Dual-Polarization Antennas With High Isolation and Polarization Purity: A Review and Comparison of Cross-Coupling Mechanisms

Existing dual-polarization antennas are categorized into three separate groups according to their topologies. Various cross-coupling mechanisms between orthogonal polarizations are specifically discussed in three categories and related to port isolation and cross-polarization radiation. Some representative antennas of each group are presented, and their performance is compared in terms of port isolation, cross polarization, frequency bandwidth (BW), dimension, and complexity. The techniques to enhance the polarization purity is discussed in the context of example antennas. Finally, further research opportunities in each category are introduced.