GB681597A - Improvements in or relating to lenses for radio waves - Google Patents

Abstract

681,597. Aerials; prevention of surface reflections. WESTERN ELECTRIC CO., Inc. March 28, 1951 [March 28, 1950], No. 7179/51. Classes 40 (v) and 40 (vii). In order to prevent the production of standing waves within an electromagnetic horn supplying energy to a lens due to reflection from the surface of the lens in the case where the lens is constructed of slabs of an artificial dielectric material comprising a plurality of spaced conducting elements arranged within an insulating medium, the slabs lying parallel to the axis of the lens, successive slabs are displaced from one another, in the direction of the lens axis and alternately in opposite directions, by approximately a quarter, or an odd multiple of a quarter, of the operating wavelength. The lens, which is of the phase delay type, comprises a large number of horizontal strip members 16 arranged parallel to the magnetic vector of the incident radiation and spaced in the propogation direction in slots arranged in respective polystyrene-foam slabs 18 arranged vertically one above the other to result in an artificial dielectric medium of the kind described in Specification 664,673. Adjacent slabs are displaced as shown by a quarter wavelength, or an odd multiple of a quarter wavelength, with respect to each other, thus cancelling reflection from the surfaces of the lens. The lens described is circularly symmetrical about its axis and may be stepped as indicated. Specification 650,767 also is referred to.