In a system for reducing sidelobes in adaptive receiving array antennas, an auxiliary signal is radiated through an omnidirectional antenna collocated with the phase center of an adaptive array antenna. The auxiliary signal is so transmited as to form a probe or pilot beam with a notch in the main-beam...http://www.google.com/patents/US4146889?utm_source=gb-gplus-sharePatent US4146889 - Method and apparatus for sidelobe reduction in radar
