Simple Techniques to Decouple 2-Port Circularly Polarized Patch Antenna

This paper introduces two simple techniques to design two-port dual-sense CP antenna with significantly high isolation. The dual-sense CP is achieved by employing a pair of square patches with different truncation sets. Regarding the isolation, the mutual coupling suppression can be conveniently accomplished by using either a defected ground structure (DGS) as band-stop filter or a grounded stub as phase shift component. The proposed 2-element antennas exhibit good operation in terms of reflection coefficient and axial ratio at the desired frequency band. Meanwhile, the most important parameter is the port-to-port isolation, which is always better than 30 dB across the operating band. By using the grounded stub and the DGS, peak isolations of 38 dB and 42 dB can be achieved, respectively.