GB1026424A - Helical antenna - Google Patents

Abstract

1,026,424. Aerials. L. J. CHU. April 29, 1963 [June 11, 1962], No. 16780/63. Heading H4A. A helical aerial 1 is magnetically coupled to a transmitter or receiver 4 by means of a loop 2 whose position may be varied (e.g. by rotation through an angle α, as shown) and the aerial may be tuned by moving an earthed sleeve 5 longitudinally to short-out, either by contact or by close proximity, a number of turns of the helix 1. The loop 2 may be arranged coaxially with, and be disposed either within or without, the helix. The loop may also be formed of a number of continuous turns or may be split radially as shown at 2<SP>1</SP>, with the outer conductor 3 of a coaxial feeder being connected to the loop directly whilst the inner conductor 3<SP>1</SP> is passed within one part of the loop and connected to the remaining part. An additional top-loaded straight aerial may be connected to either the helix 1 or the sleeve 5 as in, respectively, Figs. 1A and 1B (not shown). An embodiment for use on submarines is described with reference to Figs. 2 to 4 (not shown), in which the helix 1 is supported in fibreglass and the loop 2 is housed in a waterproof container.