Integrated active antennas with simultaneous transmit-receive operation

This paper discusses two novel active integrated antennas with same frequency transmit-receive operation. Firstly, results are presented for a two element active transmit-receive array using dual linear polarisation and sequential rotation. Each element includes an integrated oscillator and amplifier mounted on orthogonal edges of a square patch, such that transmit and receive paths are isolated and polarisation duplexed. The array gives in excess of 45dB transmit-receive isolation with an output power of 5.4dBm and a receive gain of 8.2dBi at 4.05GHz. Link budget calculations are used to show expected system performances. Secondly, an active circulator is integrated with a patch antenna to produce a same polarisation fully duplexed transceiver. The active circulator antenna is shown to have 14dBi transmit gain and 7.4dBi receive gain with a transmit-receive isolation of 26.9dB at 3.74GHz. These active antennas have potential uses in both short range communication and radar systems.