Design and Optimisation of Folded Spherical Helix Antennas: Performance and Bandwidth Analysis

Abstract

This paper examines the performance of different fundamental small antenna designs in terms of how they scale with overall length and size (measured by the electrical size parameter, ka). The goal is to identify which design approach, if any, provides the best performance in achieving a good impedance match, favourable radiation pattern, high radiation efficiency, a broad half-power bandwidth, and a 2:1 VSWR bandwidth. The antenna designs analysed include the spherical folded helix and, cylindrical folded helix. The paper discusses the methods used for impedance matching and bandwidth optimisation, presenting both simulation and experimental results.