US3332082A - Radio goniometers and radio direction finders incorporating the same - Google Patents

Description

July 18, 1967 .J. F. HATCH 3,332,082

RADIO GONIOMETERS AND RADIO DIRECTION FINDERS INCORPORATING THE SAME 2 Sheets-Sheet 1 Filed May 5, 1965 CRT July 18, 1967 J F HATCH 3,332,082

RADIO GONIOME'iER S AND RADIO DIRECTION FINDERS INCORPORATING THE SAME Filed May 5, 1965 2 Sheets-Sheet ATTORNEYS United States Patent Ofi 3,332,082 Patented July 18, 1967 ice 3,332,082 RADIO GONIOMETERS AND RADIO DIRECTION FINDERS INCORPORATING THE SAME James Frederick Hatch, Hutton, England, assignor to The Marconi Company Limited, London, England, a compauy of Great Britain Filed May 5, 1965, Ser. No. 453,388 Claims priority, application Great Britain, May 13, 1964, 20,007/ 64 1 Claim. (Cl. 343-124) ABSTRACT OF THE DISCLOSURE A radio goniometer for use in radio direction finders which comprises inner and outer relatively rotatable coaxial members. The outer member has wound thereon several equally spaced windings and the inner member has wound thereon two similar windings at right angles one to another. The inner and outer member windings are wound with the turns thereof progressing first in one direction and subsequently in another direction such that the turns in any one winding are effectively in parallel planes. Each inner member winding consists of two parallel connected winding parts, one on each side of a center line.

The two inner member windings supply input signals to the two paths of a twin-path receiver of a radio direction finder.

The outer member winding may have a common central point capable of providing input signals to one of the paths of the twin-path receiver for sense determination.

Alternatively, the outer windings may have separate central points. In this case the central point of the winding associated with an aerial which is most nearly at right angles to the incoming signal is connected to one path of the twin-path receiver for sense determination.

This invention relates to improvements in or modifications of radio goniometers and radio direction finders incorporating the same and more particularly, although not exclusively, to such goniometers and direction finders intended for operation in the high frequency (H.F.) waveband extending between the approximate limits of 2 mc./s. and 30 mc./s.

Radio goniometers of the type to be modified and improved by the present invention are disclosed in British Patent No. 944,861, the main object of which was to satisfy a requirement for a goniometer having more than two stator coils-a requirement which had previously been regarded as very difficult to satisfy both because of the danger of undesirable coupling between coils which are not perpendicular to one another and the difficulty, in a goniometer which is physically sufiiciently small to operate satisfactorily at the highest frequency in question, of providing adequate efficiency of signal transfer between the stator and rotor coils.

According to the aforementioned British patent a radio goniometer comprises two coaxial relatively rotatable members, one within the other, the outer member being formed of a ring-like ferrite body with at least three windings equally spaced around the ring and wound round the section thereof, each winding comprising two diametrically opposite half-windings arranged to produce opposing magnetic fluxes in said body and the inner member being provided with a winding for magnetically coupling in turn, during rotation, with each of said windings on the outer member. The various subordinate features of invention claimed in the above British patent include providing the inner member with a winding which progresses initially in one direction and subsequently in the opposite direction whereby all the turns thereof are effectively in parallel planes also providing the outer member with a winding which progresses initially in one direction and subsequently in the opposite direction whereby all the turns thereof are effectively in parallel planes; making the inner member with two winding parts, one on each side of the centre line, connected in parallel each winding part progressing initially in one direction and subsequently in the opposite direction whereby all the turns thereof are effectively in parallel planes and constituting the outer member by a stator of cylindrical form having four winding parts.

The particular description contained in the aforementioned British patent, however, describes only radio goniometers having but one rotor winding. Such a radio goniometer is of course adapted to provide signals to a single channel receiver. There are, however, twin-path receivers, each path containing an amplifier substantially identical with that in the other, which can be most advantageously employed in conjunction with a multi-aerial system consisting of a number of aerials spaced around a circle, to indicate directly on a cathode ray tube on incoming signal direction. A single radio goniometer as particularly described in the aforementioned British patent is obvious- 1y not suitable for supplying signals from the aerial system to the twin-path receiver since said receiver requires two inputs, one to each path. The present invention seeks to improve or modify radio goniometers as set forth in the said British patent in such manner as to make a single improved or modified goniometer suitable for supplying both input signals to the twin-path receiver.

According to this invention the inner member of a radio goniometer as claimed in the above-mentioned British patent is provided with two similar windings substantially at right angles to one another and each of Which provides, during rotation, magnetic coupling With each of the windings in the outer member in turn.

The outer member of a radio goniometer in accordance with this invention and/or the windings provided thereon may take any of the forms described or claimed in the aforementioned British patent and similarly, each of the mutually perpendicular windings on the inner member may take any of the forms described or claimed in the said British patent.

The invention is further described with reference to the accompanying drawings. In the drawings FIGURES l and 2 are diagrammatic representations of the stator, and FIGURES 3 and 4 are diagrammatic representations of the rotor, of a radio goniometer in accordance with this invention; FIGURE 5 shows diagrammatically a twinpath direction finder incorporating the goniometer of FIGURES 1, 2, 3 and 4; and FIGURE 6 shows an improved and preferred twin-path direction finder incorporating a goniometer in accordance with this invention.

Referring to FIGURE 1, the goniometer stator comprises a ring-like ferrite body P8 of cylindrical form carrying four windings wound around its section. Each winding is comprised of two half windings and there are therefore, as illustrated, eight similar half windings symmetrically disposed on the ferrite cylinder. Each winding is made up of two diametrically opposed half windings whereby one winding is constituted by half windings 1 and 1 another by the half windings 2 and 2 a third by half windings 3 and 3 and a fourth by half windings 4 and 4 The spacing of the turns of each winding and the spacing between adjacent windings are preferably arranged to be equal, as shown, so that adjacent turns, Whether on the same winding or on different windings, are equally spaced from one another. In the illustrated example each half winding is comprised of eight turns each embracing 5 of arc.

The interconnections between the half windings on the stator are represented in FIGURE 2 in which, for simplicity, only two half windings, together constituting a single stator winding, are shown. It will be seen from FIGURE 2 that the two half windings illustrated are similar windings and that they are inter-connected in such manner that the magnetic fluxes in the ferrite cylinder FS, resulting from the application of a potential between the winding terminals T1 and T2, oppose one another whereby a concentrated magnetic field extends diametrical ly across the cylinder FS.

Conveniently the windings may be so arranged that connections may be made to two of them, for example windings 11 and 3-3 at one end of the cylinder FS and connections made to the other two, for example 2-2 and 44 at the other end.

The goniometer rotor illustrated in FIGURES 3 and 4 comprise a hollow cylinder IR of ferrite material carrying thereon two similar windings W1 and W2 which are at right angles to one another and are shown purely schematically in FIGURE 3. Each of these windings consists of two symmetrically arranged coils, 1W1, 2W1 and 1W2, 2W2 respectively, each of which is wound in the manner described in the previously mentioned British patent and illustrated by FIGURE 3 thereof. FIGURE 4 of the present specification is, except for the references, identical with FIGURE 3 of the said British patent and shows the manner in which each coil is wound. In order not to complicate the accompanying FIGURE 4 only one coil is shown. This is referenced 1W1 to indicate that it forms half of the winding W1. There are three more similar coils of which one (2W1, FIGURE 3) is parallel to 1W1 and is connected electrically in parallel therewith and the other two (1W2, 2W2, FIGURE 3) are parallel to one another, connected electrically in parallel with one another and are at right angles to 1W1. As will be seen from FIGURE 4 the turns of 1W1 lie approximately parallel to one another and progress towards the left across substantially half the rotor (in the figure) for the desired number of turns and then back again towards the right (in the figure) for the same number of turns. As a result those parts of the coil which have a component in the direction of progression cancel one another out so that all the turns of the coil lie effectively parallel to one another.

The goniometer is of course provided with central spindles mounted in bearings and when completely assembled the rotor is coaxially within the stator with the rotor windings coupling in turn, during rotation, with the different stator windings. Out ut signals from the rotor windings may conveniently be taken off from the rotor by means of sliprings (not shown).

FIGURE 5 represents a direction finder incorporating a radio goniometer as above described for operation over a continuous frequency band of 2 mc./s.30 mc./s. Referring to FIGURE 5 there are eight linear vertical aerials A1, A2, A3, A4, A1 A2 A3 and A4 symmetrically disposed around a circle having a diameter of approximately at a frequency of 25 mc./s. The aerials are unbalanced uni-pole aerials and are mounted on the ground or on a simulated earth plane and have their bases insulated therefrom. The members of each pair of diametrically opposite aerials are connected via coaxial cables to respective ends of an appropriate stator winding of a goniometer as illustrated by FIGURES 1 to 4. The stator windings are indicated diagrammatically in FIGURE 1 at 1, 1 2, 2 3, 3 and 4, 4 aerials A1 and A1 being connected to the half windings 1, 1 aerials A2 and A2 being connected to the half windings 2, 2 and so on. The half windings are connected to a common point which is taken as shown to one contact of a two-position two armed switch S1. One winding W1 on the rotor is connected to two other contacts of the switch S1 as shown the remaining contact of which is earthed and the arms of which are connected to the input terminals of one amplifying channel C1 of a twin=path receiver. The other winding W2 on the rotor similarly feeds into the other amplifying channel C2 of the receiver. The output from the channel C1, normally an intermediate frequency (I.F.) output, is fed to the two arms of a second switch S2 which may be ganged with the switch S1 and which, when in the position shown, supplies the IF. signals via an amplifier IFI to one of the two co-ordinate deflection systems of a display cathode ray tube CRT. I.F. output from C2 is amplified by a similar I.F. amplifier I.F.2 fed to the other deflection system of the tube.

With the switches S1 and S2 in the positions shown the goniometer rotor can be set to a fixed position (say and bearings of incoming signals will be displayed directly by the cathode ray tube which will produce, from an incoming signal, a straight trace as indicated at T the direction of which is representative of the incoming signal direction, the tube face being provide with a suitable scale against which indicator directions can be read. If the goniometer rotor is rotated, the trace will rotate in the opposite direction and, at the positoin of the figureofeight minimum, the trace will set always in the NS. or E.W. direction, depending on which search coil is in use, irrespective of the incoming signal direction. It is convenient to arrange this direction to be horizontal on the tube face. Therefore if, at any time, the signal is fading and phase interference effects cause an indicated signal direction to wander, the goniometer rotor can be rotated to that position which gives the best average position about the horizontal on the tube face. When the signal amplitude is at a maximum an improved indicated bearing is usually obtained and this condition can be obtained by observing the tube while turning the rotor to the best position. A pointer P on the rotor shaft reads on a suitable scale as to indicate the position of the rotor.

Aerial monitoring of the signal can readily be done as well (this is not illustrated) by switching headphones to receive signals from the channel which is set to the figureof-eight maximum while swing bearings are taken on the horizontal tube trace fed from the other channel which, being energised from the other rotor winding, will carry a minimum signal at this time.

Sense of a bearing is obtained by pulling the switches S1, S2 to their other positions. As the tube shows a horizontal trace when the goniometer is set to the figure-ofeight minimum, the channel feeding the vertical deflection system of the tube is available for brilliance modulation of the tube in one direction or the other to indicate right or wrong sense, as the case may be. In the arrangement of FIGURE 4 this is done, when switches S1 and S2 are in their up positions by taking output from the common point of the stator coils to channel C1 and taking the output from this channel via a 90 phase shifter PS and amplifier P.S.A. to the control grid of the tube.

FIGURE 6 illustrates an improved direction finder which, in general principle, resembles that in FIGURE 5 but which uses a preferred method of effecting sense determination. Like references are used for like parts in FIGURES 5 and 6. FIGURE 6 is shown only so far as is necessary to an understanding of the way in which it differs from FIGURE 5, parts not shown in FIGURE 6 being as in FIGURE 5.

In FIGURE 5 the centre points of all the stator windings 1, 1 2, 2 3, 3 and 4, 4 are connected together and the common point used, when sense finding, to provide a source of vertical This, of course, involves a reduction in sense signal amplitude which occurs at .766 when all the centre points are connected together. The improved arrangement of FIGURE 6 avoids this defect. In FIGURE 6 the centre point between each pair of stator windings 1, 1 2, 2 3, 3 4, 4 is brought out separately and a selector switch is employed to select, as a source of vertical E.M.F. for sense determination, the centre point between the stator windings connected to that pair of aerials which, at the moment considered, is most nearly at right angles to the incoming signal direction. The selector switch is driven with the rotor of the goniometer and, in the particular arrangement of FIGURE 6, is constituted by a commentator switch CS which, as the rotor rotates, chooses the relay coils RL1, RL2, RL3, RL4 in turn for energisation when the sense switch SW is closed. Each relay coil operates a relay switch RS1, RS2, RS3 or RS4 and, as will be apparent from 6, these select the centre points of the stator windings 1, 1 2, 2 3, 3 4, 4 in turn for use to provide the required vertical E.M.F. for sense determination.

I claim:

A direction finder comprising a twin path receiver, a radio goniometer having an inner member and an outer member, said outer member having at least two spaced windings, said inner member having two similar winding-s substantially at right-angles to one another each of which two similar windings provides during rotation magnetic coupling with each of the windings of the outer member in turn, said two similar windings of the inner member being connected to supply input signals respectively to the two paths of said receiver, means for connecting each of the ends of each of the windings on said outer member to a different one of a plurality of pairs of aerials and each of the windings of the outer member 25 having a separate central point, selection means responsive to the position of said inner member of the radio goniometer for taking signals from the central point of A the outer member winding connected to the pair of aerials which lie on a line which is most nearly at right angles to the incoming signal direction, and switching means for disconnecting one of said two inner member windings from one path of the receiver and for applying the signal taken by the selection means to said one path of the receiver for sense determination.

References Cited UNITED STATES PATENTS 1,955,267 4/1934 Woods 343-115 2,305,257 12/1942 James et al 343124 2,479,586 8/1949 Moore et a1. 343124 2,815,506 12/1957 Tanaka et a1. 343-124 2,885,672 5/1959 Baur 343124 FOREIGN PATENTS 894,379 12/ 1944 France.

972,233 6/ 1959 Germany.

773,235 4/ 1957 Great Britain.

944,861 12/1963 Great Britain.

RODNEY D. BENNETT, Primary Examiner. CHESTER L. JUSTUS, Examiner. D. C. KAUFMAN, Assistant Examiner.

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