Isolation Enhancement of Tightly Coupled CP Antennas with Polarisation Diversity

In the past decades, isolation techniques were reported to reduce antenna coupling such as the defected ground structure (DGS) [1], electromagnetic band gap (EBG) structure [2], microstrip stubs [3], etc. But most techniques are reported for linear polarized antennas. This paper [4] proposes a method to increase the isolation of a circularly polarized antenna. A combination of defected ground structure and shorted stubs are used for isolation.