Electrically small naturally circularly polarised antenna

Abstract

A new self‐matched, naturally circularly polarised, electrically small antenna (ESA) is introduced along with its feeding structure. The antenna consists of two coplanar electric and magnetic loops representing two parallel ES magnetic and electric dipoles. These two antennas form resonant pair and exchange electric and magnetic stored energies. Therefore, their combination radiates a circularly polarised wave with a doughnut‐shaped radiation pattern. A circuit model is introduced for the antenna and the design equations are presented in addition to simulated examples. One of the simulated models with dimensions 0.0581λ×0.0581λ×0.005λ (ka = 0.18) was prototyped and measured. Axial ratios of 1.4 and 1.48 have been achieved in the simulation and measured results, respectively. The radiation efficiency and 3 dB bandwidth of the prototyped antenna are 13% and 1.39 MHz, respectively.