Self-diplexing circularly polarised antenna

A simple self-diplexing microstrip radiator that provides up to 40 dB isolation between transmit and receive is presented. The proposed approach reduces passive intermodulation interference, and this may be a decisive factor for avoiding the use of two separate arrays for transmit and receive. The radiator also has the property of canceling on-axis cross polarization and produces a symmetrical radiation pattern. Experimental results are presented on various breadboards of these radiators at L- and S-bands using different dielectrics, thicknesses, and feed circuit designs.<>