Disletric resonator antenna array at 2.4 GHz

Abstract

For many years, the dielectric resonator (DR) has primarily been used in microwave circuits, such as oscillators and filters [1], where the DR is normally made of high-permittivity material, with dielectric constant r H > 20. The unloaded Q-factor is usually between 50 and 500, but can be as high as 10,000. Because of these traditional applications, the DR was usually treated as an energy storage device rather than as a radiator. Although open DRs were found to radiate many years ago [1-2], the idea of using the DR as an antenna had not been widely accepted until the original paper on the cylindrical dielectric resonator antenna (DRA) [3] was published in 1983. At that time, it was observed that the frequency range of interest for many systems had gradually progressed upward to the millimeter and near-millimeter range (100- 300 GHz). At these frequencies, the conductor loss of metallic antennas becomes severe and the efficiency of the antennas is reduced significantly. Conversely, the only loss for a DRA is that due to the imperfect dielectric material, which can be very small in practice. The work created the foundation for future investigations of the DRA. Different shapes of DRA were also studied, including the rectangular, circular, triangular, spherical-cap, and cylindrical-ring DRAs [4]. It was found that DRAs operating at their fundamental modes radiate like a magnetic dipole, independent of their shapes.