Simultenous Transmit and Receive Circular Polarized Active Integrated Antenna

This paper discusses the design and implementation of an active transmit-receive antenna, integrating an active devices onto a printed antenna to improve its performance and combine functions within the antenna itself. It includes a circular polarized microstrip patch antenna, two amplifiers, a power divider and a rat race coupler to isolate transmit and receive paths. The beamwidth of the antenna is in the range of 60deg to 70deg for H plane. The radiation pattern for E plane is smaller compared to the H plane. The comparison between the passive and the active integrated antenna shows that the active integrated antenna has 3 dB extra gain compared to the passive antenna, for both transmit and receive. The isolation between transmit and receive is between 20 to 25 dB. This active antenna has potential uses in WLAN communication applications.