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A closed‐form solution for the continuous inverse class E (class E−1) design space is presented for the first time1. Analogous to the class‐E power amplifier (PA) modes, the zero current and its derivative conditions needed for the class E−1 switching action can also be shown to be satisfied with any second harmonic susceptance. The complementary relationship between the continuous PA modes for class E and class E−1 are analytically proven. Signal integrity limitations on the continuous class E and class E−1 PA modes are demonstrated to exist and to limit the useful range of solutions of the design space. 2Consequently, the maximum achievable bandwidth using the continuum of solutions in both class E/E−1 is not 2 octaves as previously reported but only 1 octave. [ABSTRACT FROM AUTHOR]

In this work, we present a bilateral reflectionless filter topology. A low‐pass filter prototype and its theoretical frequency responses are given. The frequency responses are obtained by means of ABCD matrices, thereby showing that the proposed prototype is reciprocal, symmetrical, and reflectionless at both ports. A first‐order bandpass filter with the reflectionless characteristic has been designed by applying the conventional low‐pass‐to‐bandpass transformation to the proposed low‐pass filter topology. It is verified by measurement results that the proposed bandpass filter can have less than −20 dB reflection coefficient over the passband and stopband at both ports with the same transmission response of a conventional first‐order bandpass filter. [ABSTRACT FROM AUTHOR]

ABSTRACT A frequency reconfigurable bandpass filter using an electronically tunable dual-mode Substrate Integrated Waveguide (SIW) resonator is presented. Four lumped capacitors as electric tuning elements are loaded near the regions of strongest electric field of TE102 and TE201 modes. The resonant frequency of these two orthogonal modes is tuned by different capacitance values of four lumped capacitors coupled to the SIW resonator. Measured results show that the proposed filter exhibits a tuning range of about 37% from 3.44 to 5 GHz with the total insertion loss variation of 1.85-5.2 dB. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:934-937, 2017 [ABSTRACT FROM AUTHOR]

ABSTRACT With the widespread and ever-increasing application of microwave technology in our daily lives, the potential adverse effects on biological systems from exposure to microwaves are extremely interesting based on thermal and nonthermal effects, especially nonthermal effects on the nervous system. To real time and dynamically elucidate the diversity of reactive oxygen species (ROS) in rat pheochromocytoma (PC12) cells using a real-time-pulsed microwave device combining laser confocal microscopy (LSCM). A LSCM system was designed, and its physical properties, including irradiation cavity simulation, field intensity distribution, and average specific absorption rate (SAR), were analyzed and a stable field intensity distribution as well as a precise average SAR were observed. Subsequently, the diversity of ROS in PC12 cells under pulsed microwave exposure was determined by LSCM online. Additionally, the total ROS in PC12 cells was determined by flow cytometry after pulsed microwave exposure. The ROS signal in single PC12 cell was rapidly quenched as the irradiation time was extended, whereas the total ROS showed no changes in flow cytometry after microwave exposure. This indicates that the change of intracellular ROS in PC12 cells by microwave exposure is a real-time and dynamic process, and provides a significant reference for studying the biological effects of microwaves. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2395-2400, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT Integrated frequency-modulation continuous-wave radars are attractive to a wide range of industrial and commercial applications. The design considerations unique to such an integrated radar front end are studied in this work. Theoretical models as well as experiment results are presented, which verify the effectiveness of the proposed design approach. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1907-1912, 2013 [ABSTRACT FROM AUTHOR]

In this article, an effective design method is presented to design a miniaturized UWB antenna with four band-notches. By carefully integrating C-shaped slots, L-shaped open circuit stub, and T-shaped parasitic strip onto the primitive miniaturized antenna, four band-notches (VSWR > 2) could be achieved at 3.38-3.65 GHz, 4.95-6.05 GHz, 7.42-7.78 GHz, and 8.1-8.9 GHz to reject WiMAX, WLAN, X-band satellite communication, and ITU 8 GHz band signals. Simulated and measured results show that this antenna could operate from 3.15-11.1 GHz (VSWR < 2), and maintain omnidirectional directivity patterns at H-plane. Moreover, the proposed antenna has a very compact size of 18.6 × 22 × 1.5 mm3. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1202-1206, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27546 [ABSTRACT FROM AUTHOR]

A thin-film barium-strontium-titanate (BST) and a conventional silicon varactor tunable dual-band quadrature hybrid couplers are characterized and compared in this article. Both structures are composed of four quarter-wavelength sections at a frequency located between the two operating frequencies, and with two pairs of open-ended stubs. Frequencies tuning make used of BST interdigital and silicon varactor diode capacitors connected at the open-ended stubs. The characterized BST interdigital capacitor presents a capacitive-tunability of 52% through an applied voltage of 0 to 25 V, while 82.5% is for the selected commercial silicon varactor diode. The silicon varactor-tuned dual-band coupler exhibits 45.9 and 5.2% center operation tuning frequency for the first and the second band, respectively, while 29.2 and 4.3% are achieved by the BST tunable coupler. With two-tone nonlinear characterization test, the BST tunable coupler biased at 0 and 25 V presents a better IP3 of +25.45 and +35 dBm, respectively, while +11.5 and +34 dBm are obtained for the silicon varactor tunable coupler. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:858-867, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26719 [ABSTRACT FROM AUTHOR]

A field effect transistor (FET) frequency doubler, with 180° out-of-phase alternate output by switching the bias status of FET at pinch-off ( V ≈ Vt) or saturation ( V ≈ 0) is proposed.With such bias conditions, the former conducts in the positive half-cycle of the input signal, while the latter conducts in the negative half-cycle. Based on this concept, a new frequency doubler architecture is proposed. Without an input balun, it is more compact than conventional balanced frequency doubler. In addition, it provides an alternate doubler with differential output. To demonstrate this concept, a single-ended 5-10 GHz doubler tested at the two bias conditions is designed and demonstrated experimentally to provide opposite-phase outputs for the two cases. The output phase difference error is less than 4° and over 42-dB fundamental frequency rejection is achieved. The conversion gain measured at 10 GHz is 2.5 dB for an input power of 5 dBm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26172 [ABSTRACT FROM AUTHOR]

New passive millimeter wave circuits built on thin alumina substrate are presented. A six-port model is generated using measurement results of a 90° hybrid coupler. Good correlations between model and circuit measurements are proven. The proposed model is suitable for advanced system simulations of V-band wireless personal area networks. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2104–2108, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25377 [ABSTRACT FROM AUTHOR]

In this article, using a novel structure, simulated and measured microwave characteristics from substrate integrated waveguide photodetector (SIWPD) are obtained and compared with the conventional microstrip waveguide photodetector. A Ka-band microstrip to rectangular waveguide multilayer transition for OC-768/STM-256 optical systems is designed and fabricated. Attenuation constant results shows that by replacing substrate integrated waveguide (SIW) instead of conventional microstrip in waveguide photodetectors, operation frequency can be increased. Microwave fields in the proposed structure show a good transition from quasi-TEM mode to TE10 mode in multilayer structure. The multilayer structure is considered to separate SIW and DC bias of the photodetector. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2204–2207, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24528 [ABSTRACT FROM AUTHOR]

A simple method for a Q-band planar triple-mode filter with quasi-elliptic function response is proposed in this letter. This filter is implemented using a high-order mode cavity with substrate-integrated waveguide (SIW) technology and standard printed circuit board (PCB) process. By adopting an orthogonal input and output feed-line and introducing some perturbation, transmission zeros are generated on both sides, which have significantly improved filter selectivity and out-of-band rejection. This triple-mode resonator is then combined with a circular dual-mode cavity to obtain a highly selective filter in Q-band with better stopband rejection. Both of the two filters are fabricated and measured. Low insertion loss and sharp sideband characteristic are observed, which is in good agreement with simulation. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 600–603, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24114 [ABSTRACT FROM AUTHOR]

A 77-GHz six-port frequency modulated continuous wave collision avoidance radar sensor is proposed. Velocity and range are determined from the slope of the instantaneous phase of radar beat signals. Digital signal processing techniques are developed to overcome DC offset and amplitude imbalance problems. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 720–725, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24144 [ABSTRACT FROM AUTHOR]

In this article, we analyze the illumination by an electromagnetic wave of an air/left-handed medium (LHM) interface. It is shown that by placing a periodic structure of resistors near the LHM it is possible to suppress or to reduce the surface wave that is present at the interface. For our demonstration, we consider a semi-infinite lossless left-handed medium having the same constitutive parameters as those of air but with opposite signs. Numerical results, obtained by using a full-wave time domain technique, are presented to validate our approach and the proposed scheme. This work can extend the potential applications of left-handed materials, because it shows that it is possible to use LHM slabs having large width. In addition, this work shows that it is possible to excite the forward wave of an LHM instead of the backward wave. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 280–284, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24036 [ABSTRACT FROM AUTHOR]

The propagation and loss characteristics of the substrate-integrated rectangular waveguide (SIRW) at microwave and millimeter-wave bands are investigated. The results further verify that the substrate-integrated rectangular waveguide has nearly the same waveguide characteristics as conventional rectangular waveguides, and it can be analyzed as a rectangular waveguide with effective width of the SIRW. The insertion loss of SIRW and its equivalent rectangular waveguide agree well with each other. However, it is observed that the derivation of the propagation characteristics of the SIRW and its equivalent rectangular waveguide indicates the frequency dependency. At the X-, K-, and Ka-bands, the effective width of the equivalent rectangular waveguide given by the empirical formula [7] should be slightly increased in order to obtain the propagation characteristic that agrees better with that of the SIRW, about 2%. In addition, at the U-band, when the effective width of the equivalent rectangular waveguide is increased 5% or so, the propagation constant of the rectangular waveguide in the whole band agrees well with that of the rectangular waveguide. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 588–592, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21059 [ABSTRACT FROM AUTHOR]

A new phased-array driver module for a two-antenna array is proposed in this paper. This driver, designed using a six-port phase discriminator, automatically controls the phase of one antenna-array element in order to maximize the received power. The results for a phased two-antenna array operating at 2.45 GHz are presented and discussed. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 346–349, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20983 [ABSTRACT FROM AUTHOR]

In this paper, a spectral–pseudospectral domain technique is presented for the full-wave analysis of a three-dimensional MMIC. This technique combines the advantages of pseudospectral method of lines with those of spectral-domain analysis. In conjunction with the cavity-resonance technique, it enables one to efficiently extract the s-parameters of three-dimensional planar circuits. To demonstrate the generality and validity of the proposed method, numerical analyses are performed for several structures such as microstrip resonators, planar transmission-line steps, and a parallel coupled-line filter. The convergence behaviors are provided for line discretization based on the pseudospectral strategy and finite difference (FD), respectively. The calculated results are compared with those published in previous literature. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 340–345, 2001. [ABSTRACT FROM AUTHOR]

In this paper, a novel semianalytical higher order numerical approach to solve electromagnetic field boundary value problems is described. This pseudospectral-based method of lines is developed by combining the pseudospectral technique and the method of lines so that it not only has a high accuracy of the semianalytical technique in the line direction, but also maintains high accuracy in the discrete direction. The pseudospectral-based discretization technique, distribution of collocation nodes, global interpolation of the differential quadrature, second-order difference matrix for various homogeneous boundary conditions, and decoupling of coupled ordinary differential equations are discussed in detail. Our numerical results demonstrate that this higher order semianalytical method can efficiently solve the boundary value problems with fewer mesh lines when compared to the conventional method of lines. It primarily shows that this method will be a competitive technique to model time-harmonic complex electromagnetic problems. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 339–342, 1999. [ABSTRACT FROM AUTHOR]

This article proposed a miniaturized bandpass filter implemented with the substrate integrated coaxial line (SICL).A four-pole quasi-elliptic SICL bandpass filter with two symmetric transmission zeros is designed, fabricated, and measured with a minimal size of 0.168 λ0 by 0.088 λ0, where λ0 is the wavelength of free space at the central operating frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:131-133, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27249 [ABSTRACT FROM AUTHOR]