Two-dimensional diffraction by half-planes and wide slits nearradiating apertures

With the complex source-point method used to produce the basis elements of an array of linearly and directionally equispaced two-dimensional (2-D) beams, the fields of any aperture distribution at any range to any degree of accuracy can be obtained. For efficiency a limited number of significant beams and beam directions is required. Approximately twice as many beams as the aperture width in wavelengths, with all beam directions normal to the aperture, is found to be sufficient here for simple uniform and cosinusoidal distributions in apertures of moderate size at ranges outside the evanescent field zone of the aperture. Now the exact solution for the far field of a line source, or here a beam source in the presence of a conducting half-plane, is used as our basis element to give the solution for antenna pattern diffraction by a local half-plane. Antenna pattern diffraction by an aperture near a wide slit is presented as simply a superposition of the solutions for two coplanar half-planes with separated parallel edges. Antenna pattern distortion by various other local obstacles can be obtained similarly