Dual Orthogonal Port Stacked Patch Antenna With Vertical Pins for Simultaneous Transmit and Receive Application

In this communication, a dual-orthogonal-port stacked annular ring microstrip patch antenna for polarization diversity applications and full-duplex communications is presented. Vertical pins that extend from SMA connector inner pins have been employed to implement a port coupling cancellation mechanism and achieve high isolation between the two ports. Furthermore, the structure is completely symmetric and does not require any feed network bridge (differently from differential feeding structure), making it very suitable for simultaneous transmit and receive (STAR) applications that employ balance feeding structures and, therefore, require very similar port performance. An antenna prototype has been designed for the ultrahigh-frequency (UHF) radio frequency identification (RFID) bandwidth, and the measurement has revealed excellent isolation performance, with a peak of 42 dB at the frequency of 922 MHz.