US2465353A - Goniometer - Google Patents

Description

H 5 m l ,www f e www@ .m S Vf w Nw N065 2 wm. :MMM m um. uw mmm 2 kh rfc QV Y B F. O. CHESUS EVAL GONIOMETER A Filed-Nov. 1, 1945 Patented Mar. 29, 1949 GoNroME'raa Application November-'1, 194s, serial No. 626,128

e claims. (ci. 34a-124) The present invention relates to goniometers particularly for use with ultra or very high frequency direction nders. i

An object of the present invention is the provision of an improved goniometer of the capacitive type which is particularly adapted for use at ultra or very high frequencies and which is characterized by electrical balance as well as simple mechanical construction.

Another object of the present invention is the provision for a direction finder of a unit consisting of a motor, goniometer and sweep voltage generator for a cathode ray oscilloscope in which the motor is used to drive the goniometer and the generator in synchronism. The unit according to our invention is characterized by compact, and sturdy structure, and by the ease with which the elements of said unit may be assembled or disassembled.

Another object of the presentinvention is the provision of an improved direction finding system embodying a goniometer and unit of the type hereinabove described and characterized by electrical balance at the output of the goniometer.

Other and further objects of the present invention will become apparent and the invention will be best understood from the following description of an embodiment thereof, reference being had to the drawings, in which:

Fig. 1 is a schematic diagram of a direction iinder embodying our invention;

Fig. 2 is a sectional View, partly in elevation, of a unit including a motor, generator, and a goniometer, embodying our invention;

Fig. 3 is an enlarged detail view taken along the line 3-3 of Fig. 2; and

Fig. 4 is an enlarged detailed sectional view o the output capacitive coupling arrangement for the goniometer, Figs. 3 and 4 having certain features thereof exaggerated for the sake of clarity. Referring now to Fig. 1, the direction finder there illustrated includes an antenna system which may be in the form of an Adcock array consisting of four monopoles lof which units l and 2 form a spaced pair substantially at right angles to the pair formed by units 3 and t. Units l, 2, 3, 4 may be coupled to a goniometer 5 vthrough suitable couplers Since the output of the units and their associated couplers is unbalanced with respect to ground, and since the goniometer, as will be de- 6-9 respectively.

scribed hereinafter, while symmetrical in relaeter, to interpose between the couplers and the goniometer, means for converting the potential output of the couplers into balanced-to-ground potentials. For this purpose, the output of couplers 8 and 'l is fed to an unbalanced-to-balanced transformer l0 while the output of couplers B and 9 is fed to a similar type of unbalanced-tobalanced transformer il. Any suitable type of such transformer may be employed such as for example, the type herein illustrated including a pair of coaxial lines I2 and I3 havingtheir inner conductors le and l5 connected together at adjacent ends IS thereof and having the input energy, as for example, from couplers 6 and'v'l applied to the outer conductors at said adjacent ends I6 and a ground connection to said outer conductors made at points Il on said outer conductorsequidistantly remote from point lli, this distance varying in accordance with the frequencies involved and other parameters. The free ends i8 and i9 of the inner conductors are the balanced-to-ground output lines of said transformer.

The goniometer 5 includes two stators 20 and 2l each consisting of two plates 22 and 23, and 2d and 25 respectively. Output lines i8 and i3 of transformer in are coupled to plates 22 and 23 and output lines i8 and i9 of transformer .il are coupled to plates 25 and 25. Stators 20 and 2l are cylindrical and are arranged toward opposite ends of and surrounding an elongated cylindrical rotor 2@ which is coaxial with the stators. Stator plates 22 and 23 are substantially semicircular in cross section, and stator plates 24 and 25 arelikewise semi-circular in cross section, with a small space 21 extending longitudinally of the rotor between the stator plates of each stator. Likewise the rotor 26 includes two semi-circular plates 28 and 29 winch are similarly separated from each other by a narrow space 30.

The output of the goniometer is taken off rotor plates 28 and 29 by means of a capacitive arrangement midway between the stators including disks 3| and 32, shown schematically in Fig. 1,- whch rotate with the rotor, disk 3l being electrically connected to rotor plate 28 and disk 32 being electrically connected to rotor plate 29. Disks 3l and 32 are continuously capacitively coupled to stator plates 33 and 3B respectively which in turn are coupled to the direction finding receiver 35. i

In order that the rotor. plates may sinusoidally derive the energy applied to the stators, the stator plates are cut back as indicated at 36 so that .as the rotor plates rotate and move out of sacaste coupling relationship with the stator plates, they do so sinusoidally.

While in-Fig. 1 the stator plates are shown as being aligned, this is merely for the sake of clarity and as will be seen in Fig, 2, the plates of stator 2| are rotated 90 with respect to the plates of stator 20.

The output of receiver 35 is applied through couplers 31 and 38 respectively to the vertically deilecting plates 39 and the horizontally deecting plates 40 respectively of the cathode ray oscillograph tube 4| and to the grid 42 of said tube. To produce a circular trace on the screen of the Y cathode ray oscillograph tube 4| a two-phase are at right angles to each other have alternat-A ing current energy induced therein in two diilerent phases correspondingly related to each other or 90 out of phase. The outputs of stationary coils 48 and 49 are fed through couplers 31 and 38 to the deflecting plates of the cathode ray oscillograph tube 4| to produce a circular sweep. The rotor of the generator 43 and the rotor of the goniometer 5 are both driven by a suitable motor 5U. The motor 50, goniometer 5 and generator 43 are arranged together to form a single, compact unit which may be readily assembled or disassembled, This unit is best seen in Fig. 2.

Referring now to Fig. 2 the goniometer 5 includes a housing 5| with the rotor 26 being journalled at opposite ends thereof in ballbearing races 52 and 53 set in the end walls 54 and 55 of the housing. The plates of stator 28 and the plates of stator 2l are supported in intermediate walls 56 and 51 respectively by means of for example, collars 58 preferably of insulating material. The stators are fastened to their collars so as to maintain the space 21 between the plates of each stator and so that stator 2| is rotated at a 90 angle to stator 20, this angle being measured circumferentially in the direction of curvature of said stator members. The stator platesmay be connected to the collars by any suitable means as for example, screws 59.

The rotor plates 28 and 29 are connected to rotating disks 3| and 32 respectively, which disks are in continuous capacitive coupling relationship with the stator plates 33 and 34, The details of the construction of the stator plates and 2|, the rotor 26 and the capacitive coupling arrangement are best seen in Figs. 3 and 4.

Referring now Ato Fig. 3, it will be seen that the stator plates 24 and 25 of stator 2| are chamfered at the space 21 separating them so as to reduce the capacity between said plates at these ends to a minimum. This is also true of the plates of stator 22. Rotor plates 28 and 29 are very thin and may be in the form of a metallic film or layer deposited on a cylindrical member 60 of .Bakelite or some other suitable insulating mate'- rial, and these plates, as indicated at 30, are separated from each other.

Referring to Fig. 4, the arrangement of rotat ing disks 3| and 32 is there most clearly seen. Surrounding the insulating cylinder 60 forming part of the rotor, are the rotor plates 28 and 29. On top of these plates is arranged a cylindrical layer 6| of insulating material, on top of which the disks 3| and 32, together with their base portions 62 and 63, are arranged. Disks 3| and 32, together with their base portions, may be machined out of a solid piece of cylindrical metal. Electrical control between these disks and the rotor plates associated with them may be made by any suitable means. For example at one point of its circumference, the base Portion 83 has a metallic tab 84 with a threaded opening 85 in which an internally and externally-threaded member 88 is screwed down on a peered male member 81 extending upwardly through the insulating member 40. The member 88 presses down upon the rotor plate 29 and makes electrical contact between it and the base portion 83 of the disk 32. A similar arrangement is provided for disks 3| and its base portion 82.

Referring back to Fig, 2, and the rest of the mechanical construction of the unit including the motor 50. goniometer 5 and generator 43, motor 88 is demountably attached by means of screws 68, through the housing 5|, and is mechanically coupled to the rotor 26 of goniometer 5 by means of a clutch arrangement 89, consisting of two plates 18, secured to the shafts of the motor, and of the goniometer rotor respectively and mechanically coupled together by means of a pin 1I in one of said plates extending into a key or slot 12 in the other of said plates. At the opposite end of goniometer 5 the generator 43 is demountably secured by means of screws 13 to said end o! the housing 5| of goniometer 5, and may also be surrounded by another housing 14. The rotor shaft 15 of the generator 43 is driven by the rotor of goniometer 5 through the medium of arrangement 16, similar to the arrangement 88. It will be seen that the shaft of the goniometer rotor, generator rotor and the motor rotor are all aligned. Suitable sockets for connections to the interior of the goniometer and the rest of the unit are provided, as for example, socket 11 through which power connections are made to the motor 50 and to the generator 43; sockets 18 and 19 through which connections are made to stators 20 and 2| respectively, and output plug and socket 83 through which the output of the rotor is obtained.

From the foregoing description it will be seen that while the goniometer 5 is a symmetrical arrangement with respect to the stators balanced on opposite sides of the rotor and the output capacitive coupling means in the center of the rotor, it is not altogether symmetrical with respect to the housing 5| and therefore to ground, as can be seen in Fig. 2. Due to the use of transformers i0 and Il, this does not aiect the balance of the output of goniometer 5, The input to the goniometer is symmetrical, that is, the antenna system, the length of the input lines and the values of the balancing transformers III and Such symmetry becomes necessary at higher frequencies for accurate operation.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of our invention 'as deilned in the accompanying claims.

We claim:

1. A capacitive goniometer comprising a cylindrical rotor and two cylindrical stators surrounding said rotor and coaxial therewith, said stators being spaced from each other and positioned toward opposite ends of the rotor, each of said stators and said rotor consisting of two circum-V ferentially-spaced conductive plates substantially arcuate in cross section with the plates of one stator circumferentially rotated substantially 90 with respect to the plates of the other stator, and means for coupling the plates of the rotor to output terminals.

2'. A capacitive goniometer according to claim 1 wherein said stator plates are shaped with respect to said rotor plates so as to provide for the sinusoidal variation of coupling between said rotor plates and said stator plates as the rotor is rotated.

3. A capacitive goniometer according to claim 1 wherein said coupling means are capacitive and are arranged intermediate said stators.

4.- In a direction ilnder the combination comprising an antenna system whose output is unbalanced with respect to ground. a goniometer comprising a cylindrical rotor and two cylindrical stators coaxial with said rotor and axially spaced apart along said rotor equidistant from the middle thereof and a metallic housing about said rotor and stators, coupled to ground and asymmetrical zu with respect to said rotor and stators, and means for coupling said antenna system output to said goniometer including an unbalanced-to-balanced transformer.

5. In a direction iinder, a unit comprising a goniometer having a cylindrical rotor and two coaxial cylindrical stators spaced apart an equal distance from the middle of said rotor. a motor for driving said rotor rdemountably arranged with its shaft aligned with said rotor, a two phase generator for generating voltages tor pro- .other in an axial direction with respect to said rotor and coupled thereto,.each of said stators being cylindrical and coaxial with said rotor, each of said stators and said rotor consisting essentially of two circumferentially-shaped conductive plates substantially arcuate in cross section and said coupling means including means for separately coupling each of said plates of said rotor to separate output terminals.

- F. O. CHESUS.

FRANK G. THOMAS. C. S. BEDNASH.

REFERENCES CITED The following references are of record in the file of this patent:

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