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This paper presents the design, manufacturing and measurements of antennas on paper, realized using ink-jetprinting of conductive inks based on nano-silver particles (nSPs). The extraction of the substrate characteristicssuch as the dielectric constant and dielectric loss is performed using a printed ring resonator technique. Thecharacterization of the nSPs conductive inks assesses different parameters as sintering time and temperature.Two antennas are realized corresponding to the most common needs for Wireless Sensor Networks (WSN) inTrains Environment. The first one is a patch antenna characterized by a broadside radiation pattern and suitedfor operation on metallic structures. The second one is a quasi-yagi antenna, with an end fire radiation patternand higher directivity, without requiring a metallic ground plane. Both antennas present a good matching (S11 < -20 dB and S11 < -30 dB, respectively) and acceptable efficiency (55 % and 45 %, respectively) for the papersubstrate used at the center frequency of 2.4 GHz, corresponding to the first channel of the IEEE 802.15.4 band.

The letter presents the design, fabrication, and measurement of a configurable radio frequency identification (RFID) tag based on time-domain reflections. The tag circuit contains a microstrip line (ML) that propagates radio frequency (RF) signals, and a group of capacitors that introduce impedance discontinuities to encode binary codes. The configurability of the tag circuit is allowed by connecting the nearby-placed capacitors with the ML. Ink-jet printing technology is employed to implement the layout of the proposed tag on paper substrate. To overcome the limitations of printed metallic tracks, a linearly tapering technique is proposed. With this technique, a four-bit configurable passive chipless RFID tag is realized. Both time-domain reflectometry (TDR) measurements and ultrawideband (UWB) characterizations were conducted for the proposed tag, and the results are in good consistence with the simulation ones from the circuit simulator advanced design system (ADS). Owing to its low cost fabrication and environmentally friendly nature, the proposed tag has great potential to be widely employed in low-end RFID applications. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 2781-2786, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26412

A compact dual-WLAN-band antenna, in the shape of a paper clip, is presented. The antenna can be easily manufactured by bending few times a single copper wire with a length of about 65 mm, and it operates in the 2.4 and 5.2 GHz bands in the WLAN environment. In addition to the simple configuration, the antenna is easily fed by a 50-Ω mini-coaxial cable which allows it to be flexible in a defined location for installation. An experimental prototype of the proposed antenna with the overall dimensions of about 5 mm × 23.5 mm is constructed, tested, and demonstrated. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2572–2574, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23760

Applications of HTS to radiating elements and beam-forming networks of multibeam and/or multifrequency arrays are discussed. This includes radiating elements which meet special requirements with respect to size and frequency response. Realized versions of both a three-port HTS array and a April × 4 Butler matrix are presented. © 1993 John Wiley & Sons, Inc.

In this paper, traditional microstrip resonator is meandered to construct a compact multi-mode resonator (MMR). The meander resonator is very simple but convenient for ultra-wide band (UWB) passband filter. And then, a UWB microstrip filter with six transmission poles in the passband is achieved by using only two resonators. The filter has an amplitude frequency response with a passband from 1.8 GHz to 4.7 GHz, the simulated return loss in passband is better than −20dB, and the measured one is better than −19dB. The tested insertion loss at center frequency is about 0.38 dB. Methods of adjusting the bandwidth of this new kind of UWB filter is also discussed in this paper. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2026–2029, 2016

Wideband microwave filters cover a wide band of continuous frequencies. In this paper, the design and implementation of an ultra-wideband filter is firstly introduced. In real applications, there might be interference inside the passband of the filter, and it is usually necessary to suppress the interference to make most use of the available bandwidth. Traditionally this can be done either by cascading a bandstop filter to the wideband filter, or by designing multiband filters. To achieve compactness, it will be shown in this paper that it is possible to add an extra resonator weakly coupled to the filter. Without any other changes to the original filter, a transmission zero can be produced in the passband of the filter, while the performance of the filter at other frequencies is not significantly affected. This zero can be used to suppress any potential in-band interferences. (c) 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2165-2168, 2013

An ID generating circuit is unquestionably the core of a chipless RFID tag. For convenience of printing process and cost consideration, the circuit should be kept as simple as possible. Based on the cognition, an 8-bit time-domain based ID generating circuit that merely consists of a ML and eight capacitors was offered, and implemented on photo-paper substrates via inkjet printing process. In addition to the experimental measurements, the circuit was also input into circuit simulators for cross-validation. The good agreement between simulations and measurements is observed, exhibiting the tag technical feasibility. Besides of low cost, the tag has wide compatibility with current licensed RFID spectrum, which will facilitate the future deployment in real applications.Compared to time-domain based chipless tags, frequency signatures based chipless RFID tags are expected to offer a larger coding capacity. As a response, we presented a 10-bit frequency-domain based chipless RFID tag. The tag composed of ten configurable LC resonators was implemented on flexible polyimide substrate by using fast toner-transferring process. Field measurements revealed not only the practicability of the tag, but also the high signal to noise ratio (SNR). Another frequency domain tag consists of a configurable coplanar LC resonator. With the use of all printing process, the tag was for the first time realized on common packaging papers. The tag feasibility was confirmed by subsequent measurements. Owing to the ultra-low cost potential and large SNR, The tag may find wide applications in typical RFID solutions such as management of paper tickets for social events and governing of smart documents.Ultra wide band (UWB) technology possesses a number of inherent merits such as high speed communication and large capacity, multi-path immunity, accurate ranging and positioning, penetration through obstacles, as well as extremely low-cost and low- power transmitters. Thus, passive UWB RFIDs are expected to play an important pole in the future identification applications for IoT. We explained the feature difference between UWB chipless tags and chip based tags, and forecasted the applications respectively based on the comparison between the two technologies. It is expected that the two technologies will coexist and compensate each other in the applications of IoT.Lastly, the thesis ends up with brief summary of the author’s contributions, and technical prospect for the future development of printable chipless RFID tags.

This paper proposes an innovative application of passive optical networks with optimized bus topology for local backbone data networks. Passive optical networks represent a promising solution for modern access networks to meet the increasing demands on transmission rate for demanding multimedia services. As these networks rely exclusively on passive components implemented in their entire infrastructure, it is necessary to consider their certain specific features and optimize properly necessary parameters, especially an attenuation balance. Considering the possibility of such optimization, the passive optical network with optimized bus topology provides several interesting opportunities for specific applications. Its potential application is, for example, a high-speed local backbone infrastructure connecting local data switches and routers. For that purpose, the passive optical splitter with adjustable power splitting ratio at its outputs can be used for the optimization process of attenuation balance. This paper presents a mathematical apparatus for calculating the maximum number of splits and the number of bridge taps in the passive optical network with the bus topology and an example of obtained results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2351–2355, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26291

The paper explores the properties of mixed-mode (MM) S-parameters, which are widely used in computer PCB and wireless RF industries and have not received serious discussion in the current literature. In this paper, to compare these MM S-parameter properties to the corresponding ones of the conventional single-ended S-parameters, we have developed the symmetric and unitary properties in terms of the mixed-mode S-parameter matrix. Also, we have developed a method to deal with the reference plane shift, which is expressed in a mixed-mode S-parameter fashion for the cases of both the coupled and uncoupled transmission lines. To validate the developed mixed-mode S-parameter properties, we have herein analyzed a 10-dB coupled line-directional coupler constructed by a pair of coupled transmission lines. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2869–2874, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23862

This paper presents an innovative methodology for designing three new Artificial Magnetic Conductors (AMC) with very little sensitivity to the angle of incidence and compact size. The AMC structures are composed of a Frequency Selective Surface (FSS) placed at the interface of a metal-backed dielectric slab. The FSSs used belong to the family of Skewed Crosses (SC). The paper begins by investigating the properties of a GA-designed AMC presented in a previous literature. After that, a basic SC-based AMC is extracted from this AMC and is modified step by step to improve the desired features. The modifications are performed not based on time-consuming optimization methods, but by utilizing the theoretical clues presented in another literature for similar structures. Taking these strategies, such AMCs are obtained that have very good angular stability, compact size, and acceptable bandwidth. Periodic Method of Moments (PMM) is used to analyze and study the proposed periodic structure. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 781–786, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22280

In this paper we discuss a number of UHF/RFID tag designs including the hybrid loop (Chen and Hsu, International Symposium on Antennas and Propagation, Korea, Vol. 3, 2005, 1045-1048), dual crossed-dipoles, the dual crossed-dipoles utilizing an inductively coupled feed (Choo and Ling, Electron Lett 39 (2003) 3080-3081). We have carried out extensive parametric studies in the process of analyzing the characteristics of the earlier-mentioned antennas, and have investigated several techniques (Choo and Ling, Electron Lett 39 (2003) 3080-3081), including meandering, for size-reduction of these antennas. A design methodology based on the Genetic Algorithm (GA) is presented for the optimization of conformal antennas with Electromagnetic Bandgap (EBG) surfaces (Mittra, Proceedings of International Symposium on Antennas and Propagation 2005 (ISAP2005) Seoul, Korea, 2005, 325-328; Sievenpiper et al., IEEE Trans Microwave Theory Tech 47 (1999), 2059-2074) to improve the antenna performance. The EBG characteristic is realized by utilizing a Frequency Selective Surface (FSS) placed above a thin dielectric substrate backed by a metallic ground plane to act as an Artificial Magnetic Conductor (AMC). The antenna is then placed above the EBG surface to create a conformal integrated EBG - antenna. The initial design of the AMC is carried out by synthesizing a surface whose reflectivity is +1, for a normally incident plane wave. However, since the antenna situated above it produces not just a single plane wave but a spectrum of these waves, it becomes necessary to refine the initial design to optimize the performance of the antenna/AMC composite, and techniques for doing this are discussed in the paper. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 858-867, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22265

This paper presents an internal dual-band patch antennato be mounted above the system ground plane of the PDA (personal dig-ital assistant) phone for GSM/DCS operation. The antenna is supportedby conducting pins (5 mm long in this study) and mounted above thesystem ground plane of the PDA phone. In this case, the antenna doesnot directly occupy the system ground plane, and a usable space be-tween the antenna ground portion and the system ground plane is pro-vided for accommodating associated conducting elements or electroniccomponents of the PDA phone. A design example is demonstrated, andobtained results are presented and discussed. © 2007 Wiley Periodicals,Inc. Microwave Opt Technol Lett 49: 2002–2006, 2007; Published on-line in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22593 Key words: antennas; mobile antennas; internal mobile phone anten-nas; dual-band antennas; GSM/DCS antennas 1. INTRODUCTION The conventional planar inverted-F antenna (PIFA) has beenwidely applied in mobile devices as an internal antenna for GSM(global system for mobile communication, 890–960 MHz) andDCS (digital communication system, 1710–1880 MHz) operation[1]. This kind of conventional PIFA, however, mainly occupies acertain portion of the system circuit board or ground plane of themobile device, and uses it as the antenna ground plane. Hence,when such a conventional PIFA is employed in the mobile device,valuable board space is occupied. This limits the efficient integra-tion of the employed internal antenna and the electronic compo-nents in the mobile device.In this paper, we present a novel internal patch antenna suitableto be mounted above the system ground plane of the mobiledevice, without occupying the valuable space of the system groundplane. The proposed antenna mainly comprises a bottom antennaground portion and a top radiating portion. When applied in themobile device, the antenna ground portion, which encircles the topradiating portion in this design, is supported by conducting pinsand mounted above the system ground plane. This configurationmakes the portion of the system ground plane below the antennareusable for accommodating the associated conducting elements orelectronic components of the mobile device. Note that the antennaground portion has a three-dimensional structure consisting of aplanar ground plane and a vertical ground wall. The latter isexpected to function as an effective shielding wall to suppress theantenna’s possible fringing electromagnetic (EM) fields from en-tering the interiors of the mobile device [2–6]. In this case, thepossible coupling between the proposed antenna and the conduct-ing elements or electronic components mounted on the portion ofthe system ground plane below the antenna can be eliminated orgreatly suppressed, thus resulting in very slight or no variations inthe antenna performances.

This paper presents a method of moments (MoM) formulation for large thin-wire structures. In our approach, a modified version of the well-known Rao–Wilton–Glisson (RWG) basis functions for wires including a linear phase term is considered. This additional term allows an efficient representation of the travelling-wave modes on each wire, while it preserves the main advantages of RWG bases for arbitrarily complex wire topologies. The paper contains a detailed description of the algorithm used for the computation of the impedance matrix integrals. Finally, some results for scattering problems are presented to show the agreement with the conventional RWG-MoM solution. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 960–966, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21533

An improved accurate modeling for miniaturized stepped impedance resonators with a double coaxial structure is proposed in this paper. The step discontinuities of the double coaxial stepped impedance resonators (DC-SIRs) have been given full consideration in the modeling. The band-pass filters have been designed using the accurate modeling of DC-SIRs. The band-pass filters mentioned in this paper show excellent performances such as more compact size and lower insertion loss, and it can be used at lower frequencies. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2314–2317, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21910

In this paper, the regular microstrip dipole antenna shape is modified by adding upper and lower triangular patches, which makes it look like a rhombus. The rhombus shape is chosen because of its wideband characteristics over the rectangular one. The presented antenna provides a wide bandwidth of more than 100%. The measured and computed VSWR and radiation patterns for one element and the mutual coupling for two elements are presented in the paper. The proposed antenna provides endfire radiation patterns with wide beamwidth and low cross polarization level which make it a good candidate for phased arrays and radar systems. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2461–2464, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21978

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

The terminology of hard and soft boundary conditions is suggested in this paper to describe the way in which particles are enforced to stay inside the desired domain of interest. Specifically, hard boundary conditions use position-clipping criterion, while soft boundary conditions do not use this criterion. All soft domains employed before in the PSO literature rely on velocity clipping rather than position clipping. Traditionally, a velocity-clipping technique is used to prevent particles from explosion. In this paper, we investigate the hard-wall boundary conditions together with other velocity-termination criteria. The application into linear-array synthesis shows that the choice of the way in which the velocity is treated at the boundary of the problem can dramatically improve the convergence of the PSO algorithm. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 422–426, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21004

Highly tunable diodes and multidiode biasing configurations can be employed to enhance the tuning range of frequency-selective surfaces (FSS). The paper considers a variety of such diodes and configurations, demonstrating experimentally a wideband tuning that can be in excess of 500 MHz. However, the presence of varactor biasing electrodes leads to the distortion of the FSS response. The paper describes how the problem can be eliminated through the novel use of surface-mount resistors. The experimental results are obtained in a waveguide setup, within the 1.6–2.7-GHz range. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 412–416, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20651

In this paper, field patterns in V-shaped microshield transmission line are calculated by using the edge-based finite element method. The dependence of the field patterns upon the thickness of metallic signal strip and the dielectric constant of dielectric substrate is presented. The figures in this paper have important values in the design of microshield lines in microwave and millimeter-wave integrated circuits. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 43–47, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20041

In this paper, a Ka-Band 24-dBm AlGaAs/InGaAs/GaAsPHEMT MMIC power amplifier is demonstrated. This three-stage ampli-fier is designed to fully match for 50 input and output impedances.With 4 V and 250-mA DC bias, we achieve 15-dB small-signal gain, 24dBm P 1dB , 24.3% PAE, and better than 10-dB input return loss from31 to 37 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt TechnolLett 42: 277–280, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20277 Key words: Ka band; MMIC; GaAs; three-stage; power amplifier INTRODUCTION Recently, the demand for broadband data distribution has in-creased significantly. Communication providers are now focusingon the Ka-band for next-generation terrestrial systems, such assatellite communication systems, wireless local-area networks,local multipoint distribution system, personal communications net-work links, and digital radio. As a result, research activities inKa-band devices and power amplifiers have increased significantly[1–5]. Ka-band terrestrial systems require power amplifiers withcompact size and high reliability. It is also necessary that thesepower amplifiers should be mass producible so as to reduce thecost. Although traveling-wave tube amplifiers (TWTAs) can beused in Ka-band terrestrial systems, solid-state power amplifiers(SSPAs) are less expensive, smaller in size, lighter in weight, andmorereliable.Indeed,theperformancesofGaAs-basedmicrowavemonolithic integrated high power amplifiers (HPAs), such aspseudomorphic high-electron-mobility transistors (PHEMTs),have been drastically improved in the past decade. In fact, GaAs-based PHEMTs have already been extensively used as the SSPAsfor Ka-band terrestrial systems. To reduce the production cost ofKa-band HPAs, lumped-element matching circuits can be used tominiaturize the size of the GaAs-based monolithic microwaveintegrated circuit (MMIC) chips. This paper describes the design,fabrication, and testing of a three-stage Ka-band AlGaAs/InGaAs/GaAs PHEMT [6, 7] amplifier using such a technique. The pro-posed amplifier delivers a 0.25 W output and a linear power gainlarger than 15 dB in the frequency range between 31 and 37 GHz.This amplifier is designed to fully match 50 input and outputimpedances without any external circuit.

In this paper, a circuit model is developed in RF ADS in order to simulate the coupling effect of a retracted whip on a planar inverted-F antenna (PIFA) for wireless-handset application. The PIFA is designed as the main antenna of the handset to cover the 800-MHz (824–894 MHz) and 1900-MHz (1850–1990 MHz) bands. A parasitic whip antenna is used to improve the performance of the PIFA, especially when the handset is used against the human head. In such a whip–PIFA combination environment, the retracted whip will degrade the PIFA performance if it is not designed carefully. The purpose of this paper is to present an efficient method to optimize the PIFA performance when the whip antenna is in the retracted position. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 210–215, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20590

This paper deals with the design of a 4 × 4 Butler matrix with millimeter microstrip technology. The design of this matrix at around 40 GHz suggests a circuit without any crossing on single-layer substrate. Thus its main advantage is low cost. Simulations, realization, and measurements are discussed in the present paper. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 462–465, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11090

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

This paper presents a concept of a dual-band dual-port microstrip base station antenna for mobile telecommunication systems. The main part of the paper describes considerations on the antenna array configuration as well as antenna pattern synthesis. As an application example, a model of a dual-band dual-port microstrip antenna for GSM900 and GSM1800 systems, along with measured data, are described. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 218–221, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10725

This paper presents the design of a high-efficiency LDMOS power-amplifier module (PAM) at the 880-MHz band. The nonlinear parameters for the LDMOS FET are obtained through the modified SPICE level-3 static and large-signal analyses. It shows an output power of 30.2 dBm and power-added efficiency (PAE) of 64%, with a transducer power gain of 28.78 dB. In this paper, the harmonic-trap network (HTN) is introduced to maximize the PAE and the winding transmission line (WTL) is adopted to obtain the optimizing output matching point between the output power and PAE. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 164–167, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11317

In this paper, the field patterns of the TE modes in antipodal ridge waveguide (ARW) and double antipodal ridge waveguide (DARW) are presented by finite element method. The figures in this paper are useful in the design of antipodal waveguide components for wideband microwave transmission. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 79–82, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10679

A modified locally conformal finite-difference time-domain method (MLC-FDTD) is presented in this paper, which is used to analyze broadwall radiating slots in a finite wall thickness waveguide, including the longitudinal slot and the inclined slot. In this paper, we make a direct analysis of the bulletheaded slots using MLC-FDTD, and give the transformation errors of two kinds of equivalent methods frequently employed in the engineering design; the equal-area and the equal-perimeter transformations from the squareheaded slot to bulletheaded slot. The results show that the equal-area transformation is more accurate. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 198–201, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10556

This paper describes a systematic study of compensated bridges in coplanar technology. If bridges are necessary for filtering the parasitic coupled slot-line mode excited by coplanar discontinuities, they modify the electrical characteristics associated with the fundamental even mode. Based on a low-pass filter approach, a very simple technique is used to compensate for this parasitic effect. Here, emphasis is placed on the flexibility of this compensation technique, which allows us to reduce the technological constraints. Several solutions based on this approach are presented in the case of transmission lines, discontinuities such as tee junctions, and classical distributed bandpass filters. This study is valid for air bridges in classical coplanar technology, as well as for integrated dielectric bridges in multilayer coplanar technology. The concepts developed in this paper are illustrated theoretically and experimentally on multilayer devices over the 1–50 GHz frequency band. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 402–408, 2002.

In this paper, a method is presented to model the electromagnetic structure that is smaller than an MRTD cell. As an example, the power-plane resonance problem in a multilayered PCB is analyzed by using a Haar-wavelet-based MRTD. This paper demonstrates the accuracy and efficiency of the MRTD. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 6–9, 2001.

In this paper, a new empirical model for the dc I–V characteristics of a GaAs MESFET transistor is presented. The conventional approach for modeling the dc I–V characteristics of a MESFET transistor adopts the hyperbolic-tangent dependence on Vds through the observation of the Ids versus Vds curve. The derived model is capable of accurately modeling the device current–voltage behavior in different operation regions. The new model equations describe the device drain current as a polynomial of the effective gate–source voltage Veff, which is in turn a rational function of Vgs, and the parameters for the polynomial vary with Vds. Model parameter extraction is made for a 0.5 μm gate-length MESFET device. Measured and modeled results are compared, and good agreement is obtained. A comparison among the proposed model, Curtice's and Chalmers' model, and Parker's model are also made in this paper. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 226–230, 2001.

In this paper, ultra-wideband arrays using interconnected transverse electromagnetic (TEM) horns are studied. The paper analyzes the radiation characteristics of four-element arrays using the finite-difference time-domain (FDTD) method. The computed results for arrays are compared with those for the single TEM horn and two-element array. Some properties of the four-element array, such as the input impedance, voltage standing-wave ratio, and energy pattern, are presented in this paper. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 190–194, 2001.

In this paper, we present a far-field pattern calculation technique in the body-of-revolution finite-difference time-domain (BOR–FDTD) method. Because the BOR–FDTD solves two- and half-dimensional problems, it has different features from the three-dimensional FDTD method in the far-field pattern calculation. A monopole antenna fed by a coax is used to validate the technique described in this paper. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 47–50, 2001.

This paper presents a compact, simple, low-cost coplanar waeguide actie antenna oscillator which can be used for wireless communication applications. The circuit uses the actie MGA86576 MMIC amplifier, which is biased through its output port using simple lumped elements. A closed feedback loop is implemented with two slot antennas fed by coplanar waeguide transmission lines. The paper pre- sents a design procedure to systematically dimension the different parts of the structure until the oscillation condition is satisfied. An actie antenna oscillator has been designed, manufactured, and tested, and measured results are in good agreement with predictions. The circuit exhibits aery clean, stable oscillation, and the radiation patterns are smooth and quasiomnidirectional. The measured gain of the actie antenna is 3.2 dBi. Q 1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 18)25, 1999.

The analysis of electromagnetic fields radiated in the far zone from a circular aperture antenna has been one of the useful topics in classical antenna textbooks. In this paper, not only the far-zone radiated fields, but also the near-zone radiated fields are considered in this paper. Moreover, electromagnetic fields radiated by the circular aperture antenna in the presence of a dielectric hemispherical shell radome over the ground plane are formulated in closed form. Both the Fresnel and the Fraunhofer fields including and excluding the effects of the dielectric radome are obtained and discussed. Numerical computation is also made to show the difference between the antenna patterns for the near and far zones, and to demonstrate the effects of the dielectric radome on the radiation patterns. The results show the considerable effects due to the dielectric radome. The major and sidelobes of the power patterns in the E- and H-planes change significantly when the inner radius of the radome is comparable to the dimension of the aperture and its thickness is comparable to the wavelength. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 238–243, 1999.

This paper presents the concept of using a harmonic trap to design a wideband reconfigurable antenna. The reconfigurable antennas can be used to select one of a number of operating frequency bands. If these bands cover a very wide frequency range, then one of the higher-frequency bands can be a harmonic of a lower band. When the antenna operates at the lower band, it can have a good match at the high frequency. This paper proposes a technique for designing a wideband reconfigurable printed dipole antenna so as to select only one of the operating frequency bands by using a harmonic trap. The antenna is designed, fabricated, and measured. It is shown that by using switches and harmonic traps, a reconfigurable printed dipole antenna can be designed over a frequency range of 3:1. The antenna is thus suitable for frequency switching in the FCC ultra-wideband allocation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 927–929, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21521

This paper presents the design simulation, implementation, and measurement of a miniaturized GPS/K-PCS/ISM (2.4-GHz) triple-band LTCC meander-chip antenna for mobile-communication handsets. The dimensions of the LTCC chip antenna is 8.6 × 15 × 1.5 mm. In this paper, the bottom meander radiating patch is tuned to the GPS-band, the middle meander antenna with via-hole connection contributes to the K-PCS-band operation and the top radiating patch is tuned to the ISM-band (2.4 GHz). With 2.0:1 VSWR impedance bandwidth definition, the lower, middle and upper bands have impedance-bandwidth values of 110, 140, and 60 MHz, covering the bandwidth of the GPS/K-PCS/ISM (2.4-GHz) bands. Satisfactory agreement between the simulated and measured results for the antenna patterns and impedance bandwidth are achieved. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 160–162, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21292

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

This paper presents a new approach based on multilayer perceptron networks to determine the 3(rd)-order intermodulation distortion levels in microwave-intensity-modulated GaAIAs laser diodes. The Levenberg-Marquardt algorithm is used to train the network. The results obtained from the network are in excellent agreement with the experimental results reported elsewhere. (C) 2004 Wiley Periodicals, Inc., This paper presents a new approach based on multilayer perceptron networks to determine the 3rd-order intermodulation distortion levels in microwave-intensity-modulated GaAIAs laser diodes. The Levenberg–Marquardt algorithm is used to train the network. The resultsobtained from the network are in excellent agreement with the experimental results reported elsewhere.

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

6. CONCLUSION The integrated macromodeling method proposed in this paper is an accurate approach to address the high-speed interconnect problem, which is based on a rational function approximation of the Y-parameter transfer function from the full-wave FDTD sim- ulation and equivalent circuit approach in the context of a SPICE simulator. The VFM employed for rational function approximation in this paper provides a considerably accurate way to construct the macromodel of the interconnect subnetwork. Conversion of the interconnect macromodel to an equivalent circuit can facilitate the signal integrity analysis, involving both distributed interconnect and linear/nonlinear circuit components, by using SPICE circuit simulation. Signal integrity analysis of large hybrid interconnect and circuit problems using this approach will be further studied in the future. ACKNOWLEDGMENTS The authors wish to express their thanks to Dr. Yuan Weiliang of the Institute of High Performance Computing (IHPC) for his useful discussion and suggestions. This work is jointly supported by the IHPC and National University of Singapore. ABSTRACT: A new design methodology for compact single-level and multilevel folded-line radio frequency (RF) power dividers is presented. Simple design equations are developed for compact 3-dB Wilkinson power dividers with single and cascaded folded-line C-sections. The new topologies show a reduction in footprint area to less than 40% of the conventional topology for single-level compact designs and to less than 17% of the conventional topology for a multilevel compact design. The new compact designs are validated by full-wave electromagnetic simula- tion as well as measurements. Excellent agreement is reported. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 187-189, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11164

In this paper, the field patterns of the dominant mode in unilateral finline are calculated by the hybrid finite-element method. Dependence of the field patterns on thickness of metallic fins and dielectric constant of dielectric substrate are presented. The figures in this paper have important values in the design of finline millimeter wave integrated circuits. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 193–195, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11012

Multipath interference can be removed from constant envelope signals using adaptive channel equalization based on the constant modulus algorithm (CMA). To be useful in a vehicular mobile radio system, adaptation must occur rapidly by using uncomplicated and cost-effective hardware. This paper will present a new multiplier-less filter structure based on logarithmic algebra with anticipated savings in computational complexity. This paper will discuss the filter application for analogue FM multipath reduction. The simulated distortion is observed to be consistent with that of published measurements. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 1–3, 2003

In this paper a solution for the focalization of the new 40-m radiotelescope at the observatory of the Centro Astronomico de Yebes (CAY) in Guadalajara, Spain, is presented. Quasi-optics theory is used in this paper for the propagation analysis of the beams through the different optics elements. The goal of this paper is to design an optical system that can focalize several bands in order to reduce to the minimum number of possible optic elements, and share the maximum number of them. Parameters for hyperbolic lenses and ellipsoidal mirrors, focal distances, and the feeder dimensions necessary for the focalization in each band are calculated. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 121–123, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10842

In this paper, an R-band hybrid amplifier with a coplanar-waveguide (CPW) and photonic-bandgap (PBG) structure is designed and fabricated. We use PBG and CPW simultaneously in the amplifier to improve power-added efficiency (PAE) and intermodulation distortion (IMD) in the R-band. In this paper, the PBG structures are optimized to obtain a matching network. The output impedance of amplifier and the input impedance of PBG are matched to minimize the return loss. The PAE and IMD were improved by 15% and 4.5 dB, respectively, compared with a conventional amplifier. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 108–110, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10689

A multiband diamond-shaped Sierpinski gasket monopoleantenna is described. The radiation pattern of wideband monopole an-tennas like the circular-disk and diamond monopole antennas degradesas frequency increases. In this paper, several cutouts based on the Sier-pinski gasket geometry are made in the diamond monopole antenna inorder to improve the radiation pattern of the antenna. It is experimen-tally shown that a multiband diamond-shaped Sierpinski gasket mono-pole antenna with a significant improved radiation pattern can beachieved by making cutouts in the diamond monopole antenna. © 2006Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1069–1073,2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21603 Key words: wideband monopole antenna; diamond monopole; radiationpattern; Sierpinski gasket; multiband 1. INTRODUCTION Multiband and wideband monopole antennas have attracted a greatdeal of attention for modern wireless communication systems. Thecircular-disk monopole antenna with a very large impedance band-width was introduced in [1] and further studied in [2]. The patternof the circular-disk monopole antenna degrades as frequency in-creases. The multiple-ring monopole antenna was proposed in [3].It consists of a set of self-similar circular rings, which are super-imposed to form the single antenna unit, as shown in Figure 1. Themultiple-ring monopole antenna is a multiband antenna and due tothe discrete structure of the multiple rings, it shows improvedradiation pattern at higher operating bands in comparison to thecircular disk.In this paper, the diamond monopole antenna is investigatedandseveralcutoutsbasedontheSierpinskigasketgeometry[4]aremade in the antenna in order to improve the radiation pattern athigh frequencies. Two diamond monopole antennas with flare

In the paper of German Torregrosa-Penalva et al. 1, a confusing result has been presented. The paper demonstrates the compensation of the small-signal gain drift with change of temperature and improvement of the FET amplifier's PAE using active biasing, which contradicts the previous published work and our experimental results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 827–828, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21487

Diplexers are three-port filtering devices with a junction connecting two channel filters; the common port connects to an antenna which serves the two channel filters bearing the second and the third port. In the design of diplexers, the technique used in connecting the two channel filters is of great importance to the designers. This is because it determines the size, the effectiveness of signal splitting and combining as well as the ease in implementation. In this paper, an asynchronously tuned double split-ring resonator (SRR) was used in joining the two channel filters. Without incurring any extra space for the junction, the SRR, being a dual-mode resonator, also functioned as a resonant pole for each channel filter. A diplexer operating at 2 GHz and 3 GHz with 4% fractional bandwidths and 20 dB return loss has been demonstrated. The interactions between the SRR and the channel filters were investigated. Good agreement between the simulated and the measured responses was achieved.

This paper presents a dual sleeve monopole antenna that covers Global System for Mobile Communications (GSM), worldwide interoperability microwave access (WiMAX), and wireless local area network (WLAN) frequency bands. This new antenna is more wideband and compact structure in compare to other works. Simulation is done by Ansoft HFSS14 and results show the proposed omnidirectional antenna, ranging from 360 MHz to 5.1 GHz that bandwidth is 174% for return loss below −10 dB. The height of structure is 0.16 λ that has been achieved size reduction about 35% in compare to conventional monopole antenna with height 0.25 λ. These characterizations make this antenna very beneficial for jammer application. Jammers make places more secure and comfortable by reducing cell phones disruptions from some public places. The prototype of this structure has been made and the measure results are in good agreement with simulation results. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1271–1277, 2017

This paper discusses the effect of receiver field-of-view (FOV) on the power distribution and bandwidth performance of short-range diffuse line-of-sight (LOS) links. Monte Carlo simulation is used to investigate the performance of the links for the on-axis and off-axis scenarios in clear, coastal and turbid water. In both clear and coastal water, the receiver FOV has little influence on the on-axis power reception but has a significant effect on the off-axis power reception where there is an approximately 30 dB gain (off-axis) when the receiver FOV is increased from 10° to 180°. However, in turbid water receiver FOV significantly affects the power received both on-axis and off-axis, with gains of 15-18 dB for the same change in receiver FOV. In terms of bandwidth performance, the FOV only affects the on-axis bandwidth in clear and coastal water but not in turbid water.

This paper presents a novel 434MHz asynchronous time difference of arrival (A-TDOA) Indoor Localization System (ILS) using three CC1101 ultra low power radio transceivers from Texas Instruments as asynchronous measuring receivers for time difference of arrival estimation. The three deployed TDOA measuring units are not required to be precisely synchronized in contrast to conventional TDOA localization systems where stringent time synchronization is required between measuring units. Time synchronization is achieved by using a reference transmitter to record the time offset in two TDOA measurements. Actual TDOA measurements are obtained by compensating the time difference measurements for real transmitter using time offsets caused by asynchronous receivers. The implemented system demodulates the obtained time difference pulses to mitigate the clock jitter effect and provides voltage levels corresponding to time differences which are mapped to distance differences. The performance of implemented ILS is evaluated using two sets of real time indoor measurements to estimate the position of mobile transmit node in two dimensional space. The positioning accuracy of implemented system is better than 1.8m along with telemetry data reception capability and low DC power consumption.