Reconfigurable microstrip antenna with polarisation diversity and frequency agility

A circularly-polarised (CP) microstrip antenna with polarisation and frequency diversities is presented. The antenna has a square radiating patch and is excited through the coupling of a cross-slot with unequal lengths. Two diodes are used to reconfigure the radiating patch, and by controlling the states of the diodes, the polarisation sense of the antenna can be switched between left-hand and right-hand circular polarisation. Moreover, the two CP modes are operated at different frequencies. An antenna prototype is implemented and the obtained results are shown.