US2463475A

US2463475A - Direction finder

Info

Publication number: US2463475A
Application number: US614526A
Authority: US
Inventors: Hepri G Busignies
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC; Federal Telephone and Radio Corp
Priority date: 1945-09-05
Filing date: 1945-09-05
Publication date: 1949-03-01
Anticipated expiration: 1966-03-01

Description

arch 1949 H. G.' BuslGNiEs DIRECTION FINDER Filed sept, 5,` 1945 ATmR/VEY Patented Mar. 1, 1949 DIRECTON FINDER Henri G. Busgnies, Forest Hills, N. Y., assigner to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application September 5, 1945, Serial No. 614,526

6 Claims.. 1

The present invention relates to direction finders and particularly to direction iinders for use on ships.

The antenna system or wave collectors of short wave direction finders are customarily mounted on top of a mast on board ship to reduce the elfect of other masts and the effects of the superstructure.

The types of wave collector or antenna system which reduce polarization errors, such as spaced monopoles, spaced loops or spaced dipoles, have.

been found to operate unsatisfactorily under such conditions.

An object of the present invention is the provision of an improved direction under, particularly for ships.

Another object of the present invention is the provision of a direction finder for structures such as ships, in which the errors due to masts or to the ships superstructure, are relatively small, and in which polarization errors are relatively less than are found in conventional crossed-loop direction finders.

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 and block diagram of a direction iinder embodying my invention as arranged on a ship; and

Fig. 2 is a detailed perspective View of a portion of the side of the ship showing the arrangement of a loop antenna associated therewith.

Referring now to the drawings and in accordance with a feature of my invention, both sides I and 2 of the metallic hull. of a ship, generally designated by the numeral 3, are employed as reiiectors for the wave collectors or antenna system of a phase comparison direction iinder which operates to cover separate sectors l and 5, sector i being covered by the portion of the antenna systern associated with side i o-f the ship 3 While sector 5 is covered by the antenna system associated with side 2. The system of sector operation is generally covered in my copending application Serial No. 553.598, led September 11, 1944. Sectors li and 5 may be approximately 120 or 130 giving a total coverage of about 240 or 250 of the total 360. On large ships, the ships large surfaces, oriented toward the front or the back of the ship, could be used to provide two more sectors of her operation especially for the highest frequencies of the spectrum covered. On small ships, like destroyers, the dimensions of the sides of the ship are such that good operation can be obtained down `to a few megacycles per second and on large ships, such as aircraft carriers, battleships, large cruisers, etc., down to one megacycle per second.

Two spaced wave collectors, preferably in the form of loops 6 and i are installed on the side I and spaced apart a distance o-f the order of a quarter wavelength. These loops extend substantially at right angles to the side of the ship. A similar set of loops 8 and Si are installed about a quarter wavelength apart on side 2 of the ship. All of said loops are insulated from the hull of the ship and use the hull as reflecting means. The transmission lines Il] from each of said loops may be brought vertically upward from the loop and directly over the side of the vessel or if convenient through an opening in the side. The transmission lines may also be used to suspend and support the loops. Each of the loops may be protected by any suitable means such as a bubble il of non-metallic material. At the lower frequencies, it is preferred that the loops be of the type using iron cores.

Because the magnetic field of any incident wave is doubled at the surface of the metal of the side of the ship. loops are much better adapted for this purpose than other types of antennas which depend primarily on the electrical eld. since at the surface of the metal of the side of the ship the electrical eld tends toward zero. Loops also have the advantage of being much smaller than open antennae. Furthermore open antennae cannot be installed at a sufficient distance from the hull to pick up an appreciable signal.

The wave collector system hereinabove described may be used for relatively low frequencies, such as for example, 1-25 megacycles. To cover such a range it may be desirable to use two or three sets of loops spacing them approximately a quarter wavelength apart. While the phase comparison system may use a transmission line type of phase shifter in making the phase comparison, at such frequencies such transmission line phase Shifters become too bulky and other systems are preferably employed such as for example, described in my copending applications, Serial No. 481,760, led April 3, 1943, and Serial No. 497,890, filed August 9, 1943, now Patent No. 2,444,425, granted July 6, 1948, or preferably the system hereinafter described which has the advantage of being relatively simple in construction.

Loop is connected by lines iii and over lines i2 directly to one iixed coil i3 of a goniometer i4. Loop -5 is also connected through a 90 phase shifter i5 to the other fixed coil It of goniometer iii which is at right angles to coil i3. Loop 'i is likewise directly connected to one coil l1 of a second goniometer i@ and indirectly connected through a 90 phase shifter I9 to the other fixed coil 20 of goniorneter i8. rEhe rotatable or search coils 2l and 22 of goniometers id and i8 respectively, are connected to the primaries 2li and 2li respectively of a transformer 25 whose secondary 26 is connected through a switch 2l to a direction iinding receiver 28 having at its output an in'- dicator 29, which may be in the form of a cathode ray oscillograph tube. Search coils ZI and: 22 are continuously rotated so as to cyclically and oppositely vary the phase of energy derived from the loops 6 and 1 and suppliedl to transformer 25. That is, search coils 2l and 22 are positioned and synchronously rotated so that as the phase of the energy derived from one of the loops and 'I is advanced, the phase relationship of energyN derived from the other of the loop-s is re t'arded. The search` coils are synchronously cont'rolled by any suitable control means 30 which is also used to control the time base of the cathode ray' oscillograph tube 29 to synchronize the sweep thereof with the rotation of the search coils.

A similar phase-shifting system 3i, such as described hereinabove, may be associated with the loops 3y and 9 on the other side 2 of the ship andv synchronization between this phase-shifting system 35|' and that heretofore described may be obtained by control means 30. The outputs oi the phase-shifting system 3l and the secondary i@ of" transformer 25 are both applied to a sector switchv 2T which switches each of these separate phase-shifting systems and their respective collectors to the direction finding receiver as the separate sectors are being scanned. The operation ofthe sector switch 2'! may also be controlled by control means 30, the control means being either electronic or utilizing commutatore, Selsyn devices, etc., orl combinations of the foregoing, as will be readily understood by those versed in the art.

Interference with the radiation patterns of the loops 6, 1, 8 and 9 by any energy induced in the lines connecting these loops together or to the` rest of the direction finding system hereinabove described, is prevented by the sides of the ship which Serve to shield the loops from the rest of the apparatus, the rest cf the apparatus being arranged either within the hull or some place in the super-structure so that any eld's produced within said apparatus or lines will not substantially aiect the radiation patterns of the loops. The loops are accordingly preferably arranged a substantial distance below the top of the sides of the ship.

In the operation of the direction finder hereinabove described, the phase-shifting system associated with each of the two antennas covering a given sector is used to continuously and cyclically vary the phase relationship of the antennas with the direction finding receiver 28. For eri-- ample' the phase relationships of loops 6 and 'i with respect to the receiver 2t are continuously and oppositely varied. At the same time the trace on the cathode ray oscillograph tube 2i? is also' continuously moving in a selected. path, such as for example, a circular path. At a given point during the phase-shifting operation, the voltages applied from loops t and 'i to the direction 'nding receiver 2B will be equal and in phase, the

point or moment at which this occurs depending on the direction from which the signal is being received. At the moment when the voltages applied to direction nding receiver 28 are equal and in phase, an indication is produced on the indicator 29, that is, the sweep or trace is deflected. rlhe position of said deflection corresponds to a given direction from which the energy is being received. After one sector, for eX- ample sector l has been covered by the phase s'iifting operation, then the sector switch operates to connect loops 6 and .fi and sector 5 is then covered. This is repeated cyclically.

While I have described the use of two goniorneters in connection with each sector, by which the phase of energy derived from the two loops covering each sector is oppositely varied, it is possible to dispense with one of said goniometers and only vary the phase of energy derived from one of the two loops of the sector while the phase of energy derived from the other loop is not changed. For example, while the phase of energy derived from loop 5 may be varied by means of the 90 phase shifter i5 and goniometer lll, loop 7 may be directly connected to the primary 2f; of transformer thus dispensing with phase shifter l5 and goniometer lo. However, the system hereinbefore described utilizing a goniometer with each loop for shifting the phase of energy derived from said loop, is a more readily balanced arrangement. It vill also be apparent that while I have described the use of my invention in connection with a ship, it may also be employed with other structures having large metallic surfaces which may serve as reflectors for the loops. Various other changes will occur to those versed in the art. Accordingly, while I have described above the principles of my invention in connection with specific apparatus, it isto be clearly understood 'that this description is made only by way of eX- ample and not as a limitation on the scope of my invention as defined in the accompanying claims.

I claim:

1. A direction finder for use with craft having a metallic hull comprising the combination of a pair of spaced loop antenna units mounted in a parallel plane on the outside of said hull adjacent one side of the craft with said side of the craft serving as a reflector therefor, a radio goniorneter for each of said antenna units, each of said goniometers comprising a rotor and two stators, means for deriving outputs of different phase from each of said antenna units, means for applying each of said outputs to separate stators,

r means for combining the outputs of each of said rotors, a direction nder receiver, an indicator, means for applying said combined outputs through said receiver to said indicator, control means for controlling the rotation of each of said rotors synchronously cyciically and oppositely to vary the phase of energy derived from said goniometers and applied to said receiver, and means for controlling the operation of said indicator by said control means.

2. An arrangement as. set forth in claim l, wherein said outputs of different phase comprise means for applying one output of each of said antenna units to one stator directly, and means for applying another output of each of said units, through a phase shifter to another of said stator units.

3. An arrangement as set forth in claim 2, wherein said indicator comprises a cathode ray oscillograph and wherein said means to control the operation of said indicator comprises means to synchronize the sweep thereof with the rotation of said rotor.

4. An arrangement as set forth in claim 3, wherein said antenna units are spaced apart substantially a quarter Wavelength at the system operating frequency.

5. A direction finder as set forth in claim 1, further comprising a second combination of a set of antenna units, radio goniometers, and a control means, substantially as described located on the 10 Number outside of said hull adjacent another side of the ship, With said last named side of the craft acting as a reector, means for combining the outputs of the rotors of said second arrangement and means for alternately applying the combined outputs of said first and second arrangements through said receiver to said indicator.

6. An arrangement as set forth in claim 5, wherein said means for alternately applying the combined outputs comprises one of said control means.

HENRI G. BUSIGN'IES.

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

UNITED STATES PATENTS