Browsing by Author "CHUNG, SJ"

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A 3-DIMENSIONAL ANALYSIS OF ELECTROOPTIC MODULATORS BY THE METHOD OF LINES
(1993-03-01)
CHUNG, SJ
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交大名義發表
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傳播研究所
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National Chiao Tung University
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Institute of Communication Studies
A 3-dimensional analysis using the method of lines is developed to study the electrostatic field within an electrooptic switch/modulator. The effect of the ends of the electrodes is investigated by considering the distributions of the electric field along the transverse and longitudinal directions. Also, the capacitance related to the abrupt ends is calculated for several parameters of the structure.
A FINITE-ELEMENT ANALYSIS OF BENDING DIELECTRIC WAVE-GUIDES WITH REFLECTION WALLS
(1994-07-01)
CHUNG, SJ
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交大名義發表
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電信工程研究所
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National Chiao Tung University
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Institute of Communications Engineering
The finite-element method together with the Green's-function technique is employed to tackle the scattering problem of bending dielectric waveguides with reflection walls. The influences of the frequency, the ratio of waveguide widths, and the length of the reflection wall on the scattering characteristics of 90-degrees and 120-degrees bends are presented. (C) 1994 John Wiley & Sons, Inc.
A MODIFIED FINITE-ELEMENT METHOD FOR ANALYSIS OF FINITE PERIODIC STRUCTURES
(1994-08-01)
CHUNG, SJ
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CHEN, JL
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交大名義發表
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傳播研究所
;
National Chiao Tung University
A modified finite element method with new solving algorithm is proposed to analyze electromagnetic problems of finite periodic structures. Dielectric-loaded parallel-plate waveguides with rectangular and triangular dielectric gratings are tackled as an example of the present approach. Numerical results are checked by the self-convergence test and by comparing with those obtained by other methods. Finally, the dependence of the scattering parameters on the frequency, the period number, and the grating height is analyzed and compared.
A PARTIAL VARIATIONAL ANALYSIS OF PLANAR DIELECTRIC ANTENNAS
(1991-06-01)
CHUNG, SJ
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CHEN, CH
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電信工程研究所
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Institute of Communications Engineering
The reflection and radiation characteristics of a planar dielectric antenna with arbitrary geometrical configuration are analyzed numerically. A variational equation is first established based on the partial variational principle (PVP), and then solved by the finite element method coupled with the frontal solution technique. The radiation and boundary conditions are incorporated by combining the modal expansion method and the Green's function approach for exterior field representation. The reflection coefficients, the radiation patterns, and the directive and power gains of several antennas with linearized structures are studied and compared.
ANALYSIS OF THE EFFECTS OF A RESISTIVELY COATED UPPER DIELECTRIC LAYER ON THE PROPAGATION CHARACTERISTICS OF HYBRID MODES IN A WAVE-GUIDE-SHIELDED MICROSTRIP USING THE METHOD OF LINES
(1993-08-01)
CHUNG, SJ
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WU, LK
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交大名義發表
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傳播研究所
;
National Chiao Tung University
In this paper, propagation characteristics of even-symmetric hybrid modes in a waveguide-shielded microstrip in the presence of a resistively coated dielectric layer affixed to the top cover of the housing is analyzed with the method of lines. The resistive boundary condition is employed to model the resistive film. A shielded microstrip line having a unity strip-width-to-substrate-thickness ratio (i.e., w/h1 = 1) placed on top of a 0.635-mm-thick alumina substrate is considered. Based on a 10h1 x 7h1 reference housing, four different housing arrangements are obtained by varying the structural parameters of the resistively coated dielectric layer. Results obtained indicate that the effects of both the housing walls and the resistively coated upper dielectric layer on the dominant (quasi-TEM) mode are insignificant and may be ignored when frequency is above 15 GHz. For the higher order modes, resistive film appears to be transparent when film resistance is greater than about 1 kOMEGA, it behaves as a good conductor when film resistance is much smaller than 100 OMEGA, and in between it results in nonlinear (and even oscillatory) higher order modal behaviors. Apparently, due to the increasing field concentration inside the upper dielectric (as suggested by the increasing epsilon(reff)) for a given mode, both the maximum attenuation and the film resistance needed to achieve it increase with frequency and dielectric constant of the upper dielectric layer.
ATTENUATION OF THE PARASITIC MODES IN A SHIELDED MICROSTRIP LINE BY COATING RESISTIVE FILMS ON THE SUBSTRATE
(1995-07-01)
CHOU, YH
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CHUNG, SJ
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交大名義發表
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傳播研究所
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National Chiao Tung University
In this paper, propagation characteristics of even-symmetric hybrid modes in a waveguide-shielded microstrip line with the presence of the resistive films affixed to the two sides of the center strip is investigated. The method of lines with modifications concerning the inhomogeneity of the surface between the air and substrate layers is uded for analysis. After a validity check of the analysis by considering two special structures, i.e., a microstrip line (R(m) = infinity) and a coplanar waveguide (R(m) = 0), the resistance R(m) and the width W-m of the film are varied to see the influence on the propagation and attenuation constants of the dominant mode as well as the higher-order (parasitic) modes. Optimal combinations of the resistance and the width are found so that the resistive film has the largest attenuating effect on the higher-order modes but has no ingterference with the dominant one.
FULL-WAVE ANALYSIS OF DISCONTINUITIES IN CONDUCTOR-BACKED COPLANAR WAVE-GUIDES USING THE METHOD OF LINES
(1993-09-01)
CHUNG, SJ
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CHRANG, TR
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交大名義發表
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電信工程研究所
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National Chiao Tung University
A three-dimensional analysis using the method of lines with nonequidistant discretization is described to investigate the discontinuities in shielded conductor-backed coplanar waveguides (CBCPW's). An extended approach concerning the treatment of the boundary conditions at the input and output ports is proposed in which the reflection and transmission coefficients can be directively obtained in a single calculation. The validity and convergence of the numerical results are checked and gaps with various shapes in CBCPW's are analyzed and compared. Finally, the frequency response of a simple step discontinuity is calculated as an application to unsymmetrical structure.
RESONANT FREQUENCIES OF A MICROWAVE PACKAGE WITH VERTICAL DIAPHRAGMS ATTACHED TO THE TOP COVER
(1995-04-20)
CHUNG, SJ
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CHEN, HH
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交大名義發表
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電信工程研究所
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National Chiao Tung University
The resonant frequencies of the modes in a cabineted microwave package are investigated by the mode-matching method. The upper region of the package is partitioned into several cabinets using vertical diaphragms of a same depth and of negligible thickness. Numerical results are shown to agree with those of the measurement. The change of the resonant frequencies with the diaphragm depth is presented and explained. It is found that the resonance-free frequency bands can be broadened by suitably designing the positions and the depth of the diaphragms. (C) 1995 John Wiley & Sons, Inc.
SHIELDING EFFECT OF A DIAPHRAGM IN A PACKAGED MICROSTRIP CIRCUIT
(1995-05-01)
CHEN, HH
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CHUNG, SJ
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交大名義發表
;
電信工程研究所
;
National Chiao Tung University
The scattering of a diaphragm in a packaged microstrip line is investigated using the mode-matching method together with the method of lines. Instead of analyzing the discontinuity in the microstrip, this paper tackles the variation of the waveguide housing, The influences of the thickness and the depth of the diaphragm on the scatterings of the dominant mode and higher-order modes are analyzed based on a comparison of the modal power distributions, Finally, the shielding effect of a pair of closely spaced diaphragms is investigated.