Patent GB-552891-A (GB)
Title: Improvements in radiogoniometer direction finders
IPC: G01S1/02
Filed: 1941-09-24
Abstract: 552,891. Directive wireless receivers. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., PEAT, J. D., and VICKERS, J. Sept. 24, 1941, No. 12383. [Class 40 (v)] A radio-goniometer direction-finder system includes in the form shown in Fig. 4, and in association with each field-coil, two valves V<1>, V<2> to the grids of which are respectively connected the aerials A<1>, A2, the cathodes being connected to the ends of the field-coil FC and also through equal impedance RL<1> and RL<2> to the negative terminal of the source of anode current. The effective impedance at the cathode of the arrangement is substantially independent of frequency, so that one radio-goniometer may be used for a wide band of frequencies. Grid bias is applied from a potentiometer across the source of anode current through independent resistances RG<1>, RG2. In another form, the two impedances RL1, RL2 are replaced by a single impedance extending between a centre-tap on the field-coil and the negative terminal of the anode current supply, the condensers BC<1> and BC2 being omitted. Two arrangements are described in which two dipoles are associated with each field coil, two pairs of valves being used with their grids connected respectively to the four half dipoles. In one arrangement, the field coil is connected between the cathodes of the pair of valves to which one of the dipoles is connected, the cathodes of the other pair being joined by equal series-connected impedances having their junction connected to the negative terminal of the anode supply ; further, the cathode of each of the valves to which the upper halves of the dipoles are connected is joined to the cathode of the valve connected to the lower half of the other dipole. In another arrangement, the field coil is in halves which are connected respectively and in reverse sense, between the cathodes of the two valves to which the upper half dipoles are connected between the cathodes of the two valves to the lower half dipoles. Between the cathodes of each pair of valves connected to the two halves of a dipole are connected two equal series-connected resistances, with their junctions connected to the negative terminal of the anode supply. Fig. 7 shows an arrangement employing an Adcock aerial system with four aerials, N, E, S, W disposed at the corners of a square. The aerials N and S, and E and W which are respectively diagonally opposite one another, but are shown in displaced positions for convenience, are connected to the grids of valves VN; VS, VE and VW respectively. The goniometer field-coils FC and FC2 are connected respectively between the cathodes of the valves VN and VS and those of the valves VE and VW. Pairs of equal series impedances with their junctions connected to the negative terminal of the anode supply, are connected between the cathodes of the valves VN, VE and VS, VW respectively. For cardioid operation or for zero clearing, further equal impedances RLN<11>, RLS<11>, RLE<11>, RLW<11> are connected as shown and their junctions are connected to the grid of a valve VO, to which are thus applied signals from all four aerials, which together operate as an omni-directional aerial. The signals developed across the cathode resistance of this valve are applied by way of a transformer in series with those in the search coil and either in phase or in phase quadrature with them for obtaining a cardioid or circular diagram or for zero cleaning purposes. Similar means are described as applied to the circuits used in connection with dipole aerials, referred to above.