US2283524A

US2283524A - Adjustable antenna device

Info

Publication number: US2283524A
Application number: US321381A
Authority: US
Inventors: Sidney Y White
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-02-29
Filing date: 1940-02-29
Publication date: 1942-05-19
Anticipated expiration: 1959-05-19
Also published as: NL62302C; FR882607A; GB548202A; GB548965A; BE442118A

Description

May 19, 1942- 5. Y. WHITE ADJUSTABLE ANTENNA DEVICE Filed Feb. 29, 1940 l0 Sheets-Sheet 1 O O O O O O O O O O 0 0 -mwz-nxwox; Sidney Y Wh/fe BY ATTORNEYS y 1942- s. Y. WHITE 2,283,524

ADJUSTABLE ANTENNA DEVICE Filed Feb. 29, 1940 10 Sheets-Sheet 2 ATTORNEYS y 19, 1942- s. Y. WHITE 2,283,524

ADJUSTABLE ANTENNA DEVICE Fild Feb. 29, 1940 10 Sheets-Sheet s OOOOOOOGGOOGMO 00 ATTORNEYS y 19, 1942 s. Y. WHITE 7 2,283,524

ADJUSTABLE ANTENNA DEVICE Filed Feb. 29, 1940 10 Sheets-Sheet 4 I INVENTOR Sidney K Wh/fe ATTORNEYS y 1942' s. Y. WHITE 2,283,524

ADJUSTABLE ANTENNA DEVICE Filed Feb. 29, 1940 10 Sheets-Sheet 5 INVENTOR SM/76] W/l/le ATTORNEYS y 5. Y. WHITE 2,283,524

ADJUSTABLE ANTENNA DEVICE Filed Feb. 29, 1940 10 Sheets-Sheet s QM M ATTORNEYS May 19, 1942. 3. Y. WHITE 2,283,524

ADJUSTABLE ANTENNA DEVICE Filed Feb. 29, 1940 10 Sheets-Sheet 9 ADJUSTABLE ANTENNA DEVICE Filed F eb. 29, 1940 10 Sheets-Sheet 10 INVENTOR ATTORN EYS Patented May 19, 1942 UNITED STATES PATENT OFFICE ADJUSTQBIZ A IZZZNNA DEVICE Sidney Y. White, Wilmette, Ill.

Application February 29, 1940, Serial No. 321,381 14 Claims. (Cl. 250-33) This invention relates to antenna devices and more especially to antennas which are provided with means whereby their lengths may be adjusted in consonance with the tuning of resonant circuits with which they are associated in radio receivers or transmitters. While a broad band antenna may be designed to pick up or radiate radiant energy covering a broad band of frequencies, it has the disadvantage that it will also pick-up or radiate energy of undesired frequencies such as harmonics of its fundamental frequency. Also when used in connection with a radio receiver it contributes nothing to the selectivity of the first tuned circuit of the receiver. At ultra high frequencies, as for example in the range of 100 to 200 megacycles, it is easily possible to adjust the physical length of the antenna to a definite fraction of the wave length of the carrier frequency used, such as a quarter or half wave length, since its physical dimensions are so small. The antenna may thus be tuned so that it will act as the first selective circuit of a receiver, for example, and will thus respond to a desired carrier frequency and tend to reject undesired carriers of different frequencies which may have very high field strengths. To tune the antenna over a wide range of frequencies, it is necessary that the physical length of this type of antenna be varied in consonance with the frequency to which the receiver or transmitter is adjusted.

It is accordingly one object of this invention to provide in connection with radio receivers or transmitters having tuning means adjustable over a range of frequencies, means for adjusting the physical length of the antenna in consonance with the resonant frequency of the tuning means. when the term range of frequencies is hereafter referred to it will be understood to comprise an adjustment in the resonant frequency of greater than 5 per cent and that an adjustment of the antenna length within a degree of tolerance of 5 per cent is suflicient for the purpose of the present invention. In further pursuance of this object, a metal housing or enclosing cabinet, hereinafter referred to as a housing" is provided in which the receiver or transmitter, or both, are mounted. This housing also encloses a gearing which serves to mechanically connect the tuning means to an extensible antenna adapted to be retracted into the housing.

In the case of radio receivers or transmitters which are portable. such as in pack sets, it is often desirable to have the antenna completely retracted into the housing for facility in transportation. It is accordingly a further object of the invention to'provide an extensible antenna in the form of a flexible metallic band which is adapted to be rolled up on a reel mounted within the housing, and an adjustable stop device mechanically connected to the tuning device and which is adapted to limit the length of the antenna which is pulled out of the housing. In further pursuance of this feature, it is a further object of the invention to provide an extensible antenna in the form of a flexible, metallic ribbon of ar'ouate cross-section whereby it is stiff enough to be self-supporting when extended vertically upwards through the casing.

In installations where it is desirable to mount the antenna at a considerable distance from the receiver or transmitter as, for example, on shipboard, where it is desirable to mount it at the top of a mast, it is a still further object of the invention to provide remote control means for automatically adjusting the antenna length in consonance with the tuning means of the radio device. This remote control means preferably comprises a concentric transmission line in which the inner conductor transfers the radio frequency signaling energy between the antenna and the tunable radio device and also provides a suitable control voltage to a motor which serves to adjust the antenna length, the magnitude of this control voltage determining both the direction and extent of adjustment of the antenna length.

In accordance with a further object of the invention, the concentric transmission line is made up of two sections, the main section being of small diameter, for example /2 inch, while a short section mounted within the mast comprises a solid metallic rod of slightly less than 2 inches diameter which forms the center conductor and whose exposed length forms the antenna proper. The outer conductor of the short transmission line section comprises a metallic sleeve which engages the inner surface of the upper portion of the hollow mast and is slidable within the mast to expose different lengths of the center conductor, it being understood that only that portion of the center conductor which extends beyond the end of the outer adjustable sleeve functions as an antenna. By driving the sleeve from an electric motor through suitable reduction gearing, a powerful rigid structure is provided which is able to break away any coating of ice which may have formed on the mast. This arrangement also has the very practical and substantial advantage that since the mast and adjustable sleeve are at ground potential. no special precautions are necessary to insulate the motor or the reduction driving gearing for radio frequency potential.

According to a still further-object of the invention, the impedances of both sections of the though electrically it is a simple extension of the main section of small diameter.

Another object of the invention is to provide means for adjusting a device from a remote point by means of a reversible electric motor, the sense and extent of rotation of the motor being determined by means of a source of variable'voltage disposed at the remote point and connected to the motor through a relay which is associated with a Wheatstone bridge disposed near the device to be adjusted. In the preferred form of the invention, one arm of the bridge comprises a lamp filament whose resistance is a function of the applied voltage and another arm of the bridge is provided with a contact mechanically associated with the motor in such a manner as to restore the bridge balance upon effecting the desired adjustment of the device.

In installations where the total adjustment of the tuning means requires several revolutions of a tuning control knob, it is a further object of the invention to provide adial indicating device with a graduated scale in which the graduations are arranged in the form of a spiral having a plurality of turns and a shutter device which is automatically adjusted across the face of the scale in such a manner as to expose the graduations which indicate the adjusted position of the tuning means.

Other objects of the invention will become apparent to those skilled in the art as the description thereof proceeds. For a better understanding of the invention, however, reference is made to the following description taken in connection with the accompanying drawings, in which:

Fg. 1 is a side view partly in section taken through the line II of Fig. 3, of an adjustable antenna and associated tuning device embodying the invention;

Fig. 2 is a view similar to Fig. 1 but taken through the line 2-2 of Fig. 3;

Fig. 3 is a top plan view of the device of Fig. 1 with the cover of the enclosing housing removed;

Fig. 4 is a front view in section taken on the line 4-4 of Fig. 1, the enclosing housing being broken away and showing the arrangement of the tuning indicator scale and indicator;

Fig. 5 is a sectional view of the device of Fig. 1 taken on the line 55 of Fig. 1;

Fig. 6 is a side view of the device of Fig. 1 on a reduced scale showing the extensible antenna adjusted to position for maximum frequency of the tuning device;

Fig. 7 is a side view similar to Fig. 6, but showing the-antenna adjusted to position for minimum frequency of the tuning device;

' modified form of a portion of the gearing of Fig.

3 arranged to provide for a positive drive to the antenna reel; i

Fig. 9 is a fragmentary sectional view showing an extensible antenna embodying the invention mounted at the top of a mast;

Figs. 10 and 11 are front views of the antenna and mast shown in Fig. 9 with the antenna adjusted for positions-of minimum and maximum frequency respectively;

Figs. 12 and 13 are sectional views of the antenna structure of Fig. 9 taken on the lines I2--I2 and I3I3 thereof respectively;

Fig. 14 is a schematic view and circuit diagram of a remote control arrangement for adjusting the length of an antenna embodying the invention;

Fig. 15 is a sectional view of an antenna device embodying the invention and having two adjustable dipole antennas disposed at the top of the mast;

Fig. 16 is a sectional view taken through the line Iii-I6 of Fig. 15; and V Fig. 17 is a top plan view of the antenna device of Fig. 15 with the cover plate at the top of the mast removed.

Referring first to Figs. 1 to 5, an embodiment of the invention is shown as applied to a mobile or portable radio receiver or transmitter in which the receiver or transmitter of ultra-high frequencies (not shown) may be mounted in a metallic'housing I formed of cast aluminum. For the purpose of allowing access to the radio apparatus within the housing to authorized radio personnel, the end of housing I is provided with a door 2 (Fig. 2) hinged at 3 and provided at its lower end with a lock 4 adapted to be operated by a key (not shown) inserted through a key hole 5. For the purpose of supporting a flexible antenna 6 (Fig. 5), a reel I formed of suitable insulation material such as Bakelite is secured to a shaft 8 rotatably supported in the spaced supporting standards 9 and I0 secured to the bottom of housing I. For the purpose of suitably guiding the antenna 6 onto the reel I a hollow cylindrical casing II formed of the mating members I2 and I3 (Fig. 3) is provided about the reel 1, a suitable aperture I4 being provided in one side of the easing II for the entry of the antenna 6. In the illustrated example shown, the reel enclosing casing II is supported on a supporting bracket I5 (Fig. 5) whose lower end is secured by the screw shown to the supporting standard Ill. The antenna 6 is preferably formed of thin, flexible steel having a high tensile strength and is of arcuate cross-section when unwound from the reel as shown in Figs. 2 and 3, so that the portion unwound from the reel is sufllciently stiff to be selfsupporting in a vertical position. When wound upon the reel 1 in successive turns, the antenna ribbon flattens out, thus permitting a substantia length of antenna to be wound into a roll of small diameter.

For the purpose of permitting the antenna to be retracted from the housing I, the top I 6 of the latter is provided with an opening I l in which is seated a supporting frame I8 formed of good insulation material and adapted to support a block of compressed sponge rubber I8 through which the antenna 6 passes (Figs. 1 and 5) and which is adapted to wipe any water or dirt which may have collected on the antenna from the latter, as it enters the housing I. In order to prevent leakage of current from the antenna 6 to amass;

the housing i, the frame I. is provided with upper and lower apertures 23, 2| throlmh which the antenna passes, and which serveto provide adequate clearance spaces between the antenna and frame It. .As shown in Figs. 1 and 5, the upper end of antenna 6 is looped about one end of a link or handle 22 (Figs. 1 and which may be readily grasped and pulled by the operator toextract the desired'length of antenna'from the housing I. In order to conduct theradio frequency currents to or from the antenna a metallic spring contact 23 is provided-in engagement with the antenna, the contact 23 being secured by the screws 24 to a supporting bracket 25 formed of insulation material and secured to the inside of housing I by the screws 25 (Figs. 1 and 8) In order to limit the length of the antenna 6 which is extended from the casing to a length which is a function of the wave length of that to which the receiver or transmitter is resonant as, for example, one-quarter wave length. the shaft 8 has secured thereto a gear 21 which drives a gear 25, secured to a shaft 29, through the idler gear 30. Gear 28 carries a stop pin 3| (Figs. 1 and 5) which is adapted to engage and be arrested by a cooperating stop pin 32 carried by an arm 33 which is secured to a sector-shaped worm gear 34 supported for free rotation on the shaft 29. The latter shaft is supported in brackets 35:; and 35, the latter supporting also a shaft 35 carrying a worm 31 which gears with the gear 34. Near its forward end the shaft 35 is provided with a sprocket gear 38 having the projecting teeth 39 adapted to enter cooperating recesses 40 provided in a metal belt 4| passing around a sprocket pulley 42 whose periphery is provided with the spaced projecting teeth 43 (Fig. 5). Sprocket pulley 42 is secured to a tuning adjusting shaft 44 whose forward end is provided with a tuning knob 45 by the adjustment of which the tuning device of the receiver or transmitter may be set for a desired carrier frequency in a manner to be described.

As shown in Figs. 2 and 3, the tuning means comprises a concentric line 45 which cooperates electrically with its surrounding housing I to form a resonant circuit whose frequency is a function of the length of the line 45. To provide for this adjustment in length, the line 43 comprises a hollow outer metallic tube 41 provided at its rear end with an inner slidable extension 48 carrying a pin 49 adapted to enter a longitudinally arranged. slot in the tube 41 for the purpose of preventing rotation of the inner extension 45. The extension 45 is adapted for threaded engagement with a threaded screw 5] whose forward end passes through a supporting bracket 52 and carries a spur gear 53. Gear 53 is driven from the tuning control knob 45 through the

speed multiplying gears

54, 55 and 55 (Fig. 5), the gear 54 being secured to shaft 44 at the rear of sprocket gear 42 as shown in Fig. 2.

Since several revolutions of the tuning knob 45 are necessary to adjust the length of the concentric line 45, and the resonant frequency of the radio device over its full range of control. an extended graduated scale device is provided to indicate the adjusted position of the tuning means. This scale device comprises a thin disc 51 secured to shaft 44 (Figs. 3 and4), whose front face is provided with a series of graduations 53 arranged in spiral form and shown in Fig. 4 as extending through somewhat more than three revolutions of the disc 51. In order to indicate the graduation correspondingto the adjusted position of the tuning device comprising line 45, a movable shutter 53 is provided in front oi disc 51, this shutter being slidable in a pair of vertical guide members 33, 3| securedto the rear of a transversely extending partition plate 32 having a window opening 53 behind which the shutter 53 is movable. Shutter 55 is actuated by means of a cam 54 formed in a disc 55 secured to the shaft 44 slightly forward of the scale disc 51 (Figs. 2 and 3), a pin 55 secured to the shutter extending into the camway 54. Near its upper end the shutter 55 is provided with a transversely extending aperture 51 (Fig. 4) through which a limited portion only of the scale graduations 58 is visible, a suitable index mark 53 being provided on the shutter at the margin of the aperture 51.

In the illustrated example of the invention, see Figs. 1 and 3, the radio frequency currents are transmitted to the antenna contact spring 23 by means of the central conductor 39 of a concentric transmission line II and a condenser II which is connected to the tuning element 45. In the illustrated embodiment, the-- invention is shown as applied to a radio transmitter, the current being supplied to the concentric line 45 by the oscillator tube VTI. It will be understood that where the invention is embodied in a radio receiver, this tube would be the first radio frequency amplifier of the receiver.

In using the device, the radio operator who is authorized to tune the apparatus to a desired frequency opens the lock 4 and door 2 and then rotates the knob 45 until the scale reading of the graduations 53 corresponds to a desired transmission frequency. Rotation of knob 45 causes the rotation of screw shaft 51 'and the adjustment of the inner extension 48 (Fig. 2) so that the length of line 43 corresponds to the desired frequency. Rotation of the knob 45 is also trans-' mitted to the arm 33 which carries the stop pin 32 through the drive connections including sprocket pulley 42, belt 4|, pulley 33. worm gear 31 and sector gear 34, the amount of rotation of pin 32 being such that when this pin arrests the pin 3|, the physical length of the antenna 3 extending out of the housing I will be substantially equal to one-quarter of the desired wave length. The operator wishing to use the transmitter merely grasps the handle 22 on the antenna 3 and pulls upwardly until the rotatable stop pin 3i engages the stop pin 32 (Fig. l) which arrests further upward motion of the antenna and assures that the physical length of the antenna extending outside of the housing I is of the proper value, as for example, a quarter wave length., By reason of the interposition of the worm gear 34 and worm 31 in the gearing connections, the upward thrust of the antenna is not communicated to the tuning means and control knob 45 so that the tuning adjustment is not disturbed. It will be understood that the stop pin 32 is adjustable only through an angle of theorder of degrees, so that pin 32 will limit the length of antenna 5 extending outside of the housing I between a minimum .value as, for example, 12 inches which corresponds to the maximum frequency used, and a maximum value, such as 18 inches, which corresponds to the minimum frequency used. From the above it is apparent that the invention provides a ready means for 8 is pushed back within the housing I where the major part of it will be reeled up on the reel I, the handle 22 then lying substantially flat on the top of housing I, as shown in Fig. 1. As it passes through the sponge rubber pad I8, any water or dirt on the antenna will be automatically removed.

In Fig. 6 the tuning control is diagrammatically shown adjusted for its position of maximum frequency with the inner extension 48 in its extreme position to the right. The arm 33 is in a corresponding position and the stop pin 3| on gear 28 is in engagement with stop pin 82 of arm 83, thereby limiting the extension of antenna 6 to the length shown. 'In Fig. 7 the inner extension 48 has been adjusted to its extreme leftward position corresponding to the position of minimum frequency and arm 33 simultaneously adjusted into its corresponding position, as shown. Stop pin 3| is shown in engagement with stop pin 82, thereby limiting the extension of antenna 8 to its maximum length, as shown, in correspondence with the minimum frequency.

Fig. 8 shows a modificationof the invention similar to that shown in. Figs. 1 to 5, but in which the gear 28' is formed integral with the hub of sector gear 34, so that the antenna reel (not shown) on shaft 8 is positively driven in accordanec with the adjustment of the tuning control knob through the sector gear 34' and gears 28, 30' and 21. In this modification, the antenna is not entirely withdrawn into the housing I but has a minimum exposed length corresponding to the maximum frequency position of the tuning means. The adjustment of sector gear 34' over its full range then causes the maximum antenna length to be exposed corresponding to the minimum frequency adjustment of the tuning means. At each intermediate position, the length of the antenna is proportional to the wave length of the tuning means of the transmitter or receiver.

Another embodiment of the invention is shown in Figs. 9 to 13 in connection with the hollow mast I2 of a ship or other structure, means being provided for mounting the antenna at the top of the mast and for readily regulating its length. Secured to the top of the mast I2, as by the bolts I3, are a pair of spaced supporting plates 14, I formed of insulation material and which serve to support a cylindrical rod 16, upper and lower collars I1, 18 being secured to the rod I8 to support it and prevent its endwise mo- I tion. The rod I6 forms the central conductor of a concentric transmission line, the outer conductor of which comprises a metallic sleeve I9 which is slidable within the mast I2. At its upper end the sleeve I8 is closed by a cap 80 formed of insulation material and which has an easy sliding fit along the rod IS. The lower end of sleeve I9 is provided with a threaded cap 8| engaging a threaded shaft 82 to whose lower end the rotor of an electric motor 83, mounted within the mast I2, is connected. The sleeve 19 is shown provided with three longitudinally extending slots 84 through which the bolts 13 and portions of the plates 14, I5 extend and which cooperate with these members to prevent rotation of the sleeve I9. The sleeve I9 and rod I6 constitute a concentric transmission line having an impedance of substantially 36 ohms, the ratio between the inner diameter of sleeve I9 and the outer diameter of rod I6 being approximately 1.7 to 1, this ratio being exaggerated and illustrated in the drawings as approximately 3 to 1 for the purpose of clarity. Energy is interchanged between this transmission line and a much smaller transmission line comprising the outer conductor 85 and central conductor 88 the ratio of whose diameters is also 1.7 to 1, so that both transmission lines have the same impedance. As shown, the central conductor 88 of the smaller line is connected to rod I6 and a flared out connector 81 serves to connect the outer conductor 85 to the sleeve I9. The smaller transmission line comprising the outer conductor 85 may be extended downwardly through the mast for connection to a radio receiver or transmitter which is adapted to be operated at diflerent frequencies. A suitable aperture 88 (Figs. 9 and 13) is provided in the cap 8| for the free passage of the outer conductor of the smaller transmission line.

By means of the construction described, the physical length of the antenna" proper, which is that portion of rod I6 extending beyond the end of sleeve 19, may be readily made equal to onequarter of the wave length of the carrier wave being received or transmitted. Such a quarter wave antenna has an impedance at its base of approximately 36 ohms, so that its impedance matches that of the transmission lines and it may, therefore, be directly connected to them. Since the concentric transmission line has no standing wave on it, it may be made of any length, so that the length of its outer conductor (sleeve 19) may be readily varied to expose any desired length of its inner conductor (rod 16), the exposed length of the inner conductor forming the antenna proper. In Fig. 10 the parts are shown adjusted to a position where the maximum length of antenna is exposed, the sleeve "I5 being in its lowermost position. Fig. 11 shows the position of the parts wherein the sleeve I9 is in its uppermost position corresponding to a minimum length of the antenna proper. The arrangement described has the advantage of great strength and rigidity, sufilcient power being available from the motor to break away any ice which may form on the structure. Also, no special precautions for insulating the motor from the mast are required, since the movable parts are at ground potential, the movable sleeve I9 having a large surface area in contact with the mast I2 which is at ground potential.

The length of the antenna and control of the motor 83 of Fig. 9 is preferably provided from a point disposed near the foot of the mast or other remote point. A suitable control system for securing this object of the invention is shown schematically in Fig. 14, in which the tuning control knob 45 regulates the tuning of the transmitter by the adjustment of the length of concentric line 46 and also drives a rheostat control shaft 89 through a chain 90 and sprockets BI and 92. Shaft 89' carries a contact arm 93 which is rotatable along a resistor RI, the resistor RI being connected in series 1 with a fixed resistor R2 across a volt direct current source, resistors RI and R2 being so proportioned that a control voltage of from 80 to 110 volts may be applied to the central conductor 86 of the transmission line by the contact arm 93. In order to block the passage of radio frequency currents from the conductor 86 into the rheostat, a choke coil OH is connected between contact arm 93 and the conductor. The end of conductor 88 is connected to the tuned line 46 through a condenser CI and an adjustable contact as which may be adjusted along the hue II to a position depending on whether the apparatus is used for receiving or transmitting. The sense and amount of rotation of motor '3 depends on the direct current voltage impressed on the conductor I! by the rheostat arm 83, this voltage being a function of the length of line 46, and hence of the resonant frequency of the radio device.

Control of the motor 83 is effected by means of a Wheatstone bridge arrangement comprising the preferably equal resistors R3 and R4, a bridge arm comprising a fixed resistor R6 and an adjustable resistor R5, and a fourth bridge arm preferably comprising the carbon or tungsten filament of an electric lamp R1. Instead of a lamp filament, any suitable resistor whose re sistance varies inmccordance with the value of the current passing may be used. as the resistor B1. A center open polarized relay PR is connected across a diagonal of the bridge, the armature 95 of this rela normally standing in center position, as shown in Fig. 14, when the relay is unenergized. Armature 95 is connected to conductor 86 through a choke coil CH2 which prevents currents of radio frequency from entering the motor supply circuit from the transmission line. The upper and

lower relay contacts

96 and 91 are connected to energize the motor 83 through the separate field coils FCI and PC! which are so arranged as to cause rotation of V the motor in opposite direction. To balance the bridge and thus cause the motor to stop when the antenna has been adjusted to the proper length, a contact 98 is adjustable along the resistor R5, this contact being carried by a traveling nut 89 adjustable along a rotatable screw-threaded shaft III! which is driven by the motor 83 through any suitable speed reducing gearing device "II. The speed reducing gearing connected between the motor and the adjustable antenna is indicated at I22.

Assume the bridge to be balanced and the antenna length to be adjusted for a supply voltage 100'volts on the line 86 as determined by the position of tuning control knob 45 and a corresponding position of contact arm 93. To lengthen the antenna by a definite amount, rotation of tuning control knob! causes the wave length to be increased by the lengthening of line 46 and the simultaneous rotation of arm 93 into a position to apply 105 volts, for example, to the line 86. The increased current through the filament of lamp R1 causes a change in its resistance which unbalances the bridge in a certain direction. This causes a flow of current through the winding of relay PR in such direction as to move armature 95 into engagement with contact 96, for example. Thiscauses direct current to fiow from the transmission line to the motor 83 through the field coil FCI and rotation of the motor in such a direction as to lengthen the antenna. Rotation of the motor causes the nut 99 to adjust the contact 98 along the resistor R5 in such a direction as to restore the bridge balance for the new operating voltage, Upon the positioning of contact 98 in such bridge balancing position, current ceases to flow through the winding of relay PR whereupon its armature 95 returns to its normal central position, breaking the current supply of the motor which remains at rest with the antenna adjusted to the new wave length. If desired, the direct current voltage may now be removed from the transmission line until it is desired to again cludingtheresistorsRLR2 maybedisposedat any suitable-remote point as, for-example, at-

the foot of the mast I2.

In the embodiment of the invention shown in Figs, 15 to 17, two similar dipole antennas Al and A2 which are adjustable in length are disposed at the top of the hollow mast I2. For this D m a hollow elongated housing III of square cross-section is secured to the top of the mast, the upper end of the housing being closed by a cover cap Ill. Secured to the opposite sides of housing I by the screws ID! are the antenna supporting-collars llil and lll'l which are formed of insulation material and into which extend the hollow metallic tubes I", I" which together constitute a dipole antenna. The eflective length of this antenna is adjustable by means of a pair of adjustable extensions III, III which are slidable within the tubes I08 and I, each extension carrying a pin 2 which is slidable along a slot 2 provided in the tubes I28 and ill! to prevent the rotation of the extension members Ill and Hi. members II, III are tapped for engagement with the threaded ends of the rotatable shafts ill and 5 whose inner ends are secured to a hollow insulating sleeve lit by the pins I ii. A bevel gear 8 surrounds the sleeve H8 and is secured thereto by a pin 9, one side of the bevel gear also having a helical gear I20 secured thereto, as by a pin l2i. Gears 8; l2! are rotated by the electric motor 83' through the speed reducing gearing I02 and the bevel gear I22 which meshes with the gear H8. The helical gear I20 meshes with and drives a similar gear I23 which serves to operate the threaded shafts of the upper dipole antenna A2 (Fig. 17) only one, 5', of which is shown. It will be understood that the construction of antenna A2 It will be understood that the operation of motor 83' causes the antenna extensions II, III and H0, ill to be moved inwardly or outwardly by equal amounts according to the direction and extent of rotation of the motor 83'. It willalsobeunderstood that by operating the motor 83' bymeans of the remote control system disclosed in Fig. 14, the length of each antenna may be regulated in-consonance with the wave length to which the transmitter or receiver is adjusted. Means is thus provided by which one or more antenna circuits may be made resonant to any desired received or transmitted carrier frequency within a range of frequencies. By suitable spatial relationships between two or more elements of this nature, well known types of patterns can be obtained and retained through ranges of fre- The inner ends of the as to operate as a reflector of energy to the other so that only one need be connected to the transmission line. The lengths of the antennas,

however, will be simultaneously controlled to secure optimum response at each wave length.

I have described what I believe to be the best embodiments of my invention. I do not wish, however, to be confined to the embodiments shown; but what I desire to cover by Letters Patent is set forth in the appended claims.

I claim: 7 1. In combination, a radio device having a I tunable circuit, an adjustable antenna mounted at a point remote from said device, a concentric, line for interchanging energy between said antenna and said tunable circuit, a manual control means disposed at the radio device for tuning said circuit over a range of frequencies, a metallic shield adapted to receive the lower end of said antenna and insulated therefrom and means operated bysaid manual control means for causing the exposed length of the antenna extending beyond the metallic shield to vary in consonance with the resonant frequency of the the resonant frequency of the tunable circuit;

said driven means comprising an electric motor. gearing mechanically connecting said motor to the antenna and means whereby the adjustment of said control means causes the operation of the electric motor.

3. In combination, a concentric transmission line adapted for transferring ultra-high frequency energy, an antenna connected to said transmission line, and means for adjusting the physical length of the antenna in consonance with the frequency of the energy transferred, said means comprising a reversible motor, means for supplying a control voltage to the inner conductor of the transmission line at a point remote from the antenna, and means whereby the variation of said control voltage determines the amount and sense of rotation of said motor.

4. The combination as set forth, in claim 3 in which the inner conductor of the transmission line supplies energizing current to the motor.

5. Means for adjusting a device from a remote point comprising, in combination, a reversible motor, a Wheatstone bridge one of whose arms comprises an element whose resistance'is a function of the value of the current passing therethrough, a source of variable voltage con-,

nected to energize said bridge circuit and said motor, and means whereby a variation in the voltage of said source controls the sense and extent of rotation of the motor.

6. The combination as set forth/in claim 5, in which the last-named means comprises a single relay having the terminals of its winding con-- nected across a pair of conjugate neutral points of the bridge. v

7. In a device for adjusting the physical length of an antenna, the combination of a reversible motor, gearing connecting the antenna arms comprises an element, whose resistance is a function of the value of the current passing therethrough, a source of variable voltage located at a point remote from the antenna, a circuit tunable through a range of ultra-high frequencies a single transmission line arranged to interchange energy between said antenna and tunable circuit and to connect said voltage source to the Wheatstone bridge and motor, and means whereby a variation in the voltage of said source controls the sense and extent of rotation of the motor.

8. An antenna array comprising, in combination, a mast, a first dipole having two adjustable elements, a second dipole disposed at an angle of substantially 90 degrees to the first dipole and comprising two adjustable elements, insulation means for supporting said dipoles on said mast, and means for simultaneously adjusting the elements of said dipoles to cause the lengths of the dipoles to vary in consonance with the frequency of an axciting current and a transmilssion line connected to at least one of the dipo es.

9. An antenna device adapted for ultra-high frequency signaling currents comprising, in combination, a housing provided with an aperture, a thin, flexible metallic ribbon of arcuate cross-section supported in said housing and having an end thereof disposed in said aperture, a stop disposed in said housing and mechanically connected to said metallic ribbon, and a manually adjustable abutment member adapted to be secured at diflerent positions in the path of said stop to thereby automatically regulate the length of the portion of the metallic ribbon which may be drawn through said aperture to equal a predetermined fraction of the wave length of the current to be impressed thereon.

10. A radio device adapted for ultra-high frequency signaling currents comprising, in combination, a housing provided with an aperture, a thin, flexible metallic ribbon of arcuate crosssection supported in said housing and extending through said aperture, a circuit disposed in said housing comprising tuning means for tuning the circuit to a resonant frequency, a conductive connection between said circuit and said metallic ribbon, a stop disposed in said housing and mechanically connected to said metallic ribbon, a manually adjustable abutment member mechanically connected to said tuning means and adapted to be secured at different positions in the path of said stop to automatically regulate the length of the portion of the metallic ribbon which may be drawn through said aperture,

and means for preventing the impact caused by ing gearing mounted within the mast for simulto said motor, a Wheatstone bridge one of whose taneously adjusting the lengths of said dipoles t vary in consonance with the frequency of an exciting current.

12. An antenna array as set forth in claim 11 in which said adjusting means comprises an electric motor disposed within the tubular mast.

13. In a radio device adapted for ultra-high frequency signaling currents comprising,. in combination, a metallic housing having an aperture therein, a thin flexible metallic ribbon antennav of arcuate cross section passing through said aperture and adapted to have the major portion thereof retracted into saidhousing, a circuit disposed in said housing and having tuning means for adjusting its resonant frequency to a desired ultra-high frequency, means for interchanging energy between said metallic ribbon and said circuit, a mechanical stop device arranged to limit the maximum physical length of the portion of the metallic ribbon which may be withdrawn manually from said housing to correspond to a quarter wave length of the wave length to which said circuit is tuned and means mechanically connected to the tuning means arranged to preset said stop device to a desired position. I

14. An antenna device adapted for ultra-high frequency signaling currents comprising, in combination, a housing provided with an aperture, a thin flexible metallic ribbon supported in said housing and having an end thereof disposed in said aperture, a rotatable stop disposed in said housing and mechanically connected to said metallic ribbon, a rotatable abutment member mounted for rotation in the path of said stop and means for presetting said abutment member in any one of a plurality of positions so as to automatically regulate the length of the portion of the metallic ribbon which may be drawn through said aperture to equal a predetermined fraction of the wave length of the current to be impressed thereon.

SIDNEY Y. WHITE.