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ABSTRACT In this paper, two versions of a complete RF front-end for a 10 Gbps optical receiver are presented. The RF front-end consists of a transimpedance amplifier and a limiter amplifier. Two versions of the TIA amplifiers are proposed. The first topology has 54 dB transimpedance gain, 11.5 GHz bandwidth and has a input current noise density of only [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper is reported an experimental and numerical investigation of the microwave dielectric properties of Na2Nb4O11 (NN), ceramic matrix added with (0, 2, 5, and 10 wt%) of Bi2O3, obtained through a new procedure based on the solid-state method. The experimental and theoretical characteristics of the resonator like return loss, bandwidth, input impedance are in good agreement. The simulations of radiation patterns are presented. For NN reference sample, frequency response bandwidth is of 43MHz (simulated) and 35MHz (experimental) for frequency operation around 2.28 GHz. The NN reference sample showed a dielectric permittivity around 58.4, with loss around 7.3 × 10− 3. The adding of bismuth oxide (2 and 5 wt%) reduced the value of the dielectric permittivity, otherwise the adding of 10 wt% increases its value. The temperature coefficient of resonant frequency (τf) was also measured for all dielectric samples. The values obtained were in the range of −3378 to −250ppm/°C. The results obtained confirm the necessity of producing composites of this material with others positive τf materials for obtaining dielectric resonator antennas with τf = 0. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1211-1217, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT: This paper presents an FMCW K-band rain radar with the property of high resolution. The radar system was designed for measurement of localized torrential rain. Using DDS and FPGA control, heterodyne modulation was used to generate the FMCW down-chirp signal with 50 MHz bandwidth, and emitted a K-band signal with nominal power of 125 mW in the vertical direction. To obtain high resolution for the Doppler spectrum, the radar system used a coherent signal processing method. Several experiments were conducted and the results were compared with data from the meteorological administration. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:817-822, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT The design and performance of a dual-band circularly polarized monopole antenna for multisystem integration are shown in this paper. A triple-strip monopole structure, which is fed at the microstrip line, is designed and fabricated to excite several resonances. After optimization of the geometrical parameters of the antenna, the resonances are merged, and thus a wide impedance bandwidth is obtained. The measured impedance bandwidth of a S11 < −10 dB ranges from 1.43 to 3.29 GHz, and covers most of commercial wireless communication systems. A right-hand circularly polarized wave at 1.57 GHz for the global positioning system is not only excited, but a left-hand circularly polarized wave at 2.33 GHz for satellite digital audio radio service system is also generated. The 3-dB axial ratio bandwidths are about 70 MHz at the lower band (1.57 GHz) and 60 MHz at the upper band (2.33 GHz). Both of simulated and measured results are shown to validate the impedance and CP characteristics of the proposed monopole antenna. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:514-521, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This paper presents a novel design for an optimized circularly polarized microstrip antenna. Circular polarized microstrip antennas have many uses due to its low profile design. However, one of the microstrip antenna's main limitations arises from its narrow frequency bandwidth. Therefore, it is necessary to use special design techniques in order to increase the operating frequency bandwidth while maintaining all of the other respectable optimum radiation characteristics. The proposed design involves using a dual-feed square patch, which is gap coupled with two parasitic patches in a mirrored L-shaped configuration. This design resulted in an axial ratio bandwidth of 11%, S11 bandwidth of 14% and a gain of 9 dB at the 2.15 GHz center frequency. The proposed design was built, and the measured results were in agreement with the simulation results. Additionally, this antenna design was used in an array structure in order to increase the gain, while maintaining a good axial ratio. These enhanced radiation results allow the use of the proposed antenna design in many domains such as wireless and military applications without facing the limitations of the narrow frequency bandwidth. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:597-603, 2016 [ABSTRACT FROM AUTHOR]

The maximum realizable gain and bandwidth of an antenna of given electrical dimensions are governed by physical laws of nature, and do not depend on the particular technology used to realize the antenna. Thus, data sheets and papers presenting electrically small antennas (typically with their largest dimension smaller than a quarter of a wavelength) having a high gain (>2 dBi) for a tolerable bandwidth (a few percent) should be regarded with some caution. What usually happens is that the measurements done by the manufacturer to establish those data sheets neglect a typical characteristic of electrically small antennas: they are never unbalanced and seldom completely balanced, which means that the current distribution at their feeding point is neither symmetric or asymmetric. The usual measurement setup feeds the antenna through a coaxial cable, which is an unbalanced feed. Thus, if no precaution is taken, the shielding of the coaxial cable will radiate as much or even more than the antenna under test, and the measured gain or bandwidth will correspond to the radiator formed by the antennas under test and the feeding cable. This paper shows what happens when elementary measurement precautions are not taken, and illustrates this phenomenon with examples of data sheets of commercially available antennas. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 17: 156–160, 1998. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, an efficiency enhancement technique is proposed for a loop type ground radiation antenna on a small sized ground plane whose resonance frequency of the fundamental ground mode is significantly higher than the operating frequency. The efficiency is enhanced by matching the resonance frequency of the ground mode with the operating frequency. This was accomplished with a structure consisting of a loop of wire and inductors installed at both edges of the rectangular ground plane. The total length of each fabricated wire is 80 mm, which can be easily accommodated in the rim of a mobile device. The technique also increased the operating bandwidth. The measured efficiency of the antenna using the proposed technique is 47.44% and the bandwidth is 74 MHz at the Z-wave band. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:476-478, 2017 [ABSTRACT FROM AUTHOR]

ABSTRACT Radiation loss is a major problem of defected ground structures (DGSs) in past decades. This paper presents a novel band pass filter (BPF) employing low radiation spur-line DGS (S-LDGS) resonators and a split ring resonator (SRR). This combination results in compact size and significant reduction in radiation loss. The proposed BPF achieves controllable fractional bandwidth, ranging from 36.2% to 46.5% centered at 2.6 GHz, which covers two Wi-MAX bands. The proposal is verified with a prototype that demonstrates good agreement between simulations and measurements. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2966-2968, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This paper presents two narrowband high-temperature superconducting (HTS) filters at 10 GHz with a 0.6% fractional bandwidth. Uniform impedance rectangular resonator (UIRR) and stepped impedance H-type resonator (SIHR) are proposed to achieve HTS filters with high Q value, low sensitivity, weak coupling, and good parasitic response. A six-pole HTS filter that has UIRRs with a Q value of 17,700 is fabricated; this filter has a 19.9 dB return loss and a 0.38 dB insertion loss. An eight-pole HTS filter that has SIHRs with a Q value of 12,100 is also manufactured; this filter has a 12.2 dB return loss and a 0.64 dB insertion loss. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1516-1520, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, design and fabrication of an L-band axial mode 2 × 2 tapered dielectric- loaded helical antenna array for international maritime satellite organization (INMARSAT)-M mobile vehicles are presented. This array has compact size and light weight. By adding a tapered cylindrical dielectric resonator, for satellite communications, important parameters such as gain, side lobe level, impedance matching and axial ratio bandwidth have been improved simultaneously. This array has a gain of 15.1 dB, a radiation pattern with a side lobe level of -21 and a -3 dB axial ratio bandwidth is nearly 15%. These characteristics are suitable for INMARSAT-M antennas. A good agreement between the simulated and measured results has been achieved. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2600-2604, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT This paper presents a novel design of printed doubled-sided dipole antenna for WiFi application in 2.4 and 5.2 GHz ISM bands. The printed dipole antenna consists of one dipole arranged back to back on both sides of a dielectric substrate and is suitable for integration with monolithic microwave integrated circuit (MMIC) module. A microstrip tapered feed line is designed to match the antenna. Simulator FDTD is used to tune and verify the analysis. Both simulated and measured data are much identical. The printed dual-band dipole antenna with the dimension of 46 × 36 mm2 achieves a measured gain at 2.4 GHz band to be about 1.7 dBi with a bandwidth of 200 MHz and at 5.2 GHz band to be about 0 dBi with a bandwidth of 400 MHz, respectively. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1845-1851, 2013 [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

A single layer, single feed compact rectangular microstrip antenna is proposed. Resonant frequency has been reduced drastically by cutting unequal rectangular slots at the edge of the patch. Two rectangular slots are introduced at the left and right side of the patch to reduce the resonant frequency. The widths of the rectangular slots are different to improve the gain bandwidth performance of the antenna. The antenna size has been reduced by 73.9% when compared to a conventional rectangular microstrip patch antenna. The characteristics of the designed structure are investigated by using Method of Moment-based electromagnetic solver, IE3D. There is a reasonable agreement between these simulated data and measured values. An extensive analysis of the return loss, radiation pattern, gain, and efficiency of the proposed antenna is shown in this paper. The simple configuration and low profile nature of the proposed antenna leads to easy fabrication and make it suitable for the applications in Wireless communication system. Mainly, it is developed to operate in the mobile communication range of 900 MHz-1.8 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:954-957, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27517 [ABSTRACT FROM AUTHOR]

This paper describes the development and performance of a 2 by 4 element suspended microstrip patch antenna array with linear polarization. The proposed structure with a new geometrical composition of entire array possesses the advantages of being wide bandwidth, high gain, precise side lobe level control and low cross-polarization level. The measured antenna has the peak gain 14.12 dBi and the cross-polarization is lower than −16 dBi within the impedance bandwidth. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:825-829, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27423 [ABSTRACT FROM AUTHOR]

This paper presents a novel small square monopole antenna for UWB applications with dual band-notch function. By cutting an S-shaped slot in the ground plane, additional resonance is excited and hence, much wider impedance bandwidth can be produced, especially at the higher band that provides a wide usable fractional bandwidth of more than 120% (2.98-12.25 GHz). To generate a single frequency band-stop performance, we add a pair of C-shaped parasitic structures in the ground plane, and also in order to create the second notch frequency, we insert a horizontal rectangular strip in the center of two C-shaped parasitic structure in the ground plane. The measured results reveal that the presented dual band-notch monopole antenna offers a wide bandwidth with two notched bands, covering all the 5.2/5.8 GHz wireless local area network, 3.5/5.5 GHz WiMAX, and 4 GHz C bands. Good and radiation behavior within the UWB frequency range have also been obtained. The antenna has a small dimension of 12 × 18 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2743-2747, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27209 [ABSTRACT FROM AUTHOR]

The detailed study of a planar asymmetrical dipole, realized on a ε = 4.50 substrate, with a rectangular slit etched on one of the two dipole arms, is described in this paper. The measured prototype fulfills the bandwidth requirements of both ultrawideband and WLAN communications at 2 and 5 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26185 [ABSTRACT FROM AUTHOR]

This paper reports a simple printed dipole antenna which exhibits dual-band operations.The antenna's radiation pattern is bidirectional in the x- y plane and close-to-omnidirectional in the x- z plane. The 10 dB impedance bandwidths achieved are 38.6% and 4.7% centered at 1.1 and 2.3 GHz, respectively. The impedance and radiation characteristics of the proposed antenna, as studied by both simulation and experiment, are satisfactory. The antenna's performance compares well with that of a recently proposed dipole antenna with fractal shape. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26226 [ABSTRACT FROM AUTHOR]

In this paper, a compact hybrid coplanar waveguide (CPW) fed 1 × 2 slot antenna array with radiation pattern diversity is proposed for the wireless local area networks (WLAN) application.The antenna array consists of two rectangular slot radiation elements, two feed slots, a CPW and an open-ended strip. The feed network provides out-phase and in-phase feed with high isolation in a relatively compact structure without any lossy circuits, and difference and sum radiation patterns are achieved in the azimuth plane with wide bandwidths of 480 MHz (20%) and 580 MHz (24.2%). The measured gains of dual-pattern are better than 4.93 and 3.76 dBi in the WLAN band (2.4-2.484 GHz). The proposed dual-port array can be used as pattern diversity in modern mobile system. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:884-888, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25879 [ABSTRACT FROM AUTHOR]

A compact broadband patch antenna is proposed in this paper for global ultra-high-frequency (UHF) RF identification (RFID) applications. The antenna is composed of four synchronous shorted patches that resonate at four different frequencies, broadening its impedance bandwidth. A central loop is incorporated to feed the four patches simultaneously, which provides the required input reactance for matching to the chip as well. Since the current of neighboring patch is vertical to each other that they can radiate well without canceling each other, the gain is stable over the whole frequency band. Prototype is fabricated and tested, which shows that the impedance bandwidth can cover the whole UHF RFID band (840 MHz - 960 MHz), and the read range is over 3 meters when EIRP is set to 30 dBm at the reader. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2653-2657, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25560 [ABSTRACT FROM AUTHOR]

In this paper, a tunable antenna integrated with a Bluetooth module in printed circuit board (PCB) board for Bluetooth application was proposed and experimentally studied.The proposed tunable antenna consisted of meander-type stack antenna, Bluetooth module, strip line, and chip capacitors in PCB board. The simulation results for the effect of the variation of chip capacitor in PCB board for Bluetooth application were investigated. From the experimental results, the measured impedance bandwidth, defined by VSWR = 2, was obtained. Also, 3D radiation patterns and peak and average gains were measured and studied. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2801-2804, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25618 [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, a novel technique is proposed to design a dual band bandstop filter which is implemented with two defected stepped impedance resonators (SIRs) embedded on the input output transmission line. The embedded SIRs create a transmission zero at 2.5 GHz that generates the first stopband of the proposed filter. Introducing two Hilbert shaped fractal structure on the ground plane, the second stop band is employed at 3.5 GHz. The overall layout of the filter is realized with a size of 20 × 5 mm2. The proposed prototype is EM simulated and measured. The measured −10 dB bandwidth for first stopband is 0.1 GHz and for second stopband it is 0.14 GHz. The measured S-parameters exhibit an excellent out off band response with insertion loss less than 1.5 dB. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1345-1347, 2016 [ABSTRACT FROM AUTHOR]

This article presents an improved factor of merit for the comparison of center-frequency tunable bandpass filters. This study draws up a comparison between existing tunable filters for which different commonly used parameters demonstrating their performance are given. A first factor of merit that takes all the major characteristics of such tunable filters into account is introduced. A second factor of merit is proposed to evaluate the filter compactness. These new factors of merit are applied for the comparison of more than 30 recently published papers. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 985–988, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24220 [ABSTRACT FROM AUTHOR]

This paper analyzes the influence of amplitude and phase error of different path on single sideband modulator (SSB) which can be used as an upconverter. Unwanted sideband suppression expression and error variables equation for maximum output sideband suppression are also deduced. The simulation curve shows the variation of sideband suppression with the amplitude and phase error of the components of SSB is given. Simulation results show that components of the amplitude and phase of the highly consistent or inconsistent amplitude and phase which meet the relationship can achieve higher sideband suppression for the SSB. The completed modulator used as an upper sideband upconverter shows -11 dB typical conversion gain with 22-dB sideband suppression. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2590–2594, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23721 [ABSTRACT FROM AUTHOR]

This paper presents a dual-band bandpass filter by introducing transmission zeroes in the passband of a broadband bandpass filter using square-loop dual-mode resonators. The transmission zeroes are achieved by using a dual-mode resonator. The dual-mode resonator is attached to two transmission lines of same length. These lines are coupled to similar transmission lines that are attached to the I/O ports. The filter has a compact size, low losses, and good rejection between the two bands. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1567–1570, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23427 [ABSTRACT FROM AUTHOR]

In this letter, a novel dual-mode bandpass filter (BPF) using stepped impedance resonators (SIRs) for simultaneous low insertion-loss and wide passband has been designed. This novel wideband dual-mode BPF is formed by a microstrip square ring resonator with direct-connected orthogonal feed lines, and two impedance steps as perturbations. By varying the impedance ratio (K) of the SIRs, the wideband bandwidth can be tuned with more freedoms. The design procedure using the analysis of even and odd mode is described in this paper. The wideband BPF with relative bandwidth of 76.5% is simulated using the full wave electromagnetic simulation, and then fabricated and measured using the network analyzer. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1104–1107, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23281 [ABSTRACT FROM AUTHOR]

In this paper, a dual-band antenna covering both DTV and 2.45-GHz ISM bands is presented. An inset-fed monopole antenna is responsible for radiation in the DTV band. The ISM band is taken account by a strip dipole etched on backside of the monopole antenna. The antenna may also be used for dual RFID bands. Detailed design inclusive of using the inset-feed to broaden the bandwidth is discussed and experiment was done to verify the simulation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 425–428, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23132 [ABSTRACT FROM AUTHOR]

A novel wideband CP helix antenna with exponential spacing is presented in this paper. Since traveling wave current over a wide range of frequencies has been excited, it possesses better performance. Both numerical results and experimental results show that the axial ratio bandwidth of the exponential spacing helix (ESH) antenna is 58.6% greater than that of the linear spacing helix (LSH) antenna in the same conditions. The characteristics of impedance, power gains, and radiation patterns for the ESH antenna are also investigated and compared with LSH antenna. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1525–1530, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22485 [ABSTRACT FROM AUTHOR]

A printed monopole with coplanar waveguide-fed antenna for ultra-wideband applications is proposed. The proposed antenna includes a rectangle-shaped patch as a radiator, two ground planes with symmetrical notch, and feed excitation. It covers the all ultra wideband (UWB 3.1–10.6 GHz) and has 7.8 GHz (2.8–10.6 GHz) measured return loss bandwidth. In modifiable design, we choose to design the notches on the ground plane, the height of the proposed antenna, and the width of the radiator, and have to obtain broad impedance bandwidth and accessible measurement parameters. The experiment results have shown acceptable omnidirectional radiation pattern and fine gain in this paper. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1435–1438, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22420 [ABSTRACT FROM AUTHOR]

In this paper, by exploiting surrounding fractal UC-EBG ground plane, a 2 × 2 microstrip array capable of X-band operation is studied. Result of comparison shows that this microstrip array proposed has much lower RCS than that of 2 × 2 array with the standard ground at frequencies outside operating band within 2–18 GHz while its gain is improved in the operating band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1418–1422, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22440 [ABSTRACT FROM AUTHOR]

The propagation characteristics of double-layer SIW structures have been investigated in this paper. On the basis of the theory of resonance cavity and SIW, the simple theoretical formulas for the lower and upper frequencies in the passband have been found. The theoretical analyses have indicated that these two frequencies have much dependence on the width of SIW and the length of the coupling slot, the fractional bandwidth of the double-layer SIW structures can be controllable. Agreement between the simulation data and the calculated results from the formulas can be observed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1459–1463, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22469 [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate a 1.5- to 17-GHz ultra-wideband (UWB) low-noise amplifier (LNA) with small-inductance input inductor and multiple-feedback loops implemented in a 0.35 μm SiGe BiCMOS technology. A method named inductive peaking, which adds an inductor in series with the base-terminal of the second-stage amplifier to enhance the frequency of the dominant pole, was adopted to improve gain and bandwidth of the LNA. The measurement results show that very flat gain (S21) of 8 ± 0.5 dB was achieved for frequencies between 2 and 15 GHz. In addition, reverse isolation (S12) lower than -27 dB, input return loss (S11) and output return loss (S22 lower than -9 dB, and noise figure lower than 5.5 dB was achieved in the 3.1–10.6 GHz UWB band. The chip area was 775 × 710 μm2, excluding the test pads. This LNA drains 7 mA current at supply voltage of 3 V, i.e. it only consumes 21 mW power. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 876–879, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22284 [ABSTRACT FROM AUTHOR]

In this paper, microstrip-line-fed rectangular microstrip antenna with open-end meandering slots in the ground plane for compact broadband operation is presented. The proposed design consists of a rectangular patch which is fed by a 50-Ω center fed microstrip-line feed. Three identical narrow open-end meandering slots were embedded in the antenna's ground plane parallel to the rectangular patch's radiating edge. Experimental study is carried out by varying the length of the open-end meandering slots. Using open-end meandering slots in the ground plane, the resonant frequency of the antenna is greatly lowered with large enhancement in bandwidth when compared with conventional microstrip antenna. With the proposed design, an extreme reduction of 82.9% in the antenna size is obtained with a wide bandwidth of 40%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 824–827, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22267 [ABSTRACT FROM AUTHOR]

In this paper, a broadband microstrip Marchand balun is presented. It is implemented by new vertical coupled structure, which is suggested to improve the coupling effect in the conventional coupler. Using this vertical coupling structure, the Marchand balun shows broad bandwidth of larger than 115% at the center frequency of 2.3 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 752–755, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22281 [ABSTRACT FROM AUTHOR]

In this paper, a wide rejection bandwidth bandpass filter with stepped-impedance hairpin (SIH) resonator and interlaced coupled-line was proposed. With the former, its elliptic-function low-pass response was adopted to steepen the upper roll off characteristic and flatten the rejection level; the latter was utilized to broaden the rejection bandwidth by shifting the transmission zero. Measured results show that the filter with interlaced length λ2 mm has suppressed the second harmonic response from -19 to -53 dB when compared to three stages conventional parallel coupled-line filter. Moreover, the upper rejection bandwidth was expanded from 3.2 to 4.5 GHz when the interlaced coupled-line was increased from 0 to 3 mm, which stands for 40% improvement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 542–545, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22194 [ABSTRACT FROM AUTHOR]

In this paper, a novel Wilkinson power divider utilizing left-handed transmission lines (LHTLs) is presented. The proposed device was fabricated by using the lumped L–C (-λ/4) LHTLs instead of the right-handed transmission lines branch arms of the conventional Wilkinson power divider. Both the measured and simulated results show that the designed power divider has a wide bandwidth of return loss and isolation, and its size is 50% smaller than conventional Wilkinson power dividers. The measured results are good well with the simulated ones. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 712–715, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22227 [ABSTRACT FROM AUTHOR]

A novel end-fed modified planar dipole antenna for digital television (DTV) signal reception in the 470–806 MHz band is presented. The antenna is of a narrow rectangular shape (10 mm wide and 235 mm long) and is printed on a dielectric substrate. The antenna comprises a step-shaped radiating strip (arm 1) and a narrow rectangular radiating strip (arm 2), both separated by an L-shaped feed gap whose one open end located at the shorter edge or end edge of the antenna. Across this open end of the L-shaped feed gap, the antenna can be excited to provide a wide bandwidth (2.5:1 VSWR) of larger than 50%, which is much wider than that of a corresponding conventional center-fed dipole antenna and allows the proposed antenna easily cover the 470–806 MHz band for DTV signal reception. In addition, over the operating band, the radiation performance of the proposed antenna is similar to that of the conventional center-fed dipole antenna. The proposed end-fed modified planar dipole antenna is studied in detail in this paper. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 676–680, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22229 [ABSTRACT FROM AUTHOR]

This paper describes investigations of the longitudinally ferrite circulator realized in slot-line technology. The proposed planar structure of circulator allowed to achieve small dimensions of the device. Also, the insertion losses comparable to ones actually published for microstrip structures were obtained. The basic steps of design procedure using scattering matrix of the circulator arrangement were presented. The S-parameters of circulator were simulated and next verified via experiment. The operation bandwidth from 12 to 19 GHz with reflection loss and isolation better than 10 dB and average insertion loss 2.5 dB were measured for fabricated model of circulator. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 692–696, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22246 [ABSTRACT FROM AUTHOR]

This paper reports a circularly polarized cross-slot coupled elliptical patch antenna for implementation in a new radio-frequency identification and localization system currently under development. The radio-frequency localization system in this work is composed of a reader and a semiactive tag (a battery feeds the tag to increase its reading range but the backscattering modulation principle is used to decrease its power consumption). The overall system is designed in the ISM frequency band of 5.8 GHz. This frequency band is a good compromise that permits a large bandwidth and a good range for use in a local positioning system (∼10 m). This antenna is to be used by the reader as its radiation pattern is semispherical. It provides the circular polarization required by the targeted application to allow the tag identification within any physical position. The antenna bandwidth and axial ratio were enhanced using a proper design and a cross-slot feeding of the patch. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 336–339, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22136 [ABSTRACT FROM AUTHOR]

This paper presents the theoretical and simulation investigations of an E-shaped patch antenna applicable in modern mobile communications. It shows marked improvement in the bandwidth when compared with rectangular patch antenna with acceptable radiation pattern. Further, the bandwidth is optimized with respect to notch length, width, and position. Typically, the antenna shows an enhanced impedance bandwidth of 32.5%. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 4–7, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22024 [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]

In this paper, a compact coplanar waveguide-fed slot antenna that can operate over an octaveband (1.75–3.7 GHz) is presented. The novelty of this antenna is the wideband operation with the radial stub loading. The front-to-back ratio of the antenna with a back plate is better than 25dB in H-plane and better than 18 dB in E-plane. The cross polarization level is around -20 dB over the band and the worst being at -15 dB. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2405–2408, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21963 [ABSTRACT FROM AUTHOR]

In this paper, an isosceles triangular patch resonator with an inverted V-shaped slot pattern is fabricated to realize a miniaturized microstrip dual-mode filter. The proposed structure possesses the elliptic characteristic and has the advantage of size and loss reduction. After analyzing the results, the relationships between the filter characteristics and the geometrical parameters of the inverted V-shaped slot are derived. The dual-mode filter exhibits a fractional bandwidth of 14.5% centered at 1.93 GHz with the lowest insertion loss of 1.4 dB. It is shown that a size reduction of 37% is achieved compared with a conventional dual-mode triangular filter. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1969–1974, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21824 [ABSTRACT FROM AUTHOR]

A promising design of integrating a wideband printed monopole antenna in a system in package (AiSiP) for wireless local area network (WLAN) operation in the 2.4 GHz band is presented. The antenna is an inverted-F monopole antenna printed on the no-ground portion (6 × 18 mm2) of the module substrate of the AiSiP (total size 24 × 18 mm2). A parasitic shorted strip can also be added in the no-ground portion to double the operating bandwidth of the AiSiP. When mounted on the system ground plane of a wireless device, the AiSiP can provide a complete communication function, without the need of employing additional antennas in the wireless device. The proposed AiSiP is studied in the paper, and obtained results of the constructed prototype are presented. Effects of the system ground plane on the antenna performance of the AiSiP are also analyzed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2113–2117, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21868 [ABSTRACT FROM AUTHOR]

In this paper, a coplanar ring and patch antenna for dual-band operation is presented. The patch is placed inside a rectangular ring. A coupling strip located in between the rectangular ring and the patch is used to excite them through a 50-Ω coaxial cable. The proposed antenna was built on a two-layer (FR4 and air) substrate with an area of 28 mm by 28 mm designed for WLAN in 2.4- and 5.2-GHz bands. The size of the conducting ground plane is 65 mm by 65 mm. It has a gain of about 5 dBi for both frequencies. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1785–1789, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21801 [ABSTRACT FROM AUTHOR]

In this paper, a planar tab monopole antenna is presented for broadband antenna design for ultra-wideband (UWB) applications. The impedance bandwidth of the antenna is improved by adding slit in one side of the monopole, introducing a tapered transition between the monopole and the feed line, and adding two-step staircase notch in the ground plane. The proposed antenna has a small size of 16 × 19 mm, and provides ultra-wide bandwidth from 2.8 to 22 GHz in order to satisfy the requirements of the current and future wireless communications systems. Low VSWR level and good radiation characteristics are obtained. Additionally, an inverted U-slot is embedded in the proposed antenna to avoid interference between UWB and WLAN systems. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1650–1654, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21693 [ABSTRACT FROM AUTHOR]

This paper presents a study of a multiband prototype dielectric-loaded printed monopole performed through numerical modelling and experimental verification. The design parameters are investigated for apprehending its operating principle and optimizing to provide an even wider impedance bandwidth, covering the four frequency bands of DCS1800, PCS1900, WCDMA2100, and IEEE802.11 2400. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1519–1522, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21704 [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 this paper, a new ultra-wideband slot antenna with a simplified feeding network is presented. This antenna is composed of a circular slot coupled to a circular patch fed with 50Ω microstrip line. A proper parametric investigation was carried out for optimization of the proposed structure. Simulations and measurements show that a large bandwidth from 2.13 to 11.11 GHz can be achieved, which represents a relative bandwidth of 136.4%. Furthermore, good agreement between simulated and experimental results is obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 919–923, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21519 [ABSTRACT FROM AUTHOR]

This paper investigates the characteristics of the modified meander-line-type patch antenna for the 5-GHz band. Its design was based on a modified meander line width and shorting pin with coaxial feeding. Its maximum measured impedance bandwidth (-10 dB and below) reaches approximately 1.64 GHz (4.765–6.405 GHz). Radiation patterns at different frequencies are also discussed, and the measured gains are about 5.74 to 9.09 dBi. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 944–947, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21527 [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]