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In this paper, a circularly polarized metasurface antenna for microwave energy harvesting (MEH) is proposed. First, a 4 × 4 metasurface is analyzed and integrated with the microstrip slot based on characteristic mode analysis for broadband, low profile, and high gain metasurface antenna. The measured results show that the impedance bandwidth of the metasurface antenna is 1.82 GHz, the 3 dB axial ratio bandwidth is 0.96 GHz. Subsequently, a wideband rectifier for C‐band is fabricated and measured according complex impedance compression theory. The frequency of efficiency >50% is from 5.1 to 6.3 GHz with 17 dBm input power. Finally, the novel antenna and rectifier are connected as rectenna for MEH, which shows great potential due to the tunability of the polarization mode (right‐handed CP [RHCP]/left‐handed CP [LHCP]) and the flexibility of the structure. [ABSTRACT FROM AUTHOR]

A dielectric image line (DIL)‐based leaky wave antenna (LWA) with H‐shaped grooves is proposed in this paper. By periodically carving a set of H‐shaped grooves in the ground of the DIL, infinite space harmonics are excited, and the proposed antenna works with n = −1 order mode. The H‐shaped radiator can effectively eliminate open stopband (OSB). Over the operating band from 11.1 GHz to 15 GHz, the beam of the proposed antenna scans widely from −72° to 31° (including the broadside) with the realized gain from 9.7 dBi to 12.9 dBi. A prototype is fabricated and measured, which testifies the design theory and the simulation results. [ABSTRACT FROM AUTHOR]

Semiconductor devices are tested within a complex environment including a loadboard and a socket. In this paper, we propose a calibration methodology and a RF de‐embedding technique that allows the extraction of the device parameters. This method is based on the utilization of several calibration elements inspired by the TRL method. This study has been applied on an active device and the results have been validated using a real test solution. [ABSTRACT FROM AUTHOR]

This paper presents a directive quasi-Yagi antenna designed to ISM band application at 2.45 GHz. The directors application was analyzed, compared and the better performance antenna was manufactured. The obtained measured results presented an agreement with the performed simulations 1% error and bandwidth 27.39%, from 2.3 GHz to 3.03 GHz. [ABSTRACT FROM AUTHOR]

The microwave absorber is important in various applications and metamaterial shapes are noticed for multiband application. In this paper, we have developed a microwave absorber based on the broken cross with Jerusalem load for multiband application and in addition the prototype structure shows polarization independence for 0° to 60° incident wave angle. In this article, we have proposed and analyzed a microwave absorber based on the fractal broken cross with Jerusalem load in unit cells for multiband applications. This absorber is simulated with CST by FIT numerical method with periodic boundary condition and prototype structure have fabricated over FR-4 low cost substrate for dual band application and test in the chamber room. We have done parametric studies about the arms and parasitic elements on absorption manner and resonances. The current distribution shows that how the symmetrical shape is made uniform distribution and made independent of the incident wave polarization. As a result, the designed MA is useful for microwave application in medical imaging and communication systems. [ABSTRACT FROM AUTHOR]

ABSTRACT A microstrip diplexer that uses different types of resonant structures to exhibit four channels at two different outputs is presented in this paper. A procedure for synthesizing the diplexer with two dual-band filters having the required passband characteristics is also proposed. To reduce the interference between the filters at different outputs, the original structures of the dual-band filters are modified by inserting embedded impedance transformers at the inputs of the lumped-element resonators in the filters. Another component, working as an inductive compensation, is connected to the common input port to achieve the desired quad-channel characteristics when the filters with embedded impedance transformers cannot eliminate the interference between the channel filters. To verify the proposed design method, an experimental prototype with four channels located in commonly used wireless communication bands is fabricated on a commercial printed circuit board substrate. The diplexer is highly compact; the measured insertion losses of all passbands are <2.8 dB and the associated return losses are >15 dB in the desired passbands. The isolations between the four passbands of the two outputs are all >30 dB. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:883-888, 2017 [ABSTRACT FROM AUTHOR]

This paper describes a numerical-analysis methodology for RF characterization of various mesh reflecting surfaces used as the reflector surface of spaceborne antennas. Two mesh reflecting surfaces, which demonstrate different polarization characteristics, are studied. Because the mesh reflecting surface has a periodic weaving structure, periodic MoM with RWG basis and testing functions is applied, which allows only one periodic cell of mesh surface to be simulated. The analysis of transmission and reflection losses indicated that Single Satin mesh was much better than Single Atlas mesh, in terms of independence of transmission or reflection loss on polarization. This is because Single Satin mesh model has denser strips than the Single Atlas mesh model. Therefore, for any polarization direction, there is always at least one strip with its axis along or nearly along the incident electric field. The methodology and results presented in this paper are useful for accurate performance prediction of mesh reflector antennas. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 365–370, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21171 [ABSTRACT FROM AUTHOR]

This paper presents an improved subdomain multilevel approach (SMA), a technique efficiently used for solving large complex-shaped antennas printed in multilayered media structure. In a large electromagnetic problem, where the memory occupation and computational time have been already significantly reduced using the SMA, the calculation of the macro basis function (MBF) reaction terms remains the most time-consuming part of the procedure. In this paper, we present an efficient way of computing MBF reaction terms and reducing them to equivalent moments. The numerical results are compared with brute-force computations, the SMA, and the measurements. They demonstrate conclusively the efficiency and power of the new proposed technique. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 138–143, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20232 [ABSTRACT FROM AUTHOR]

In this paper we present some novel designs for conformal multiband antennas, based on fractal concepts, for application at three different frequencies. Although a whole host of conventional fractal type of monopole and dipole configurations have been designed in the past, they are not well suited for conformal applications. In this paper we describe a Sierpinski gasket type of fractal configuration, printed on a dielectric substrate backed by a ground plane, and propose a novel approach to enhancing its multiband performance, in terms of impedance matching characteristics as well as radiation patterns, at three operating frequencies. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 333–338, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10758 [ABSTRACT FROM AUTHOR]

A novel coaxial-fed E-shaped microstrip patch antenna is proposed in this paper. The proposed antenna is found to have a much broader impedance bandwidth as compared to the conventional U-slot antenna. An impedance bandwidth of about 33.8% is achieved for the proposed E-plane antenna. Through the use of a washer on the proposed antenna, the probe inductor is compensated, and an impedance bandwidth of 40% is thus obtained. The E-plane radiation pattern for both the proposed antenna and the one incorporated with the washer remains relatively constant through the band. A comparison between the U-slot antenna and our proposed antennas is made in the paper. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 348–352, 2000. [ABSTRACT FROM AUTHOR]

In a series of conference and journal papers [1–3], Mei has laid the foundation of the theory of Maxwellian circuits, which asserts that any wire structure, such as a thin wire antenna or a microstrip device, can be represented by an equivalent circuit, the solution of which is identical to the solution of the Maxwell equations of the structure. Such a circuit is said to be Maxwellian. This paper investigates the environmental effects of the Maxwellian circuit, in particular the role of the Green's functions of the integral equation. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 318–320, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20129 [ABSTRACT FROM AUTHOR]

In this paper, we present new types of tightly coupled lines using asymmetrical metallization thickness. A mode-matching method has been used to analyze this new structure and the simulation results are validated through comparison with the available results. The results in this paper show that the asymmetrical metallization thickness properties of coupled lines can be newly added to the design parameters to improve the tightly coupled characteristics of microwave applications. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 426–428, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11238 [ABSTRACT FROM AUTHOR]

This paper proposes an efficient high-gain multilayered antenna for wireless applications. The prototype antenna consists of a microstrip antenna which fed single or multiple parasitic patches fabricated on a low cost easily available FR4 superstrate. The patches on superstrate are suspended in air at an integral multiple of λo/2. The structured is designed, fabricated and tested. The measured VSWR [lt] 2 at 5.725–5.875-GHz frequency band. The proposed antennas with single parasitic patch provide 87% efficiency, SLL of -17 dB with an associated gain of 13.5 dB. The gain increases to 17.1 dB with three parasitic patches. The proposed structure can be packaged inside an application platform. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1923–1929, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23536 [ABSTRACT FROM AUTHOR]

In this paper, a new set of expressions are presented, which leads to accurate estimation of the mutual admittance and mutual coupling thereof for gap-coupled circular microstrip antennas. Unlike previous works, the field expressions for both the patches are obtained with respect to one coordinate system, and the circuit theory is used to obtain the admittance parameter. When this mutual admittance is converted to scattering parameters, we obtain the magnitude of mutual coupling. The results presented in the standard literature are compared with those obtained through the present formulation and the accuracy obtained is reasonably good. The method is also extended to incorporate the effects of shorting pins at the center of the two patches. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 924–927, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23251 [ABSTRACT FROM AUTHOR]

In this paper we study microstrip antenna miniaturization using partial filling of the antenna volume with dielectric materials. An analytical expression is derived for the quality factor of an antenna loaded with a combination of two different materials. This expression can be used to optimize the filling pattern for the design that most efficiently retains the impedance bandwidth after size reduction. Qualitative design rules are given, and a miniaturization example is provided where the antenna performance is compared for different filling patterns. Results given by the analytical model are verified with numerical simulations and experiments. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 155–159, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22066 [ABSTRACT FROM AUTHOR]

This paper proposed a novel design of tri-band (EGSM/GPS/PCS) antenna for mobile phone application. The measured data and detailed antenna configure are available, too. The measured results show the design is successful and applicable. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1347–1350, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21651 [ABSTRACT FROM AUTHOR]

An economical electronically-scanned patch antenna array with quasi-hemispheric coverage is under design in our laboratory for Inmarsat satellite communications. This paper reports the CAD simulation and test results of a simple-structured, electromagnetically-coupled patch antenna with circular polarization, for such array applications. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1279–1282, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21676 [ABSTRACT FROM AUTHOR]

This paper describes the design, fabrication, and measurement of a modified spiral-patch antenna with a shorting pin. The prototype consists of a modified spiral model and was made using the shorting-pin method. The prototype of the proposed antenna was designed to achieve triple-band operation at the 2.4- and 5-GHz bands. To obtain a sufficient bandwidth, a foam layer was inserted between the ground plane and the substrate. This is a microstrip antenna for IEEE 802.11a/b WLAN application. The simulated and measured results for the impedance bandwidth, radiation pattern, and gain are presented and discussed herein. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1275–1279, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21675 [ABSTRACT FROM AUTHOR]

In a distributed Bragg reflector (DBR) laser, driving currents in the tri-electrode are adjusted to generate various channels in the ITU-Band. Many driving-current combinations can generate the same ITU channel. But when we take system performance into consideration, such as the chirping and the switching time when we switch DBR lasers between ITU channels, certain current combinations will generate better system performance than the others. In this paper, we develop the principle of how to select current combinations in order to obtain better system performance and also discuss the method of how to evaluate the system performance when different current combinations are selected. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1417–1423, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21643 [ABSTRACT FROM AUTHOR]

The purpose of this paper is to report on a microstrip reconfigurable antenna in the millimeter-wave range. This antenna has directivity diversity and is based on a four-element array. An original method is outlined to guarantee matching for each configuration without changing circuit. Great results have been achieved with a passive prototype and an active antenna is under consideration. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1190–1194, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21569 [ABSTRACT FROM AUTHOR]

In this paper, a novel patch-slot-patch (PSP) structure is presented. The frequency-resonant characteristics of this structure are calculated and measured. Gain enhancement of 15 dB is obtained for a PSP structure as the superstrate of a microstrip patch antenna. A grating-lobe reduction of more than 16 dB is observed for a PSP structure applied over a 3 × 1 linear array. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 902–906, 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21513 [ABSTRACT FROM AUTHOR]

A double-layer rectangular patch microstrip antenna suitable for Bluetooth applications is investigated. The patch is etched on a separate substrate which is suspended above the ground plane and supported by an MCX connector. The air gap between the patch and the ground plane increases the impedance bandwidth and can be used to tune the resonant frequency. This paper presents experimental results on the effects of various parameters on the antenna characteristics and provides guidelines for the design of such an antenna. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 683–686, 2006; Pubished online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21442 [ABSTRACT FROM AUTHOR]

The paper contains an investigation of microstrips with finite-width ground plane. The conformal mapping method and a new method of the so-called moving perfect electric wall (MPEW) are used to obtain simple analytical relations for quasi-TEM parameters. The computed results are compared with available data from other authors obtained through various numerical methods. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 396–399, 2006; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/mop.21361 [ABSTRACT FROM AUTHOR]

In this paper, a new microstrip stepped-impedance hairpin resonator (SIR) low-pass filter (LPF) using a defected ground structure (DGS) is proposed. The proposed SIR hairpin low-pass filter using DGS provides a very sharp cutoff frequency response with low insertion loss. Furthermore, the SIR hairpin low-pass filter can provide attenuation poles for the wide-stopband characteristic due to the resonance characteristic of the DGS. Design parameters for the SIR low-pass filter are derived based on stepped-impedance theory and the equivalent-circuit model for the DGS. The experimental results show excellent agreement with the theoretical simulation results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 405–408, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21364 [ABSTRACT FROM AUTHOR]

Suppression of surface waves propagating in a grounded dielectric substrate slab can be achieved by using electromagnetic band-gap (EBG) substrates. In this paper, a 2D-planar EBG substrate is investigated experimentally and simulated by a simple method based on the chain-matrix conversion. Good agreement between the measured and simulated results is observed. We also show that other defect modes can appear in the band gap, and explain their existence by the finite size of the EBG structure under investigation. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 144–150, 2006; Published onlinePublished online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21289 [ABSTRACT FROM AUTHOR]

Different methods to increase the bandwidth of a microstrip antenna, such as use of an air-gap in-between stacked resonators and the ground plane and planar multiresonators, are combined to achieve broad bandwidth with increased gain. A configuration with two gap-coupled circular microstrip antennas on the top dielectric layer stacked with one coaxial-fed circular patch on the bottom layer and an air-gap in-between two layers and the ground plane yield a bandwidth of 1093 MHz (47%) with a gain of 9.54 dB at the S-band frequency of 2.325 GHz. Also, dual-band response with broadside radiation and improved gain at both frequencies is achieved by suitably changing parameters of this configuration. Parametric studies of this configuration on dielectric substrate for both broadband and dual-band operation are presented in this paper. The experiments are performed on broadband and dual-band configurations, which are in agreement with the theoretical results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 489–494, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21208 [ABSTRACT FROM AUTHOR]

A wideband pentagon-slot microstrip antenna with a semicircle probe feed is proposed. The broadband characteristic is achieved by cutting a pentagon slot at each corners of the patch. The proposed antenna is able to achieve an impedance bandwidth of 68.3% for a VSWR of less than 2. Experimental comparison with a similar-size retangular microstrip patch antenna has also been conducted in this paper. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 500–505, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21211 [ABSTRACT FROM AUTHOR]

This paper presents an improved approach to predicting the far fields for infinite planar structures using the finite-difference time-domain (FDTD) techniques. We have found that the equivalent magnetic current decays much faster than the electric current on the surface of the Huygens' box above the patch antenna due to the presence of the PEC ground plane. Hence, we suggest that the equivalent principle and image theory should be applied to calculate the far field using only the equivalent magnetic current to reduce the size of the computational domain. The example of a single patch antenna and a patch-antenna array are employed to validate the proposed approach. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 338–343, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21164 [ABSTRACT FROM AUTHOR]

A novel design of double-ring slot antenna with tree-shaped coupling strip for 2.4/5-GHz dual-band applications is presented in this paper. Two concentric slot rings are proposed in order to determine the certain resonated frequencies of two desired bands (5.20–5.55 and 5.55–5.80 GHz) and the inner circular disk depicts the range of 2.27–2.51 GHz. A tree-shaped coupling strip is designed with branches to couple the inner circular disk and with leaves to couple the double ring slot, respectively; therefore, it can simultaneously enhance the bands' responses using impedance-matching techniques. This is a compact microstrip antenna for IEEE 802.11a/b WLAN applications. The simulated and experimental results for the frequency responses, radiation patterns, and current distributions are presented and discussed. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 374–379, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21173 [ABSTRACT FROM AUTHOR]

A novel method, the finite-element method (FEM) using Fourier series as the interpolating function, is presented in this paper for calculating the quasi-static characteristics of coupled cylindrical striplines and microstrip lines filled with multilayered dielectrics. This method is very similar to the normal FEM, but has a much lower-order matrix equation, smaller computational contents, and higher accuracy. It is simpler and more flexible for application than the conformal transformation method. Compared with the integral-equation and spectral-domain methods, this new method is more obvious with regard to its physics and, also, it is not involved in the difficult task of selecting the base functions and relative convergence. The numerical results shown here for several examples are in good agreement with those in the references. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 265–270, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21143 [ABSTRACT FROM AUTHOR]

This paper presents the design and results of a novel broadband dual-polarized circular patch antenna. The antenna is fed by microstrip lines through proximity coupling, and H-shaped slots are cut in the ground plane below the feed lines for enhancing the coupling between the patch and the feed lines. By using only a single circular microstrip patch, the prototype antenna yields bandwidth of 21.5% and 25.9% at the input ports 1 and 2, respectively. The isolation between two input ports is below -30 dB across the bandwidth. Good broadside radiation patterns are observed, and the cross-polar levels are below -20 dB at both E- and H-planes. Due to its simple structure, it is easy to form arrays by using this antenna as an element. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 298–302, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21151 [ABSTRACT FROM AUTHOR]

A microstrip patch antenna with a 2D multiperiod electromagnetic band gap (EBG) sandwiched between the patch and the ground plane is proposed and studied in this paper. The proposed models are assessed using finite-difference time-domain (FDTD) simulations and experimental measurements. The simulated and measured results show that, with the sandwiched multiperiod EBG structure, the microstrip patch antenna can achieve wider impedance bandwidth and higher gain than the sandwiched single-period EBG structure. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 437–440, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21010 [ABSTRACT FROM AUTHOR]

Design and development of a photonic bandgap (PBG)-assisted shared-aperture dual-band orthogonal aperture-fed rectangular microstrip patch antenna element, which is suitable for a portable very small aperture terminal (VSAT), are presented in this paper. The dual-band dual-polarized antenna element achieves 21% input impedance bandwidth at the S- and C-bands. A comparison of the antenna with and without 2D PBG grids shows that the inclusion of PBG structures (PBGSs) improves the antenna performances. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 289–292, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20968 [ABSTRACT FROM AUTHOR]

The novel design of a T-coupled circular microstrip antenna with H-shaped aperture for active reflectantenna application is presented in this paper. The circular patch determines the frequency resonated; the H-shaped aperture is used to obtain the responses of the desired 2.4–2.48 GHz ISM band and the T-coupled feed line enhances the response of the band using the impedance-matching technique. Meanwhile, the dual-polarized ports of the T-coupled microstrip antenna are developed for the active reflectantenna and applied to a corner-wall structure. The antenna is capable of achieving high-directivity gain, wide bandwidth, high isolation, and low cross-polarization levels. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 120–125, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20919 [ABSTRACT FROM AUTHOR]

In this paper, a variable-width meander-slot antenna fed by CPW is proposed for the use in miniaturized personal-communication devices. By optimizing the slot width of the antenna, we design a uniplanar antenna that is 8% to 12.3% of the size to a conventional rectangular microstrip patch antenna. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 188–191, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20940 [ABSTRACT FROM AUTHOR]

This paper presents the measured reflected phase-variation curves for microstrip-patch elements of variable size, which form the most essential part in the design of a reflectarray antenna. A waveguide simulator exploiting the concept of infinite array is successfully implemented in the characterization of reflected phase, which avoids the need for large arrays for the empirical design of an element. A set of seven microstrip-array samples, each consisting of three square elements of the same size designed at 10 GHz, is measured. A comparison of the simulations using the finite-element method and the measured results shows good agreement. The phase variation is in the range of +167° to -178° for a patch-size variation of 5.5 to 13 mm. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 528–531, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20869 [ABSTRACT FROM AUTHOR]

This paper presents a novel, compact, low-insertion-loss, sharp-rejection, wideband microstrip bandpass filter. The filter is based on a ring resonator with direct-connected orthogonal feed lines, and uses two stepped-impedance open stubs to construct a wideband passband with two sharp stopbands. The unit cell of the ring resonators is easily cascaded and also has the feature of a compact structure. The filter is designed to reduce interference in full-duplex systems for satellite communications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 312–315, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20807 [ABSTRACT FROM AUTHOR]

An inverted microstripline-fed linear tapered slot antenna element and a design of its 16-element E-plane array are presented in this paper. The element is designed using the finite-difference time-domain (FDTD) method. The calculated results show that it has a wide-impedance bandwidth in the K-band. To investigate the E-plane array, the return loss at each element input port, the couplings among elements, and the array's radiation patterns are obtained using the FDTD method. Using a unique three-piece assembled structure, the array is fabricated and tested experimentally. The measured results show that it has a wide bandwidth and antenna efficiency. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 241–246, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20784 [ABSTRACT FROM AUTHOR]

Parallel coupled-line bandpass filters using the ground-aperture technique are analyzed in this paper. A design guide and design curves for this kind of coupled-line bandpass filter on commonly used high- and low-permittivity substrates are presented. Based on the proposed design curves, two sample bandpass-filter configurations are designed. The design is simulated using Ansoft HFSS and validated by the measurements. Good agreement between the simulated and measured responses is obtained. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 237–240, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20781 [ABSTRACT FROM AUTHOR]

This paper proposes a harmonic-suppression technique for a square microstrip-antenna design. In this study, the possible resonance at the 2nd and 3rd harmonic frequencies were effectively suppressed by adding loads to the antenna's feeding line, and the antenna performances for fundamental-mode operation were well retained. The design and experimental results are discussed and simple design principles for harmonic suppression of the proposed antennas are presented. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 379–383, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20641 [ABSTRACT FROM AUTHOR]

In this paper, we investigate the theoretical behavior of microstrip antennas on tapered ferrite substrates. A full-wave analysis in the spectral domain is developed to provide antenna bandwidth enhancement as a function of linear variations in the substrate-height profile that supports the patch. The results for the main parameters are presented. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 289–292, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20613 [ABSTRACT FROM AUTHOR]

A cross-shaped microstripline-fed printed slot antenna with wide bandwidth is presented in this paper. The proposed antenna is analyzed using the finite-difference time-domain (FDTD) method. It was found that the bandwidth of the antenna depends highly on the characteristics of the proposed antenna, which depend highly on the design parameters (ls, Ws, offset,lu, and ld). We also compare the optimized offset/Ws ratio and the calculated bandwidth of RT-5880 substrate for slot width Ws. When Ws is 32 mm, the optimized offset/Ws ratio is 0.344, and the calculated bandwidth is 3.744 MHz (112.6%). The experimental bandwidth of this antenna is from 1.85 to 5.70 GHz, which is approximately 115.5%, for VSWR ≤ 2.0. The proposed antenna showed triresonance characteristics due to the wide bandwidth. Experimental data for the return loss and the radiation pattern of the antenna are also presented, and are in good agreement with the FDTD results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 162–165, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20576 [ABSTRACT FROM AUTHOR]

In this paper, we introduce a novel design for a high-directivity Electromagnetic Band Gap (EBG) resonator antenna that utilizes a frequency-selective surface (FSS) superstrate. The above type of superstrate is proposed as an alternative to an EBG type of dielectric superstrate—investigated previously by the authors—to reduce its height and facilitate the fabrication process. Although FSS superstrate and the patch antenna comprise a composite resonator, we begin by investigating the FSS structure characteristics first before dealing with the combination. We vary several important parameters, such as the distance between the FSS superstrate and the ground plane of the antenna, and the dimensions of the FSS superstrate, to determine their effect on the resonant frequency and the quality factor of the unit cell of the FSS. The above study enables us to derive some guidelines for an optimum array size of the FSS superstrate that eventually leads to a maximum directivity for the FSS antenna composite, as evidenced via a comparison of the quality factors of the FSS, the unit cell, and the composite. It is demonstrated that the directivity of the antenna with an optimized array size of the FSS superstrate increases by 17.29 to 24.92 dBi for three different strip-dipole lengths, as compared to that of the patch antenna alone (maximum 6 dBi). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 462–467, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20502 [ABSTRACT FROM AUTHOR]

In this paper, we describe a fixed-beam broadband planar antenna array at millimeter-wave frequencies. The antenna is fed by waveguide-feed and microstrip-feed networks. In order to ensure fixed beams and a broad bandwidth, a subarray concept is introduced. For efficient coupling, a novel waveguide-to-slot transition consisting of a slot pair and a narrow conductive bar is proposed. Simulated and measured bandwidth is found to be more than 7.1% from 40.5–43.5 GHz. The main beam directions are broadside over all frequencies. The maximum measured antenna gain is 30.2 dBi at 42.0 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 283–287, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20279 [ABSTRACT FROM AUTHOR]

In this paper, we propose a new dual-band antenna for applications of the ISM band. The proposed antenna is designed to operate at 2.4 and 5.8 GHz. The lower-frequency band (2.4 GHz) can be obtained by using the meandering technique, and the upper-frequency band (5.8 GHz) for dual-band operation was achieved by embedding a backed microstrip line. Details of the proposed antenna design and experimental results are presented and discussed. The measured radiation patterns at 2.4 and 5.8 GHz and antenna gain across the respective frequency bands are also presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 457–460, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20170 [ABSTRACT FROM AUTHOR]

In this paper, a microstrip filter has been designed, fabricated, and measured for application in ultra-wideband antennas. By using the combination of a band-stop filter and a low-pass filter, the band-selective characteristics can be demonstrated. In order to enhance the suppression of the out-of-band signals, a defected ground structure (DGS) with stopband performance is used. The passband responses of the filter, which range below 2.8 GHz and from 5.0 to 6.0 GHz, cover most commercial wireless communication systems. The LC-lumped equivalent circuit of the filter has been extracted and simulated by using transmission-line analysis. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 248–251, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20107 [ABSTRACT FROM AUTHOR]

This paper presents a new fundamental single-balanced ring mixer incorporating T-shaped compact microstrip resonant cells (TS-CMRCs). The measured minimum single side-band (SSB) down-conversion loss of 3.3 dB is achieved for a 10.4-GHz RF signal and is better than 6 dB from 9.6–11.5 GHz with a 0.1-GHz IF. In addition, our working prototype demonstrates an excellent linearity response, in which the third-order intercept point (IP3) is 17 dBm with a spurious free-dynamic range of more than 55 dB. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 206–209, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20095 [ABSTRACT FROM AUTHOR]

This paper deals with the 3D modeling of the photo-induced load created by a laser that illuminates a semiconductor substrate. This independent optical command allows us to change the microwave behavior of the microstrip device. We present a 3D-equivalent microwave model for the photo-injection in terms of equivalent conductivity plasma. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 356–359, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11380 [ABSTRACT FROM AUTHOR]

The mutual coupling between rectangular microstrip patches mounted on a spherical structure is studied in this paper. The analysis approach is based on the spectral-domain method of moments (MoM). An approximate method is developed to calculate coupling between currents located on different patches. A laboratory model is built to test different configurations of patches and to validate the calculated results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 387–391, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11389 [ABSTRACT FROM AUTHOR]

This paper describes the thin-film fabrication process and the performance of 60-GHz aperture-coupled microstrip patch antennas printed on fused quartz substrates. It is shown that their characteristics (input impedance, axial ratio) are strongly modified by residual air gaps located between the two substrates of the antenna. In particular, FDTD simulations demonstrate that these parasitic effects can be minimized by using two ground/reflecting planes and by keeping the thickness of the air layer thinner than λ0/250, where λ0 is the free-space wavelength. To face this technological problem, two intermediate metal and adhesive (low-temperature) wafer bonding techniques, respectively based on indium and polymer layers, have been developed and validated experimentally for linear and circular polarization patch antennas and arrays. The lift-off fabrication process is also described. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 41–47, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11281 [ABSTRACT FROM AUTHOR]