SLOW WAVE-MODIFIED LOW PROFILE PLANAR SPIRAL ANTENNA ON EBG

摘要

A two arm Archimedean spiral antenna is modified to form various slow wave structures that have much lower operating frequency than the conventional spirals, making them compact elements for wideband array applications. Uni-directional patterns are obtained from a slow wave modified circular star spiral with electromagnetic band gap (EBG) structure. Measured return loss of circular star spiral at 2 GHz backed by perfect electric conductor at λ/4 is -16.37 dB and this is improved to -20.25 dB when the antenna is placed over an EBG at a separation ofλ/10. The radiation pattern of antenna on EBG provides a back lobe suppression of 30 dB over an isolated planar modified spiral antenna.