Modeling of a waveguide probe excitation for dielectric resonator antennas

Analysis of a dielectric resonator antenna (DRA) fed by a waveguide probe is presented. The probe is excited by the dominant mode of a waveguide and extends into the DRA through a hole in the waveguide wall. The DRA has, in general, an arbitrary shape and resides on an infinite ground plane, which coincides with the exterior of the waveguide broad wall. The input impedance of the DRA is obtained independent of the waveguide part, and then transferred using transmission line transformation to the waveguide side to take into account the effect of the wall thickness. The rectangular waveguide dyadic Green´s functions are used to analyze the waveguide part, where the input impedance of the DRA appears as a concentrated load at the end of the probe segment in the waveguide. Results obtained using the MoM are compared with those obtained using the FDTD method and exhibit very good agreement.