Abstract: Null steering apparatus in a multiple antenna array including means associated with each antenna for separating signals therefrom into in-phase and quadrature components which can be adjusted so that unwanted signals from the array are cancelled and further including circuitry for separating an identifier signal, which is a low level signal substantially in-phase with the carrier, to produce a reference signal which is substracted from signals in the feedback loop of the null steering apparatus to form a lobe in the antenna pattern in the direction of the carrier modulated with the FM signal. In the transmitter, the FM modulation is periodically blanked for a short period of time so that only the carrier modulated with the identifier signal is transmitted and the feedback loop of the null steering apparatus is only activated during the blanking periods with the null steering apparatus maintaining the status quo between blanking periods.