US3499171A

US3499171A - Insulated reel mechanism for highpower aircraft trailing antenna

Info

Publication number: US3499171A
Application number: US370901A
Authority: US
Inventors: Robert L Carrel; Richard C Fenwick; Robert A Fowler
Original assignee: Collins Radio Co
Current assignee: Collins Radio Co
Priority date: 1964-05-28
Filing date: 1964-05-28
Publication date: 1970-03-03
Anticipated expiration: 1987-03-03

Description

March 3, 1970 R, L, CARREL ETAL 3,499,171

INSULATED REEL MECHANISM FOR HIGH-POWER AIRCRAFT TRAILING ANTENNA Filed My 28, 1964 2 Sheets-Sheet 1 Yr ,l :e

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Y gs) l 'n o al) t?) IR /X n f 0 N a gf :CD O: .@RQ g M l f@ 'n m K n g Q Q CK g W s Q lNvENToRs Q g: m ROBERT L. cARREL w z RICHARD c. FENwlcK ROBERT A. FowLER ATTORNEY March 3, 1970 R, L, CARREL ETAL 3,499,171

INSULATED REEL MECHANISM FOR HIGH-POWER AIRCRAFT TRAILING ANTENNA Filed May 28, 1964 2 Sheets-Sheet 2 58 INVENTORS 3 ROBERT L. CARREL RICHARD C. FENWICK ROBERT A. FOWLER BYW- ATTORNEY United States Patent O 3,499,171 INSULATED REEL MECHANISM FOR HIGH- POWER AIRCRAFT TRAILING ANTENNA Robert L. Carrel, Richard C. Fenwick, and Robert A.

Fowler, Richardson, Tex., assignors to `Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Filed May 28, 1964, Ser. No. 370,901 Int. Cl. H01q l/l4 U.S. Cl. 343-877 Claims This invention relates in general to a variable length airborne trailing wire antenna and in particular to a design which provides shielding for personnel safety and prevention of undesired radiation.

At particular radio frequencies a variable length trailing wire antenna provides the best type of antenna. The length of a trailing wire antenna varies with the frequency.

It is an object of this invention, therefore, to provide a trailing wire antenna which may be remotely adjusted in length.

Another object of this invention is to provide a trailing wire antenna which assures personnel safety from the high voltages used in such antenna.

Yet another object is to provide a trailing wire antenna which eliminates capacitance in the reel supporting the unused portion of the antenna wire.

A feature of this invention is found in the provision for an enclosed container which is insulated from a cover member which is electrically connected to the air frame so that shielding is provided by the inner container and which has remote control for adjusting the length of the trailing wire antenna.

Further features and objects of the invention will become apparent from the following description and claims when read in view of the drawings in which;

FIGURE l is a sectional view of the trailing wire antenna system according to this invention,

FIGURE 2 is an enlarged cutaway detailed view of the apparatus for moving the electrical plug associated with the reel motor and FIGURE 3 is an enlarged detailed view of the plug shown in FIGURE 2.

FIGURE 1 illustrates a transceiver 10 which is mounted in the fuselage of an aircraft and which has a coaxial cable feed line 11 containing an outer conductor 12 and an inner conductor 13 separated by insulation in a conventional manner.

An outer container 14 is formed with a base 16 which may be suitably mounted to the aircraft structure by bolts 17 and 18. The container 14 is constructed of electrically conducting material and the bolts 17 and 18 electrically connect it to the aircraft fuselage and aircraft skin 19. This assures that the container 14 is at ground potential.

Supported within the container 14 is an inner container 21 also formed of electrical conducting material. The base 22 of the inner container 21 is supported and attached to the outer conductor by insulating supports 20, 23, 24, 25 and 26. These insulating supports comprise dielectric plates. Plates and 25 are longitudinal of the containers and

plates

23, 24 and 26 are transverse of the containers. The dielectric plates insulate .the inner and outer containers from each other. The outer conductor 12 of the coaxial cable 11 is electrically connected to the outer container 14 and the inner container 13 is electrically connected to the side wall 27 of the inner container 21. A drive motor 28 is mounted within the inner container 21 by a suitable supporting bracket 29 and has an output shaft 31 which carries a gear 32. A belt 33 passes over gear 32 and is in mesh with a gear 34. Gear 34 is mounted on the shaft 36 of the storage reel 37 which is supported by bracket 38 from the base ICC of inner container 21. The reel 37 contains a supply of antenna wire 39 which extends from the reel across a feed roller 41 which is supported by suitable bearings carried by bracket 42. Bracket 42 is connected to the base 22 of the inner container 21. The antenna wire 39 passes over the electrical feed roller 41 and through a tube 43 which extends from the wall 44 of the inner container. The tube 43 also extends through the wall 46 of the outer container and through the aircraft skin 19. An outer cylinder 47 extends from inner wall 46 of the outer container to the skin 19 of the aircraft.

Insulating discs

48, 49 and 5t) extend between the outside of tube 43 and the inside of tube 47. A biasing drag 51 is attached to the end 52 of the trailing wire antenna to give a suitable aerodynamic characteristic.

Since the inner conductor 13 of the coaxial cable 11 is attached to the inner container 21 electrical energy will be fed through the bracket 42 and reel 41 to the antenna wire at point A on the reel. Thus, energy may be radiated from the wire which extends from the aircraft skin 19.

During landings and takeoff it is desirable that the trailing wire antenna be retracted and also it is desirable to adjust the length of the trailing wire to tune it. To accomplish this a pair of

electrical leads

53 and 54 extend from the reel motor 28 to a female plug 56 mounted in the end wall 44 of the inner container. A male plug 57 carries two contacts for engaging the plug 56 and is connected to

feed wires

58 and 59.

Feed wires

58 and 59 are connected by leads 61 and 62 to movable contact 63 of a reversing switch 64. Reversing switch 64 is connected to a suitable power supply 66. Thus, when the plug 57 is in engagement with plug 56 the reel motor 28 may be energized to turn in either direction in response to the position of Contact 63. Thus the reel motor 28 will drive the rcel 37 to extend or retract the trailing wire antenna as desired.

At all times when the plug 57 is in engagement with plug 56, the transmitter 10 is turned olf so that an electrical short between the outer container 12 and inner conf tainer 13 does not occur through the

motor power lines

58 and 59. When the trailing wire antenna has been adjusted to the desired length the plug 57 is retracted so that it disengages the plug 56.

This is accomplished by an electrically insulated rotatable lead screw 67 which is rotatably supported between the end wall 44 and a plate 68. Plate 68 is supported by an extension cylinder 69 that is attached to the wall 46 of the outer container.

AS best shown in FIGURE 3 a pair of electrically nsulating guide rods 69 and 71 are mounted adjacent lead screw 67 between the end wall 44 and plate 68. The plug 57 carries prongs 72 and 73 for making electrical contact and is formed with a pair of

extensions

74 and 75 which are formed with openings through which rods 69 and 71 extend.

As best shown in FIGURE 2 a gear 76 is attached on the end of lead screw 67 and is in mesh with gear `77 which is carried by the shaft 78 of motor 79. Motor 79 is connected to the cylinder 69 by

suitable set screws

81 and 82.

A pair of

retractable doors

83 and 84 are supported from the end wall 46 and cover the opening formed by extension 69 when the plug 67 is in the retracted position as shown in FIGURES 2 and 3. Spring hinges 86 and 87 bias the

doors

83 and 84 to the open position shown in FIGURE 1. However, a pair of

springs

88 and 89 have first ends connected to

doors

83 and 84 respectively and have their seconds ends joined by wire 91. Prong 92 of plug 57 engages Wire 91 so that when the plug 57 is moved to its retracted position wire 91 and

springs

88 and 89 close the

doors

83 and 84 as shown in 3 FIGURES 2 and 3. As best shown in FIGURE 3 a second prong 93 extends from plug S7 on the side opposite to prong 92 and engages a wire 94 which is attached to springs that are connected respectively to

doors

83 and 84. Door 84 has a lip 96 which engages the end portion 97 of door 83. As best shown in FIGURE 3

openings

98 and 99 and 100 are formed in the doors t0 allow the guide rods 69 and 71 and the lead screw -67 pass therethrough. As best shown in FIGURE 1 the motor 79 is fed power by a pair of leads 101 and 102 which are connected to the movable contact 103 of reversing switch 104. The reversing switch 104 is connected to power supply 66.

Assuming that the plug 57 is in a retracted position as shown in FIGURES 2 and 3, the movable contact 103 may be moved to cause the motor 79 to drive the lead screw 67 such that the plug 57 moves toward the plug 56. As the plug 57 moves toward the

doors

83 and 84

springs

88 and 89 will be released and spring hinges 86 and 87 will bias the doors to the open position. The motor 79 will continue to run until plug 57 engages plug 56 to make electrical contact, then switch 104 is opened. It is to be noted that the

leads

58 and 59 are flexible to allow extension of plug 57. The switch 63 may then be engaged to cause the reel motor to extend or retract the antenna. When the antenna is at the desired length the switch 63 is opened and the switch 104 is reenergized to drive the motor 79 to retract the plug 57. Plug 57 disengages plug 56 to break electrical contact and moves within the extension 69. As it does so the

prongs

92 and 93 exert tension on

wires

91 and 94 connected to the springs and close the

doors

83 and 84 as shown in FIGURES 2 and 3.

- Switch 103 is opened and the transmitter may be turned on. Since the lead screw 67 and guide rods 69 and 71 are made of insulating material the outer and inner container remain insulated from each other.

Some advantages of this system are:

(l) Radio frequency interference-Since the transmitter current flows on the surface of the inner enclosure, which is surrounded by the metal outer enclosure at ground potential, there is virtually no power radiated within the aircraft which could interfere with the aircraft instruments and equipment.

(2) Corona control.-By controlling the outside corner radii of the inner enclosure, the inside corner radii of the outer enclosure and the spacing 'between enclosures, the corona and breakdown voltages can be controlled. If the antenna reel and associated drive equipment were not surrounded by an inner enclosure, the sharp corners of this equipment would reduce the corona and breakdown voltages.

(3) Reel capacitance- Since the antenna must operate with various lengths of wire extended, some wire is spooled on the reel at all times. If the wire was `fed at the reel, the impedance of the antenna would be affected by the amount of Wire spooled on the reel. ln this system the current does not ow through the reel, instead it flows run both transverse and longitudinal so they can support very large loads applied in any direction.

Although it is seen that this invention describes a new and novel trailing wire antenna system it is not to be so limited, as changes and modifications may be made therein which are within the spirit and scope of the invention as deiined by the appended claims.

We claim:

1; A variable length airborne trailing wire antenna device for mounting in an aircraft having conductive skin comprising: an electrically conductive outer enclosure having an opening therein; an opening formed in the conductive skin of the aircraft in alignment with the opening in the outer enclosure, a hollow conductive-cylinder connecting the skin of the aircraft to the outer enclosure with the openings in the skin and outer enclosure aligned with the center opening of the hollow cylinder, an electrically conductive inner enclosure within and insulated from said outer enclosure and the conductive skin of the aircraft, said inner enclosure having an opening therein in substantial alignment with the openings in said outer enclosure and conductive skin, radio frequency means connected to said inner and outer enclosures, an electrical feed means within and connected to said inner enclosure adjacent the opening in the inner enclosure, said feed means also serving as a guide means for said antenna, a length of electrically conductive antenna wire, a portion of which is within said inner enclosure and engages said feed means and another portion of which extends through around the reel and into the wire just before it exits the aircraft. Thus reel capacitance does not influence antenna impedance.

(4) Shmilt capacitance controls-By controlling the spacing between the inner and outer enclosures the shunt capacitance of the antenna may be controlled.

(5) Lighting protection-This design facilitates the use of a lightning arrestor or spark gap between the two enclosures.

(6) Personnel safety.-Since the outer enclosure is at ground potential personnel are shielded from all of the high voltage areas.

(7) Packaging-Since the reel and its drive mechanism are located within the inner enclosure; compact, weatherproof packaging is achieved.

(8) Structural design-The dielectric plates used to space the inner enclosure away from the outer enclosure said openings and is outside said enclosures and the aircraft, and means for controlling the length of the portion of said antenna wire extending outside said enclosures.

2. The trailing wire antenna device of claim 1 wherein said openings in said enclosures are small in diameter relative to the size of said enclosures but are larger in diameter than said antenna wire so that said antenna Wire freely passes therethrough.

3. The trailing wire antenna device of claim 1 wherein said means adapting said enclosure for connection to radio signal generating and receiving means includes a length of coaxial cable the outer conductor of which is connected to said outer enclosure and the inner conductor of which is connected to said inner enclosure.

4. The trailing wire antenna device of claim 1 wherein said guide means includes a metallic roller adjacent to said opening in said inner enclosure.

i. The trailing wire antenna device of claim 1 wherein said antenna wire within said inner enclosure is stored on a reel and engages said guide means only after being unwound from said reel.

6. The trailing Vwire antenna device of claim 5 wherein said last named means includes an externally controlled motor, said motor being connected to said reel to adjust the length of said antenna wire outside said enclosures.

7. A variable length airborne trailing wire antenna for an aircraft having conductive skin comprising: an electrically conductive outer enclosure electrically connected to the skin of the aircraft and having a small insulated 4opening therein, an opening in the aircraft skin, a hollow conductive cylinder connected between the aircraft skin and the outer enclosure with the central opening of the cylinder aligned with the openings in the'skin and outer enclosure, an electrically conductive inner enclosure within and insulated from said outer conductor, said inner conductor having a small opening therein in substantial alignment with the openings in said outer enclosure and the skin, a coaxial cable the inner conductor of which is connected to said inner enclosure and the outer conductor of which is connected-t0 said outer enclosure, a radiant energy device connected to the other end of said coaxial cable; electrically conductive feed and guide means mounted within said inner enclosure adjacent to said opening therein; a reel rotatably mounted within said inner enclosure; antenna wire a portion of which is wound on said reel and another portion of which engages said feed and guide means and extends from said enclosures and the aircraft through said openings therein; a motor connected to rotate said reel; and control means connected to said motor to control the amount of antenna wire extending from said enclosures and the aircraft.

8. The trailing wire antenna device of claim 7 wherein said outer enclosure has a second opening therein; wherein said control means includes plug means one portion of which is mounted on said first enclosure and the other portion of which is retractable from said enclosure through said second opening in said outer enclosure; and further characterized by means for automatically closing said second opening upon retraction of said other portion of said plug means.

9. The trailing wire antenna device of claim 8 wherein said last named means includes doors actuated by said other portion of said plug means during retraction.

References Cited UNITED STATES PATENTS 2,036,456 4/1936 Buschbeck 343-877 XR 2,374,892 5/1945 Peterson 343-877 XR 2,834,012 5/1958 Allen .343-877 XR RODNEY D. BENNETT, J R., Primary Examiner J. P. MORRIS, Assistant Examiner U.S. Cl. X.R. 343--723

Claims

1. A VARIABLE LENGTH AIRBORNE TRAILING WIRE ANTENNA DEVICE FOR MOUNTING IN AN AIRCRAFT HAVING CONDUCTIVE SKIN COMPRISING: AN ELECTRICALLY CONDUCTIVE OUTER ENCLOSURE HAVING AN OPENING THEREIN; AN OPENING FORMED IN THE CONDUCTIVE SKIN OF THE AIRCRAFT IN ALIGNMENT WITH THE OPENING IN THE OUTER ENCLOSURE, A HOLLOW CONDUCTIVE CYLINDER CONNECTING THE SKIN OF THE AIRCRAFT TO THE OUTER ENCLOSURE WITH THE OPENINGS IN THE SKIN AND OUTER ENCLOSURE ALIGNED WITH THE CENTER OPENING OF THE HOLLOW CYLINDER, AN ELECRICALLY CONDUCTIVE INNER ENCLOSURE WITHIN AND INSULATED FROM SAID OUTER ENCLOSURE AND THE CONDUCTIVE SKIN OF THE AIRCRAFT, SAID INNER ENCLOSURE HAVING AN OPENING THEREIN IN SUBSTANTIAL ALIGNMENT WITH THE OPENINGS IN SAID OUTER ENCLOSURE AND CONDUCTIVE SKIN, RADIO FREQUENCY MEANS CON-