Tzyy-Sheng Horng

Radiation of printed antennas with a coplanar waveguide feed

This paper presents an analysis of conductor-backed aperture antennas with multilayered substrate. These printed antennas are fed by a coplanar waveguide (CPW). The theoretical approach taken is to develop an integral equation over the aperture region and apply Galerkins procedure in the spectral domain. The properties of printed antennas with a CPW feed are characterized. Numerical results include the scattering parameters, antenna pattern, and radiation efficiency. The reflection coefficient, input impedance, and far-field pattern are also compared with measurements and good agreement is observed. >

A generalized method for distinguishing between radiation and surface-wave losses in microstrip discontinuities

A generalized method for calculating both radiation and surface-wave losses is developed for microstrip discontinuities. The losses are determined by a rigorous Poynting vector analysis where the current distribution over the microstrip discontinuities is a result of a full-wave moment method solution. The power loss mechanism of such microstrip discontinuities as open-end, right-angle-bend, gap and stub lines, EMC lines, and rectangular patches are investigated. A self-consistency check of the result based on power conservation is performed to confirm the numerical results. It is found that, above a certain frequency, the surface-wave loss becomes more important than the radiation loss. >

Analysis of cavity-backed aperture antennas with a dielectric overlay

A full-wave analysis of cavity-backed aperture antennas with a dielectric overlay is presented. The theoretical approach uses a closed-form dyadic Greens function in the spectral domain. The aperture equivalent magnetic currents are obtained using the surface equivalence theorem and an integral equation is obtained by matching the fields across the aperture. The moment method applied in spectral domain analysis is employed to solve the integral equation for the equivalent magnetic currents with proper combination of subdomain or entire domain expansion functions. Numerical results include the aperture field distribution and antenna parameters such as input impedance, bandwidth, and efficiency. A set of measurements data is compared with results based on the theoretical work. >

Corporate feed design for microstrip arrays

A design technique for an embedded microstrip corporate feed is presented. The aim of the design is to shape each corporate feed junction to achieve a tapered and in-phase output current distribution. From this, a Dolph-Chebyshev array sum pattern may be constructed. In the experiments, the designed corporate feed is used to excite a five-element equispaced linear array of overlay microstrip dipoles. It is found both theoretically and experimentally that a 20-dB Dolph-Chebyshev broadside sum pattern can be synthesized in the H-plane at 8.5 GHz. Mutual coupling among the dipoles is included in this analysis. The pattern degradation due to manufacturing tolerances on the alignment between the feed network and the dipole array is discussed. >

A Rigorous Study of Package and PCB Effects on W-CDMA Upconverter RFICs

A Volterra-series analysis is presented to study the package and printed circuit board (PCB) effects on the linearity of two wideband code-division multiple-access upconverter RF integrated circuit (RFIC) designs. The first design adopts a recently popular micromixer with a class AB input stage. The second design is based on a commonly used Gilbert mixer with emitter degeneration. Both upconverter RFICs are designed to have the same adjacent channel power ratio (ACPR) in the chip-level simulation. After fabrication, packaging, and testing on the PCB, the micromixer-based design consumes less direct current, but causes more degradation in the ACPR performance due to the influence of package and PCB when compared to the Gilbert mixer-based design. The theoretical analysis indicates that the micromixer-based upconverter RFIC is rather susceptible to the parasitic effects from the ground interconnect and, therefore, it needs a better package solution with a lower ground inductance for practical use. Comparison between theory and measurement shows good agreement in predicting the variations of conversion gain and ACPR due to the presence of the package and PCB

Via hole, bond wire and shorting pin modeling for multi-layered circuits

This paper presents a full-wave spectral-domain analysis to model generalized three-dimensional circuits for multilayered structures. To describe properly the current along the vertical post, such as via holes, bond wires and shorting pins, etc., the simple pulse function is used in the procedure of the moment method. Several numerical techniques are applied to improve the evaluation of matrix elements. Comparison of numerical results with experimental and available analytical data shows good agreement.<<ETX>>

A full-wave analysis of shielded microstrip line-to-line transitions

A rigorous procedure is used to analyze several microstrip line-to-line transitions in a shielded multilayer structure. The transitions studied include edge-coupled lines, overlay-coupled lines, and coupled-to-single lines. A power conservation check based on a rigorous Poynting vector analysis is used to determine the accuracy of the numerical convergence. The results of power distributions and coupling coefficients of the line-to-line transitions are studied parametrically to identify the properties and applications of each transition.<<ETX>>

Multiple arbitrary shape via-hole and air-bridge transitions in multilayered structures

This paper presents a methodology for the design of multiple via-hole and air-bridge transitions of arbitrary shape in multilayered multi-port microstrip circuits. Application of multiple via holes to the design of microstrip filters and other devices will be presented. To describe properly the current along the vertical post, the simple pulse function with a triangular cross section is used. Circular, rectangular and triangular vertical transitions are analyzed and optimized for practical applications. The developed algorithms are much faster than existing softwares. The Greens function applies for any distance between and any location of field and source points.

A generalized method for the distinction of radiation and surface-wave losses in microstrip discontinuities

A generalized method for calculating both radiation and surface-wave losses is developed for microstrip discontinuities. The losses are determined by a rigorous Poynting vector analysis where the current distribution over the microstrip discontinuities is a result of a full-wave moment-method solution. It is found that above a certain frequency, the surface-wave loss becomes more important than the radiation loss. A self-consistency check of the result based on power conservation is also presented.<<ETX>>

Full-wave analysis of superstrate cavity-backed aperture antennas

A dynamic model based on a full-wave analysis which accounts for both radiation and surface waves is presented to characterize superstrate cavity-backed aperture antennas. Several examples are studied parametrically using this technique. To verify the numerical accuracy, both the equivalent magnetic current distribution and the input impedance for a center-fed slot are compared with the theoretical results of A. Hadidi and M. Hamid (1989). The results are in good agreement.<<ETX>>