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ABSTRACT A closed-form iterative procedure for synthesizing quasi-arbitrary phase responses with cascaded microwave C-section all-pass phasers is presented. The synthesis consists in mapping the transmission poles of the cascaded C-section structure onto the transmission poles of the specified transfer function, where the latter poles are computed using a closed-form polynomial generation method. The real and complex transmission poles of the specified transfer function are realized using C-sections of different lengths and different couplings coefficients. The proposved synthesis is validated by both full-wave analysis and measured multilayer prototypes. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY An in-depth stability analysis of the FDTD method under the upwinding scheme for the Boltzmann transport equation (BTE) under the relaxation time approximation is provided. Both time forward and time backward difference equations are considered. In the time forward differencing case, a sufficient stability condition is derived for the BTE with variable coefficients, and a necessary and sufficient condition is derived for the BTE with constant coefficients. In the time backward differencing case, it is shown that the differencing equations are unconditionally stable. It is shown numerically that the previously reported stability conditions in the literature are not accurate. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The principle of group delay swing enhancement in a transmission-line all-pass network using the combined coupling and dispersion boosting properties of a ferromagnetic substrate is proposed; full-wave verified and experimentally demonstrated using ferrite substrates as a proof of concept. The proposed group delay swing enhanced structures are compact in size, exhibiting a larger dispersion per unit area compared with other alternative techniques for dispersion enhancement, and a magnetically tunable group delay swing. The proposal to suppress the requirement of an external magnet is discussed based on self-biased ferromagnetic nanowire substrates and expected improvements are further pointed out. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:589-593, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26658 [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]

The coupling frequency range of the asymmetric coupler composed of a conventional microstrip right-handed (RH) transmission line and a composite right/left-handed (CRLH) transmission line with lumped-elements is investigated. It shows theoretically that the coupling frequency range can be explicitly determined by the given formulas. In the coupling frequency range, the effective permittivity and permeability of the CRLH transmission lines are both negative, at the same time the product of the average permittivity and the average permeability is negative, i.e., εL < 0, μL < 0, and $\bar{\varepsilon}$ · $\bar{\mu}$ < 0. Two types of RH-CRLH couplers are designed, simulated, and measured. The coupling frequency range obtained from the simulated and the experimental results confirms the theoretical results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2063–2068, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22643 [ABSTRACT FROM AUTHOR]

An experimental demonstration of transparency in the epsilon-negative (ENG) and mu-negative (MNG) pair using the composite right/left-handed transmission line (CRLH-TL) is presented. An eight-cell 1D microstrip transmission-line structure consisting of a ladder network of four CRLH unit cells with MNG characteristics connected to a ladder network of four CRLH unit cells with ENG characteristics is fabricated and tested. The transparency resulting from the cascading of MNG unit cells with ENG unit cells is observed in the S-parameter measurements and a circuit simulation of the voltage distribution. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 476–481, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21022 [ABSTRACT FROM AUTHOR]

An analytical expression for the admittance matrix of a lossy composite right/left-handed transmission line (CRLH-TL) based on the Mittag–Leffler series expansion is presented. This expression can be used to model a periodic CRLH-TL with an expansion truncated to a small number of terms over a prescribed frequency range, which provides the transient response of the line in a faster and more efficient manner than full lumped-element analysis. A numerical study comparing the admittance parameters calculated using the ideal-TL infinitesimal model, the lumped-element model, and the Mittag–Leffler expansion (MLE) is conducted. The transient responses of a CRLH-TL using the lumped-element model and the MLE are compared. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 26–29, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20364 [ABSTRACT FROM AUTHOR]

The phased-array method (PAM), recently introduced to compute Green's functions in infinite photonic crystals (PCs), is extended to the problem of a parallel-plate waveguide (PPWG) structure loaded by a 2-D PC. Numerical results show that the final Green's function exhibits a standing-wave behavior and a high confinement of energy near the source, which emphasize the filtering effect of the photonic bandgap (PBG). Other characteristics of the Green's function are also discussed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 405–408, 2001. [ABSTRACT FROM AUTHOR]

A comparative study of two methods, the eigenmode-expansion method (EEM) and the phased-array method (PAM), for the computation of Green's functions in photonic crystals (PCs) or photonic bandgap (PBG) materials is presented. The Green's functions computed show an excellent agreement between the two methods, and provide an interesting insight into the behavior of a PC excited by a localized source in comparison with the case of a homogeneous medium. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 323–330, 2000. [ABSTRACT FROM AUTHOR]

A comparative study of the electromagnetic behavior of two types of unbounded two-dimensional (2-D) photonic crystals (PCs) is presented. The first PC possesses a sinusoidal permittivity (SI) profile, while the second one, constituted of an array of dielectric rods in air, presents a sharp permittivity (SHA) profile. The dispersion relations of the two types of PCs, computed with the plane-wave method (PWM), are shown and compared. In particular, the evolution of the photonic bandgaps (PBGs) as a function of the permittivity contrast is investigated and discussed for both cases. The Green's functions derivation, by the efficient phased-array method (PAM) recently introduced, is briefly described, and numerical results for radiation patterns in the SI–PC and SHA–PC are shown and compared for different positions of the source within the crystal at a frequency lying inside the PBG. ©2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 24: 316–322, 2000. [ABSTRACT FROM AUTHOR]

ABSTRACT A hybrid-cascade (HC) coupled-line phaser configuration is presented to synthesize enhanced group delay responses for high-resolution radio-analog signal processing. Using exact analytical transfer functions, the superiority of HC coupled-line phasers over conventional transversally cascaded C-section phasers is demonstrated and verified using full-wave simulations. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2502-2504, 2014 [ABSTRACT FROM AUTHOR]

A dual-band (DB) composite right/left-handed (CRLH) branch-line coupler implemented in metal–insulator–metal technology is presented. A simple and accurate circuit-model design procedure for DB CRLH transmission lines is described and applied to the coupler. A prototype operating at 4.2 and 5.2 GHz is demonstrated in excellent agreement with both circuit and full-wave simulations. © 2006 Wiley Periodicals,Inc. Microwave Opt Technol Lett 48:2331–2333, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21948 [ABSTRACT FROM AUTHOR]

Introduces several articles on numerical modelling of metamaterial properties, structures and devices.

Lossy purely LH and generalized CRLH TL metamaterials are analyzed using both an ideal approach, assuming perfectly homogeneous media, and a lumped-element approach, taking into account the real periodic LC configuration of artificial metastructures. The effects of losses are identified and discussed. A CRLH TL metamaterial with small losses is shown to exhibit propagation characteristics identical to that of a lossless metamaterial. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 112–114, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20392 [ABSTRACT FROM AUTHOR]

The characteristics of nonlinear left-handed (NL-LH) transmission lines (TLs) are discussed for the first time. A LH-TL with varactor-diode series capacitance is analyzed in terms of dispersion and nonlinearity characteristics, and its voltage-wave partial differential equation is derived. Numerical responses of the NL-LH-TL to harmonic and pulse waves illustrate the conjoint effects of frequency dispersion and nonlinearity. Potential applications are suggested. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 471–473, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20007 [ABSTRACT FROM AUTHOR]

ABSTRACT A novel type of power divider, featuring arbitrary power ratio and arbitrary ripple level, is proposed. This divider consists of a two-port filtering structure connected to a circulator and is straightforwardly designed using microwave filter synthesis techniques. An example is provided, with low-pass domain synthesis and experimental divider demonstration at the X-band, after low-pass to bandpass transformation. The experimental divider prototype is an iris coupled-resonator waveguide structure, whose response is found in good agreement with theoretical predictions. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1819-1820, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT Originally published Microwave Opt Technol Lett 55:1819-1820, 2013; © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2524, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27945 (Original article DOI 10.1002/mop.27722) [ABSTRACT FROM AUTHOR]