Broadband and Gain Enhanced Bowtie Antenna with AMC Ground

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 6x9 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 lambda/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 (S-11 < -10 dB) band from 3.05GHz 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.