Modelling of probe-fed cylindrical dielectric resonator antennas

Probe-fed cylindrical dielectric resonator antennas (CDRAs), with dielectri c constant epsilon(r) = 37 and supported by an infinite ground plane, are s imulated using the finite element method. From this, closed form expression s are obtained for the resonant frequency, directivity, and unloaded e-fact or, applicable to a wide range of antenna dimensions. The effects of (a) th e finite circular ground plane, (b) the air gap between the CDRA and the gr ound plane, (c) the air gap between the CDRA and the feed probe, and (d) th e length of the probe on these parameters are studied for a particular CDRA and appropriate correction factors are derived. The simulated results are compared with those obtained experimentally for various ground planes, prob e lengths, and probe spacings. The closed form expressions provide good agr eement with the experiments in resonant frequency, unloaded e-factor, and i mpedance bandwidth, but less accurate prediction in antenna directivity for the specified range of parameters. (C) 1999 John Wiley gr Sons, Inc.