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NONLINEAR STABILITY ANALYSIS OF AN OSCILLATOR WITH DISTRIBUTED ELEMENT RESONATOR
"... Abstract—In this paper a complete analysis to the stability of a microwave oscillator with distributed element resonator is presented. In this type of oscillators, the circuit description changes form ordinary differential equations to partial deferential equations. In this paper a Gunn diode oscill ..."
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Abstract—In this paper a complete analysis to the stability of a microwave oscillator with distributed element resonator is presented. In this type of oscillators, the circuit description changes form ordinary differential equations to partial deferential equations. In this paper a Gunn diode oscillator with distributed elements resonator is analyzed. The instability condition of the startup phase and the stability condition of the steady state oscillation is investigated. 1.
Charge transport by a pulse Ewave in a waveguide with conductive medium
 Progress In Electromagnetics Research B
"... Abstract—An Ewave excites longitudinal conductivity currents in a waveguide filled with lossy medium. Total flow of this current through a crosssection is nonzero for odd Emodes; it means that some charge is transported by the pulse along the waveguide. This phenomenon is considered in the paper ..."
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Abstract—An Ewave excites longitudinal conductivity currents in a waveguide filled with lossy medium. Total flow of this current through a crosssection is nonzero for odd Emodes; it means that some charge is transported by the pulse along the waveguide. This phenomenon is considered in the paper using analytical approach based on mode expansion of the fields in Time Domain (known as Mode Basis Method) and using Finite Difference in Time Domain method (FDTD). Volume conductivity charges being moved by the pulse wave are determined. In order to set the problem as much physically as possible we consider diffraction of a pulse Ewave on the boundary between a hollow waveguide and a waveguide with conductive medium. Behavior of the transient fields and surface charges at the interface are also examined. It is shown that an incident pulse wave excites a surface wave at the interface that results in transversal resonance with relaxation time much greater than that of the conductive medium. Characteristics of the travelling charge pulse wave are studied based on the obtained closedform solution. 1.
Mode matching in time domain
 Proceedings of UWBUSIS, 225–227, Sevastopol
, 2008
"... Abstract—A new method is presented for analysis of transient electromagnetic fields in regular structures with abrupt discontinuities. The method is based on mode expansion of the fields in the Time Domain. The modes propagate independently in the regular parts of the structure and are coupled at th ..."
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Abstract—A new method is presented for analysis of transient electromagnetic fields in regular structures with abrupt discontinuities. The method is based on mode expansion of the fields in the Time Domain. The modes propagate independently in the regular parts of the structure and are coupled at the discontinuity. The main idea consists in solving 1D FDTD equations for each independent mode channel in the regular waveguides and using modematching at the junction crosssection in order to relate the mode amplitudes in all the channels at the same time instant via imposing boundary conditions. As examples the problems of pulse signal diffraction at a step discontinuity in a parallelplate waveguide, diffraction at a junction of circular and coaxial waveguides, and pulse radiation of a biconical antenna are considered. The latter problem is treated as a junction of two conical lines (one of which is the free space) that are regular in spherical coordinates. 1.
MODE EXPANSION IN TIME DOMAIN FOR CONICAL LINES WITH ANGULAR MEDIUM INHOMOGENEITY
"... Abstract—A new modification of the method of Mode Expansion in Time Domain is proposed for studying transient signals propagation in conical lines (including multiconnected ones) with inhomogeneous and timedependent medium. The method is based on expanding the fields in spherical coordinate system ..."
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Abstract—A new modification of the method of Mode Expansion in Time Domain is proposed for studying transient signals propagation in conical lines (including multiconnected ones) with inhomogeneous and timedependent medium. The method is based on expanding the fields in spherical coordinate system into series of angular dependent modes with mode amplitudes being governed by a system of coupled evolutionary equations. The medium parameters (permittivity and permeability) are taken in a factorized form as a product of angular dependent factor and a factor that depends on time and radial coordinate. The introduced method can be applied to analysis of propagation and radiation in conicallike antennas with dielectric filling. 1.
THE DESIGN TECHNIQUE FOR COAXIAL RESONATOR CAVITY DUPLEXER
"... Abstract—A general design technique for the coaxial resonator cavity duplexer is proposed in this paper, based on the design method of the general Chebyshev bandpass filter. We can obtain the coupling matrixes of crosscoupled resonator duplexer by optimization technique, and complete the design of ..."
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Abstract—A general design technique for the coaxial resonator cavity duplexer is proposed in this paper, based on the design method of the general Chebyshev bandpass filter. We can obtain the coupling matrixes of crosscoupled resonator duplexer by optimization technique, and complete the design of duplexer fast. The proposed duplexer is designed and fabricated with the 1.92–1.98 GHz downlink and 2.11–2.17 GHz uplink frequencies. Across the bandwidth, the measured insertion losses at the both bands are less than 1 dB, while the input and output return losses are well below 20 dB. More than 50 dB isolation performance is obtained from the duplexer. The measured results approximately meet all the conditions of the design targets. 1.
CIRCULARLY POLARIZED ARRAYS OF CAVITY BACKED SLOT ANTENNAS FOR XBAND SATELLITE COMMUNICATIONS
"... Abstract—Circularlypolarized arrays of cavity backed slot (CBS) antennas are proposed for Xband satelliteearth communications. Two configurations of such circularly polarized arrays are investigated: crossshaped and squareshaped arrays. Both configurations can produce righthand circular polari ..."
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Abstract—Circularlypolarized arrays of cavity backed slot (CBS) antennas are proposed for Xband satelliteearth communications. Two configurations of such circularly polarized arrays are investigated: crossshaped and squareshaped arrays. Both configurations can produce righthand circular polarization (RHCP) as well as lefthand circular polarization (LHCP) by proper setting of excitation phase for each element in the array. The finitedifference timedomain (FDTD) method is used to analyze the characteristics of the proposed arrays including the input impedance, Sparameters, radiation pattern, gain and axial ratio. The results show that the proposed array configurations seem very promising and useful for geostationary satellite applications. 1.
Determination of electromagnetic cavity modes using the Finite Difference FrequencyDomain Method
, 2010
"... In this communication we propose a numerical determination of the electromagnetic modes in a cavity by using the Finite Difference FrequencyDomain Method. We first derive the analytical solution of the system and subsequently we introduce the numerical approximation. The cavity modes are obtained b ..."
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In this communication we propose a numerical determination of the electromagnetic modes in a cavity by using the Finite Difference FrequencyDomain Method. We first derive the analytical solution of the system and subsequently we introduce the numerical approximation. The cavity modes are obtained by solving an eigenvalue equation where the eigenvectors describe the eigenfunctions on the real space. It is found that this finite difference method can efficiently and accurately determine the resonance modes of the cavity with a small amount of numerical calculation.