An in-band full-duplex antenna for dual-band application

A dual-band, dual-polarized in-band full-duplex antenna with good isolation performance is presented for wireless local area network (WLAN) applications. A neutralization line is connected between the grounds of the transmitter (Tx) and receiver (Rx) antennas to enhance the isolation. Further enhancement in isolation is achieved by using a 180 degrees ring hybrid coupler between receiving antenna elements. Here the dual-band monopole antennas are used as transmitting and receiving antenna elements. For better isolation, the receiving antenna elements are placed opposite to each other and fed through the differential ports of the 180 degrees ring hybrid coupler. The proposed structure is fabricated, and the comparison of measured results and simulated results are studied. The simulated and measured impedance bandwidths (<=-10 dB) of the antenna cover the entire 2.4 GHz WLAN band (2.4-2.48 GHz), and for this band, the measured isolation is better than 40 dB. For the higher band, the measured isolation is more than 40 dB for 200 MHz (5.15-5.35 GHz) of bandwidth. The simulated radiation patterns of the antenna are well-matched with the measured patterns at both the frequencies.