Dual-port Stacked Annular Ring Microstrip Patch Antenna with Vertical Pins for Isolation Enhancement

In this paper, a dual-port stacked annular ring microstrip patch antenna (ARMSA) for polarization diversity applications and/or full-duplex communications is presented and implemented. Differently to traditional designs which employ an highly symmetrical dual anti-phase feed network structure for achieving two ports with identical performance and canceling coupling effects, in this design vertical pins which extend from SMA connector internal pins have been employed to realize a coupling cancellation path. Isolation between the two ports have been optimized with the commercial software Ansys HFSS, and measurement on a manufactured prototype for ultra-high frequency (UHF) radio frequency identification (RFID) applications have revealed a maximum isolation of 42 dB at the frequency 922 MHz and a maximum difference of only 2 dB between two ports behavior in terms of impedance matching.