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WOS: 000531764100019, In this paper, a new design of microstrip power limiter which is based on microstrip technology and zero bias Schottky diode is introduced. In this context, the FR-4 substrate that was characterized by dielectric permittivity (4.4), dielectric thickness (1.6 mm), and the HSMS 286k Schottky diode is used to design the proposed power limiter. The planar resonators are designed, optimized, and simulated with the shunting of the HSMS 286k diodes by using Schematic solver integrated in ADS from Agilent Technologies. The simulation results are significant in terms of high impedance matching, strong insertion of the low power, and good limitation ratio of the high power. The proposed power limiter is fabricated and tested in the measurement part. It is observed that the results are in agreement with the numerical analysis in terms of matching, isolation, and power limitation. The achieved microwave power limiter offers simple construction, small size (44 x 40 mm(2)), wide bandwidth, and good limitation ratio less than 10 dBm when the input power reaches 30 dBm.

Research of the design of a coupler with an operating frequency of 1.8 GHz has been conducted. This construction has a small area and can be used in microwave circuits for power division. Suggested construction, taking into consideration the reduced dimensions, has characteristics comparable to the design in the traditional version. Miniaturization of the device was achieved by using synthesized microstrip cells which were installed instead of ordinary sections. The coupler was modeled and fabricated and the measured characteristics are well coincide with the calculations.

In this letter, a dual-mode dual-band microstrip bandpass filter design with center frequency control methodology is presented by using dual-mode meandered loop resonator. Center frequencies of the passbands can be controlled by changing the connection points of internally located square loop loading elements without changing the total surface area. These loading elements are also useful to obtain a compact configuration. In addition, while the first passband has two reflection zeros, the second passband has one reflection zero, as it is obtained from the harmonic of the first passband. Therefore, degenerate modes of the first passband can be excited by a perturbation element. Using patch or corner cut perturbation elements, elliptical and linear phase filtering characteristics can be obtained in the first passband, respectively. Two dual-mode microstrip bandpass filters having elliptical and linear phase filtering characteristics were designed, fabricated, and measured. Measured results are in a very good agreement with the simulated results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:639–642, 2015

In this paper, a novel microstrip diplexer with tunable bandwidths and switchable channels is presented by using dual-mode square loop resonators (DMSLRs). Two resonators at different electrical lengths are coupled to input and output ports with lumped capacitors, and the isolation between the output ports is optimized by means of these capacitors. In order to obtain tunable bandwidth in each channel, varactor diodes are located at the orthogonal corners of the proposed resonators. In addition, the proposed resonators have reference patch elements at the lateral arms to provide convenience of varactor diode capacitances, such as perturbation elements. Depending on the capacitances of the varactor diodes, the bandwidths of each channel can be tuned. Furthermore, each channel can be switched off. The designed diplexer has two channels at the center frequencies of 1.8 and 2.6 GHz, which are allocated to 4.5G applications. Three-dB bandwidths can be tuned between 60 and 160 MHz for the first channel and between 150 and 350 MHz for the second channel. Isolation between the output ports is obtained as better than 18 dB in each channel. The designed diplexer was fabricated and measured, and the measured results were consistent with the predicted results. © TUBITAK.

In this paper, a compact design of a five-stub microstrip 3-dB coupler with significantly reduced overall dimensions has been developed and investigated. To downsize the conventional layout, artificial transmission line segments, whose characteristics are equivalent to quarter-wave segments at the frequency of 2000 MHz and its neighbourhood, were used. This enables to obtain an area of the compact coupler which is 83.15% less than the conventional one, with just 26.15 % reduction in the operating frequency band. © Published under licence by IOP Publishing Ltd. The author is grateful to National Instruments for providing the simulation software NI-AWR Design Environment. The research was executed by the grant of the Ministry of Education and Science of the Russian Federation (project № 8.2538.2017/4.6). The research was performed using the equipment of the Urals Federal University common use center. IEEE Antennas and Propagation Society (APS)

In this paper, a novel microstrip triplexer is designed by using meandered dual-mode loop resonators. Proposed resonators are coupled to input and output ports by means of lumped capacitors in order to simplify the coupling paths. Thus, feedlines for the input and three output ports are not required. Center frequencies of channels can be controlled depending on the electrical lengths of the resonators. The designed triplexer has three channels at 2.5 GHz, 2.8 GHz and 3.5 GHz and it has also been fabricated and measured to validate the proposed approach. Measurements are in a good agreement with the simulations. Insertion losses have been obtained as better than 3 dB at three channels and isolations between the output ports have been observed as better than 20 dB. © 2017 IEEE.

In this article, a novel dual-mode dual-band bandstop filter design with independently tunable center frequencies is presented by using dual-mode square loop resonators. Tuning operation can be achieved with a constant fractional bandwidth. Varactor diodes are used instead of perturbation and reference elements. Two dual-mode square loop resonators in different electrical lengths are coupled to a transmission line connecting input and output ports. Center frequencies of both stopbands can be independently tuned by changing the capacitances of varactor diodes of both perturbation and reference elements. While the perturbation and reference varactors tune even mode resonance frequency together, odd mode resonance frequency can only be tuned by reference varactors. The designed filter was also fabricated for the experimental studies and it exhibits acceptable tunability operations in measurements. Center frequencies of the first and second stopbands can be tuned between 2.2 and 2.54 GHz and between 3 and 3.38 GHz, respectively. Rejection levels for both stopbands were obtained as better than -13 dB in the whole tuning range. © 2017 Wiley Periodicals, Inc.

The article presents the ability of using low-pass filters for creating the miniaturized microstrip line based microwave devices. Numerical simulation and experimental research were made for branch-line hybrid coupler with 3 dB power division at 2000 MHz. Isolation bandwidth with the level of 20 dB is 745 MHz. Dimensions of the miniaturized device are 15.5 mm × 23.9 mm = 370.45 mm2, that is 66% less than of the conventional one. © 2016 IEEE.

Microwave (MW) radiometry is proposed for passive monitoring of kidney temperature to detect vesicoureteral reflux (VUR) of urine that is externally heated by a MW hyperthermia device and thereafter reflows from the bladder to kidneys during reflux. Here, we characterize in tissue-mimicking phantoms the performance of a 1.375 GHz radiometry system connected to an electromagnetically (EM) shielded microstrip log spiral antenna optimized for VUR detection. Phantom EM properties are characterized using a coaxial dielectric probe and network analyzer (NA). Power reflection and receive patterns of the antenna are measured in layered tissue phantom. Receiver spectral measurements are used to assess EM shielding provided by a metal cup surrounding the antenna. Radiometer and fiberoptic temperature data are recorded for varying volumes (10-30 mL) and temperaturesg (40-46�C) of the urine phantom at 35 mm depth surrounded by 36.5�C muscle phantom. Directional receive pattern with about 5 power spectral density at 35 mm target depth and better than 10 dB return loss from tissue load are measured for the antenna. Antenna measurements demonstrate no deterioration in power reception and effective EM shielding in the presence of the metal cup. Radiometry power measurements are in excellent agreement with the temperature of the kidney phantom. Laboratory testing of the radiometry system in temperature-controlled phantoms supports the feasibility of passive kidney thermometry for VUR detection. � 2010 IEEE.

Planar quasi-Yagi antennas including a printed balun are designed and experimentally characterised. The parasitic array driver is a folded dipole connected to a parallel stripline. The unbalanced to balanced transition between the input microstrip and the folded dipole terminals is obtained by linearly tapering both the microstrip and the ground plane widths. These printed antennas are more compact and directive than their counterparts based on resonant half-wavelength dipole drivers: indeed, in the presence of one director, the size of the board is about 0.4 λ0 × 0.5 λ0 and the measured gain is 7 dB.

Design of an X band horn antenna and a wideband unit element microstrip bandpass filter (UEBPF) for this antenna are presented with satisfactory agreement between theoretical and simulation results. Numerical methods known as real frequency techniques (RFTs) have been utilized in Richards domain to yield optimum driving point Darlington input impedance function belonging to the UEBPF that enables a maximum RF power transmission between the designed horn antenna and an RF driving source. Using a high precision Richards immittance synthesis package in Matlab, characteristic impedance values of each UE, out of k number of commensurate (equal length) transmission lines forming the UEBPF, is extracted from the input impedance function. Theoretical design (Matlab of Mathworks Inc.) and simulation (ADS of Agilent Inc., HFSS of ANSYS Corp.) results are shown to be very promising and in a high degree of agreement with each other. Publisher's Version

44th European Microwave Conference (EuMC) -- OCT 05-10, 2014 -- Rome, ITALY, WOS: 000392912200236, In this letter, design of a quad-band microstrip bandpass filter is presented by using nested placed four dual-mode square loop resonators (DMSLR) having different electrical lengths. Arms of the square loop resonators (SLR) are formed with low/high impedance parts, in order to obtain a maximum miniaturization by nesting DMSLRs and perturbation effects by changing the lengths of low impedance parts for the excitation of degenerate modes. Thus, the proposed configuration allows the control of mode frequencies, bandwidths and transmission zeros for each passband individually. Resonators are coupled to input/output (I/O) ports by feedlines having open-circuited stubs which suppress the harmonics. A dual-mode quad-band bandpass filter has been designed with an electrical length of 0.25 lambda(g) x 0.25 lambda(g) and fabricated, where lambda(g) is the guided wavelength at 1.79 GHz (the lowest resonance frequency). Measured and simulated results are in a good agreement., APS, European Microwave Assoc, IEEE MTT S, horizon house, Scientific and Technological Research Council of Turkey (TUBITAK) [112E041], This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant 112E041.

43rd European Microwave Conference (EuMC) -- OCT 07-10, 2013 -- Nuremberg, GERMANY, WOS: 000330768700010, A novel microstrip dual-mode bandstop filter with Coplanar Waveguide (CPW) fed structure is proposed by using a microstrip square loop resonator. Two types of coupling between the degenerate modes are described by changing the perturbation's sizes as in conventional ones. The difference between the proposed filters and conventional ones is resonator fed structures. In the proposed filter design method, CPW-fed structure is used to excite the degenerate modes of the resonator with degenere modes of the square loop resonator. Finally, two dual-mode bandstop filters are designed and realized with using degenerate modes of the microstrip square loop. It is shown that the size of the perturbation element determines the location of the reflection zeros of the filter according to the coupling type of the resonator., APS

A compact printed multimode antenna for Multiple-Input Multiple-Output (MIMO) systems is presented. The antenna consists of a slotted metallic ring antenna excited by four L-shaped microstrip feeding lines, which are necessary to generate four orthogonal radiating modes. The proposed antenna exhibits a performance similar to traditional antenna arrays in MIMO systems, and due to its compact size it is very suitable for mobile terminals or sensors. The Theory of Characteristic Modes is first used to identify the different radiating modes of the antenna and then a set of feeding configurations is proposed so as to excite these modes. A compact printed 2-stage network of 180° hybrid couplers is implemented to feed the proposed antenna. Measured S-parameters and radiation patterns confirm the excellent behavior of the proposed antenna.

ANN has a wide application areas. One of these applications areas is the optimization of microwave filters. In this study, of optimization ANN solution techniques have been applied to optimize RF and microwave structures Using Artificial neural networks (ANN) modeling technique in a filter design with the inset-feeding open-loop resonator is presented. With helping the Sonnet EM Simulator, to develop a new ANN model, the datas was produced. The modeling techniques which is in the Neuro Solutions Program were used for this process. The geometrical dimension of filter and coupling gap can be used to determine input output(I/O) relations of ANN model. As a result, for the -linear phase- microstrip filter, the results , which was obtained from the ANN model were compared with the experiment and simulation result. And provided a good agreement was observed.

Numerical study of a high impedance surface built in microstrip technology by using periodically arranged elliptical patches, grounded through one to four vias is presented. The effect of the variation of the number of vias manifests in different manner on the electromagnetic band gap aperture and position, as results from the parametric study in function of the patch dimensions and diameters of the vias. We show that stop bands cover a frequency range with limits in a ratio of 2.48∶1. The results are useful in the design of high impedance surfaces for various applications.

Artificial Neural Network computational modules have recently gained recognition RF and microwave modeling. This situation is very important for computer aided tuning of microwave components. Neural networks can be trained to learn the behavior of passive/active components/circuits. This paper presents a design approach for a microstrip dual mode filter by using the artificial neural network modeling (ANN) technique. First to develop new models available in the programs a simple modeling technique were used. To these end important dimensions of the filter layout are used to capture critical input output relationships. Once fully developed, the ANN model has been shown to be as accurate as an EM simulator and much more efficient results in the filter optimization.

Asia Pacific Microwave Conference 2009 -- DEC 07-10, 2009 -- Singapore, SINGAPORE, WOS: 000279924300227, This paper presents a new class of microstrip bandstop resonator filters. The folded open-circuited stub resonator located into microstrip loop structure is investigated using full-wave electromagnetic simulations. The utilization of the novel stub resonator allows a compact bandstop filter configuration to be realized. The proposed filter not only has a compact size, but also has a wider upper passband. Both simulated and measured results are presented to demonstrate the proposed filter., Scientific and Technological Research Council of Turkey (TUBITAK) [107E117]; Turkish Academy of Sciences (TUBA), This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant 107E117 and Turkish Academy of Sciences (TUBA).

Asia Pacific Microwave Conference 2009 -- DEC 07-10, 2009 -- Singapore, SINGAPORE, WOS: 000279924300235, A novel simple and understandable topology is proposed for dual-mode dual-band bandstop filters with asymmetric frequency response. Two microstrip square loop resonators are used to obtain the dual-band filter characteristic. Each resonator uses a perturbation element to excite dual-modes. Distinct characteristics of new filters are investigated using full-wave electromagnetic simulations. It is also found that there are five reflection zeros. Three of them are inherently associated with the proposed topology, whereas the other reflection zeros near stopbands are associated with the perturbation. They may be easily adjusted by changing the size of the perturbation element. Four dual-band filters using dual-mode resonators are demonstrated with different asymmetric responses, which result from different locations of adjustable reflection zeros. Both simulated and measured results are presented and exhibit dual-mode dual-band bandstop responses with high sharpness., Scientific and Technological Research Council of Turkey (TUB TAK) [107E117]; Turkish Academy of Sciences (TUBA), This work was supported by the Scientific and Technological Research Council of Turkey (TUB TAK) under Grant 107E117 and Turkish Academy of Sciences (TUBA).

An improved model for analyzing electrically small NRI-TL antennas is proposed, that highlights the methods that enable these antennas to offer a good impedance match and a high radiation efficiency compared to previously reported designs. An even-odd mode analysis reveals that the antenna supports a predominately even-mode current on the vertical vias, allowing the antenna to be modeled using a multiple folded monopole topology, which provides a substantial increase in the radiation resistance of the antenna. This, together with the top-loading effect of the microstrip line on the vias, enables the antenna to be matched to 50 Omega without the use of an external matching network, while maintaining a high radiation efficiency. The validity of the proposed model is confirmed with a fabricated prototype, that consists of four microstrip zero-degree NRI-TL unit cells with dimensions of lambda0/10 times lambda0/10 times lambda/20 over a 0.45lambda0 times 0.45lambda0 ground plane. The antenna's performance is verified by full-wave simulations and experimental data obtained at 3.1 GHz, which yield a vertical linear electric field polarization, a measured -10dB return-loss bandwidth of 53 MHz and a measured efficiency of 70%.