Dual-polarised patch antenna with wide bandwidth using electromagnetic feeds

A compact dual-polarised patch antenna with wide impedance bandwidth is proposed. Two different feed mechanisms are designed to excite a dual orthogonal linearly-polarised mode from a single radiating patch. One of the two modes is excited by an electrically-coupled L-shaped probe while the other is excited by a magnetically-coupled loop. The L-shaped probe consists of a copper pin and a coupled strip. The magnetic loop is comprised of a metal loop with a gap and an open-ended transmission line. The proposed antenna has been fabricated and measured. The impedance bandwidth of return loss less than -10 dB is 43.9- (2.4-3.75 GHz) and 32.8- (2.8-3.9 GHz) at port 1 and port 2, respectively. Due to the complementary nature of the electromagnetic feeding structure, the isolation between the two ports of the antenna is better than -23 dB. Moreover, the proposed antenna has a compact structure and stable gain over the operating band, thus making it suitable for use in 3.5 GHz WiMAX systems.