Broadband and gain enhanced bowtie antenna with AMC ground

Abstract

A low-profile wideband bowtie antenna backed by artificial magnetic conductor (AMC) ground is presented for gain enhancement. The proposed bowtie antenna, loaded with an open stub in the upper layer, has broadband property. By using an AMC reflector, consisting of 6×9 metallic patches, the bidirectional radiation of the bowtie antenna is changed to unidirectional radiation. The distance between the bowtie antenna and the AMC surface is only λ/10 at 3.75 GHz. Both the bowtie antenna and the AMC surface are fabricated and measured. The measured results demonstrate good and stable performances, including maximum gain of 8.27 dBi, and flat gain response with variation of 0.6 dB in the wide impedance matching (S11 < −10 dB) band from 3.05 GHz to 4.35 GHz (35.1%). Furthermore, the maximum cross-polarization level is −17 dB for both E and H planes, and the measured front-to-back ratios are more than 18 dB. Good agreement between the simulated and measured results validates the proposed design approach.