Compact Filtering Dielectric Resonator Antenna With Quasi-Isotropic Radiation Pattern

A compact filtering dielectric resonator antenna (DRA) is proposed in this paper. The hemisphere dielectric resonator (DR) is fed by a microstrip line with two stubs. Due to the different loading effects of the two feeding stubs, the DR TE111 mode is excited with two adjacent resonances, showing a bandwidth of 6.8%. Two controllable radiation nulls are generated at the lower and upper edges of the passband, bring about high frequency selectivity. Also, the DR operating at TE111 mode is equivalent to a magnetic dipole, while a small ground plane used in the DRA radiates like an electric dipole. The combination of the two orthogonal dipoles leads to a quasiisotropic radiation pattern. This antenna has a small size (ka = 0.88) and bandpass filtering function.