A compact circularly polarized microstrip transmit-receive antenna for LAN applications

A circularly polarized microstrip antenna integrated within a 90/spl deg//180/spl deg/ hybrid network for the construction of a compact transmit-receive antenna is presented. The hybrid network allows a signal to be transmitted with a left-hand polarization and to be received with a right-hand polarization, while providing at least 20 dB of isolation between the transmitting and receiving ports. Simulated and measured results are presented.