GB773765A - Directional aerial comprising metal discs - Google Patents

Abstract

773,765. Aerials COMPAGNIE GENERALE DE TFLEGRAPHIE SANS FII. Sept. 19. 1955 [Sept. 18, 1954], No. 26755/55. Class 40(7) A directional aerial for the transmission or reception of wave energy comprises an imperforate metal plate 1 and at least one coplanar set of metallic discs 2 supported on metal rods 3 in a regular pattern. The aerial may be excited, or energy arriving from the correct direction received, by means of a receiving horn 6 at one'end of the aerial containing a primary element 4 attached to a feed cable 5. The plane or planes containing the set or sets of discs 2 are arranged parallel to the plate 1 and each disc is supported at its centre by a perpendicular rod 3. The centres form a regular system of quadrilaterals of a side length between 0.4# and #, # being the wavelength of the energy in air. Preferably the diameter of the discs is arranged to increase as the distance from the horn 6 increases so as to give a symmetrical energy density variation with respect to the centre line of the plate parallel to the end provided with the horn 6. The rods 3 are perpendicular to the electric field and do not participate in the radiation. As shown in Fig. 4 a V compound aerial system may be arranged having a radiation pattern L, and fed at the apex of the V by means of a waveguide 7 and two horns 9 and 10 oriented parallel to the plates 1, and 1<SP>1</SP>. A second set of surface elements may be mounted above the first on extensions of the support rods 3 and the exciting or receiving arrangement may consist of a waveguide along one edge of the imperforate plate pierced with appropriate radiating slots (Figs. 5 and 6, not shown). Four compound aerials such as that described with reference to Fig. 4 can be arranged on the four sides of a square support mast 8 to give a substantially omnidirectional wave propagation pattern in the horizontal plane and a narrow pattern in a vertical plane.