Ultracompact all-dielectric superdirective antennas

TL;DR

This paper presents a novel design for electrically small dielectric antennas with superdirectivity, achieved through resonant excitation of high-order multipole modes in a spherical dielectric particle with a notch, validated both theoretically and experimentally.

Contribution

It introduces a simple design method for superdirective antennas using dielectric spheres with notches, combining theoretical predictions and experimental validation.

Findings

Theoretical prediction of superdirectivity in nanoantennas with dielectric spheres.

Experimental confirmation of superdirectivity at microwave frequencies.

Resonant excitation of high-order multipole modes explains the superdirectivity.

Abstract

We demonstrate a simple way to achieve superdirectivity of electrically small antennas based on a spherical dielectric particle with a notch. We predict this effect theoretically for nanoantennas excited by a point-like emitter located in the notch, and then confirm it experimentally at microwaves for a ceramic sphere excited by a small wire dipole. We explain the effect of superdirectivity by the resonant excitation of high-order multipole modes of electric and magnetic fields which are usually negligible for small perfect spherical particles.