Multimode array antenna
AssigneeUnited Technologies Corporation
InventorPeter W. Smith
Life of this patent
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Abstract
An array antenna having a plurality of radiating elements positioned in a planar configuration is divided into four separate quadrants. The array antenna is capable of being switched between two modes, a narrow pencil beam mode and a cosec.sup.2 .theta.cos.theta. mode, through the use of a single switch and a pair of phase shifters. In the pencil beam mode, the transmitted energy is symmetrically divided between the four quadrants of the antenna. By changing the switch to its second position the power is diverted to only the upper half of the antenna and a pair of phase shifters introduces a phase shift to the radiating elements along the lower half of the upper portion of the antenna. This causes an asymmetric radiation pattern from the antenna creating the cosec.sup.2 .theta.cos.theta. beam which is well suited for ground mapping.
Claims10
An array antenna connectable to an input/output port for forming an aperture to transmit or receive radar signals, said array antenna being switchable between at least two modes, comprising:
- aperture means having an upper portion and a lower portion, each including a plurality of laterally extending waveguides with a number of radiating elements disposed thereon;
- a lower intermediate feed means communicating with each of said laterally extending waveguides of said lower portion of said aperture means, for dividing the energy of an illuminating radar signal among, or for combining the energy of a received radar signal from, said laterally extending waveguides;
- upper intermediate feed means communicating with each of said laterally extending waveguides of said upper portion of said aperture means, for dividing the energy of an illuminating radar signal among, or for combining the energy of a received radar signal from, said laterally extending waveguides;
- and
- switch means having at least a first position and a second position, and connected between said input/output port, and said lower intermediate feed and said upper intermediate feed for coupling radar signals;
- whereby when said switch means is in said first position, said input/output port is connected to both said upper intermediate feed and said lower intermediate feed causing said array antenna to be in its first mode, and when said switch means is in said second position, only one of said intermediate feed means is connected to said input/output port causing said array antenna to be in its second mode.
Dependencies are inferred from the claim text.