Quasi-Planar Transmission Lines

A newly proposed and tested full-wave mixed potential mode-matching method is presented for the analysis of planar and/or quasi-planar transmission lines. The transmission lines under investigation consist of layered (stratified) and nonlayered dielectric substrates and metal strips of finite thickness. The y-directed hybrid TE and TM Hertzian potentials, perpendicular to the interfaces between each layered region, are employed in the layered regions. The nonlayered regions, which consist of dielectric step discontinuities that destroy the layered configuration in the horizontal plane, utilize the x -directed hybrid TE and TM Hertzian potentials parallel to the horizontal plane. As a direct result, the full-wave formulation of the transmission line problem becomes systematic and easy to handle. Extensive analyses of a particular case study show that the relative convergence criterion needs to be satisfied to obtain accurate electromagnetic field solutions. The theoretical results obtained here are in very good agreement with the published data for various transmission line structures, which are the special limiting cases of the particular case study. The applications of the new formulation to the proximity effects of microstrip and Microslab' lines are also illustrated by examples. Fig. 1. A generalized planar and/or quasi-planar transmission lines structure for microwave, millimeter-wave, and optoelectronic applicaI . INTRODUCTION tions. ONOLITHIC microwave integrated circuits ated and demonstrated the potential for extensive use in military and civilian com-"ication systems []I, 121. The capability of achieving first-pass success in MMIC chip design will improve the competitiveness of GaAs MMIC M (MMIC's) and lightwave technologies have Prolifersoftware, this paper proposes a full-+,ave field-theorybased technique to solve the propagation characteristics of the quasi-planar transmission lines shown in Fig. 1, which consists of finite-thickness coupled metal strips embedded in multidielectric media. These dielectric subvendors [3i and is closely to the so-ca11ed producibility engineering Of MMIC's L1l, 13i. The key to the strates are of two types. One is commonly known as the layered (or stratified) configuration, defined in regions y €(O,y l ) , ( Y , , Y J , ( y s , y , ) , and ( y 7 , y 8 ) . The other is the configuration, defined in regions E ( y 2 , y 3 ) first-time design success is the utilization of accurate simulation tools at the subsystem, circuit, device, and process levels in an integrated CAD-based environment