High-isolation microstrip patch array antenna for single channel full duplex communications

An orthogonally polarised stacked square microstrip patch array antenna structure with high-isolation performance is proposed for single channel full duplex wireless communications. A double symmetric microstrip array structure is collaborated with a special self-interference cancelling network called differential feeding network (DFN) in order to achieve high-isolation performance. The proposed 2 × 2 and 4 × 4 symmetric array antenna structures with the DFNs were designed to operate at the idustrial, scientific and medical band of 2.34–2.54 GHz. By measurement, the average isolation performances of 53 and 60.7 dB were obtained in 200 MHz frequency band by the 2 × 2 and 4 × 4 array antennas, respectively. The measured average gains of the 2 × 2 and 4 × 4 array antennas were found to be 14.4 and 19.4 dBi, respectively.