Importance

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Abstract

A phased array antenna system (20; 120) having an array (22; 122) of radiating elements (24-30; H1-H32), such as pyramidal horns, and a distribution network (32; 124) connected thereto, has a dual mode of operation where each mode produces a composite beam which can and preferably does produce an identical far-field electromagnetic radiation pattern. The first composite beam is made up of a plurality of individual beams, forming a linear combination of excitation coefficients (a.sub.1 -a.sub.4) that are mathematically orthogonal to the linear combination of excitation coefficients (b.sub.1 -b.sub.4) of the individual beams of the other composite beam. A plurality of input ports (42-44; 176-178) are provided, and each composite beam is associated with an information-bearing input signal applied to one of the input ports. The distribution network (32; 124) is preferably constructed with at least two stages of signal-dividing devices (52-58; 222-228, 270-282) such as directional couplers and at least a pair of phase-shifting devices (60-62; 230-232, 284-296). By using passive devices, the distribution network (32; 124) is substantially lossless and reciprocal, and can thus also be used for dual mode reception of two distinct beams.

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First Claim