US2484817A

US2484817A - Antenna for aircraft

Info

Publication number: US2484817A
Application number: US469079A
Authority: US
Inventors: Armond James Keller De
Original assignee: Individual
Current assignee: Individual
Priority date: 1942-12-15
Filing date: 1942-12-15
Publication date: 1949-10-18
Anticipated expiration: 1966-10-18

Description

M3 8 2 ssmw m Get. 18, 1949 3L K. as; ARMQN 254341317 ANTENNA FOR AIRGHAFT Filed D90. 15, 1942 3 Sheets-Sheet l J. K. DE ARMOND A 7TOHNEY SEARCH RGUN Oct. 18, 19491. J. K. DE ARMQND ANTENNA FOR AIRCRAFT-1 s Sheets-Sheet '3 Filed Dec. 15, 19 42 J. K175 ARMOND ATTORNEY Patented Oct. 18, 1949 blllilititl ttUUllil UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to an antenna system for aircraft.

One object of this invention is to provide a system for easily adjusting the height of an antenna for tuning, by protecting the antenna from wind stresses.

Another object of this invention is to provide a housing to surround the active antenna element.

The construction and the arrangement of the various parts of the system, including the antenna and its control equipment, are illustrated in the accompanying drawings, in which:

Figure 1 is a schematic perspective view showing the function and disposition of the various parts of the equipment for controlling the antenna;

Figure 2 is a schematic side view of an airplane, showing the relative disposition of the antenna;

Figure 3 is a front elevational view of the antenna and the upper end of the mast housing for the antenna with the front of the mast housing broken away to show the antenna;

Figure 4 is a schematic end view of the several cam and switch assemblies, showin their relative positions at one selected instant;

Figure 5 is a diagramatic circuit of the operating motor for the antenna system, and illustrates the arrangement of the control switches in the assemblies in Figure 4;

Figures 6, 7, and 8 are perspective views of one of the cam and switch. assemblies showing the provision of travel limiting stops for controlling the associated cams.

As shown in Figure l, a control system for an antenna, that is particularly to be employed in aircraft, is illustrated as including a reversible motor I l, whose operating energy is derived from a suitable source or circuit H, to operate a train of gear mechanism, to adjustably position an antenna mast l3 at any one of a number of preselected positions that will provide an antenna of suitable length to receive radiant energy of a pre-selected frequency. The gear train for controlling the antenna I3 is shown as comprising i a worm I4 on the motor shaft, and worm gear l meshed with the worm I4, and a sprocket wheel I6 provided with sprocket teeth l6-a that fit into spaced sprocket openings l3-a centrally along the length of the antenna mast I3.

The antenna mast I3 is preferably made of a spring strip material, and is concavely shaped across its width in such manner as to be selfsupporting in its extended portion. The antenna mast material is similar to the well-known spring measuring tapes which are concave in form across their width, and which may be easily coiled and retracted into a suitable housing. In this case, the antenna mast I3 is similarly provided with a receiving enclosing housing 11 for the retracted or unextended portion of the antenna strip material.

One of the particular difficulties that was encountered in the past, in providing an adjustable antenna for aircraft, was the fact that the extremely high wind pressure on the antenna imposed a heavy load upon the operating motor for the antenna mast, and therefore required a motor of relatively large power capacity and correspondingly large weight.

In the present arrangement, I have eliminated the efiect of the wind stresses on the antenna by extending the antenna mast upward into a protective enclosing housing l8 of dielectric material. The housing material may be transparent. The housing is, of course, of sufficient strength to withstand the wind pressures encountered during flight, and it is provided with suitable flow-line contours to diminish its resistance. Consequently, the operating motor for the antenna mast need have but small power capacity, and can be correspondingly small in size and of relatively light weight.

In order to position the antenna l3 to provide an extended portion of proper length and to receive the wave length or frequency that is to be detected, the electric circuit of the motor is controlled by suitably effective limit switches that are disposed to be operated to control the motor circuit when the extended portion of the antenna has attained a pre-determined selected position.

The control equipment for the limit switches is also shown in Figure 1, wherein a pinion 2|, on the shaft with the worm gear I5 and the sprocket I6, is meshed with a gear 22 on a control shaft 23 on which are disposed several control cams 25-a, 25-b, and 25-c, corresponding in number to the number of positions to which the antenna is to be adjustably positioned. The three cams are mounted initially for frictional rotary movement on the shaft 23, but are held against axial movement, to permit the cams to be selectively adjusted on the shaft 23.

Each of the three contro1 cams controls an associated pair of switches. Cam 25-a controls the operation of two associated switches 3I-a and 32-41 by means of a pivoted operating arm 33--a. The cam -a consists of a circular disk having a notch or slot 34-a extending radially inward from the periphery of the disk, providing a small recess or pocket into which the tip 35c of the operating arm 33a can extend when the cam disk 25-a reaches proper position to permit the tip 35-a to enter the slot 34a.

The cam disk 25b and the cam disk 25-c are correspondingly shaped and each disk includes in its control assembly a similar pair of switches and a similar operating arm, that are identified by the corresponding numerals as those controlled by cam 25-a but with the subscripts b and 0, respectively, as indicated particularly in Figure 4.

In order that the cams may operate properly, to control the associated switches, to interrupt the circuit of the control motor, when the antenna has been adjustably moved to the proper position, the cams 25-a, 25b, and 25-0 are first selectively adjusted to appropriate positions on the control shaft 23, and are then held against relative motion on the shaft 23, by suitable means such as a spacer 38 that is secured to the control shaft 23 by a key 39, for example.

The limit switches 3l-a and 32--a, associated with cam 25-11, and the other limit switches that are associated with the other cams, are normally biased toward their open positions, and are moved to their respective closed positions only so long as the associated pressure operating pins 42 and 43 are respectively pressed inwardly into the housing for the associated switch. When the pressure is removed from either of these pins 42 and 43, the biasing force or restoring force of the switch restores the switch to normal open position.

The limit switches may be of any suitable type that will provide the functional operation required, as described, but are here shown merely by way of illustration as being of a type at present available on the market, that are operable from their normal position to their desired position,

such as the closed position, upon the pressing movement of the operating pin 42, through a relatively short distance, of the order of onethousandth of an inch. A correspondingly small pressure force is suificient to operate these 4 switches, and the load upon the operating motor I l is thus correspondingly held to a minimum.

In Figure 5, the circuit diagram illustrates the manner in which the equipment is controlled to move the extended portion of the antenna to desired position, by the use of a selector switch 45 that embodies a contact arm 46, and three

contact buttons

41, 48, and 49, respectively. The control motor H includes a common field winding 50, the armature 5i, and two

directional windings

52 and 53, for controlling the direction of rotation of the motor in opposite directions. Each control button of the selector switch 45 controls the energization and operation of the control motor I I to move the antenna l3 to a respectively corresponding extended position. One pair of limit switches is connected with each of the

contact buttons

41, 48, or 49 of the selector switch 45. Each pair of switches is controlled by the motor ll, through the cam that is associated with that pair of limit switches, to insure an accurate extension or retraction of the antenna mast to the proper length, corresponding to each position selected at the selector switch 45.

The limit switches are illustrated in the diagram in Figure 5, in the positions corresponding to the physical positions shown in Figure 4, when the cams are in the positions shown in Figure 4.

The switches and the cams are shown in Figure 4, at the time the antenna mast has reached and is at its second position. The cam 25-?) has reached its neutral position, at which the operating arm 33-19 is also in neutral position, and the associated switches 31-!) and 32h are both open at that position, as shown in the diagram in Figure 5. In Figure 4, the operating stems of the two switches are in their respective extended positions, under the influence of the biasing forces that move the respective associated switches to open position.

The energizing circuit for the motor I l is therefore open at these two switches 3 l-b and 32--b, and the motor will therefore have come to a stop, with the antenna moved exactly to the desired length, corresponding to the second position.

When it is desired to move the antenna to either of the other two positions, that is, to the first position or to the third position, the movable contact arm of the selector switch 45 should be shifted to engage the contact button 41 or the contact button 49, according to the position to which it is desired to move the antenna.

Assuming that the antenna is to be moved to the third position, the contact arm 46 will be moved to engage contact button 49, from which the circuit conductor 55 proceeds to the two limit switches 3I--c and 32-0, connected as shown in Figure 5.

The energizing circuit through contact button 49, conductor 55, and limit switch 3 lc energizes directional winding 52 of the motor, and rotates the motor in such direction as to move all the cams in the clock-wise direction.

The motor circuit, after being thus established, through switch 3 l--c, will be maintained so long as the limit switch 3l--c is closed. Limit switch 3lc will remain closed until cam 25--c is rotated into neutral position, where its peripheral slot 34-0 will move into alignment with the tip 35c of the operating arm 33-c. When such alignment occurs, the cam 25-0 and the arm 33-c will assume the position illustrated in Figure 4 as position 2. At that time the limit switch 3Ic will open, and will open the motor circuit. The motor will thereupon stop, and the antenna l3 will stop and remain in the stopped position, corresponding to the third position for the antenna so long as the selector switch contact arm 46 remains on contact button 49.

While the antenna is in that third position, with the contact arm 46 on button 49, the two associated limit switches 3|c and 32-c will be open. The other two cams 25a and 25b, however, will both be in positions where their respective notches or slots 34-a and 34b are to the clock-wise side beyond their respective neutral positions. Under these conditions, the switches 32-a and 32b for first and for second positions, will both be closed. Consequently, when it is desired to retract the antenna back to the second position or to the first position, the selector switch contact arm will be moved over to engage button 48 or button 41. The circuit to the counter-clockwise winding 53 of the motor will have been already set up at the switches 32-a and 32--b, and will be completed by the movement of the contact arm of the selector switch 45 to either button 48 or 41. When either such operation is made at the selector switch, and the motor is consequently energized through the counter-clock-wise winding Shiite some 53, all of the cams will be rotated in a counterclock-wise direction until the cam 25--a or the cam 25-47 reaches its respective neutral position, depending upon which position was selected for the readjustment of the antenna.

Thus, by means of the cams 25-a, 25-1), and 25-0, and the co-operating pivoted arms 33-0, 33--b and 33--c, the limit switches may be accurately and sensitively controlled to move the antenna to the exact position that is desired, without any hunting or over-travel.

In the functional operation of the cams as illustrated schematically in Figure 4, it will be clear that each cam is respectively controlled according to its position on the shaft. After each cam is adjusted to proper operating position, the operating pin 40 on each spacer 38, is not needed.

In order to aid in the adjustment of each cam to predetermine its neutral position, according to the frequency to which the antenna is to be adjusted, a frequency dial B is fixed to shaft 23.

For simplicity of operation and other obvious advantages, the selector switch 45 may be arranged for gang or mutual operation with the frequency selecting switch 56 on the radio equipment 51 that uses the antenna.

In Figures 2 and 3, the arrangement is shown whereby the antenna mast I3 when extended to its extreme position in the housing I8, is caused to engage and enter the jaws of a contacting clip 60 that constitutes a terminal for a horizontal antenna wire ii for reception of longer wave lengths than the antenna 13 is intended for. The antenna BI is shown supported between the housing l8 for the antenna mast l3, and a structural part of the support 52 for the rudder, at the rear of the plane.

By means of the arrangement shown, the antenna mast I! may be selectively and automatically extended or retracted to any one of several predetermined tuning positions, while protected from wind pressure. motor is thus reduced; to a minimum, and the size and weight of the motor and of the associated control equipment may be correspondingly reduced to a minimum;

Although I have referred to the antenna as used forreceiving operations, it may equally well be used for transmitting. The enclosing housing strut being a dielectric, may be made of transparent material. By means of such enclosing housing around the antenna, wind pressures on the antenna are prevented, and any resistance resulting from the presence of the housing is reduced to a minimum by streamlining of the housing.

My invention is notrlimited to the specific details of the construction as is shown in the specific arrangement and location, since various modifications may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims,

I claim:

1. An antenna system for aircraft, comprising a rod mounted for movement inwardly and out- The operating load on the wardly of the aircraft, a hollow fixed-length ing the motor selectively thereby determining the degree of projection or retraction of said rod.

2. An antenna system for aircraft, comprising a rod mounted for reciprocation relatively to the aircraft, a fixed-length streamlined housing :lnounted contiguous to the upper end of the rod, a reversible motor mounted contiguous to the lower end of the rod and in electrical circuit with the electrical source in the aircraft, powertransmitting connections between the motor and the rod, circuit-controlling means terminating adjacent the pilot for causing the motor to, run in either direction to raise or lower the rod within and longitudinally of said housing, and means for automatically breaking the circuit when the rod approaches extreme limits of travel,

3. In combination, an all metal aircraft fuselage, a rigid antenna rod mounted for reciprocation inwardly and outwardly of said fuselage, a. hollow-fixed housing positioned exteriorly of the fuselage in alignment with the path of movement of said rod and into and from which it may be protracted and retracted, and means under the control of the pilot to regulate and determine the protracted or retracted positions of the rod with respect to said housing and the fuselage.

4. An antenna system for aircraft comprising a rod mounted for reciprocation relative to the aircraft, a fixed-length streamlined housing mounted contiguous to the upper end of the rod, a reversible motor mounted contiguous to the lower end of the rod and in electrical circuit with the electrical source in the aircraft, powertransmitting connections between the motor and the rod, circuit-controlling means operable from within the aircraft for causing the motor to run,

in either direction to raise or lower the rod within and longitudinally of said housing, and means for automatically breaking the circuit when the rod approaches extreme limits of travel.

JAMES KELLER. DE Armour).

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

UNITED STA'I'ES PATENTS Number Name Date 2,062,129 Hefele Nov. 24, 1936 2,222,588 Williams Nov. 19,1940 2,283,524 White May 19, 1942 2,313,046 Bruce Mar. 9, 1943 2,368,298 Harris Jan. 30, 1945 2317.191 Fox Mar. 11, 1947