GB438900A - Improvements in and relating to radio direction finding - Google Patents

Abstract

438,900. Directive wireless signalling. BARFIELD, R. H., and BELL, L. H. BAINBRIDGE-, Radio Research Station, Slough, Buckinghamshire. May 26, 1934, No. 15761. [Class 40 (v)] In a direction-finding system using spaced vertical aerials, the effect of the horizontally polarized component of the received waves due to the coupling between the horizontal members and the aerials is compensated for either by the provision of additional coupling or by introducing a compensating e.m.f. from an additional aerial. In one embodiment, Fig. 2, two vertical aerials are connected to the receiver through a screened horizontal feeder and compensating couplings x, x<1> are provided between the aerial circuits and the earthing wires of the screen, which latter include phase adjusters z, z<1> to ensure exact neutralization of the undesired coupling. In a modification, Fig. 3 (not shown), an unscreened horizontal member has the earthed coils of the coupling devices x, x<1> connected directly thereto. When two aerials such as e, f, g, h, Fig. 4, are coupled by a screened two-wire coupling feeder, an additional neutralizing coupling is effected between a coil b in the screen-earthing lead and the coil g in the aerial circuit. A further system comprises two halves, an unscreened U-shape portion a, b, c, d, Fig. 5, and a lower portion p, x, y, q, consisting of a horizontal wire earthed at its extremities and running close to the horizontal member b, c, compensation being provided by the coupling L, L<1> therebetween, which may be part of a radiogoniometer. The lower part may be replaced by a loop aerial with its plane in the plane of the two vertical aerials and coupled to the coil L, Fig. 6 (not shown). In a system similar to Fig. 4, the coupling b, g is omitted and the feeder screen is connected to an electrostatic screen s1, Fig. 7, between the coils p coupling the aerial and the feeder. A further screen s2 is connected to the mid-point of the aerial coil and a balancing impedance z inserted between said coil and earth so that the impedance of the aerial below the centre tapping of transformer p is equal to the impedance above that point. Specifications 130,490, [Class 40 (v)], and 344,783 are referred to.