A WIENER-HOPF-TYPE ANALYSIS OF UNIAXIAL SUBSTRATE SUPERSTRATE MICROSTRIP STRUCTURES

A Wiener-Hopf-type technique in conjunction with the hybrid-mode analy sis and a space-domain Fourier transform pair was employed for the sol ution of the canonical problem of a TEM wave obliquely incident upon t he edge and defined by a semi-infinite plate conductor lying at the in terface of two uniaxial dielectrics, forming an otherwise grounded dou ble-layer geometry. The single-cover layer and double-layer surface-wa ve modes' characteristic equations are examined and their cutoff condi tions, along with safe conditions avoiding longitudinal-section magnet ic (LSM) modes are given, The scattered field components and the TEM-w ave reflection coefficient are given analytically in the form of Somme rfeld-type integrals. A thin layers approximation and a numerical inte gration scheme were adopted for the evaluation of; the reflection coef ficient. Its expression can be directly used for the analysis of wide microstrip lines and patch antennas printed in a substrate/superstrate geometry. The whole analysis gives a clear physical insight into the problem. Furthermore, a twofold theoretical verification was adopted b y either forcing the absence of the superstrate or considering both la yers to be isotropic. Numerical parametric investigations show the eff ects of either the presence of the superstrate or both layers' dielect ric anisotropy.