High Inter-port Isolation Dual Circularly Polarized Modified Franklin Microstrip Antenna

A dual circularly polarized microstrip antenna with high interport isolation is presented. The design comprises of 12 series-fed radiating patch elements separated by phase shifters arranged in a circular fashion with two ports at the feed-lines connected to terminal patches- one each for transmission (Tx) and reception (Rx). The impedance bandwidth of the antenna is 399 MHz (6.727 GHz to 7.126 GHz) and the axial ratio (AR) bandwidth is 256 MHz (6.87 GHz to 7.12 GHz). The interport isolation is better than 30.8 dB in the entire band and reaches as high as 59.4 dB. Because of its high inter-port isolation and moderate impedance and AR bandwidth, the design is a suitable for usage as a DCP antenna for C-band applications.