b/g (2.4~2.45GHz). In this dissertation, experimental result proved the single layer Compact designed by Coplanar Waveguide has been scaled-down dimension from 51mm*42mm to 39.75mm*37.25mm(69.12%) and the double layer compact designed by microstrip line has been scaled-down dimension form 40mm*24mm to 35mm*20mm(72.92%).

碩士<br>逢甲大學<br>產業研發碩士班<br>95<br>The applications of wireless communication technology are much more in our daily life. The more lighter, more thinner, and more smaller of the communication equipments we required, the more important role the antenna plays in a whole wireless communication system, and therefore, the more worth we want to study and develop the design work of the antenna. The proposed antennas in this thesis are fed by using the CPW (coplanar waveguide), in addition to the advantages of low cost, lightweight, easy to fabricate, they are especially suitable for dual-frequency applications. The proposed antennas are suitable for WLAN ( Wireless Local Area Network ) application in 2.4 GHz and 5.2 GHz, the operation frequency are fit for IEEE 802.11 b ( 2.4 GHz ) and 802.11 a ( 5.2 GHz ) . The antenna has been constructed based on theories from textbooks and papers, which also verified by commercial electromagnetic simulation software-IE3D. The measured input impedance, return loss and radiation pattern are presented and discussed.

博士<br>國立交通大學<br>電信工程研究所<br>102<br>This dissertation can be categorized into two parts; the first part is about the design and analysis for on-body antenna, and the second part studies the implementation of polarization diversity at 60 GHz and also the array design with polarization switchable characteristics. In the study of on-body antenna design, an adhesive-bandage like antenna which is able to be bent and be placed on human body tissue has been presented. An offset feeding method is proposed which can be used to excite transverse resonant mode (TM01 mode) on a long and thin patch. Also, the virtual ground method is applied in this design to virtually connect the metal conductor on the back side of the circuit board to the ground conductor of the feed line, no via or any vertical connection is required. Therefore, this design is very suitable for bendable applications. In addition, by a special design of the edge extension on the ground conductor, the problem in antenna gain degradation and the radiated power directed to the backside of the antenna when the patch antenna bent in E-plane can be solved. The achieved antenna gain is about 2.01 dBi and the measured radiation efficiency is 41.7% when the proposed antenna placed on the human body tissue and space by 1 mm. The calculated SAR is 1.183 W/kg3. The antenna configuration is simple, which is very suitable for wireless body area network. In the second part of this dissertation regarding the design of 60-GHz polarization diversity antenna, some designs which are planar and can realize polarization switchable characteristics at 60 GHz have been presented. These antennas have four input ports, and each port corresponds to different polarization. Therefore, polarizations of the millimeter wave antenna are possible to be changed by selecting various inputs. A four-port quadri-polarization diversity antenna design which can improve the axial-ratio bandwidth when it operates in circular polarized mode is also presented. For antenna array with polarization agile capability, a 2×2 array is proposed, and this design can be extended to a 4×4 configuration. These 60-GHz polarization switchable antenna array have two input ports, the polarization of which can be switched to right-hand circular polarization, left-hand circular polarization, or the linear polarization in four directions by controlling the phase difference of the two input ports. The measured antenna gain of the 2×2 and 4×4 polarization switchable antenna array is 12.03 dBi and 16 dBi, respectively, successfully demonstrate polarization switchable antenna array at 60 GHz.

碩士<br>國立臺灣科技大學<br>電機工程系<br>100<br>In this thesis, the proposed periodic leaky wave antenna, which has a simple planar geometry, provides a circularly polarized beam steerable via frequency scanning. The antenna comprises serially connected phase inverters made of parallel strip line. Radiations emit from geometric discontinuities in phase inverter structures and hence form a leaky wave antenna. From simulation and verification results, broad scanning beam coverage is observed with good circular polarization performance. In the second part, an electronically reconfigurable beam switching array antenna applicable to MIMO technology in the 2.4 GHz band is proposed in this work. The array antenna contains a Rotman lens and four element antennas. The Rotman lens, which is a true time delay device, allows simultaneous operation of multiple beams. From the results, the simple beam switching mechanism implemented with the Rotman lens suits well to the MIMO transceiver need.

碩士<br>淡江大學<br>電機工程學系碩士班<br>93<br>The goal of this thesis is to design a miniature fully-planar antenna that satisfies for UWB (3.1GHz~10.6GHz) released by the FCC. Most of the planar monopoles reside on a large orthogonal ground plane, and thus the antennas are not fully planar structures.. The fully planar coplanar waveguide-fed or microstrip-fed UWB monopole antennas have attracted the attention of many researchers. None of them has both the impedance bandwidth and radiation bandwidth covering the UWB simultaneously. In this study, the UWB antennas are fabricated on an FR4 board of thickness 0.8mm, for which the relative dielectric constant 4.4 is used for design. In this paper, the miniature ultra wideband (UWB) fully-planar monopole antennas fed by microstrip line are investigated in order to take full advantages of the planar antenna structure, such as the light weight, small size, low cost, conformal and ease of integration with the microwave networks. The empirical formula is employed to determine the initial size of a square monopole, by which the influences of the dimensions upon the reflection coefficient are investigated. It is found that the reflection coefficient is very sensitive to the gap. It is thus proposed to change the shape and size of the gap between the monopole and the ground in order to achieve the goal of miniature wideband antenna. The optimized results show that the radiation patterns in the E plane and the omni-directional characteristic in the H-plane are improved.

碩士<br>正修科技大學<br>電子工程研究所<br>97<br>A novel circular polarization patch antenna having a shorting mechanism has been proposed. The proposed antenna placed on the center of the system ground plane consists of a highεr dielectric substrate, an upper patch electrode, an antenna ground plane, a system ground plane, a shorting pin system and a feeding point. The purposes of the proposed antenna are to achieve circular polarization and easy to produce. For antenna construction, the shorting pins were set on the corner(s) of the antenna ground plane of the ceramics substrate to improve impedance matching. For bandwidth, it can be reached about 10MHz and tuned by capacitance coupling feed. For axial ratio, it can be controlled by the shape of the upper patch. In this study, the bandwidth of the axial ratio less then 3dB is about 2 MHz. Additional, there is a good agreement between Ansoft HFSS and practical measurement. There are several advantages of the proposed antenna, including low profile, SMT, good axial ratio and sufficient bandwidth.

碩士<br>國立臺灣大學<br>電信工程學研究所<br>95<br>The main theme of this study is to make a fundamental discussion of vehicle antenna systems and to design an integrated vehicle antenna system. The frequency bands cover the applications of DTV, GSM, DCS, GPS, and WLAN. The designed antenna system has multiple output ports and each port can be directly connected to different transceivers. The tasks to be investigated include: possible architectures of the integrated antenna systems and their advantages and limitations; possible locations for placing the antenna; feasibility of replacing part of the car body with materials suitable for antenna design; design of planar antennas for different frequency bands and integration of them on a single circuit board. In this study, SEMCAD-X was used to simulate antennas and car bodies, and design of planar antennas for different frequency bands was in the simulated environment with car body effect. Integration of these designed antennas subsequently proceeded. Based on different layouts, simulated results of return loss for the impacts on resonant bands were observed. Finally, according to the simulated results, an integrated planar antenna was actually fabricated. It was measured in an anechoic chamber to obtain return loss and radiation pattern of the integrated planar antenna on a car roof model. From the measured results, the feasibility of integrated planar antenna for vehicles was verified. Several new design concepts for vehicular antennas can be obtained in this thesis.

博士<br>國立中山大學<br>電機工程學系研究所<br>93<br>In this dissertation, many novel low-cost planar antenna designs are presented for on-vehicle applications. Promising planar antennas showing the desired broadside and omnidirectional radiation patterns and having low-profile configurations are demonstrated. Also, studies on controlling the radiation patterns are conducted. Details of the measured and simulated results of the studied antennas are presented and discussed.

碩士<br>國立交通大學<br>電信工程系<br>89<br>Utilizing the recently developed Electric-Magnetic-Electric (EME) composite metal strips, which can increase the slow-wave factor and have a broad stopband, two applications are introduced in this thesis. First one uses slow-wave structures to minimize the patch antenna employing PCB (printed-circuit-board) fabrication process. The resonant length and area of the slow-wave patch antenna are reduced to be 76 % and 58 % when compared with the conventional one. Gain enhancement of the patch antenna by suppressing surface waves is the other application in our studies. According to the experimental results, the peak gain of the design patch antenna is 1.03 dBi higher than the conventional one. Statements and measurement results of both patch antennas are also included in this thesis.