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 industrial, 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.