Innovative Antenna Front End with High T/R Isolation over a Wide RF Band

Advanced MDA phased array antennas will require fractional bandwidths of at least 10:1, e.g. 2 - 20 GHz. The relatively low return loss of broad bandwidth antenna elements, typically < 15 dB, means that ~1/10 of transmit signal leaks into the receive path; for a 100 W transmit signal, this means ~10 W in the receive path! To avoid damage to the receive path requires protection devices that introduce loss, which in turn increases the noise figure, thereby reducing the radar's range and detection ability. A wide bandwidth, low return loss antenna element has remained a classic, outstanding problem in antenna design. PSI proposes to solve this problem through an innovative design concept that takes a fundamentally new approach. This approach is particularly well suited to interfacing with antenna elements using fiber optic antenna remoting. The result will be a broad bandwidth antenna element, suitable for use in a phased array, that has a return loss of at least 30 dB. As a calibration on the magnitude of this break through, recall that heretofore this level of antenna return loss has only been available in single element, narrow bandwidth (resonant) antennas, which typically have ~10% bandwidth