Journal articles: 'Multi-band microwave filters'

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Gomez-Garcia, Roberto, and Andrew C. Guyette. "Reconfigurable Multi-Band Microwave Filters." IEEE Transactions on Microwave Theory and Techniques 63, no. 4 (April 2015): 1294–307. http://dx.doi.org/10.1109/tmtt.2015.2405066.

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Sazali, M. A., N. A. Shairi, and Z. Zakaria. "Hybrid Microstrip Diplexer Design for Multi-band WiMAX Application in 2.3 and 3.5 GHz Bands." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 1 (February 1, 2018): 576. http://dx.doi.org/10.11591/ijece.v8i1.pp576-584.

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In this paper, a design of hybrid microstrip diplexer is proposed for multi-band Worldwide Interoperability for Microwave Access (WiMAX) application in 2.3 and 3.5 GHz bands. The diplexer consists of a combination of two different filter designs. These filters were designed based on microstripline coupling techniques in order to obtain minimum insertion losses and achieve the desired frequency bandwidth. Therefore, a coupled open loop ring resonator was chosen for the filter design in 2.3 GHz band and a folded coupled line resonator was chosen for the filter design in 3.5 GHz band. Then, these filters were combined with a ring manifold matching network to be a hybrid microstrip diplexer. Based on the results, good agreements were achieved between the simulation and measurement results in terms of insertion loss, return loss and bandwidth in the 2.3 and 3.5 GHz bands.

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Mrvic, Marija, Snezana Stefanovski-Pajovic, Milka Potrebic, and Dejan Tosic. "Design of microwave waveguide filters with effects of fabrication imperfections." Facta universitatis - series: Electronics and Energetics 30, no. 4 (2017): 431–58. http://dx.doi.org/10.2298/fuee1704431m.

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This paper presents results of a study on a bandpass and bandstop waveguide filter design using printed-circuit discontinuities, representing resonating elements. These inserts may be implemented using relatively simple types of resonators, and the amplitude response may be controlled by tuning the parameters of the resonators. The proper layout of the resonators on the insert may lead to a single or multiple resonant frequencies, using single resonating insert. The inserts may be placed in the E-plane or the H-plane of the standard rectangular waveguide. Various solutions using quarter-wave resonators and split-ring resonators for bandstop filters, and complementary split-ring resonators for bandpass filters are proposed, including multi-band filters and compact filters. They are designed to operate in the X-frequency band and standard rectangular waveguide (WR-90) is used. Besides three dimensional electromagnetic models and equivalent microwave circuits, experimental results are also provided to verify proposed design. Another aspect of the research represents a study of imperfections demonstrated on a bandpass waveguide filter. Fabrication side effects and implementation imperfections are analyzed in details, providing relevant results regarding the most critical parameters affecting filter performance. The analysis is primarily based on software simulations, to shorten and improve design procedure. However, measurement results represent additional contribution to validate the approach and confirm conclusions regarding crucial phenomena affecting filter response.

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Ashley, Andrea, Dakotah J. Simpson, and Dimitra Psychogiou. "Quasi-elliptic dual-band bandpass filters based on series-cascaded multi-resonant cells." International Journal of Microwave and Wireless Technologies 12, no. 7 (June 22, 2020): 609–14. http://dx.doi.org/10.1017/s1759078720000756.

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AbstractThis paper reports on quasi-elliptic dual-band bandpass filters (BPFs) that were designed for the Filter Student Design Competition of the 2019 European Microwave Week. The proposed lumped-element (LE) BPF concept is based on two dual-band transversal cells and one multi-resonant cell that allow the realization of symmetric and asymmetric dual-band transfer functions shaped by six poles and five transmission zeros. A compact implementation scheme based on LE series resonators is proposed for size compactness and wide spurious free out-of-band response. For proof-of-concept demonstration purposes, a dual-band LE prototype with two passbands centered 1 and 1.5 GHz was designed, manufactured, and measured. It exhibited the following radio frequency measured performance characteristics. Passbands centered at 1.02 and 1.45 GHz, minimum insertion loss levels of 2.0 and 2.7 dB, and bandwidth of 146 and 105 MHz, respectively, for the first and the second passband, and out-of-band rejection >30 dB between 0 and 894 MHz, 1.17–1.34 GHz, and 1.72–6.9 GHz.

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CASSINESE, A., A. ANDREONE, P. ORGIANI, F. PALOMBA, G. PICA, R. VAGLIO, G. PANARIELLO, F. SCHETTINO, M. CIRILLO, and R. RUSSO. "HIGH POWER HANDLING SUPERCONDUCTING PLANAR FILTERS FOR TELECOMMUNICATION APPLICATIONS." International Journal of Modern Physics B 14, no. 25n27 (October 30, 2000): 3092–97. http://dx.doi.org/10.1142/s0217979200003368.

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Passive microwave filters based on HTS films are very promising for telecommunication applications. We report on the design, obtained using a commercial 2.5D software, and the realization of filters, fabricated with double sided YBCO films grown on LaAlO 3 substrates, for both receiving and transmission systems. For the receiving side, planar multi-pole interdigital L-band filters with 75 MHz transmission bandwidths have been fabricated on 2" substrates. Up to 80 K this kind of filter, based on a Tchebischev response, shows an insertion loss lower than 0.5 dB with a ripple of 0.3 dB for a maximum input power of 2 Watts. For the transmitting side, dual-mode filters represent one of the main interesting configuration to exploit since they can combine a high power handling capability with miniaturization requirements. A novel kind of dual-mode C-band filter based on cross slotted square resonators is presented. The novelty of the proposed structure is to use a pair of unequal crossed slots that are formed on a square patch resonator such that its structure size can be significantly reduced. A prototypal device operating at 3.7 GHz is fabricated with different type of couplings on 10 × 10 mm 2 LaAlO 3 substrate to showcase our proposal. The behavior of the filter as a function of the input power has been tested up to 2 Watts limited by the amplified power supply.

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Hsue, C. W., J. W. Hsu, C. H. Lu, and S. T. Peng. "Design and implementation of microwave multi-band/multi-level filters using equal-length transmission lines and Yule–Walker scheme." IET Microwaves, Antennas & Propagation 3, no. 5 (2009): 826. http://dx.doi.org/10.1049/iet-map.2008.0231.

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Mitkov, A. S., A. A. Stolyarenko, and M. G. Rubanovich. "FILM ATTENUATORS BASED ON FILTER STRUCTURES WITH DISSIPATIVE LOSSES." Issues of radio electronics, no. 4 (May 10, 2019): 84–89. http://dx.doi.org/10.21778/2218-5453-2019-4-84-89.

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The article presents the results of a study of the frequency properties of a multi-stage high-power attenuator with attenuation of 10 dB in the frequency range 0–3 GHz, obtained on a dielectric substrate made of beryllium ceramics. For its construction, microstrip filters with quarter-wave couplings and dissipative losses are used, as well as additional film resistors made in the form of trapezoidal plumes. These loops have a minimum size in the area of a short circuit. The design features of wide-band microwave attenuators of high power are determined, including the conditions for ensuring uniform distribution of the dissipated microwave power and distribution of the resonant frequencies of low-Q resonators. Equivalent circuits were compiled, which allow to determine the initial structure of the attenuator and optimize its frequency characteristics for any power level.

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Sagues, Mikel, Raimundo García Olcina, Alayn Loayssa, Salvador Sales, and José Capmany. "Multi-tap complex-coefficient incoherent microwave photonic filters based on optical single-sideband modulation and narrow band optical filtering." Optics Express 16, no. 1 (2008): 295. http://dx.doi.org/10.1364/oe.16.000295.

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Goudos, Sotirios K., Zaharias D. Zaharis, and Traianos Yioultsis. "APPLICATION OF A DIFFERENTIAL EVOLUTION ALGORITHM WITH STRATEGY ADAPTATION TO THE DESIGN OF MULTI-BAND MICROWAVE FILTERS FOR WIRELESS COMMUNICATIONS." Progress In Electromagnetics Research 109 (2010): 123–37. http://dx.doi.org/10.2528/pier10081704.

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Sorrentino, Roberto, Paola Farinelli, Alessandro Cazzorla, and Luca Pelliccia. "RF-MEMS Application to RF Tuneable Circuits." Advances in Science and Technology 100 (October 2016): 100–108. http://dx.doi.org/10.4028/www.scientific.net/ast.100.100.

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The bursting wireless communication market, including 5G, advanced satellite communication systems and COTM (Communication On The Move) terminals, require ever more sophisticated functions, from multi-band and multi-function operations to electronically steerable and reconfigurable antennas, pushing technological developments towards the use of tunable microwave components and circuits. Reconfigurability allows indeed for reduced complexity and cost of the apparatuses. In this context, RF MEMS (Micro-Electro-Mechanical-Systems) technology has emerged as a very attractive solution to realize both tunable devices (e.g. variable capacitors, inductors and micro-relays), as well as complex circuits (e.g. tunable filters, reconfigurable matching networks and reconfigurable beam forming networks for phased array antennas). High linearity, low loss and high miniaturization are the typical advantages of RF MEMS over conventional technologies. Micromechanical components fabricated via IC-compatible MEMS technologies and capable of low-loss filtering, switching and frequency generation allow for miniaturized wireless front-ends via higher levels of integration. In addition, the inherent high linearity of the MEMS switches enables carrier aggregations without introducing intermodulation distortions. This paper will review the recent advances in the development of the RF MEMS to RF tunable circuits and systems.

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Kingsly, Saffrine, Malathi Kanagasabai, Gulam Nabi Alsath Mohammed, Sangeetha Subbaraj, Yogeshwari Panneer Selvam, and Rajesh Natarajan. "Multi-band reconfigurable microwave filter using dual concentric resonators." International Journal of RF and Microwave Computer-Aided Engineering 28, no. 6 (March 22, 2018): e21290. http://dx.doi.org/10.1002/mmce.21290.

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12

Jin, Yu-Ting, Li-Ming Si, Qing-Le Zhang, Yu-Ming Wu, and Xin Lv. "Dual-band bandpass filter using composite metamaterial resonator." Modern Physics Letters B 30, no. 07 (March 20, 2016): 1650079. http://dx.doi.org/10.1142/s0217984916500792.

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A dual-band bandpass filter at X-band is proposed using composite metamaterial resonator consisting of an outer square closed-ring resonator (SCRR) and two inner electric inductance–capacitance (ELC) resonators. Numerical simulation and microwave measurement reveal that the filter exhibits two passbands centered at 8.76 GHz and 11.04 GHz, with 3 dB bandwidths of 130 MHz and 290 MHz, respectively. The complex dispersion relation of the filter is further derived based on the effective medium theory, where two balanced composite right-/left-handed bands are found, i.e. lines exhibiting two left-handed and two right-handed bands alternating. The proposed filter may find useful in dual-band or multi-band wireless communication systems.

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Lobato-Morales, Humberto, Alonso Corona-Chavez, Tatsuo Itoh, and José L. Olvera-Cervantes. "Dual-Band Multi-Pole Directional Filter for Microwave Multiplexing Applications." IEEE Microwave and Wireless Components Letters 21, no. 12 (December 2011): 643–45. http://dx.doi.org/10.1109/lmwc.2011.2172683.

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Sghir, Elmahjouby, Ahmed Errkik, Jamal Zbitou, Larbi El abdellaoui, Abdelali Tajmouati, and Mohamed Latrach. "A novel compact CPW Band-stop filter using O-DGS configuration." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 6 (December 1, 2019): 4836. http://dx.doi.org/10.11591/ijece.v9i6.pp4836-4844.

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<p>A novel and compact multi-band stop filter using two different structures of circular DGS and circular DGS loaded with O-DGS unit, has good selectivity and wide upper pass band performance with good rejection based on defected ground structure (DGS) integrating a circular ring resonator to suppress undesired spurious bands frequency or harmonics in radio frequency and microwave circuits is proposed. An equivalent circuit model has been derived for the both structures of circular DGS and circular DGS loaded. The presented filter has a compact size because the circular ring resonator is integrated in DGS, the both of them are etching in the ground plane. The proposed filter presents an optimization method for generating multi-band characteristics without using a periodic cells or other complicate topology. The simulated results by ADS Agilent are presented and compared with the results simulated by two others software: CST and HFSS. Good agreement between the three simulated results is observed.</p>

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Liu, Hai-Wen, Fan Liu, Bao-Ping Ren, Ai-Ping Yao, Xiang Xiao, Yun-Xiu Yang, and Xue-Hui Guan. "Compact tri-band bandpass filter using asymmetric stub-loaded stepped-impedance resonator with multiple transmission zeros." International Journal of Microwave and Wireless Technologies 9, no. 7 (February 10, 2017): 1453–57. http://dx.doi.org/10.1017/s1759078717000058.

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In this paper, a tri-band bandpass filter (BPF) using asymmetric stub-loaded stepped-impedance resonator (SL-SIR) is presented. The asymmetric characteristic of SL-SIR broadens degrees of freedom for three controllable modes design. Also, the coupling coefficients (Mij) and the external quality factors (Qei) at each passband of the filter can be independently adjusted by the proposed mixed-type feedline structure. Besides, multi-transmission zeros are produced to improve the isolation and selectivity of the passbands. Finally, a tri-band BPF is operated at 1.9 GHz (time division long term evolution – TD-LTE band), 3.2 GHz (worldwide interoperability for microwave access – WiMAX band), and 5.8 GHz (wireless local area networks – WLAN band) and their insertion loss are 1.03, 0.94, and 1.27 dB, respectively. The measured results of the fabricated tri-band BPF exhibit good agreement with simulated results.

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Atuchin, Victor V., Anatoly P. Gorbachev, Vladimir A. Khrustalev, and Natalya V. Tarasenko. "The Reentrant Four-Layer Quasi-Elliptic Bandstop Filter." Electronics 8, no. 1 (January 10, 2019): 81. http://dx.doi.org/10.3390/electronics8010081.

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The novel microwave quasi-elliptic bandstop filter, which uses the initially uncoupled strip transmission lines, is considered in this work. The proposed filter is based on the reentrant structure, where the metallic body with a floating potential is asymmetric. Generally speaking, the internal and external dielectric fillings must have their unequal relative permittivities. As a result, additional symmetrical reflection zeros are reached at the lower and upper pass bands of the stop band leading to the quasi-elliptic function response that improves the filter selectivity. The general transverse electromagnetic (TEM) circuit model for the proposed filter in terms of a series connection of the multi-ports is presented and then used to predict the initial electrical and geometrical parameters. An experimental printed circuit prototype has been manufactured and evaluated to validate the design concept. The measured filter parameters correlate well with the simulation-derived ones and that increases the degree of freedom in the fabrication of microwave frequency selective components.

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Hsue, Ching-Wen, Jer-Wei Hsu, Yen-Jen Chen, and Kuo-Lung Chen. "Microwave multi-level band-pass filter using discrete-time Yule-Walker method." Microwave and Optical Technology Letters 51, no. 1 (November 13, 2008): 225–29. http://dx.doi.org/10.1002/mop.24006.

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Al-Badri, Khalid. "Design of A Perfect Metamaterial Absorber for Microwave Applications." Basic and Applied Sciences - Scientific Journal of King Faisal University 22, no. 1 (2021): 1–4. http://dx.doi.org/10.37575/b/sci/0050.

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In this manuscript, a multi-band and low-profile metamaterial absorber with polarisation independence from 00 to 450 is presented. The proposed metamaterial structure is composed of a single ring with a rectangular patch, consisting of periodic unit cells with a size of 150mm × 250mm × 1.5mm. The structure exhibits three absorption peaks under normal incidence, which cover the X-band. According to the results, the desired material can excellently absorb the electromagnetic wave signal, with an outstanding absorption rate of about 95% at the microwave x-band frequency. The proposed structure shows three absorption bands where two of them exceed 90% absorption level. The results displayed a high Q-factor of 103.5 at a resonance frequency of 8.58 GHz and the figure of merit (FOM) is 98.4, which can be used to enhance the sensor sensing, narrowband band filter and image sensing. The proposed structure is fabricated, and experiments are carried out to validate the design principle. Strong agreements are observed between the measured and the corresponding simulated results.

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Phuong, Linh Ta, Bernard Journet, and Duong Bach Gia. "A microwave active filter for nanosatellite’s receiver front-ends at s-bands." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 2 (April 1, 2019): 973. http://dx.doi.org/10.11591/ijece.v9i2.pp973-981.

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<p>In satellite technology, the communication between space segment and ground segment plays a vital role in the success of the mission. This paper is targeted at study, design and fabrication of a microwave active filter for the receiver front-ends using coupled line filter structure, which can be applied to the nanosatellite’s communication subsystem. The whole active filter module is a combination of a microstrip bandpass filter and a preceding two-stage wideband low noise amplifier using FET devices. The proposed module operates in the frequency range of 2 - 2.4 GHz, which can be divided to 10 frequency slots of about 40 MHz for each. These frequency slots will be used for the S-band multi-frequency receiving function of the ground station, as well as the nanosatellite. The simulated and measured results of this active filter configuration are presented.</p>

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Lan, Siang-Wen, Min-Hang Weng, Chang-Sin Ye, and Cheng-Yuan Hung. "Compact quad-band bandpass filter based on uniform impedance stub-loaded resonators." International Journal of Microwave and Wireless Technologies 7, no. 2 (April 24, 2014): 121–26. http://dx.doi.org/10.1017/s175907871400052x.

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A new quad-band bandpass filter for Global System for Mobile Communications, Wireless Local Area Network, and Worldwide Interoperability for Microwave Access is designed and fabricated using the stub-loaded resonator (SLR) technology without complex fabrication process, such as via-hole or multi-layer substrate. Owing to the embedded SLR, the proposed quad-mode resonator is compact. Equivalent circuits of the proposed quad-mode resonator are analyzed in detail, and high design freedom is shown because of shifting the passband frequencies individually. Good passband selectivity and isolation of the each passband at 1.8, 2.4, 3.5, and 5.2 GHz can be well achieved due to the transmission zeros appeared near the each passband edges. Experimental results show good agreement with the simulated results.

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Ye Deng, Ming Li, Ningbo Huang, and Ninghua Zhu. "Ka-Band Tunable Flat-Top Microwave Photonic Filter Using a Multi-Phase-Shifted Fiber Bragg Grating." IEEE Photonics Journal 6, no. 4 (August 2014): 1–8. http://dx.doi.org/10.1109/jphot.2014.2339327.

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Song, Yiran, Qingsha S. Cheng, and Slawomir Koziel. "Multi-Fidelity Local Surrogate Model for Computationally Efficient Microwave Component Design Optimization." Sensors 19, no. 13 (July 9, 2019): 3023. http://dx.doi.org/10.3390/s19133023.

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In order to minimize the number of evaluations of high-fidelity (“fine”) model in the optimization process, to increase the optimization speed, and to improve optimal solution accuracy, a robust and computational-efficient multi-fidelity local surrogate-model optimization method is proposed. Based on the principle of response surface approximation, the proposed method exploits the multi-fidelity coarse models and polynomial interpolation to construct a series of local surrogate models. In the optimization process, local region modeling and optimization are performed iteratively. A judgment factor is introduced to provide information for local region size update. The last local surrogate model is refined by space mapping techniques to obtain the optimal design with high accuracy. The operation and efficiency of the approach are demonstrated through design of a bandpass filter and a compact ultra-wide-band (UWB) multiple-in multiple-out (MIMO) antenna. The response of the optimized design of the fine model meet the design specification. The proposed method not only has better convergence compared to an existing local surrogate method, but also reduces the computational cost substantially.

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Wentzel, Andreas, Maruf Hossain, Dimitri Stoppel, Nils Weimann, Viktor Krozer, and Wolfgang Heinrich. "An efficient W-band InP DHBT digital power amplifier." International Journal of Microwave and Wireless Technologies 9, no. 6 (March 14, 2017): 1241–49. http://dx.doi.org/10.1017/s1759078717000198.

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This paper presents for the first time high-efficiency W-band power amplifiers (PAs), the design of which follows the digital PA (DPA) design concept. Two DPAs with different output networks have been realized: a single-band version (S-DPA) for 95 GHz and a dual-band design (D-DPA) for signal frequencies fSof 68 GHz (first band) and 76 GHz (second band), respectively. The PAs are realized as monolithic microwave-integrated circuits (MMICs) in a 0.8 μm InP DHBT transferred-substrate process. They utilize a double-emitter-finger DHBT unit cell with an emitter area of 2 × 0.8 × 6 μm3each. In contrast to the usual W-band PAs, the proposed single-stage amplifier MMICs do not apply any special reactive matching for the transistor, which leads to very compact chip sizes of 0.27 mm2(S-DPA) and 0.39 mm2(D-DPA). The S-DPA includes one band-pass filter (BPF) at the output with 0.6 dB insertion loss (IL) and 24 dB input return loss (RL) at the signal frequency of 95 GHz. The dual-band BPF shows 0.7 dB IL in both bands with a RL of more than 21 dB each. Applying an overdriven sinusoidal input signal to emulate digital operation the DPAs achieve a maximum output power of 14.4 dBm and power-added efficiency of 31% when using the single-band configuration. Collector efficiencies of more than 80% and the flexible multi-band operation demonstrated prove the great potential of the digital PA concept for future high-speed communications.

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Chen, Bo, Yangyu Fan, Zhou Tian, Wuying Wang, Bochao Kang, Wei Jiang, and Yongsheng Gao. "An Ultra-Wideband Microwave Photonic Channelized Receiver with Zero-IF Architecture." Applied Sciences 10, no. 1 (December 19, 2019): 30. http://dx.doi.org/10.3390/app10010030.

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A scheme for realizing a zero-intermediate frequency (IF) channelized receiver using a dual-polarization quadrature phase-shift keying (DP-QPSK) modulator and a narrow-band optical filter is proposed. The channelized system only requires one optical frequency comb to achieve zero-IF multi-channel reception of wideband signals, and the spacing of the optical frequency comb only needs to be equal to the sub-channel width, which is very easy to implement. It is found that using photonic IQ demodulation and balanced detection and reception technology can not only eliminate many disadvantages of the traditional zero-IF receiver, including local oscillator (LO) leakage, direct current (DC) offset, even-order distortion, and in-phase/quadrature (I/Q) imbalance, but also reduce the bandwidth and sample rate of the analog-to-digital converter (ADC). It is theoretically proven that the radio frequency (RF) signal with a bandwidth of 3 GHz can be divided into five sub-channels with a bandwidth of 600 MHz and finally demodulated to I/Q basebands, which are also verified with simulation.

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Han, X., X. Li, G. He, P. Kumbhar, C. Montzka, S. Kollet, T. Miyoshi, et al. "DasPy 1.0 – the Open Source Multivariate Land Data Assimilation Framework in combination with the Community Land Model 4.5." Geoscientific Model Development Discussions 8, no. 8 (August 28, 2015): 7395–444. http://dx.doi.org/10.5194/gmdd-8-7395-2015.

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Abstract. Data assimilation has become a popular method to integrate observations from multiple sources with land surface models to improve predictions of the water and energy cycles of the soil-vegetation-atmosphere continuum. Multivariate data assimilation refers to the simultaneous assimilation of observation data from multiple model state variables into a simulation model. In recent years, several land data assimilation systems have been developed in different research agencies. Because of the software availability or adaptability, these systems are not easy to apply for the purpose of multivariate land data assimilation research. We developed an open source multivariate land data assimilation framework (DasPy) which is implemented using the Python script language mixed with the C++ and Fortran programming languages. LETKF (Local Ensemble Transform Kalman Filter) is implemented as the main data assimilation algorithm, and uncertainties in the data assimilation can be introduced by perturbed atmospheric forcing data, and represented by perturbed soil and vegetation parameters and model initial conditions. The Community Land Model (CLM) was integrated as the model operator. The implementation allows also parameter estimation (soil properties and/or leaf area index) on the basis of the joint state and parameter estimation approach. The Community Microwave Emission Modelling platform (CMEM), COsmic-ray Soil Moisture Interaction Code (COSMIC) and the Two-Source Formulation (TSF) were integrated as observation operators for the assimilation of L-band passive microwave, cosmic-ray soil moisture probe and land surface temperature measurements, respectively. DasPy has been evaluated in several assimilation studies of neutron count intensity (soil moisture), L-band brightness temperature and land surface temperature. DasPy is parallelized using the hybrid Message Passing Interface and Open Multi-Processing techniques. All the input and output data flows are organized efficiently using the commonly used NetCDF file format. Online 1-D and 2-D visualization of data assimilation results is also implemented to facilitate the post simulation analysis. In summary, DasPy is a ready to use open source parallel multivariate land data assimilation framework.

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Albergel, C., J. C. Calvet, P. de Rosnay, G. Balsamo, W. Wagner, S. Hasenauer, V. Naeimi, et al. "Cross-evaluation of modelled and remotely sensed surface soil moisture with in situ data in southwestern France." Hydrology and Earth System Sciences 14, no. 11 (November 3, 2010): 2177–91. http://dx.doi.org/10.5194/hess-14-2177-2010.

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Abstract. The SMOSMANIA soil moisture network in Southwestern France is used to evaluate modelled and remotely sensed soil moisture products. The surface soil moisture (SSM) measured in situ at 5 cm permits to evaluate SSM from the SIM operational hydrometeorological model of Météo-France and to perform a cross-evaluation of the normalised SSM estimates derived from coarse-resolution (25 km) active microwave observations from the ASCAT scatterometer instrument (C-band, onboard METOP), issued by EUMETSAT and resampled to the Discrete Global Grid (DGG, 12.5 km gridspacing) by TU-Wien (Vienna University of Technology) over a two year period (2007–2008). A downscaled ASCAT product at one kilometre scale is evaluated as well, together with operational soil moisture products of two meteorological services, namely the ALADIN numerical weather prediction model (NWP) and the Integrated Forecasting System (IFS) analysis of Météo-France and ECMWF, respectively. In addition to the operational SSM analysis of ECMWF, a second analysis using a simplified extended Kalman filter and assimilating the ASCAT SSM estimates is tested. The ECMWF SSM estimates correlate better with the in situ observations than the Météo-France products. This may be due to the higher ability of the multi-layer land surface model used at ECMWF to represent the soil moisture profile. However, the SSM derived from SIM corresponds to a thin soil surface layer and presents good correlations with ASCAT SSM estimates for the very first centimetres of soil. At ECMWF, the use of a new data assimilation technique, which is able to use the ASCAT SSM, improves the SSM and the root-zone soil moisture analyses.

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Albergel, C., J. C. Calvet, P. de Rosnay, G. Balsamo, W. Wagner, S. Hasenauer, V. Naeimi, et al. "Cross-evaluation of modelled and remotely sensed surface soil moisture with in situ data in Southwestern France." Hydrology and Earth System Sciences Discussions 7, no. 4 (July 6, 2010): 4291–330. http://dx.doi.org/10.5194/hessd-7-4291-2010.

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Abstract. The SMOSMANIA soil moisture network in Southwestern France is used to evaluate synthetic and remotely sensed soil moisture products. The surface soil moisture (SSM) measured in situ at 5 cm permits to evaluate synthetic SSM from the SIM operational hydrometeorological model of Météo-France and to perform a cross-evaluation of the normalised SSM estimates derived from coarse-resolution (25 km) active microwave observations from the ASCAT scatterometer instrument (C-band, onboard METOP), issued by EUMETSAT and resampled to the Discrete Global Grid (DGG, 12.5 km grid spacing) by TU-Wien (Vienna University of Technology) over a two year period (2007–2008). A downscaled ASCAT product at one kilometre scale is evaluated as well, together with operational soil moisture products of two meteorological services, namely the ALADIN numerical weather prediction model (NWP) and the Integrated Forecasting System (IFS) analysis of Météo-France and ECMWF, respectively. In addition to the operational SSM analysis of ECMWF, a second analysis using a simplified extended Kalman filter and assimilating the ASCAT SSM estimates is tested. The ECMWF SSM estimates correlate better with the in situ observations than the Météo-France products. This may be due to the higher ability of the multi-layer land surface model used at ECMWF to represent the soil moisture profile. However, the SSM derived from SIM corresponds to a thin soil surface layer and presents good correlations with ASCAT SSM estimates for the very first centimetres of soil. At ECMWF, the use of a new data assimilation technique, which is able to use the ASCAT SSM, improves the SSM and the root-zone soil moisture analyses.

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Savishnikov, Maksim O., Dmitry D. Dmitriev, and Eduard D. Kabanov. "Miniature Bandpass Microwave Filter with Ultradeep Suppression in a Wide Stopband." Journal of Siberian Federal University. Engineering & Technologies, November 2019, 758–64. http://dx.doi.org/10.17516/1999-494x-0175.

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The paper presents the results of a study of the design of a miniature band-pass filter based on multi-conductor strip resonators. Using the software for electrodynamic analysis, a sixthorder band-pass filter on seven-conductor resonators was designed and manufactured. Designed filter is characterized by small size and deep repression of the stop band. The measured filter characteristics exceed the characteristics of known analogs. The measured width of the highfrequency stop band of 24 times the center frequency of the bandwidth at the level of suppression at least 160 dB

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Molimoli Hajamohideen, Masood, and Sreeja Balakrishanapillai Suseela. "Compact multiple electromagnetic band gap (EBG) cells based ultra wide band (UWB) filter with improved stop-band characteristics." Circuit World ahead-of-print, ahead-of-print (January 11, 2021). http://dx.doi.org/10.1108/cw-11-2019-0169.

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Purpose The purpose of the study is – in Microwave filter design, the performances of passive components are deteriorated by parasitics at gigahertz (GHz) frequency range. A compact and multi-stack electromagnetic band gap (EBG) structure is proposed with improved stop band characteristics at GHz frequency range in this work. This paper proposes a new design for ultra wide band pass filter (resonator BPF) with periodically loaded one-dimensional EBG to achieve the harmonic suppression. This basic EBG structure is developed with combination of a signal strip and ground plane in the slotted section. The resonator BPF is loaded with one EBG, two EBG and three EBGs to improve the stop-band rejection. Design/methodology/approach The proposed filter is with multi-stack EBG cell for achieving good pass band and stop bands performance. Circuit model is analyzed in Section 2. Section 3 discuses band pass filter loaded with one EBG. In Sections 4 and 5, filter with two and three EBG loaded resonators are discussed, respectively. Section 6 is concluded with comparison of simulation and measured results. Findings The stop-band rejection is 20 dB, 40 dB and 50 dB, respectively, in the frequency range of 6 GHz to 20 GHz. The simulation analysis is carried out with advanced system design software. To validate the simulation results, proposed structure is fabricated, and results are found to be in good agreement. Originality/value This paper accounts for designing resonator BPF, which has slow wave pass band and stop band characteristics. Second and third harmonics are suppressed using multi-stack EBG. Various stacks with basic designs are proposed and improved results have been demonstrated which is open for future research.

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Journal articles on the topic 'Multi-band microwave filters'

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