US2474242A - Adjustable antenna - Google Patents

Description

June 28, 1949.

Filed June 13, 1945 c. K. GIERINGER ADJUSTABLE ANTENNA 2 Sheets-Sheet 1 INVENTOR.

CARL K.G|ER|NGER BY v ATTORNEY June 28, 1949. c. KUGIERINGER 2,474,242

- ADJUSTABLE'ANTENNA v Filed June 15, 1945 2 Sheets-Sheet 2.

INVENTOR. C'ARL K. GIE RINGER ATTORNEY Patented June 28, 1949 UNITED STATES PATENT OFFICE ADJUSTABLE ANTENNA Carl K. Gieringcr, Long Branch, N. J.

Application June 13, 1945, Serial No. 599,296

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3'70 0. G. 757) 1 Claim.

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 antennas and more particularly to dipole antennas adjustable over a wide frequency range.

Dipole antennas are well known and understood in radio communication art and comprise a pair of metallic radiators whose length is in part determined by the wave length of the signals to be transmitted or received. To obtain maximum efficiency, the antenna length must be adjusted as different wave lengths are used. The design of presently used antennas renders it dinicult to adjust the antenna length quickly and easily.

It is, therefor, an object of this invention to provide an antenna that may be quickly and easily varied in length as the wave-length of the radio energy transmitted or received thereby is varied.

It is also an object of this invention to provide an antenna that may be varied over a wide frequency range.

It is also an object of this invention to provide an antenna that will be electrically matched to its transmission line for all positions of the antenna.

It is a further object of this invention to provide an antenna that may be remotely adjusted while in its erected position.

These and other objects are accomplished by the use of radiating elements having one end fixed and the other end free to move, and means operative upon the free end of the said element whereby the lengths of the elements may be equally and simultaneously varied from a remote point.

The scope of the invention will be pointed out and defined in the attached claim. An understanding of the invention will best be obtained, however, from the following description of two antenna arrangements, the said description to be read in connection with the accompanying drawings, in which Figure 1 is a perspective view of a preferred form of an antenna structure embodying the invention and connected to a transmission line.

Figure 2 is a perspective view of another form of an antenna structure connected to a transmission line.

Referring to Figure 1, the antenna comprises a flexible radiator l2, vertically supported from a pulley l4 and constituting an extension of the 5 inner conductor it of a coaxial transmission line 18, and a plurality of flexible radiators 20, constituting an extension of the outer conductor 22 of the line 18 folded back upon itself. An electrically conductive, spring supporting, wheel-like ring 24 is positioned coaxially about the upper periphery of the outer conductor 22. A short, upwardly extending non-conductive spring mount 26 is positioned at one point on the circumference of the ring 24, and is fixed thereto by any suitable means.

A plurality of fiat coiled springs 28 are radially disposed equidistantly about the cricumference of the ring 24, the inner ends of said springs being fixed thereto. Another spring 30, identical to the springs 28, is longitudinally positioned at the top of mount 26, the inner end of the spring 30 being fixed thereto by any suitable means.

The springs 28, 30 are constructed of spring steel or any other suitable resilient conductive material. They may be fixed to the ring 24 and the mount 26 by any conventional means, such as bolts.

To the outer end of each spring 28 there is affixed one end of a radiator 20 of a plurality of radiators 20. The radiators 20 may be aflixed to the springs 28 by any conventional means, such as rivets.

The other ends of the radiators 20 are fastened to equally spaced points on the outer circumference of an insulator member 32. The insulator member 32 comprises an insulating ring concentric with the outer conductor 22 and is slidably positionable thereabout. The insulator 32 is provided with suitable means whereby the ends of the radiators 20 may be fastened thereto, and is further provided with suitable means whereby a tension means, such as a rope 34, may be attached thereto.

Referring now to the aforementioned spring 30, one end of the radiator I2 is affixed by any suitable means to the outer end thereof. The other end of the radiator I2 is affixed to insulator 36.

The radiators i2, 20 are formed of thin flexible metal strips of good radiating characteristics. As will be hereinafter pointed out, they are sulficiently flexible so as to be readily coilable about the springs 28, 30. Electrical contact may be made between the conductor l6 and the radiator l2 by any well known means, a contact brush 38 positioned on the conductor I6 being shown here as illustrative of one method of making contact.

The rope 34 is fastened to the insulator 36 and passes upwardly over the pulley I4, then down- Wardly to the insulator 32, where it is fastened thereto, and thence to the hand of the operator. The pulley l4 and the line I8 may be supported by an antenna mast (not shown), or may be suspended from a tree limb or other suitable frame or support in the vicinity of the antenna.

The operation of the antenna system will now be described. Assume that the rope 34 is allowed to lie slack in the hand of the operator. The operation of the springs 28, 30 will wind the radiators 20, I2 to a predetermined minimum length. This minimum length determines the shortest wave length at which the antenna will operate most efiiciently. It will be understood that radiator element 20, since they are in common connection with ring 24, in effect behave as a single radiator which in combination with radiator l2 completes the dipole.

As has been heretofore stated, an antenna transmits and receives most efficiently when its length is matched to the wave length used. Thus, if the wave length that is transmitted or received is increased, the antenna will be most efficient if its length is increased.

The length of the antenna may be increased by causing a downward movement of the rope 34. A downward movement of the rope 34 will result in a downward movement of insulator 32 and in an upward movement of insulator 36, thus increasing the effective length of the radiator elements and I2 until the optimum operating length is obtained in accordance with the frequency. Similarly the antenna radiatin length may be decreased by removing the downward force on the rope 34, thus allowing the potential energy in the coiled springs 28, 38 to wind 2. portion of the radiator lengths.

The lower end of the rope 34 may be fixed to winding means such as a reel at the operator's station whereby Vernier adjustments of the rope movement may be obtained.

Many modifications of this system are possible and within the spirit of the invention as defined by the claim. For instance, the coiled springs might well be replaced by a revolvable cylinder arrangement, whereby the radiators might be wound thereabout when it is necessary to shorten them for operation on shorter wave lengths. Further, I have shown a rope as being the most simple means to use to move the radiators. Any other suitable means might be used equally well, and the use of a more rigid means would be desirable if horizontally polarized waves were to be transmitted.

There has thus been disclosed a simple and efficient system whereby an antenna may be accurately controlled over a wide frequency range from a remote point. The advantages of such a system are obvious. The antenna may be adjusted to cover a wide frequency range. The adjustment may be easily efiected without lowering the antenna, and may be accomplished from a remotely situated radio station. The antenna is light and may be compactly folded into a portable condition. It is easy to install and disassemble.

Referring now to Figure 2, the drawing shows another antenna arrangement. An antenna mast 48 is provided with a pair of coplanar pulleys 42, disposed one on either side of the mast near the top thereof, and toward the bottom thereof with a pair of parallel pulleys 44, coaxial with one another and disposed one on either side of the mast. The plane of the coplanar pulleys 42 lies generally normal to the planes of the parallel pulleys 44. Intermediate the said two pairs of pulleys 42, 44 is disposed a single pulley 46, positioned at the end of a short arm 48 that is fixed to the mast 40. A pair of coaxial pulleys 50 are suspended from the single pulley 46 by a rope 52, the free end thereof terminating near a radio set 54.

Parallel conductors 55 extending from a radio set 54 pass in sequence over pulleys 55, under pulleys 44, over pulleys 42, then under and over pulleys 68, to connect at a binding post 62 on mast 48, said post being located above the axis of coplanar pulleys 42 a distance equal to the diameter of spaced pulleys 68. The length of parallel conductors 55 up to the point of pulleys 42 serves as a transmission line while the folded over portion of the inductors from this point functions as a dipole radiator 58.

The spacing between the conductors in trans mission line 56 is such as to provide optimum radiation cancellation at the mean frequency in the operating range of the antenna.

The antenna 58 is held in tension by weights 84, one of said weights beingconnected to each spaced pulley 60 by flexible lines passing over pulleys 68. The pulleys 68 may be supported from secondary arms or masts (not shown) or from a natural object of the terrain. The antenna 58 is electrically isolated from the lines 68 by insulators 18, disposed in the lines 86 between the spaced pulleys 60 and the pulleys 68.

The device thus described is capable of eflicient operation over a wide frequency range. The antenna 58 is always matched electrically to the transmission line 56. If it is necessary that the length of the antenna be shortened in accordance with a shorter wave length, this shortening may be done by moving the free end of the rope 52 downward. The antenna ,will at all times be held taut by virtue of the weights 84. Similarly, if it is necessary to lengthen the antenna 58, this lengthening may be accomplished by removing the force on the rope 52, allowing the weights 64 to pull out the antenna to the desired length. The rope may be attached to a gear system (not shown) whereby accurate and delicate movements of the rope may be accomplished.

Many modifications and changes are possible and within the scope of the invention as defined in the attached claim. For example, the rope in each figure may be replaced by any suitable flexible means. Further, the pulleys might be supported by buttresses (not shown) positioned on the mast. The pulleys, of course, might be replaced by other direction mechanism, such as wire guides. Further, both of the devices here shown may readily be enclosed in dielectric shelters whereby the devices may be protected from the weather.

The device thus discloses a means whereby an antenna may be adjusted from a remote point. The device is simple in construction and may be readily assembled. Since the necessary fixtures are few in number and small in size, the device may be packed for shipment into a small kit. A wide frequency range is possible and may be easily achieved from a point remote from the antenna itself. For all positions of the antenna, the eifective load impedance that is offered to the line is a resistance equal to the characteristic impedance of the line.

What is claimed is:

An adjustable doublet antenna system comprising a coaxial transmission line, a first coiled spring, an antenna radiator element connected at one end to the outer end of said first coiled spring, means electrically connecting said first named spring to the inner conductor of the coaxial transmission line, a second coiled spring, at least one antenna radiator element connected at one end to the outer end of said second coiled spring, means electrically connecting the inner end of said second named spring to the outer conductor of the coaxial transmission line, nonconductive mounting means positioned adjacent the said transmission line and mechanically connected to the inner end of said first coiled spring, an annular insulating member coaxial with the said outer conductor, the said member including means whereby the free ends of the said second named radiator element may be attached thereto, and means connected to the free end of the first named radiator and to the said insulating member whereby the efiective length of the said radiators may be varied from a remote point.

CARL K. GIERINGER.

REFERENCES CITED The following referemoes are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,438,290 Beakes Dec. 12, 1922 1,860,128 Bethenod May 24, 1932 1,911,234 Meyer May 30, 1933 2,028,498 Clavier Jan. 21, 1936 2,036,456 Buschbeck Apr. '7, 1936 2253,1379 Kinn Aug. 19, 1941 FOREIGN PATENTS Number Country Date 464,769 Great Britain Apr. 23, 1937

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