CRITICAL DISTANCE FOR GRATING LOBE SERIES

It is shown that as an observation point approaches a periodic planar phased array of point sources, the corresponding spectral-domain Green's function, or grating lobe series, converges dramatically slower than an equivalent mixed-domain representation exhibiting Gaussian convergence. For a given argument of the Green's function, the critical transition distance above the array for which both representations take the same time to compute can be estimated numerically. Since phased array antenna structures with cavity or waveguide type backings often have dimensions that fall well below the critical distance, investigations of such structures would seem to benefit significantly from formulations incorporating such hybrid Green's functions.