Circular Polarization Array Antenna

A 4 by 4 circular polarization microstrip square patch array antennas based on quarter-wave impedance matching and T-junction power divider were designed, simulated, fabricated and measured. The patch type used to generate circular polarization is corner-truncated square microstrip antenna. All the designs met the WLAN circular polarization point to point application set by IEEE802.11b standard and operates in ISM band at 2.4 GHz. Analysis shows that larger arrays provide better return loss, more bandwidth, smaller beam width and higher gain comparing with single element antenna as a reference. A 4 by 4 circular polarization square patch arrays have a side lobe IEEE802.11b standardes. This is due to mutual coupling effects occurred in arrays. All the measurement results show a good return loss more than -15dB. These indicate a good impedance matching is achieved in designing the patches and feeds.