Phased array sequential switching between short and long distance targets

Claim 2

A phased array radar system carried aloft by aircraft for detecting long range and short range elevated targets, while suppressing ground clutter, the system comprising: a phased array antenna; transmitter means having its output connected to the antenna for radiating a beam outwardly; function generating means having first input connected to altimeter means, the generating means being provided for generating a beam steering signal to the antenna, dependent upon the altitude of the antenna; an output of the generating means connected to a second input of the antenna for steering the transmitted beam between at least two elevational angles, namely, a high beam and a low beam; receiving means connected to the output of the antenna for processing an incoming signal; recording means connected to the output of the receiving means for recording the processed signal; means connecting a second output of the function generating means to the recording means for blanking noise and signals, at relatively long range from a signal fed to the recording means from the receiving means, while the antenna transmits and receives on the high beam; the function generating means further sequentially blanking the short range ground return from the recording means while the antenna transmits and receives on the low beam; and whereby the sequential blanking prevents recording of false targets.

Claim 3

The subject matter set forth in claim 1 wherein the recording means are display means for simultaneously displaying the short range and long range targets, relatively free of ground clutter.

Claim 4

The subject matter of claim 1 wherein the antenna includes phasor elements symmetrically positioned at varying locations relative to an axis of symmetry for respectively introducing phase shifts in signals being transmitted and received; an elevation microwave feed structure communicating with the phasor elements for transmitting and receiving signals to and from the elements respectively.

Claim 5

The subject matter of claim 3 together with at least one phasor element connected to the microwave feed structure for introducing and receiving an azimuth scan signal during transmitting and receiving, respectively, and an azimuth feed structure connected to the azimuth phasor element for distributing azimuth information to and from the transmittor and receiver, respectively.

Claim 6

A phased radar system carried aloft by aircraft for detecting long range and short range elevated targets, while suppressing ground clutter, the system having a transmitter, and a receiver, comprising: a two dimensional 2N by 2M array (2N high and 2M wide) antenna structure including 2M elevation microwave feed structures, each such structure collecting signals from 2N individual radiators via respective elevation phasor means that selectively vary the elevation phase of the signal fed therethrough, the antenna Structure further including 2M azimuth scan phasor means respectively connected to the elevation microwave feed structures for receiving the collected signals and varying the azimuth phase thereof in response to an aximuth scan signal, and an azimuth feed structure connected to the output of the azimuth scan phasor means for producing a predetermined azimuth beam width; a function generator connected at its output to the elevation and azimuth phasor means to control the phase shifts respectively therethrough in accordance with a beam steering program, a transmitter connected to a first input of the function generator for making the beam steering program a function of time, a second input of the function generator being connected to altimeter means for also making the beam steering program a function of antenna altitude; and output means provided at the azimuth feed structure for presenting thereat a steered receive beam signal.

Claim 7

A phased radar system carried aloft by aircraft for detecting long range and short range elevated targets, while suppressing ground clutter, the system having a transmitter, and a receiver, comprising: a two dimensional 2N by 2M array (2N high and 2M wide) antenna structure including 2M elevation microwave feed structures, each such structure collecting signals from 2N individual radiators via respective elevation phasor means that selectively vary the elevation phase of the signal fed therethrough, the antenna Structure further including 2M azimuth scan phasor means respectively connected to the elevation microwave feed structures for receiving the collected signals and varying the azimuth phase thereof in response to an aximuth scan signal, and an azimuth feed structure connected to the output of the azimuth scan phasor means for producing a predetermined azimuth beam width; a function generator connected at its output to the elevation and azimuth phasor means to control the phase shifts respectively therethrough in accordance with a beam steering program, a transmitter connected to a first input of the function generator for making the beam steering program a function of time, a second input of the function generator being connected to altimeter means for also making the beam steering program a function of antenna altitude; and output means provided at the azimuth feed structure for presenting thereat a steered receive beam signal.