Integrated active antennas with full duplex operation

This paper discusses two types of active integrated antenna. Firstly, results are presented for a novel 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 55 dB transmit-receive isolation at 3.77 GHz. 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 14 dBi transmit gain and 7.4 dBi receive gain with a transmit-receive isolation of 26.9 dB. These active antennas have potential uses in both short range communication and radar systems