Modified cavity-backed 4-arm spiral antenna for GPS

In this paper, a modified cavity-backed spiral GPS antenna is proposed. The presented antenna consists of a modified four-arm Archimedean spiral, an absorber and a cavity which is fed by ut-47 cables. In order to confirm the broadband characteristic, S-parameter result at 1-2GHz is calculated. The gain for mode 1 and mode 2 of the antenna at 1.575GHz, is 0.9dB and -8.7dB respectively. The axial ratio is below 1.25dB between the range of ±45o, which validates circular polarization characteristic. Moreover, the performance of the proposed antenna is verified through the current distribution also.