Multipolar On-Resonance Interference for Super-Gain Electrically Small Dielectric Resonator Antenna (ESDRA) Design

Wheelers definition of an electrically small antenna is one circumscribed by a one-radian sphere (ka < 1). The electrical size ka approximates the highest-order multipole contributing to radiation. Thus, antenna miniaturization should consider the excited multipoles. Following this definition, current literature lacks references to electrically small dielectric resonator antennas (ESDRAs) in the microwave regime. One reason is the lack of design approaches that monitor and engineer the excited multipoles in the dielectric resonator. In this study, a Mie scattering-based approach is proposed, employing multipolar decomposition to tailor the dielectric resonator multipoles. The poor radiation efficiency associated with small size (ka < 1) is remedied by on-resonance multipole overlapping, subsequently increasing aperture efficiency and gain. Two simple single-ported ESDRAs with the smallest reported ka of 0.99 and 0.62 are presented. Driven by a deeply subwavelength, poorly radiating elementary electric dipole, high-efficiency ESDRAs are obtained. The presented ESDRAs have similar geometrical configurations yet drastically different radiation characteristics: unidirectional and magnetic omnidirectional patterns, 2.2 dB and 1.9 dB peak realized gains, 166% and 403% aperture efficiencies, 66% and 86% radiation efficiencies, -41 dB and -25 dB reflection losses, and 42% and 64% smaller size than the smallest reported ESDRA in the microwave regime—ka = 1.7.