Properties of Ultrawideband Arrays
Highly thinning the elements required in a filled λ / 2-element spaced array can greatly reduce the quantity of electronics in the array and the data-handling requirements of an imaging system for a fixed number of array channels, greatly enlarge the aperture, and correspondingly improve its resolving power. The cost is a dramatic decrease in dynamic range. The resulting sparse array generally leaves the shapes of the main lobe and near-in sidelobes intact, but the loss in absolute gain implies that main lobe energy has been redistributed into the side radiation region. In conventional narrowband arrays, periodic thinning produces grating lobes of similar shape and strength to the main lobe. Aperiodic thinning destroys the coherent sidelobe buildup in the grating lobes but not the grating lobe energy, which becomes distributed throughout the visible region in a manner determined by the particular thinning procedure. It is common knowledge that sidelobe statistics are similar for a wide variety of thinning procedures, both deterministic and random, with a few notable exceptions1. Thus many proposed designs for high resolution two-dimensional arrays are based upon a random distribution of elements2.
KeywordsPeriodic Array Main Lobe Dimensional Array Random Array Maximum Projection
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