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In this paper, we present a novel combline filter using periodically loaded resonators. A resonator with a periodic N-disk mounted onto its inner conductor is used as novel combline resonator. A significantly improved Q factor is achieved within the same volume of the conventional combline resonator. An example of a two-pole combline filter is designed. Simulation and experimental results are presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 189–191, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11324 [ABSTRACT FROM AUTHOR]

The basic dielectric properties of biological materials are required for the development of next-generation microwave-based medical instrumentation. The purpose of this paper is to further the study of the properties of blood using several different commonly used measurement methods. New data on the complex permittivity of chicken blood are presented in the frequency range between 45 MHz and 26.5 GHz at room temperature by using open-ended coaxial probe techniques, and in the Ku-band using waveguide techniques, with an Agilent 8510C network analyzer. A commonly used reference material, methanol, is used to verify the efficacy of these techniques. This data favorably compares to the general permittivity of blood that previous authors have published. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 54–56, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11125 [ABSTRACT FROM AUTHOR]

This paper presents a novel configuration for dual-mode cylindrical cavity filters operating in the TE111 mode. The proposed configuration is compact yet simple, with only one coupling probe to excite two orthogonal TE111 modes in a cylindrical waveguide cavity. A prototype is designed to operate at 10 GHz. Simulated and experimental results are provided. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 335–337, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11053 [ABSTRACT FROM AUTHOR]

In this paper, a novel defected ground structure (DGS), connected in parallel to two periodic structures with different center frequencies of the stopband, is proposed for increasing the output power of a voltage-controlled oscillator (VCO) in microstrip circuits. To evaluate the effects of DGS on the output power, two GaAs field-effect transistor (FET) VCOs have been designed and fabricated. One of them has a 50Ω microstrip line with DGS at the output section, while the other has only a 50Ω straight line. Measured results show that DGS rejects the second harmonic at the output and yields improved output power by 1–5%. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 279–281, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11038 [ABSTRACT FROM AUTHOR]

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

In this paper, error-control coding is used with a six-port direct-digital QPSK receiver [1] in an AWGN channel. The direct-conversion wideband six-port millimeter wave receiver proposed herein meets the needs of MMIC mass-market wireless communications. Convolutional code and Turbo code are used as the channel codes for the first time in this type of receiver. The BER results for the convolutional code, turbo code, and the uncoded system in the six-port receiver, are presented at a bit rate of 1 Mbps. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 465–467, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10791 [ABSTRACT FROM AUTHOR]

In this paper, microstrip photonic bandgap structures based on etching a nonperiodic pattern of circles in the ground plane of a microstrip line are investigated. Three topologies based on placing two defects in a periodic circle pattern, with a different spacing between them for each structure, are considered and their responses are compared. Multiple-frequency and bandwidth-tuned bandgaps are obtained. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 479–481, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10795 [ABSTRACT FROM AUTHOR]

An experimental study of a smart-materials actuator driven by a microwave is presented in this paper. A proof-of-concept experiment using a smart material, such as thin layer composite unimorph ferroelectric driver and sensor (THUNDER), has been demonstrated with wirelessly transmitted microwave power. Such an advance system will offer a new class of smart devices that are remotely controlled via wirelessly transmitted power. Thus, a system of this nature autonomously functions without an onboard power infrastructure. Potential applications are integrated sensors, actuators, and smart flight control in space applications, as well as biologically-inspired systems. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 331–333, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10757 [ABSTRACT FROM AUTHOR]

Microwaves play a vital role in the diagnosis and treatment of diseases caused by the abnormal mineralization of biological fluids in human body. First hand information regarding the dielectric behavior of these minerals facilitates to detect these crystals. This paper attempts a comparative study of the dielectric properties of urinary crystals grown in vitro by gel technique with natural stones procured from patients who had undergone stone removal surgery. Cavity perturbation technique was employed and measurements were made in the S band. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 297–299, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10588 [ABSTRACT FROM AUTHOR]

With the advent of planar photonic bandgap (PBG) materials, different topologies of PBG structures have been proposed to improve the bandgap performances of microwave signals. Conventional circular-patterned PBGs have constraints in the broadband stopband performance due to the high ripple heights in S-parameters. In this paper, we suggest a novel annular-ring-patterned PBG to improve the stopband bandwidth and the ripples. The aspect ratio of the annular-ring-patterned PBG plays an important role in controlling the bandwidth of the rejection band, as well as the ripple heights in the S-parameters of the PBG-engineered transmission lines. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 431–433, 2002. [ABSTRACT FROM AUTHOR]

In this paper, the design and measurement of a 10 GHz thin-film microstrip (TFMS) rat-race coupler using a thick-film photoimageable technology is presented. The fabricated hybrid occupies 2.10 mm×0.61 mm, and offers good performance. This is a promising technology for low-cost large-volume multichip modules (MCMs) for future wireless systems. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 5–7, 2002. [ABSTRACT FROM AUTHOR]

The present paper proposes a new design method of a miniatrized combline BEF. The degradation of the BEF characteristics due to close placement of the resonators is canceled with the aid of a capacitor between them. Simulation and experimental results based on the proposed design method are also presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 327–329, 2001. [ABSTRACT FROM AUTHOR]

We show, in this paper, the results obtained in the sterilization process by using different irradiating structures. Starting from our earlier findings of the existence of an important synergy on the killing effect caused by the simultaneous application of oxidant agents such as hydrogen peroxide and microwave irradiation, we have now extended the work to identify the power threshold and the optimum frequency range for the effect. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 404–406, 2001. [ABSTRACT FROM AUTHOR]

The selective gate recess etching technology has been investigated extensively using citric acid and H2O2 etchant for AlGaAs/InGaAs/GaAs pHEMT in this paper. A suitable ratio of this etchant has been determined by experiment. Then we studied the effect of the gate recess depth on the microwave properties of a 0.8 μm gate length pHEMT. The recess depth was varied by changing the recess etch time, and was measured by Taylor–Hobson test instruments. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 410–412, 2001. [ABSTRACT FROM AUTHOR]

In this paper, we present a hybrid coordinate FDTD scheme, in which we insert a local conformal coordinate system which conforms with the scatterers in a Cartesian coordinate system, when there exists a nonrectangular scatterer in the Cartesian coordinate system. We propose a new interpolation scheme in the overlap region to achieve low reflection from the interface between the built-in and Cartesian regions. The numerical experiment demonstrates that this scheme has a significant improvement in the staircasing approximation. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 114–116, 2001. [ABSTRACT FROM AUTHOR]

The traditional approach to microwave low-noise amplifier design is to use graphical aids involving gain, noise, mismatch, and stability circles. In this paper, we propose a method, which avoids graphical methods, and uses a formula for the source reflection coefficient to minimize noise measure, and a robust numerical method for the load reflection coefficient to optimize the match at each port. The method is tested on a number of different transistors. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 321–323, 2000. [ABSTRACT FROM AUTHOR]

This paper describes an accurate design technique for multilayer bandpass filters for wireless communication system applications. Using coupled strip-line and J-inverter theories, the filters were analyzed and designed in a multilayer structure. The designed structures were simulated using MDS and IE3D simulators. Fabricated filters were measured by an HP8757D network analyzer. Sample results of the filter performances demonstrate excellent potential of the multilayer structure. It indicates that the filter can have a response that is in good agreement with the simulation result without a cofiring process. ©2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 24: 258–260, 2000. [ABSTRACT FROM AUTHOR]

GaN is a suitable material for millimeter-wave high-power IMPATT oscillators because of its superior electronic properties—high breakdown electric fields and high electron saturation velocity. In this paper, millimeter-wave wurtzite phase and zincblende phase GaN IMPATT oscillators at elevated temperature are analyzed by a Read-type large-signal model. The power density of GaN IMPATT devices at millimeter-wave frequencies is two orders magnitude higher than that of conventional GaAs and Si IMPATT devices. The simulations showed that GaN wurtzite phase p+-n single-drift flat-profile IMPATT oscillators at 300 GHz have an efficiency of 11% and an RF power density of 1.6 MW/cm2 when operated at 800 K. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 257–259, 1999. [ABSTRACT FROM AUTHOR]

This paper details an accurate broadband model of an inductive slot in a single-ridge waveguide, and demonstrates how the model can be used for low-pass filter design using a commercial linear circuit analysis program. A slot is modeled as a series nondispersive short-circuit stub with dispersive waveguide elements on either side. Experimental results show that the method is accurate for filter design, and predicts the cutoff frequencies to typically within 0.6%. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 116–118, 1999. [ABSTRACT FROM AUTHOR]

In this paper, the shielding effects for various door seals of a microwave oven are discussed. The FDTD method is adopted in the numerical calculations. It is shown here that there are optimum combinations of part sizes and structures by which the high shielding effect is obtained. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 333–335, 1998. [ABSTRACT FROM AUTHOR]

A microstrip bandpass filter (BPF) using a triangular patch resonator is introduced in this paper. With one coupling gap between the input and output ports together with the patch configurations, the filter can realize DC block, lower insertion loss, and higher power-handling capability. For demonstration purposes, a filter of this type is designed, fabricated, and tested and the measured results for the fabricated BPF show good consistency with the calculated results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 914–915, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21517 [ABSTRACT FROM AUTHOR]

In this paper, after setting up easy-to-install plaster board-type wave absorbers in a model room (assuming a wireless LAN environment), transfer rates are measured using a wireless communication system conforming to IEEE 802.11a (5.2-GHz band) and IEEE 802.11g (2.45-GHz band) and improvements in transfer rates are inspected. The results of the experiment confirm that, compared to the status prior to installation of the wave absorbers, improvements of roughly 7.4% upstream and 10.8% downstream in the case of 11a, and roughly 116.7% upstream and 57% downstream improvements in the case of 11g, are obtained. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 107–108, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21277 [ABSTRACT FROM AUTHOR]

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

In this paper, we describe a variation of a folded slot antenna that is formed by a nonuniform-width slot. The antenna is fed by a coplanar waveguide on which a pair of small slits are located on both sides for broadband matching. The simulated results and measured data reveal that it enjoys a relatively wide bandwidth of 37.4%. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 147–148, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20403 [ABSTRACT FROM AUTHOR]

Most commercial degree-two waveguide circulators using gyromagnetic turnstile and post resonators are quarter-wave coupled by metal transformers. The purpose of this short paper is to experimentally describe one post-resonator geometry using a self-jigging, partially dielectric-loaded radial waveguide transformer. The assembly developed in this work has a return loss of 20 dB and an insertion loss of 0.20 dB over a bandwidth of approximately 12% in the WR90 waveguide. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 263–264, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11033 [ABSTRACT FROM AUTHOR]

The one-dimensional (1D) defected ground structure (DGS) is used to control the cut-off frequency characteristic. In this paper three non-periodic filters are built, in order to show the versatility of DGS. Five unit cells of different shape with the same attenuation pole frequency were combined in each filter. The frequency response is essentially the same as in the case of periodic filters with equal square unit cells. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 249–250, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10734 [ABSTRACT FROM AUTHOR]

The influence of via hole inductance on millimeter-wave single-ended pHEMT gate-mixer down-converter conversion gain is examined by a closed formula and by measurement. It is shown that feedback inductance acts as a voltage divider, reducing the conversion gain and increasing the LO power requirements. Analytical considerations presented in the paper predict that this effect can reduce the conversion gain by up to 9 dB. Additionally, a method to minimize the influence of via hole inductance on mixer performance is presented. Two circuits, one with and one without resonating stubs, have been manufactured and tested. The new circuit exhibits 3.5 dB more conversion gain than the classical topology, RF 65.3 GHz, nominal IF 1.3 GHz. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 399–400, 2002. [ABSTRACT FROM AUTHOR]

Presents a response to a commentary on a proposed approach to a four-way hybrid ring power divider design. Purpose and scope of the paper; Failure of earlier approaches to consider junction effects; Problem in the implementation in a large array of stripline dividers; Reasons for the decision to use microstrip implementation.