Broadband meanderline slot spiral antenna

A new broadband, cavity-backed slot spiral antenna is proposed. It combines variable growth rates at the centre region for improved high band radiation, with meandering in the outer turns for more efficient low band operation. A detailed characterisation of all antenna components and parameters is provided along with guidelines and recommendations for miniaturisation and realisation. The performance degradation due to cavity resonances is discussed and their suppression is also demonstrated. The developed design has broadband UHF to S-band operation with up to 20 dB gain improvement at 250 MHz using a 15 cm aperture. Using the same design concept, 45 cm apertures are realised and their operation from VHF to S-band is demonstrated.