Ga. Kyriacou et Jn. Sahalos, A WIENER-HOPF-TYPE ANALYSIS OF UNIAXIAL SUBSTRATE SUPERSTRATE MICROSTRIP STRUCTURES, IEEE transactions on microwave theory and techniques, 45(5), 1997, pp. 616-629
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.