AN APPLICATION OF FDTD IN STUDYING THE END EFFECTS OF SLOTLINE AND COPLANAR WAVE-GUIDE WITH ANISOTROPIC SUBSTRATES

In this paper, the finite-difference time-domain (FDTD) method is appl ied in conjunction with the generalized pencil of function (GPOF) tech nique to evaluate the reflection coefficient from shorted slotlines an d coplanar waveguides (CPW) on anisotropic substrates, and to extract the propagation constant along the line from these data, For each freq uency, the field solutions at different locations are processed by usi ng the GPOF technique to extract two complex exponents that correspond to the forward and backward traveling waves, which provide all the in formation about the reflection coefficient and the dispersion characte ristic of the transmission line, The advantage of combining the GPOF t echnique with the FDTD method is that the reflection coefficients can be obtained with a single run, Recognizing that there is a dearth of r esults for the reflection coefficients of slotline and CPW-line discon tinuities with anisotropic substrates, the present problem is also sol ved by using the spectral-domain method for the purpose of validation, and the two results are found to compare quite well with each other, For further validation, the FDTD and GPOF solutions are derived fcr is otropic substrates, and are compared with the published theoretical an d experimental results.