Abstract: A radar detection system with four transducers accurately determines the azimuth angle of a radar emitting object. The three strongest signals from the four transducers are combined to generate two differential signal values. A table is provided which contains angle of arrival values associated with all possible combinations of the two differential signal values. To determine the angle or arrival of a particular object, an index value is derived from the corresponding pair of differential signal values, and that index value is used to select the record in the table with the angle of arrival of the object, relative to the transducer which received the strongest signal. The table also stores a signal measurement correction for each combination of the two difference signal values. The signal measurement correction is to adjust the measured signal strength when calculating the distance of the object from the radar detection system.

Abstract: A multiband microwave filter that can selectively transmit a broadband signal or any discret or combination of predefined frequency bands. The filter has two transmission lines, with an output port at one end of a first one of the transmission lines. A switch selectively transmits an input signal to one of the transmission lines. The filter also has a plurality of narrowband directional filters, each of which is used to transmit signals in a corresonding frequency band from one of the transmission lines to the other. Each directional filter includes at least one diode for enabling and disabling the operation of the direction filter in accordance with a bias voltage applied to the diodes. By controlling the switch and applying appropriate bias voltages to each of the diodes, the microwave filter can selectively transmit a broadband signal or any discret or combination of the frequency bands transmitted by the directional filters.