GB573896A - Improvements in radio aerials - Google Patents

Abstract

573,896. Directive wireless signalling ; aerials. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and FRANKLIN, C. S. March 24, 1941, No. 3983. [Class 40 (v)] Relates to directional aerials comprising a helix with spaced turns. (1) The length l of each turn in wavelengths and the spacing s between turns are such that lŒs=#. (2) The A length l =n and the spac- 2 A ing s=(m - 1) -, m and n being any even whole 2 number. (3) The aerial may be formed from a pair of conductors wound in like sense, Fig. 3 (not shown), or in unlike sense, Fig. 2 (not shown), the currents being in phase or antiphase in the two conductors. (4) Each pair of conductors may be crossed over at every half-wavelength along the conductors to. form loops, Fig. 4 (not shown), the conductors being formed into a helix in which the plane of the loops is substantially at right angles to the axis of the helix, Fig. 5 (not shown). Several such units may be connected in parallel to a common feeder, all being wound in the same sense, Fig. (not shown). In all cases, the helix may be wound on a square, polygonal, or circular former. The direction of maximum radiation of the aerial shown in Fig. 1 is along the axis of the helix or in a plane at right angles thereto according to the relation between l, s and A, whilst in the other Figures the direction depends also upon whether the two turns are fed in phase or anti-phase. The aerial may be wound round a vertical supporting tower so as to radiate uniformly in all directions. The conductors of the helices may be terminated with resistances. Specifications 357,480 and 476,726 are referred to.