GB631324A - Improvements in antenna system - Google Patents

Abstract

631,324. Aerials ; aerial coupling arrangements. BENDIX AVIATION CORPORATION. Sept. 6, 1946, No. 26794. Convention date, Sept. 7, 1945. [Classes 40 (v) and 40 (vii)] A wide band aerial comprises a cylindrical member and a conical member in co-axial relationship, the apex of the conical member, which is constituted by a plurality of rod-like conductive members uniformly distributed around the axis of the aerial, being directed towards the cylindrical member. The aerial is supported by a mast structure 10, Fig. 1, which may be formed from conductive or non-conductive material and the upper end which is closed by a conductive plate 18 is arranged to support, by means of an insulating collar 11, a conductive cylindrical member 12, the length of which is #/4 at the mean operating wavelength. The member 12 is closed at its lower end by a conductive plate 15 provided with a central aperture from which the outer conductor 16 of a co-axial line 17 extends upwardly into the member 12, the inner conductor 23 being connected to the periphery of the plate 18. Departure of the line 17, which forms an impedance matching element, from a length of #/4 is compensated by the capacity existing between the cylindrical and conical members, i.e. between the plates 15 and 18. This latter plate is also provided with a central aperture which locates the outer conductor 19 of a co-axial feed line 20, the inner conductor 25 of which is connected to the periphery of the plate 15. Suitably attached, e.g. by fastening members 13, Fig. 2, and symmetrically arranged about the periphery of the plate 18 are conductive rod members 22 each of length #/2 at the mean operating wavelength and each forming an element of a conical surface, optimum results being obtained when the angle between the rod members and the axis of the system is approximately 45 degrees.