Compact dual-port polarization-reconfigurable antenna with high isolations for MIMO application

Abstract

This letter proposes the design of a dual-port microstrip patch antenna with polarization reconfigurability features. The reconfigurability is realized through the modification of the feed network. The antenna consists of a circular-shaped patch on the upper substrate as a radiating element, and a coplanar-waveguide (CPW) slotline transmission located in the ground plane. To obtain a good impedance matching, the CPW slotline is terminated with a tapered impedance transformer. Dual ports are constructed by utilizing the CPW feeding structure and the odd and even feedline modes of the CPW. Four p-i-n diodes are used as switches to alter the flow of the current. The p-i-n diodes are placed on the CPW transmission slotline interjunction. Consequently, the excited polarization can be altered and determined, depending on the switch configurations. This antenna demonstrates good port-to-port isolation and a compact structure and is suitable to be used in systems that operate in a wireless local area network (WLAN) frequency band.