EBG Placement Optimization in a Via-Fed Stacked Patch Antenna for Full-Duplex Wireless

Full-Duplex (FD) wireless communication has the potential to double the capacity of a wireless link. The key challenge to FD is self-interference (SI): a node's transmitting signal generates significant interference to its own receiver. Several prior works have shown the potential to reduce SI and build FD radios but they are limited to Sub-6 GHz systems. In this paper, we focus on the emerging mmWave systems and the potential reduction in SI through antenna design. The increased bandwidth requirements of mmWave systems necessitate the use of higher bandwidth antenna designs such as stacked patch antennas for transmission (Tx) and reception (Rx). Specifically, we investigate the optimal placement of a mushroom electromagnetic band gap (EBG) structure for maximum Tx and Rx isolation (coupling reduction) in a 4-layer substrate stacked patch antenna design targeted for small mobile devices. Through extensive simulations we show that top&inner layer EBG ("slacked") provides more than 80 dB of isolation at 28 GHz frequency, which is 20 dB more isolation than either top or inner layer EBG. We also show that the frequency bandwidth and gain of the stacked patch antenna are not negatively impacted due to the EBG integration.