Superdirective dielectric spherical multilayer antennae

Abstract

Dielectric electrically small antennae are attracting high interest due to their promising applications both in optical and microwave bands. Efficiency of such antennas is usually bounded by low directivity. The stochastic optimization procedure is used to demonstrate superdirective designs of small all-dielectric antennas being spherical multilayer structure. The procedure is based on an efficient and accurate rigorous electromagnetic model which allows for performing large scale optimization on personal computers with limited resources. For optimization we compared different stochastic algorithms, and the JADE demonstrated the best performance. The found designs possess the directivity that go beyond the conventional theoretical bounds for antennas smaller than the wavelength and outperform previously attained results.