US2156055A - Goniometer - Google Patents

Description

April 25, 1939. K. G, HOLSTEN GONIOMETER FiledJan. 25, 1937 2 Sheets-Sheet l fJWsmzvr: far/61? mi? April 25, 1939. K G, HOLSTEN 2,156,055

GONIOMETER Filed Jan. 25, 1957 2 Sheets-Sheet 2 Patented Apr. 25, 1939 UNITED STATES GONIOMETER Application January 25, 1937, Serial No. 122,228

In Germany January 24, 1936 11 Claims.

( Grant ed under the provisions of sec. 14, act of March 2, 1927; 357 O. G. 5)

Goniometers as hitherto constructed are of comparatively large dimensions and therefore can not be employed everywhere. The invention has for its object so to reduce the dimensions of 5 goniometers that these devices shall be adapted also for use on vehicles, for example on board an aeroplane or ship, and shall in addition allow of being combined here with other apparatus, such as a receiver, gyrocompass, or similar device. Further, the reduction of dimensions shall be effected with the aid of means which at the same time serve to improve the electrical properties of goniometers.

The invention fulfils these requirements by employing high frequency iron in connection with all the self-inductances and couplings providedin goniometers. In fact, apart from enabling a spatial decrease the application of high frequency iron does away with certain errors involved in the operation of goniometers.

The invention will be understood from the following description and be particularly pointed out in the appended claims, reference being had to the accompanying drawings in which some embodiments of the invention are shown by way of example.

In these drawings:

Fig. 1 is a wiring diagram of a goniometer as provided by the invention. Fig. 2 is a detail view illustrating a modification of the arrangement shown in Fig. 1. Fig. 3 represents a fragmentary section on line 3-3 of Fig. 2. Fig. 4 is a graphic representation of certain errors involved in the operation of goniometers as hitherto constructed. Fig. 5 is a partially sectioned and partially diagrammatic view illustrating another modification of the arrangement shown in Fig. 1. Fig. 6 is a plan view of Fig. 5. Fig. 7 is a partially diagrammatic underside view of the arrangement represented in Fig. 1. Fig. 8 shows a fragmentary section on line 88 of Fig. '7. Fig. 9 is a partially diagrammatic sectional view illustrating still another modification of the arrangement shown in Fig. 1. Fig. 10 represents a section on line Ill-l of Fig. 9. Fig. 11 is a wiring diagram that relates to Figs. 9 and 10.

The goniometer shown in Fig. 1 has two loop aerials RI, R2 connected to coils Fl, F2, F3, F4, designated as field coils. These are arranged at right angles with respect to each other and are fitted with cores 1, II, III, IV made of high frequency iron. The aerials Rl, R2 are for simplicity shown as located in the same plane, whereas in reality their planes intersect at right angles in a well known manner. In the centre common to the coils Fl to F4 the seeker coil S is disposed whose winding I is wound onto a core B of high frequency iron and in the manner customary with H-armatures. b denotes the shaft of core B.

One of the coils Fl to F4, or a pair thereof, 5 is fitted with a shunt coil 3 or 3. In the case' represented, coil 3 is shunted to coil F4 while coil 3' is so with respect to coil F3. The coils 3, 3 are provided with cores n, n of high frequency iron, and these are associated with complemental core pieces 4, 4' likewise of high frequency iron and displaceable in the manner indicated by the arrows. Further, shunt pieces of high frequency iron, for instance A or A may be fitted to the cores I to IV and provided with pins P, P like- 15 wise of high frequency iron, such pins being in serted in bores of these shunt pieces in order to be displaceable therein. Equally, the cores I to IV may be equipped with adjustable pins of high frequency iron, such as pin P4 seated in an axial bore of core IV.

The winding 1 of coil S is connected to the external terminals a, b by twisted leads 5, 6. Lead 5 is by two twisted branch leads 5, 5 joined to the terminals 0., b of a coil K so that this coil is connected in series with coil S. Coil K is intended to be coupled to either one or another of the coilsFl to F4. To such end. as shown in Figs. 7 and 8, the bottom plate D of the goniometer has slots 1, 8, H), II each adapted to receive an insulating socket 9 carrying the coil K and terminals or, b. The dotted line position of the parts 5', 5", 9, Fig. 7, is a representative example of changing from one position of socket 9 and coil K to another. It will be readily seen that this arrangement also allows of reversing the polarities of coil K and further, that this coil may be replaced by any other different therefrom as to the number of turns. Coils for such exchange may be kept in stock.

Owing to the use of high frequency iron it is possible considerably to reduce the dimensions of goniometers while the losses are the same as those in goniometers of the type having air core coils, and the use of high frequency iron further enables that the coupling factor between coils Fl to F4 on the one hand and coil S on the other hand can be made to be of the value 0.9. Furthermore, since the iron acts to concentrate the coil fields effectively, the arrangement will be 5 much less influenced by outer fields than has been the case heretofore.

The iron parts may be of any other configuration or construction than that represented in Fig. 1, without departing from the idea of the invention. For example, the cores I to IV may be interconnected by a ring A in the manner shown in Fig. 2, so as to form a closed magnetic system of the kind customary with electric machines. Ring A may be furnished with a pin P of high frequency iron, inserted in a bore thereof in order to be adjustable for the purpose of regulating the magnetic shunt constituted by this ring, in a manner similar to the shunts A, P or A, P before described.

As shown in Figs. 5 and 6, the core of the coil S may be composed of two parts B, B. Part B has a shaft 2) which is provided with a trunnion d seated in an axial bore of the shaft b of part B. c, c engaging in a groove of B or B, respectively. The winding of S consists of two serially connected sections l, 2, section I being arranged o B, section 2 arranged on B.

By the invention as thus far described also the electric properties of goniometers are improved in as much as certain errors in the operation of goniometers are avoided. Such errors are mainly due to the mode of effecting the several couplings and may therefore be designated as structural errors. These are in a well known manner classified as follows:

1. Octantal error,

2. Quadrantal error,

3. Lack of symmetry error.

In Fig. 4 these errors are plotted with respect to the direction-finding angle, indicated on the abscissa line by 0, 90, I80, 210, 360. Curve I is the curve of octantal error, curve II that of quadrantal error, curve III that of lack of symmetry error. These curves are not of correct scale, being merely to illustrate the different maxima and minima.

Re error 1: In the case of goniometers having air core coils it is well known to compensate the octantal error by subdividing the seeker coil into two coils offset with respect to each other. In arrangements as provided by the invention such subdivision is of the kind before described with reference to Figs. 5 and 6, where the two core parts B, B with the coil sections I, 2 thereon can be turned with respect to one another on trunnion d.

Re error 2: There are two kinds of quadrantal error. One kind is illustrated by curve II in Fig. 4. An illustration of the other kind is obtained by displacing the curve II either upward or downward in a position parallel with the zeroline. With goniometers having air core coils, the first kind of quadrantal error has been avoided heretofore by connecting a coil in parallel with a pair of field coils so as to afford an electric shunt that acts to compensate such error. This mode however requires the size of the coils to be chosen carefully, whereby the manufacture of goniometers has been difficult in some respects.

In accordance with the invention the quadrantal error, whose curve is positioned symmetrically in relation to the zero line, is avoided by means of an electric shunt constituted for instance by the coil 3 before described with reference to Fig. 1. This compensation coil does not require the number of turns to be varied, because its self-induction is regulated simply by displacing the complemental core piece 4 in relation to core 12.

C'oil 3 may not only be provided with an iron core 12 and complemental core piece 4 but may be equipped instead with a closed iron circuit and any means for permeability variation or a-tuning.

The shafts b, b are each fitted with a key The compensation aimed at may be effected also by displacing the cores I to IV in the direction of radii so as to vary the air gaps between these cores and coil S, or the coils Fl to F4 may be displaced on the cores I to IV, or finally a pin such as pin P l, before described with reference to Fig. 1, may be displaced in the core carrying it.

The quadrantal error of the second kind is avoided by means of magnetic shunts provided between two adjacent cores I to IV, such as shunts A, A or A before described with reference to Figs. 1 and 2. The shunts A, and A may be adjusted simply by varying the air gaps between the iron parts A or A and the cores which in the case represented are cores III, IV, or pins P or P may be displaced accordingly in the parts A, A. Preferably, the variableness of the air gaps, which is indicated by the arrow shown at A, should be used, being more symmetrical in relation to the seeker coil S than an adjustment effected by means of the pins P, P. The shunt afforded by ring A, Fig. 2, is variable with the aid of pin P or may be variable in any other suitable manner.

Re error 3: To avoid the lack of symmetry error has been most difficult heretofore as compared with the possibility of avoiding the other two errors. In accordance with the invention, this error is obviated by means of the coil K, which as before described with reference to Figs. 1, 7, 8 is intended to be coupled to either one or another of the coils F! to F4. It is possible in this way to confine the lack of symmetry error to a region whose limits are :l.-

The means here disclosed also allow of compensating the influence which the metal parts of a vehicle that carries a goniometer tend to exert upon the characteristic of the antenna. In fact, in such metal parts, currents are induced that cause the direction indicated by the goniometer to be somewhat different from the actual one. The error here involved is quadrantal and therefore can be compensated by means of an electric shunt associated with one of the coils Fl to F4, for example by means of the coil arrangement 3', n, 4 before described with reference to Fig. 1, where coil 3' is shunted to coil F3. The advantage here is likewise that a tuning or variation of permeability is enabled without the number of turns having to be varied. In this way when manufacturing a goniometer it is possible to compensate a known curve that illustrates the influence attributable to the metal parts of the vehicle, and then to effect only a slight readjustment when installing the goniometer.

It will thus be evident that by the described use of high frequency iron with goniometers all the said disadvantages are avoidable, and that with the aid of the described additional features of the invention the said structural errors in the function of goniometers can be simply and quickly compensated.

In the case of aerials crossing at right angles, as is the case with the aerials Rl, R2 before described, it is not possible to tune the aerial circuits themselves. Therefore it is customary to tune the seeker coil S and to govern the aerial circuits through the tuning of this coil. In order to render this reaction sufiiciently effective care should be taken that the coupling factor between coil S on the one hand and coils Fl to F5; on the other hand is as great as possible, that further the attenuation of the oscillatory circuits is small enough, and finally that the effective inductivity of coil S is independent of the angle of the mutual rotation of these coils.

These requirements are to the greatest possible extent fulfilled by arrangements of the kind shown in Figs. 9, 10, 11 by way of example.

Here, the field coils Fl, F2 are disposed on a core B of high frequency iron and field coils F3, F4 disposed on a second core B that likewise consists of high frequency iron. Coils Fl, F2 are wound at right angles with respect to each other, as are also coils F3, F4. Further, coils Fl, F3 are connected in series with each other, and coils F2, F4 as well. These particulars are represented in Fig. 11, which also shows that the serially connected coils F2, F4 are joined to aerial RI and that the serially connected coils Fl F3 are joined to aerial R2. They are so with the aid of contact rings e of a shaft 1) on which the cores B, B are fastened. The seeker coil S has two serially connected windings l, 2 each disposed on a casing made in two cup-shaped parts. These casings are arranged to encompass the cores B, B so as to form a sort of cage therefor. The two-part casing provided with winding l is denoted by H while the other is designated l2. In this way the air gaps between coil S on the one hand and coils Fl to F4 on the other hand can be made small enough to obtain a high coupling factor.

In order to compensate the octantal error that always occurs in goniometers, cup ll is turned with respect to cup l2.

The windings l, 2 of coil S are connected to a condenser C, Fig. 11, so as to form a tuned oscillatory circuit therewith.

High frequency iron cylinders l3, l4 are arranged around the coils in order to increase the coupling effect and inductivity thereof.

All these parts, except the contact rings e, are contained in a screening l5.

It will thus be seen that in distinction from the arrangement disclosed in Figs. 1, 2, 3 and 5 to 8 the field coils Fl to F4 are rotatable by means of shaft 1) whilst the seeker coil S is stationary, being only adjustable in itself.

In order to render the effective inductivity of the windings l, 2 independent of the angle of rotation of the coils Fl to F4, as stated, the windings l, 2 are arranged symmetrically, as shown in Fig. 10, so as to produce a homogeneous field.

The coupling degree obtained by means of the arrangement shown in Figs. 9 to 11 is much greater than that of the arrangement disclosed in Figs. 1, 2, 3 and 5 to 8.

What is claimed is:

1. A goniometer having field coils provided with cores of high frequency iron and having their windings perpendicularly related to one another, and seeker coils likewise having cores of high-frequency iron and being rotatably mounted in the field of said first mentioned coils, said field coils being connected to directive antennas, and said seeker coils being associated with a high frequency device.

2. A goniometer according to claim 1, wherein the cores of the field coils are supported by a ring of high frequency iron.

3. A goniometer according to claim 1, having a seeker coil and a core therefor composed of two parts of high frequency iron adjustable in relation toeach other.

4. A goniometer according to claim 1, having an auxiliary coil connected in parallel with a field coil, a core of high frequency iron for this auxiliary coil, and means to vary the inductivity of said auxiliary coil.

5. A goniometer according to claim 1, having a seeker coil, a core of high frequency iron therefor, and a regulable magnetic shunt of high frequency iron associated with adjacent cores of the said field coils.

6. A goniometer according to claim 1, having a seeker coil, a core of high frequency iron therefor, and displaceable parts of high frequency iron associated with adjacent cores of the said field coils.

'7. A goniometer according to claim 1, having a seeker coil, a core of high frequency iron therefor, and an auxiliary coil serially connected with the seeker coil and coupled to one of the field coils.

8. A goniometer according to claim 1, having a seeker coil, a core of high frequency iron therefor, an auxiliary coil serially connected with the seeker coil, and means to couple this auxiliary coil to any one of the field coils.

9. A goniometer comprising a rotatable shaft, two iron cores fastened on this shaft, field coils on each of these cores, a stationary casing containing one of these iron cores, a stationary casing containing the other iron core, a seeker coil winding disposed on one of these casings, and a seeker coil winding arranged on the other cas ing and connected in series with the other said winding.

10. A goniometer according to claim 9, wherein the two windings are each disposed symmetrically in relation to the said shaft.

11. A goniometer comprising, field coils provided with cores of high-frequency iron and mounted on a rotatable shaft, seeker coils encircling said field coils, and an annular member of high-frequency iron surrounding each of said stationary seeker coils.

KARL GEORG HOLSTEN.

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