Weigan Lin

Analytical analyses of v, elliptic, and circular-shaped microshield transmission lines

Several new types of monolithic coplanar transmission lines, v, elliptic, and circular-shaped microshield coplanar waveguide, have been proposed. The characteristic impedance expressions for those transmission lines have been derived using the conformal mapping method (CMM) under the assumption of the pure-TEM propagation and zero dispersion. In the analyses of the elliptic and the circular-shaped microshield coplanar lines, the methods using the graphical approximation and taking the geometric mean value of the upper and the lower bounds to the size of the line are put forward to calculate the characteristic impedance of this two kinds of microshield coplanar lines. The numerical results show the effects of the different shaped microshield walls on characteristic impedances. >

A Millimeter-Wave E-Plane Band-pass Filter using Multilayer Low Temperature Co-Fired Ceramic (LTCC) Technology

This paper presents a substrate integrated waveguide (SIW)-based millimeter-wave E-plane band-pass filter (BPF) with multilayer Low Temperature Co-fired Ceramic (LTCC) technology. The vertical metal walls of SIW and metal fins of the evanescent waveguides are realized by closely spacing metallic via-holes. A three-order Chebyshev E-plane BPF is developed and verified by full-wave simulation. The proposed filter is fabricated using LTCC technology, and a tapered line is designed as the transition between the SIW and microstrip line. Good agreement between simulated and measured results is observed.

Substrate Integrated Folded Waveguide (SIFW) Partial H-Plane Filter with Quarter Wavelength Resonators

In this paper, the design and experiment of a novel substrate integrated folded waveguide (SIFW) partial H-plane bandpass filter, consisting of quarter wavelength resonators, is presented. In the proposed filter, two adjacent quarter wavelength resonators are coupled by connecting an admittance inverter and an impedance inverter alternately. Here, the admittance inverter and impedance inverter are realized by H-plane slot of open-ended evanescent waveguide and H-plane septa of short-ended evanescent waveguide, respectively. In order to validate the new proposed topology, a four-pole narrowband bandpass filter is designed and fabricated using standard printed circuit board process. The tapered line is used as transition between SIFW and microstrip-line for easy integration and measurement. The measured results are in good agreement with simulated results.

New theorems for bianisotropic media

The general volume equivalence theorem for bianisotropic scatterers is presented, where the equivalent electric and magnetic currents are determined by a pair of coupled vector integral equations. Moreover, using the general volume equivalence theorem and conventional image principle, image theory is developed for a bianisotropic body over an infinite perfect electric or magnetic conducting ground plane.

Scattering response of an electrically small bianisotropic particle

Scattering response of an electrically small bianisotropic particle suspended in free space is presented. Formulation of this problem is based on the assumption that the electrical small bianisotropic particle can be modelled as both an equivalent electric and a magnetic dipole moments. It is found that cross-polarization and/or co-polarization phenomena may occur for certain constitutive relations, separatively.

A Partial H-plane Substrate Integrated Folded Waveguide (SIFW) Bandpass Filter Based on H-plane Slot

This paper presents a novel partial H-plane bandpass filter based on substrate integrated folded waveguide (SIFW), which employs H-plane slot of open-ended evanescent waveguide as admittance inverter. In order to validate the new proposed topology, a three-pole narrowband bandpass filter is designed and fabricated using standard printed circuit board process. The tapered line is used as transition between SIFW and microstrip for easy integration and measurement. The filter is considerably smaller than its metallic waveguide counterpart. The measured results are in good agreement with simulated results.

Design of Novel Millimeter-Wave Wideband Bandpass Filter Based on Three-Line Microstrip Structure

A novel three-line microstrip structure wideband bandpass filter is presented. Diamond structures of input/output ports are employed as matching circuits. Compared with the traditional three-line filter, the proposed three-line filter not only retains virtues of the traditional three-line filter, but also resolves drawbacks of it, which include discontinuities between adjacent sections, number of design parameters, and no effective matching circuits at input/output ports. To validate the proposed three-line filter, an eleven-pole millimeter-wave wideband bandpass filter is designed and fabricated. Good agreement between simulated and measured responses is observed.

Scattering response of a bianisotropic cylinder with electrically small cross-section

EM scattering response of an infinitely long bianisotropic cylinder with electrically small cross-section suspended in free space is presented. Formulation of this problem is based on the coupled integral equation method with the long wavelength approximation. Reduced expressions for the scattering of plane waves, both E-wave and H-wave types, are obtained. It is revealed that for certain polarization matrices determined by the constitutive parameters of the scatterer, cross-polarization and/or co-polarization phenomena may occur, respectively.

Investigation of Terahertz Wave Propagation Along Parallel-Plate Dielectric Waveguide using Various Metal Conductivity Models

In this paper, an investigation of parallel-plate dielectric waveguide is proposed by theoretical calculation at terahertz frequencies. In the previous study, the electromagnetic analysis of waveguide employed simplified intrinsic frequency dispersion models — classical skin-effect model for the bulk conductivity of normal metals used in terahertz wave structures. To analyze the deviation between various metal conductivity models, the accurate classical relaxation-effect frequency dispersion model and the traditional and much simpler classical skin-effect model are used to analyze the propagation characteristic of the proposed waveguide. The propagation loss with different conductivity models has been obtained by numerically solving the complex eigenvalue equation for the propagation constant. The energy coupling characteristic of this waveguide is also proposed. The conductor loss deviation between the classical relaxation-effect model and the classical skin-effect model varies from 1.1% to 6.4%, and the total loss varies from 1.1% to 5.4% at 0.1–1 THz. The analysis results are very useful for the development of terahertz power propagation, spectroscopy and detectors.

A critical study of a dielectric sphere near a grounded plane

The perturbed field by a dielectric sphere near a grounded plane bounding a uniform field is given so as to fill the gap between the solution of the case where the sphere is resting on the grounded plane and the case where the sphere is away from the grounded plane. We can now calculate the perturbed field when the sphere is located near the grounded plane. The case of a conducting sphere is studied and used as a check.