TLM Simulation of Patch Antenna on Magnetized Ferrite Substrate

Patch antennas on magnetized ferrite substrate have useful properties like steerable beam direction, tunable resonance frequency and circular polarization. Conventional TLM (SCN) algorithm using open and short circuit stubs are not sufficient to model the magnetized ferrite substrate. A new TLM (SCN) algorithm has therefore been developed. General state equations are used to model the anisotropic and dispersive permeability of the magnetized ferrite substrate. Equivalent circuit for the magnetized ferrite substrate are first derived from the Polder permeability tensor and then transformed to state equations. The new TLM (SCN) algorithm is applied to compute the reflection coefficient S11 and the radiation pattern of a sample patch antenna on magnetized ferrite substrate. The algorithm is numerically stable and computed results agree with measurement.