Noise figure reduction by port decoupling for dual circular polarised microstrip antenna

A planar dual circular polarised (CP) feed is highly desirable for dish-type satellite communication terminals, but isolation between ports is typically poorer for CP microstrip antennas than for linearly polarised elements. Mutual coupling between the output ports of a dual CP planar feed can affect the equivalent noise temperature of the satellite ground terminal receiver. A port decoupling network is designed for a single-layer dual CP microstrip antenna to increase the isolation to >20 dB between the antenna ports while maintaining CP quality. The effect of decoupling for the single-layer dual CP feed on the performance of a high sensitivity dual polarised receiver for satellite communication applications is analysed.