Electric-field distribution in the focal region of an offset paraboloid

The electric field in the vicinity of the focus of a finite offset-paraboloid reflector, illuminated by a linearly polarised plane wave, is investigated. The paper begins with a general formulation of the reflected field calculation procedure for an arbitrary reflecting surface. The formulation is then specialised to apply to an offset paraboloid. Extensive computed data of the field in the focal region of an offset paraboloid are presented and compared with the field distribution in the focal region of a symmetrical paraboloid. It is shown that the electric-field distribution in the focal region of an offset paraboloid is almost the same as for a symmetrical paraboloid with the equivalent focal length.