US2375418A

US2375418A - Fixed loop antenna mounting

Info

Publication number: US2375418A
Application number: US484961A
Authority: US
Inventors: Fred E Johnston
Original assignee: Stewart Warner Corp
Current assignee: Stewart Warner Corp
Priority date: 1943-04-29
Filing date: 1943-04-29
Publication date: 1945-05-08
Anticipated expiration: 1962-05-08

Description

y f F. E. JOHNSTON 2,375,418

FIXED LOOP ANTENNA MOUNTING Filed April 29, 1943 2 Sheets-Sheet 1 Mew).-

QWAMM F. E. JOHNSTON FIXED LOOP ANTENNA MOUNTING 2 sheets sheet 2 Filed April 29, 1943 May 8, 1945.

t rlillfllllllllfllll' 1 i llfll/IIIAIIIIIIIII!I1O Patented May 8, 1945 FIXED LOOP ANTENNA MOUNTING Fred E. Johnston, Evanston, Ill., assignor to Stewart-Warner Corporation, Chicago, 111., a corporation of Virginia Application April 29, 1943, Serial No. 484,961

4 Claims.

The invention relates to directional loop antennae and has reference more particularly to an improved construction for fixedly mounting a pair of loops in close association and at right angles with each other and in a manner to effectively eliminate undesired electric and magnetic influences.

The primary object of the invention is to provide a mounting for a pair of loop antennae to be used for direction finding purposes which will position the loops at right angles in relatively close superposed relation and wherein the electrical conditions surrounding the loops will provide for eflicient reception with the most accurate directional indications since all possible sources for disturbances either by induction or by magnetic influences have been eliminated.

Another object of the present invention resides in the provision of loop antennae of the fixed type which will have particular application to the Bellini-Tosi system of radio direction finding. This system uses two stationary loops which heretoiore comprised a large and bulky structure unsuited to present day conditions. The invention contemplates the substitution of the improved mounting and loop construction herein disclosed for the antennae previously employed. The familiar directional properties of a loop antenna are utilized in the Bellini-Tosi method of radio direction finding but since the loops are stationary the angular displacement variations are taken care of by a oniometer including a moving search coil which gives the direction of the received radio waves.

Therefore another object is to provide a mounting for fixed loop antennae which will be compact and highly eflicient, employing relatively short leads and which are shielded in an improved manner to eliminate distortion of the radio waves before they are picked up by the loops and to also minimize absorption of the energy between loops.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out 7 in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the invention and wherein like reference characters are used to designate like parts-- Figure l is an elevational view of the loop mounting of the invention with parts of the top 65 e1 p the deck of a ship by a conventional supporting means such as indicated in its entirety by numeral it, Figure 1. As illustrated the support comprises the standards H, I 2, l3 and I l. The junction box IE contains the necessary sockets 16, ll, l8 and 19 for electrically connecting with the leads to the several loops. The external housing 20 of the junction box provides four tubular members of non-ferrous material such as brass, and which are angularly spaced ninety degrees from each other. The members 2| and 22 form the support for the top loop 23 and the other members 24 and 25, Figure 2, provide the support for the bottom loop 26. All four members are bent so as to project upwardly and members 2| and 22 additionally include a, vertical portion 28 which extends past the bottom loop 26, being disposed on the respective sides thereof. Said members 2i and 22 thus comprise a yoke and a similar yoke is formed by members 24 and with the junction box 15 being located centrally of the arrangement.

The top loop 23, as shown in Figure 1, essen tially consists of an elongated iron core 30 of finely divided iron particles having a coil 3| in close association therewith and which coil comprises a large number of turns of wire extending for substantially the entire length of the core. A circular form or shell 32 of insulating material is placed over the iron core and said shell provides the necessary recess for receiving the windings of the coil 3|. The core and coil combination is suitably enclosed by a second tubular casing 33 also of insulating material to protect the windings from the atmosphere. This casing 33 is secured to form 32 by' a plurality of screws 34. The screws additionally secure the casing to the iron core since they have threaded connection with inserts 3'5 of circular shape located in recesses formed in each end of said iron core. The inserts are of non-ferrous material since it is necessary to magnetically insulate the screws from the iron core of the loop. The loop 23 is also closed at its ends by the insulating discs 36 which are held in position by the longated screw 31 having a head 38 at one end and a nut 39 at its opposite end. The winding 3| of the loop above described is ectrically connected to sockets within the junction box I5 by the conductors 40 and 4| which extend centrally through the tubular members 2| and 22, being suitably insulated and spaced therefrom by the beads 42. Since a tubular member is secured to each end of the loop a convenient arrangement is provided as the conductors upon leaving the members are in the desired position for winding on the iron core. The end of each conductor within junction box is provided with a plug 43 adapted to have interfitting relation with its respective socket. At the other end of the tubular members each conductor extends through a saddle bracket 44 suitably secured to its respective member and to the loop. Certain of the screws 34 pass through the lateral portions of the saddle bracket for securing the bracket to the inserts 35 mounted. on the iron core 30. Figure 3 is a sectional view illustrating the use of the insulating beads 42 for centrally positioning the conductors such as the wire lead 40 within its respective tubular member 2|.

The top loop 23 is located directly above the bottom loop 26 and said loops have a fixed right angular relation. The yokes formed by the members 2| and 22 and 24 and 25, respectively, support said loops one above the other and therefore the yokes are likewise arranged at right angles. The bottom loop 26 is similar in construction to the top loop and the same is supported by means of saddle brackets at its respective ends on the tubular members 24 and 25. The coreof the bottom loop 26 is not shown in Figure 2 but it will be understood that an elongated core of finely divided iron particles is employed, suitably encased within an insulating shell or form providing the desired recess for receiving the windings of the coil 45. Said coil extends for substantially the length of the iron core and the same has close association therewith. The core and coil combination is suitably enclosed within the tubular casing 46 which protects the windings from the atmosphere and discs 41 of insulating material close the loop at its ends, the said discs being held in position by the elon ated screw extending axially of the iron core and having a head 48 at one end and a nut 49 at its opposite end.

The coil of this bottom loop is electrically connected to sockets within the junction box IE by the conductors 50 and 5! which extend centrally through the tubular members 24 and 25. In the same manner as described with respect to the top loop the said conductors are insulated and spaced from the tubular members by insulating beads. Thus the conductors are located centrally of their respective tubular member. 7

The end of said conductors within junction box 15 is provided with a plug 52 adapted to have interfitting relation with its respective socket. At the opposite end each conductor extends through a saddle bracket 53 and through the insulatin casing 46 of the bottom loop, whereupon the conductor is properly positioned for electrically connecting with the ends of the coil 45. The saddle brackets 53 are similar in construction and they are employed in a similar manner to the said brackets. Each saddle bracket is suitably fixed to the upper end of its particular tubular member and each bracket performs the function of securing the loop to its tubular member and of also providing a passage for the conductor or lead to the winding of its particular loop. The saddle brackets 53 like brackets 44 are secured by means of screws 34 to metal inserts which are mounted on the iron core of its loop.

In direction finding loops the direction of the transmitter is indicated by a zero signal when the loop axis points toward the transmitter. It is desired that only the electromagnetic component of the radio wave act on the loop and to accomplish this the electrostatic component is suppressed by an electrostatic shield which substantially encases each loop. Referring to Figures 1 and 2, it will be seen that each loop antenna is covered by special cloth into which metal wires are woven in one direction. This cloth provides the wires 55 which extend around the cylindrical exterior except for a gap at the top of each loop for the purpose of forming an open circuit for said wires. However, all the wires are electrically connected in the vicinity of the lower portion of the casing and the same is grounded at 56 for the top loop and at 5'! for the bottom loop. The insulating discs closing the end of each loop are also covered with cloth providing the vertically disposed wires 58. These wires are also electrically connected at their lower ends and the connection is suitably ground at 59 for the top loop 23 and 60 for the bottom loop 28.

In actual operation of the loop arrangement herein disclosed the sockets in the junction box l5 are electrically connected to a goniometer by any conventional means such as a cable, or wires from the sockets may extend individually through the standards supporting the junction box. A feature of the invention resides in the provision of tubular members for supporting the loops one above the other and in right angle relation. It will be understood that short leads are desired in a loop antenna and proper shielding especially of the leads to the top loop are a necessary requirement for efiicient operation.

The leads in the present structure have a length which is a minimum since the tubular members are fixed to each loop at its ends where the leads can directly connect with the coil windings. Surplus length as regards the leads is thus eliminated and by means of the beads 42 each lead is centrally located and insulated from its tubular member. Each tubular member is also magnetically insulated from the iron core and its loop since the screws 34 in securing the saddle brackets in place have threaded connection with non-ferrous inserts 35.

Electric shielding is secured by locating the leads to the loops within said tubular members which for purposes of the present invention are made of non-ferrous material, preferably brass. The junction box should also be constructed of non-ferrous material in order to complete the electric shielding. As a result the fields generated by said leads 4!], 4 l, for example, included in the electric circuit of the top loop, are not radiated through the metal barrier and external electromagnetic and electrostatic fields are prevented from reaching the enclosed conductors. It is particularly important that the leads 40 and 4! be properly shielded since the currents flowing in these conductors could otherwise set up electrical influences which would seriously interfere with reception by the bottom loop. It is also important to note that the members 2| and 22 are located in spaced relation on the respective sides of the bottom loop. The spacing naturally results by reason of the fact that the loops have a length which is greater than their diameter and the location of the members at the sides of the bottom loop resents the least interference to the received radio waves.

What is claimed is:

1. In a loop antenna system, a top loop and a bottom loop each including a winding having close association with a cylindrical iron core and extending from end to end thereof, supporting means for fixedly mounting the loops in right angle relation with their magnetic axes horizontal, said supporting means including a pair of upwardly projecting tubular members secured to each loop adjacent the respective ends thereof and in close proximity to the respective ends of the winding on the loop, the tubular members for the top loop extending past the bottom loop on the respective sides and being spaced some distance therefrom, and leads extendin through said members for electrically connecting with the windings, said tubular members comprising nonferrous metal whereby the leads are electrically the tubular members of each yoke to its loop, said fastening means being magnetically insulated from the iron core of its loop, and leads from said junction box extending through the tubular members for electrically connecting with the windings, said junction box and tubular members comprising non-ferrous metal whereby the leads are electrically shielded.

3. In a loop antenna system, a top loop and a bottom loop each including a cylindrical iron core having a winding extending from end to end, supporting means for fixedly mounting the loops one above the other in right angle relation with their magnetic axes horizontal, said supporting means including a junction box, tubular members projecting upwardly from said box, and a saddle bracket secured to the upper extremity of each member, said members being arranged in pairs to provide yokes with the saddle brackets of each yoke having securement to its respective loop at the ends thereof, one yoke supporting the bottom loop and the other yoke supporting the top loop, leads from said junction box extending through said tubular members and through said saddle brackets for electrically connecting with the windings whereby said leads have a minimum length, and said junction box and tubular members comprising non-ferrous metal for electrically shielding said leads.

4. In a loop antenna system, a top loop and a bottom loop each including a cylindrical iron core having a winding extending from end to end, supporting means for fixedly mounting the loops in right angle relation with one loop directly over the other, said supporting means comprising tubular members arranged in pairs to provide yokes with the upper extremity of the members of each yoke having securement to its respective loop adjacent the ends thereof, leads for the winding of each loop whereby the same may be connected in an electric circuit, said leads extending through the tubular members whereby they have minimum length and are properly positioned for connection with the respective ends of the loop windings, and said tubular members comprising nonferrous metal for electrically shielding said leads.

FRED E. JOHNSTON.