Wearable applications of quarter-wave patch and half-mode cavity antennas

Abstract

The quarter-wave patch and half-mode cavity antennas are two typical designs of half-size resonator antennas that are suitable for wearable applications. Despite their similar appearance, they have distinctively different properties. In this letter, the quarter-wave patch and rectangular half-mode cavity antennas are first theoretically analysed with a cavity model to allow a direct comparison of size and internal field distribution. On that basis, wearable realizations of those two antennas using embroidered conductive shorting/side walls are investigated. It is demonstrated through full-wave simulations that the designs need to consider the resonance frequency stability against compression at seams, and that design optimization for both antennas will benefit from taking into account all expected bending conditions. With this procedure, the overall operational bandwidth over a range of bending conditions can be markedly improved, and a drift of the resonance frequency with bending can be mitigated. Realizations of the two antennas with conductive textiles and embroidered conductive threads for operation at 2.45 GHz validate the findings.