Dielectric Resonator Antennas (DRAs) have received increased interest in recent years for their potential applications in microwave and millimetre wave communication systems. DRAs are normally used with the support of a ground plane. The radiation and impedance properties therefore depend not only on their physical dimensions and dielectric properties, but also on the size of the ground plane. In this paper a probe-fed Rectangular Dielectric Resonator Antenna (RDRA) with dielectric constant r=38 located on top of a ground plane operating at TE111 mode is investigated numerically and experimentally. The antenna is numerically simulated using the High Frequency Structure Simulator (HFSS) based on the Finite Element Method (FEM). The effect of the finite size of a circular ground plane on the radiation performance of the antenna including resonance frequency, radiation patterns, impedance bandwidth, quality factor and directivity of the RDRA is studied. The experimental results are also presented for various ground plane sizes and compared with those obtained by simulation. It is shown that the size of ground plane and considering an air gap in antenna structure could significantly affect the radiation and impedance properties of a DRA. They should be considered in the design of the antenna for practical applications.

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