GB548193A - Radiators and absorbers of electromagnetic waves - Google Patents

Abstract

548,193. Aerials. STANDARD TELEPHONES & CABLES, Ltd. Dec. 6, 1940, No. 17375. Convention date, Dec. 9. 1939. [Class 40 (v)] An arrangement for radiating or collecting polarized electromagnetic waves limited to a narrow horizontal region comprises a pair of co-axial conical conducting surfaces having their apices vertically opposed, an antenna symmetrically placed between the surfaces in the neighbourhood of the apices for exciting or receiving the waves, the dimensions of the antenna being small compared with half the operating wavelength, and a transmission line connected to the antenna. In Fig. 1 the cones 29, 31 are excited by an antenna 72 to produce horizontally polarized waves, while vertically polarized waves are produced by a pair of crossed dipoles between the cones (Fig. 4, not shown). The loops 72 may be replaced by a series of arcuate dipoles connected alternately to the inner and outer conductors of a concentric transmission line (Figs. 2 and 3, not shown). Specification 469,366 is referred to. The Specification as open to inspection under Sect. 91 also includes the following subjectmatter which does not appear in the Specification as accepted. In the embodiment of Fig. 1 (Cancelled), the antenna comprises a pair of conical members 29, 31 which may be of metal or of dielectric which is metallized on the opposed surfaces of the two members. Connection is made to the respective members by an exciting or absorbing rod 14 and by a pipe-like member 27, which, in the transmitting arrangement shown are connected by leads 10, 12 to an amplifier 6 energized by an oscillator 2 and modulator 3 modulated by a microphone 4. Graphs are shown relating the radial length of the horn to the flare angle which for greatest power should be between 20 degrees and 50 degrees. By making the angles of the cones different, and, in the limit, making one member a plane disc, the plane of greatest radiation may be changed to a cone. Also the surfaces of the cones may be slightly curved either inwardly or outwardly. Fig. 3 (Cancelled) shows an arrangement suitable for reception or transmission in which the elements 29, 31 are directly connected to a Barkhausen tube 120 which may not be directly between the elements 29, 31 but may be connected to them by parallel lines (Fig. 5 (Cancelled), not shown). Several locations of the apparatus relative to the radiant elements are described. Fig. 10 (Cancelled) shows an adjustable'impedance matching connection between the antenna and its transmission line 10, 12. Member 31 is supported by rod 14 forming the centre conductor of a co-axial line 14, 27 which is connected to 10, 12. Matching is effected by adjusting a plunger 47 by means of a handle 18. A modification having the matching device on the upper member is also described (Fig. 11 (Cancelled), not shown). Fig. 14 (Cancelled) shows an arrangement for the transmission of vertically polarized waves produced by an oscillator 70 connected to the element 29 by a suitable terminal 71 and a dielectric guide 271. A similar arrangement for horizontally polarized waves is also described (Fig. 15 (Cancelled), not shown). Fig. 20 (Cancelled) shows the use of a set of conductors 75 to inhibit the propagation of vertically polarized waves. Directive properties are produced by baffle plates such as 77, Fig. 23 (Cancelled).