Improvements in aerial arrays particularly for short-wave communication

摘要

539,602. Aerials. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. May 20, 1940, No. 8971. Convention date, May 20, 1939. [Class 40 (v)] An aerial array for radiating a rotating field in a vertical direction comprises two or more sets of aerials in parallel planes which are located a quarter of a wave-length, or an odd number of quarterwave-lengths, (2n+1) #/4, apart in order to prevent reflection from the aerials into the feeder. The aerials may be constructed as described, for instance, in Specification 528,817. Fig. 3 shows two arrays, 5, 6, 7 and 51, 61, 71 of three-phase aerials each radiating a rotating field. Thus the horizontal aerials 5, 6, 7 are connected to the feeder 10 by paths 25, 26, 27 which differ from one another by one third of a wave-length, so that a rotating field is radiated vertically. A similar set of aerials 5SP1/SP, 61, 7SP1/SP are fed through extensions 35, 36, 37 of the same paths, these extensions being (2n+1) #/4 long ; and the aerials 5SP1/SP, 61, 71 are oriented 90‹ forward with respect to the aerials 5, 6, 7, in order that the fields radiated vertically from the two sets may be in phase with one another. Reflection from the aerials back into the feeder is prevented by the two sets being separated by a length of (2n+1) #/4 of conductor. A similar arrangement employing two sets of four aerials, or turnstiles, fed in quadrature is described with reference to Fig. 4 (not shown). Further pairs of sets of aerials, similarly spaced, may be stacked vertically above the first pair.