Dynamically focused thinned array

Abstract

A thinned array real time radar system having an antenna array with receiving elements spaced more than one wavelength apart and having a dynamic means for programming the focus of the array so that it is time sequentially focused to accommodate radar echoes over a range interval from a near range out to infinity to provide an improvement in azimuth resolution, the improvement being substantially large for the near ranges. The system includes a separate mixer for every element of the array for receiving return energy therefrom and with each mixer having a separate local oscillator input. The local oscillator frequency varies as a prescribed first function during each period of processing over the selected range interval and the path length distribution of the feeds between the local oscillator and each individual mixer vaires as a prescribed second function. The first and second functions may be separable functions of an expression approximating the time-space variations of the spherical phase front received by the antenna array. The local oscillator feed is selected so that the distance from the local oscillator to each particular mixer varies as a function of the distance squared from the center of the array or processing point of the array.

Dependencies are inferred from the claim text.