Signal injection apparatus for avoiding monopulse anomalies in a monopulse array

Claim 2

In a monopulse receiver system having a sum channel and a difference channel and means responsive to said sum and difference channels for determining the angle-off-boresight, beta, of a detected target, the improvement comprising means for avoiding beta anomalies by the injection of an ancillary sum channel received-energy sample into the difference channel, whereby the level of the difference channel sidelobe response to said target is maintained above that of the first mentioned sum channel.

Claim 3

The device of claim 1 in which said means for avoiding beta anomalies further includes an auxiliary feedhorn for providing said received energy sample.

Claim 4

In an array type microwave antenna having at least two pluralities of feeds oppositely disposed about a boresight axis of said antenna, and coupled to a magic tee for utilization as a monopulse system, the improvement comprising an ancillary feed; a first microwave directional coupler having a first input port coupled to a sum output of said magic tee and a second input port coupled to said ancillary feed, and further having a third port comprising a system sum port and a fourth port; and a second microwave directional coupler having a first port coupled to a difference output port of said magic tee, a second port coupled to said fourth port of said first directional coupler, and an output port comprising a monopulse system difference port.

Claim 5

In an array type microwave antenna having at least two pluralities of feeds oppositely disposed about a boresight axis of said antenna, and coupled to a magic tee for utilization as a monopulse system, the improvement comprising an ancillary feed; a first microwave directional coupler having a first input port coupled to a sum output of said magic tee and a second input port coupled to said ancillary feed, and further having a third port comprising a system sum port and a fourth port; and a second microwave directional coupler having a first port coupled to a difference output port of said magic tee, a second port coupled to said fourth port of said first directional coupler, and an output port comprising a monopulse system difference port.

Claim 6

The device of claim 3 in which the aperture of said ancillary feed is substantially less than that provided by said pluralities of feeds.

Claim 7

The device of claim 3 in which said directional couplers comprise phase-shifting directional couplers and in which there is further provided compensatory phase-shift means interposed in microwave circuit between said ancillary feed and said second port of said first coupler and between said fourth port of said first coupler and said second port of said second coupler, a fourth port of said second coupler being terminated by a nonreflective terminating impedance.

Claim 8

The device of claim 3 in which the aperture of said ancillary feed is substantially less than that provided by said pluralities of feeds and centrally disposed relative thereto.

Claim 9

In an array type microwave antenna including at least one plurality of feeds forming a subarray having a selected aperture, the monopulse improvement comprising an additional feed in said array and having an aperture substantially less than that of said subarray; a microwave directional coupler having a first input port coupled to said subarray and a second input port coupled to said additional feed; and a phase-shifter interposed in series circuit between said coupler and one of said subarray and said additional feed, a respective first and second output of said coupler providing a respective sum and difference monopulse output.

Claim 10

In an array type microwave antenna including at least one plurality of feeds forming a subarray having a selected aperture, the monopulse improvement comprising an additional feed in said array and having an aperture substantially less than that of said subarray; a microwave directional coupler having a first input port coupled to said subarray and a second input port coupled to said additional feed; and a phase-shifter interposed in series circuit between said coupler and one of said subarray and said additional feed, a respective first and second output of said coupler providing a respective sum and difference monopulse output.

Claim 11

The device of claim 7 in which the on-boresight gain of said array at said second output of said coupler is adjusted to be equal to the on-boresight gain of said additional feed at said second output of said coupler.

Claim 12

The device of claim 7 in which the on-boresight gain of said array at said second output of said coupler is adjusted to be equal to the on-boresight gain in said additional feed at said second output of said coupler, and which phase shifter and said coupler are arranged to provide an antiphase relation between said subarray and said additional feed at said difference monopulse output of said directional coupler.

Claim 13

An antenna system, comprising a first and second antenna aperture means, said second aperture being substantially less than that of said first aperture; and means having a first output port for differentially coupling said first and second apertures, said means for differentially coupling further providing attenuation of said coupling of said first aperture, and further having a second output port providing an output indicative of the monopulse sum of said first and second apertures, said first output port providing a monopulse difference signal.

Claim 14

An antenna system, comprising a first and second antenna aperture means, said second aperture being substantially less than that of said first aperture; and means having a first output port for differentially coupling said first and second apertures, said means for differentially coupling further providing attenuation of said coupling of said first aperture, and further having a second output port providing an output indicative of the monopulse sum of said first and second apertures, said first output port providing a monopulse difference signal.

Claim 15

An antenna system, comprising a first and second antenna aperture means, said second aperture being substantially less than that of said first aperture; and means having a first output port for differentially coupling said first and second apertures, said means for differentially coupling further providing attenuation of said coupling of said first aperture being comprised of a first and second subarray and in which there is further provided monopulse signalling means coupled to said first and second subarrays for providing a monopulse sum and difference output, said means for differentially coupling being coupled to said monopulse sum output of said monopulse signalling means; and injection signalling means for injecting a differential signal output of said means for differentially coupling iNto said monopulse difference output.

Claim 16

An antenna system, comprising a first and second antenna aperture means, said second aperture being substantially less than that of said first aperture; and means having a first output port for differentially coupling said first and second apertures, said means for differentially coupling further providing attenuation of said coupling of said first aperture being comprised of a first and second subarray and in which there is further provided monopulse signalling means coupled to said first and second subarrays for providing a monopulse sum and difference output, said means for differentially coupling being coupled to said monopulse sum output of said monopulse signalling means; and injection signalling means for injecting a differential signal output of said means for differentially coupling iNto said monopulse difference output.

Claim 17

In a monopulse receiver system having a sum channel and a difference channel and means responsive to said sum and difference channels for determining the angle-off-boresight, beta, of a detected target, the improvement comprising means for avoiding beta anomalies by the injection of a received-energy sample into the difference channel, whereby the level of the difference channel sidelobe response to said target is maintained above that of the sum channel; said means for avoiding beta anomalies further including an auxiliary feedhorn disposed at the boresight axis of said system for providing said received energy sample.

Claim 18

In a monopulse receiver system having a sum channel and a difference channel and means responsive to said sum and difference channels for determining the angle-off-boresight, beta, of a detected target, the improvement comprising means for avoiding beta anomalies by the injection of a received-energy sample into the difference channel, whereby the level of the difference channel sidelobe response to said target is maintained above that of the sum channel; said means for avoiding beta anomalies further including an auxiliary feedhorn disposed at the boresight axis of said system for providing said received energy sample.

Claim 19

In a monopulse receiver system having a sum channel and a difference channel and means responsive to said sum and difference channels for determining the angle-off-boresight, beta, of a detected target, the improvement comprising means for avoiding beta anomalies by the injection of a received-energy sample into the difference channel, whereby the level of the difference channel sidelobe response to said target is maintained above that of the sum channel; said means for avoiding beta anomalies further including a feedhorn having an aperture less than that of said system for providing said received energy sample.

Claim 20

In a monopulse receiver system having a sum channel and a difference channel and means responsive to said sum and difference channels for determining the angle-off-boresight, beta, of a detected target, the improvement comprising means for avoiding beta anomalies by the injection of a received-energy sample into the difference channel, whereby the level of the difference channel sidelobe response to said target is maintained above that of the sum channel; said means for avoiding beta anomalies further including a feedhorn having an aperture less than that of said system for providing said received energy sample.