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This paper presents unequal microstrip power divider designs using the hierarchal genetic algorithm (HGA). The dividing ratio and return loss are the design specifications leading the evolution direction. By employing the HGA chromosome formulation, the system structure and its associated parameters can be minimized in a simultaneous manner. The computational performance of the design methodology is enhanced with the use of a parallel computing platform. The subsequent power dividers derived from the design have been fabricated, tested, and experimentally verified. Its performance matches very well with the result obtained from the simulation study. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 421–423, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10937 [ABSTRACT FROM AUTHOR]

This paper proposes a novel structure called a compact coplanar waveguide resonant cell (CCRC), which can exhibit slow-wave and bandstop characteristics by only one single unit. The same pattern has been adopted in the compact microstrip resonant cell (CMRC) as reported previously and here is applied to CPW with both infinite and finite ground planes. Experimental results show quite good agreement with simulations. By alternating the slot width of the CCRC section from that of normal CPW, good transmitting characteristics can be achieved at a passband of low frequency. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 408–410, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10933 [ABSTRACT FROM AUTHOR]

Two novel low-pass filters (LPFs) of wide stop-band are proposed in this paper. One filter is implemented by a photonic band-gap (PBG) microstrip structure with T-junction opened stubs and its frequency characteristics are discussed. The other filter is implemented by a PBG microstrip structure with cross-junction opened stubs. The new wide-band harmonic rejection LPFs are easy to design and fabricate. The simulated and experimental results verify the validity of the LPFs. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 470–472, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10953 [ABSTRACT FROM AUTHOR]

In this paper, the genetic algorithm (GA) has been applied to calculate the optimized length and width of rectangular microstrip antennas. The inputs to the problem are the desired resonant frequency, dielectric constant, and thickness of the substrate; the outputs are the optimized length and width. The antennas considered are electrically thin. Method of moments (MoM)-based IE3D software from Zealand Inc., USA, and experimental results are used to validate the GA-based code. The results are in good agreement. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 431–433, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10940 [ABSTRACT FROM AUTHOR]

In this paper, a novel linear dual-polarized stacked microstrip antenna that operates well within the ISM band (2.40–2.4835 GHz) for Bluetooth applications is experimentally presented. The square patch of the microstrip antenna is fed diagonally by a microstrip line. Another square patch with a superstrate is stacked above the corner-fed patch in order to increase the operating bandwidth. The impedance and radiation characteristics of the optimized antenna configuration are presented, with variations of the sizes of the top and bottom patches and the spacing between the patches. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 364–366, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10919 [ABSTRACT FROM AUTHOR]

This paper proposes a novel compact dual-slot antenna for 5-GHz WLAN applications. The prototype comprises a rectangular slot, a H-shaped slot, and an open-circuited microstrip feed line. The simulation and experimental results indicate broad operating bandwidth from 4.9 GHz to 6.3 GHz at 10-dB return loss and 3-dBi gain. The proposed antenna is compact, easy to fabricate, and inexpensive, and it presents good broadband characteristics that cover all 5-GHz WLAN bands. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 311–313, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10904 [ABSTRACT FROM AUTHOR]

In this paper, a new type of slow-wave 1D PBG microstrip band-pass filter with a half-wavelength linear resonator is introduced. Reduction of the central frequency (slow-wave effect) is over 50%, as compared to the conventional band-pass filter of the same type. Additional coupling is over tuning narrow lines that can be used to regulate the filter's performance. In addition, it has very good S11 parameters and low losses in the band-pass. Simulation and experimental results are in good agreement. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 201–203, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10868 [ABSTRACT FROM AUTHOR]

In this paper, we analyze a patch fed by a hybrid system microstrip-coplanar waveguide. The proposed feeding structure allows us to design an antenna with a significant reduction of the back-radiation especially in the broadside direction. The analysis is made using the MPIE formulation of the method of moments (MoM). © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 481–483, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10796 [ABSTRACT FROM AUTHOR]

This paper describes the design, fabrication, and measurement of a sequential-rotation microstrip-array antenna for the Electronic Toll Collection System (ETCS). The ETCS is made possible by using roadside equipment with a radiation pattern that can accurately pinpoint the designated communication area, without interference from other lanes. The sequential-rotation microstrip-array antenna is designed and applied to the absorber to reduce the side lobe level (SLL) for the ETCS antenna. Results show that the antenna yields a return loss at a center frequency of -20.675 dB, an axial ratio of 1.15 dB, and a gain of 20.26 dBi. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 77–79, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10678 [ABSTRACT FROM AUTHOR]

A new stacked microstrip antenna structure that enhances the bandwidth without changing the resonance frequency is proposed and studied in this paper. The effect of the various antenna parameters on the bandwidth is investigated. The resulting antenna, using the proposed structure, has an ultra-wide bandwidth of 35%, compared to 21.8% for the conventional stacked antenna structure. The proposed structure has little effect on the antenna's radiation characteristics. The analysis of the proposed structure is carried out using the FDTD method. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 26–28, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10660 [ABSTRACT FROM AUTHOR]

This paper presents a two-arm microstrip spiral antenna with a circular aperture on the ground plane that produces either an axial beam or a tilted beam, depending on the operating frequency. A 50-Ω microstrip feedline is divided into two 100-Ω lines that feed the spiral antenna from the outer end of the spiral arms with a 180° phase difference at fo. The antenna is realized on a planar form without any balun circuit using a microstrip structure, which is easily compatible with millimeter- and microwave-integrated circuits. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 453–455, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10636 [ABSTRACT FROM AUTHOR]

How to extract equivalent circuit parameters from full-wave results is becoming an increasingly important aspect of microstrip filter design. In this paper, a microstrip low-pass filter that is made of six stubs is analyzed by a novel differential equation whose coefficients are determined from full-wave numerical solutions. In comparison with the conventional nonuniform transmission line equation, the novel differential equation has two additional terms—dependent series voltage and shunt current sources—which represent local radiation effect from discontinuities of the nonuniform transmission line itself. A whole structure of the above microstrip low-pass filter can be regarded as a special case with a finite-length non-uniform transmission line. Thus, the novel differential equation can be used to analyze this kind of microstrip low-pass filter. The novel differential equation established at a frequency of 10 GHz could cover a very wide frequency range from 6 GHz to 15 GHz. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 368–370, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10609 [ABSTRACT FROM AUTHOR]

In this paper an array of four shorting post loaded square microstrip antennas (SMSA) in a cross fashion yielding conical as well as broadside radiation pattern is presented. Each element of the array is loaded with two shorting posts. The elements when fed with equal amplitude and phase yield a conical beam. A linearly polarized (LP) broadside pattern is obtained when two elements of the array, along either of the axis is fed with equal amplitude but a phase difference of 180° while a circularly polarized (CP) broadside pattern is obtained when all the elements of the array are fed with a phase difference of 0° -90° -180° -270°. Experimental and simulated results are presented and are in agreement. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 97–99, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10527 [ABSTRACT FROM AUTHOR]

A new method of using artificial neural networks (ANNs) for the calculation of the input impedance of rectangular microstrip patch antennas has been adopted in this paper. The results obtained using ANNs are compared with the experimental findings, theoretical values, and with the simulation results obtained using an IE3D package. The ANNs result are more in agreement with experimental findings. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 381–383, 2002. [ABSTRACT FROM AUTHOR]

This paper describes a wire-patch air-filled antenna, made up of two metallic stacked plates and center fed by a coaxial probe. This radiating element, which uses the original resonance phenomenon due to the presence of wires between the ground plane, the first and the second metallic stacked patches, has a wide bandwidth. This antenna also works like a short monopole for frequencies located below the fundamental cavity resonance mode, and close to the GSM frequency band. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 323–325, 2002. [ABSTRACT FROM AUTHOR]

A printed microstrip window antenna is proposed in this paper. The window antenna is obtained by perforating a conventional microstrip patch antenna into a window-like geometry. This perforation not only induces a size reduction of more than 50%, but also makes it possible for antenna and RF circuits to be integrated into a unified subsystem by embedding passive and active circuits into the windows of the antenna. The 10 dB return-loss bandwidth of the window antenna is 1.7%, with a gain of 3.7 dBi. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 192–194, 2002. [ABSTRACT FROM AUTHOR]

In this paper, a broadband 20×20 microstrip antenna array is presented. Once a rectangular microstrip patch antenna with parasitic patches as an element antenna has been optimized at 24.2–26.7 GHz, a parallel-series feed network with minimum feed lengths can be utilized to combine element antennas. From simulation and measurement, the array antenna yields relatively high gains of 26.0–30 dB and narrow 3 dB beamwidths of 4.5–5.1° in the H-plane and 4.1–7.1° in the E-plane, respectively, in an LMDS band. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 35–37, 2002. [ABSTRACT FROM AUTHOR]

A novel small microstrip patch antenna with a C-shaped slot is presented in this paper. The size of the antenna is only 33% of a conventional microstrip patch antenna, and is much easier for fabrication than shorted patch antennas. The antenna is theoretically investigated using the finite-difference time-domain (FDTD) method, and its return loss and radiation properties are presented. For purposes of comparison, method-of-moment (MoM) results are also presented, and good agreement is achieved. Such an antenna may be useful for applications where reduced antenna size and simplicity are major concerns. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 170–172, 2001. [ABSTRACT FROM AUTHOR]

This paper presents a very wideband circular polarization (CP) design of a single-layer probe-fed circular microstrip antenna. Two gap-coupled probe feeds having a concentric annular slot in the radiating patch to tune out the probe inductance are used. The two feeds are placed in orthogonal directions, and are connected to a Wilkinson power divider having a 90° phase shift between its two outputs. The present CP design with a thick air substrate has been implemented, and results show that a 65% impedance bandwidth (VSWR≤2) and a 46% 3 dB axial-ratio CP bandwidth can be achieved. Within the CP bandwidth, the gain bandwidth, defined to be within 3 dB of the peak antenna gain obtained (about 6 dBi), is as large as 44.6%. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 74–76, 2000. [ABSTRACT FROM AUTHOR]

This paper presents an electronically tunable microstrip patch antenna with improved radiation characteristics. The directive gain of the antenna is improved by as much as 5.5 dB, by the addition of a high dielectric superstrate, with a thin air gap interspersed between the dielectric layers. Three different high-dielectric sheets have been tested, and it is observed that the gain improvement is the maximum for the highest dielectric. The air gap is experimentally adjusted to optimize for the best gain of the antenna, without degrading its input characteristics. The total addition to the thickness is only 3.2 mm for an antenna operating at about 850 MHz. The resonant frequency of the antenna shifts toward low with the addition of the superstrate layers. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 368–370, 1999. [ABSTRACT FROM AUTHOR]

Coplanar waveguides nowadays are successfully used to feed printed antennas. This technique is very interesting for antenna arrays. However, the complete system involves the association of several microwave functions, essentially power divisions and phase shifts, which are easier to implement in microstrip technology than in CPW technology. In order to match these requirements, this paper presents some compact and easy to realize microstrip/CPW transitions. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 131–133, 1999. [ABSTRACT FROM AUTHOR]

This paper presents a new, compact, dual-frequency design of single-feed circular microstrip antennas with an offset circular slot placed close to the patch boundary. It is found that, when the radius of the offset slot is about 0.38–0.62 times the radius of the circular patch, dual-frequency operation can be achieved using a single probe feed. The two operating frequencies have orthogonal polarization planes, and have a low frequency ratio of about 1.15–1.18. The two frequencies can also be much lower than the fundamental resonant frequency of a corresponding simple circular patch antenna without the offset slot. This behavior makes the proposed antenna have a reduced antenna size as compared to a simple circular patch antenna operated at either one of the two frequencies. Details of the antenna design and experimental results are presented. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 254–256, 1999. [ABSTRACT FROM AUTHOR]

In this paper, we present the characteristics of circular polarization of an elliptical microstrip patch fed by a coaxial probe through the method of moments in conjunction with the reaction integration method. After obtaining the general Green's function, the input impedance was calculated by superposition of two circular patches whose radii pertain to the major and minor axes of the elliptical patch, respectively, and then the characteristics of circular polarization are shown. The attachment mode was contained to ensure the continuity and singularity of the currents at the patch–probe conjunction point, and plays a role in accelerating the convergence for solving matrix equations. Results showed that the elliptical patch can be used to generate circular polarization characteristics with one probe feed, and attachment modes also should be contained in the formulation to obtain the exact impedance. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 111–113, 1999. [ABSTRACT FROM AUTHOR]

This paper deals with millimeter-wave microstrip antenna arrays. The objectives were to develop and optimize a microstrip-to-thick-slot-line transition near 40 GHz, and to feed a printed array with this kind of transition. The influence of such a transition between the two layers, and its effect on the radiation properties (pattern symmetry, sidelobe level) have been checked. A study of the microstrip/thick-slot/microstrip transition is first presented. Then, a comparison is made between radiated fields of arrays fed directly and through slot transitions. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 51–53, 1999. [ABSTRACT FROM AUTHOR]

An original theoretical approach for antenna optimization and design is introduced in this paper. This method consists of coupling between the FDTD method applied to the study of microstrip patch antennas and the genetic algorithm (GA) as an optimization tool. A neural network allows the computing time to be deceased by acting as a database, thus avoiding multiple calls to the FDTD code. The principle of this approach is illustrated. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 72–74, 1997. [ABSTRACT FROM AUTHOR]

This paper describes a printed rectangular-plate monopole fed by microstrip line. The effect of varying the plate width, feed-gap height, and feedline width on the impedance bandwidth is examined. It is shown that for a fixed ground-plane size, that optimization of these parameters can yield an impedance bandwidth ratio of 4.3:1, without using any broadbanding techniques. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 153–154, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21109 [ABSTRACT FROM AUTHOR]

This paper presents the design of novel 1D compact microstrip resonant cells (CMRC). Several thin line arrays in the 50Ω microstrip line with special configurations are fabricated without the requirement of any additional process. Three cells of the proposed structure can provide a wide stopband of -10 dB from 12.7 to 35.9 GHz and -30 dB from 13.8 to 35.9 GHz, respectively. This novel CMRC structure can be used for various compact and wideband microwave-circuit applications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 386–387, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20831 [ABSTRACT FROM AUTHOR]

Photonic bandgap materials have significant applications in the elimination of surface wave on a microstrip antenna. In this paper, several kinds of microstrip structures are analyzed in order to assess their potential for constructing PBG materials. The microstrip structures are periodically loaded with cross dipoles, Jerusalem crosses, or square loops. Periodic Green's functions plus the method of moments (MoM) are introduced to obtain the nonlinear characteristics equation. The real roots are found to show the propagation characteristics of the periodic structure and the existence of bandgap is revealed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 457–458, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10949 [ABSTRACT FROM AUTHOR]

Bandwidth enhancement of a rectangular microstrip antenna using a T-shaped microstrip feed is explored in this paper. A 2:1 VSWR impedance bandwidth of 23% is achieved by employing this technique. The far-field patterns are stable across the pass band. The proposed antenna can be used conveniently in broadband communications. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 235–236, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10566 [ABSTRACT FROM AUTHOR]

In this paper, an eight-element shaped-beam-pattern microstrip antenna array for the base station in a mobile communication system has been designed. A cosecant pattern in the main beam which allows a constant power distribution in the service zone is achieved by feeding linearly varied amplitudes and phases into elements of the array. The array operates at 27.5 GHz, and a tilt angle of about 20° from the broadside is obtained. The sidelobes are on the order of -10 dB, and the cross-polarization level is about -20 dB. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 296–297, 2000. [ABSTRACT FROM AUTHOR]

An electrically small microstrip meander antenna incorporating the folded technology is fabricated and experimental results are presented in this paper. This antenna has the advantages of compact size, ease of manufacturing, broad bandwidth, and multiband characteristics. Different-feed and different-length antennas are tested. Techniques to reduce the antenna size are presented, and performance trends are established. The measured results show that the variation of the return loss can be easily tuned by changing the feeding points and the microstrip-line length. The maximum measured bandwidth is approximately 770 MHz (12.6% operational bandwidth around 6.115 GHz) when the middle feeding point is chosen. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 413–414, 1999 [ABSTRACT FROM AUTHOR]

In this paper, the tilt (θ) of a feedline with regard to a slot is taken into account to improve the cavity model, and also to see the effect of this angle θ on the input impedance. In fact, the angle is introduced in the voltage discontinuity of the slot on the feeding line. The computed results are compared to experiments with several θ-tilts, and give good results. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 395–396, 1999 [ABSTRACT FROM AUTHOR]

This section presents a correction to the paper A Broadband Microstrip Antenna: SGMEP Antenna, by S. Gao, A. Sambell, T. Korolkiewicz and D. Smith, which appeared in the 2003 issue of the journal Microwave and Optical Technology Letters.