Radio frequency signal direction finding systems

A radio frequency signal direction finding system comprising:

• (a) a multi-beam antenna having a plurality of feed ports, each one in such feed ports receiving radio frequency energy from a received radio frequency signal, the levels of such energy received at the feed ports being associated with the angle of arrival of the received signal;
• (b) receiver means, coupled to the plurality of feed ports, for producing a plurality of output signals, each one of the plurality of output signals having a level related to the level of radio frequency energy received at a corresponding one of the plurality of feed ports;
• (c) a plurality of high pass filter means, each one fed by a corresponding one of the output signals produced by the receiver means, for differentiating the output signal fed thereto producing a pulse in response to, and having a level related to, a change in level of the output signal fed thereto;
• and,
• (d) means, responsive to the pulse produced by each one of the plurality of high pass filter means, for determining the angle of arrival of the received signal in accordance with the relative levels of pulses produced by each one of the plurality of high pass filter means.