Three ports microstrip patch antenna with dual linear and linear co-polarisation characteristics

Abstract

In this Letter, three ports proximity coupled microstrip patch antenna with linear co-polarisation and linear dual polarisation characteristics has been presented for in-band full duplex and active antenna applications. Depending upon the excitation ports, antenna can perform transmit and receive operation either with dual linear polarisation or linear co-polarisation at same carrier frequency with dc isolated ports in both cases. It provides >10 dB interport isolation with linear co-polarisation when compared with around 2.5 dB port-to-port isolation of simple linear co-polarised antenna with two anti-parallel feeds. With dual polarisation, interport isolation is >43 dB at centre frequency when compared with 36 dB port isolation provided by dual polarised antenna with two orthogonal feeds. Proposed antenna has been implemented on FR4 substrate to compare its simulated and measured input matching and port-to-port isolation performances.