Abstract: An amplitude monopulse direction finding system is disclosed. The system is built around a circular array with a circular lens in which the antenna elements and array ports are larger than in conventional systems. The oversized antenna elements and array ports provide a wide range of operating frequencies for the direction finding system. Additionally, the direction finding system contains an omni-directional probe at the center of the lens to detect the presence of signals. In an alternative embodiment, each array port is split into two halves which can be combined in different ways to produce different beam patterns, allowing the beam pattern providing the best signal to noise ratio to be selected. Also, built-in-test circuitry is described.

Abstract: A radio frequency antenna system comprising a plurality of antenna elements arranged in an array, such array comprising a pair of subarrays of antenna elements coupled to a pair of electromagnetic lenses. Each lens includes a plurality of array ports, the plurality of array ports of the first lens being coupled to the antenna elements of a first one of the pair of subarrays, and the plurality of array ports of the second lens being coupled to the antenna elements of a second one of the pair of subarrays. The first lens further comprises a first set of beam ports, and the second lens further comprises a second set of beam ports, the first and second sets of beam ports being arranged to form corresponding first and second sets of interleaved beams of radio frequency energy.

Abstract: Radio frequency array antenna structures and methods for fabricating such structures are disclosed wherein a plurality of radio frequency circuits forming the radiating face of an array antenna and a corporate feed are formed on one or more relatively flexible dielectric sheets and then bonded to a suitable core material to form a complete array structure which is light weight, inexpensive and structurally sound.