Grating lobe considerations for the APATS array

The spacing of the elements which comprise a phased array antenna, such as APATS, is usually selected to prevent the occurrence of grating lobes when the main beam is steered to any position within the specified field of view. Array designers may desire to use the maximum element separation consistent with grating lobe constraints in order to minimize the number of elements needed to fill a given aperture, and thereby reduce antenna cost and complexity. Analysis founded upon reciprocal (Fourier) space construction concepts commonly employed by crystallographers is used to determine the optimum element lattice for planar arrays having the nominal specified APATS field of view and boresight elevations of 10 degrees and 15 degrees respectively. The theory is discussed in sufficient detail and generality to permit application to other array systems.