Sectionalized antenna array with a controlled zone of local sidelobe suppression

Abstract

For spaceborne and airborne Synthetic Aperture Radar (SAR) antennas, the problem of sensed Earth strip variation and simultaneous terrain backscatter or irradiated clutter signal suppression, in a given angular sector, is actual. This problem can be solved by using various approaches and techniques. Often it is desirable to provide a sufficient simplicity of the control system based on the variation of a limited set of antenna aperture amplitude and phase distribution parameters. Besides, such antennas frequently contain a number of sub-apertures.

Our paper presents the structure of such a sectionalized array, for which the sensed strip and clutter suppression in the local zone position variation is obtained due to a variation of the relative amplitude and phase relationships for sub-apertures. Besides, amplitude factors within each sub-aperture remain constant, and phase shifts are identical but depend on the angular position of the sensed strip center.

It is shown that depending on the width of the sector of desired sidelobe suppression, as well as on its displacement with respect to the sensed strip, the obtained clutter suppression varies from -22 to -50 dB. As the problem has several possible solutions, the recommendations are given for taking into account the other factors. In particular, these are the pattern main lobe width, the limits of reasonable variation of amplitude and phase relationships, construction and technological peculiarities of antenna manufacturing, etc. Other approaches to providing the desirable SAR characteristics are discussed relating to the use of antenna arrays with the digital signal processing.