GB851923A - Improvements in or relating to radomes - Google Patents

Abstract

851,923. Aerial housings. GENERAL ELECTRIC CO. Ltd., and CORNBLEET, S. March 25, 1959 [March 18, 1958], No. 8731/58. Class 40(7). [Also in Group VIII] A radome is formed from wall material consisting of at least four layers of solid dielectric material spaced apart from one another through the thickness of the wall by regions having a substantially lower dielectric constant. The relationship between the layer thicknesses and the wavelength of the energy to be transmitted is so chosen that the wall is effectively homogeneous to the wave energy with an apparent dielectric constant substantially less than that of the solid dielectric material. Radomes of adequate strength and wide electrical bandwidth can be made from such wall materials. In a wall material suitable for use up to 18,000 megacycles per second eight layers of fibre-glass, each of thickness 0À005 inches, are used spaced apart by seven layers of nitrile rubber. The nitrile rubber layers may be 0À063 inches thick and bonded to the fibre-glass by very thin layers of an adhesive having a low dielectric loss. The dielectric constants of the fibre-glass and nitrile rubber layers are respectively 4 and 1À2 giving an apparent dielectric constant of 1À4 for the wall. If the overall wall thickness is made half of the proposed operating wavelength in material having this dielectric constant there will be a high percentage power transmission even up to angles of incidence of 60 degrees. The dielectric medium between the solid dielectric layers may be expanded by foaming.