US 2063303 A
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Dec. 3, 1936. J, EVANS 2,063,303
ANTENNA Filed April 28 1934 7'0 TRRNSMI'I'TER INVENTOR:
Joh n E'vans Patented Dec. 8, 1936 UNITED STATES ANTENNA John Evans, Riverside, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application April 28, 1934, Serial No. 722,837
10 Claims This invention relates to antennas and more particularly to a device of that class in which short-wave radio frequency energy may be transmitted or collected.
'5 In certain instances it is desirable that the radiant energy be propagated into space from a point of rather high elevation and considerablyremoved from the transmitting apparatus. In order. that the transmission line intercon- 10 necting the transmitter and the radiating antenna shall be of such construction as to minimize the energy losses therein, I have evolved a means suitable for this purpose which has many advantages, including those of simplicity,
15 low cost of installation, and low upkeep cost.
Accordingly, it is an object of my invention to provide an antenna system in whichthe energy radiating or collecting element thereof is located at a considerable height above ground while the 20 radio apparatus may be located near the ground.
Another object of my invention is to provide a supporting structure for a transmitting or receiving antenna which has sufiicient strength and durability to make it advantageous over 25 other forms of antenna structure.
Another object of my invention is to so connect a transmitting apparatus with the radiating portion of an antenna system as to minimize the attenuation of signals transmitted.
30 The novel features considered characteristic of my invention are set forth with particularity in the appended claims. The invention in its entirety, however, both as to its organization and its method of operation, together with addi- 35 tional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the single figure of the accompanying drawing.
40 It is now well known that in the transmission of, intelligence by means of ultra short-wave and quasi-optical radio frequencies it is highly advantageous that the actual radiator should be of suflicient height above the earths surface so 5 that the emitted signals shall not be tangential thereto except outside the range of reception of such signals. Going quite contrary to the generally accepted practice, I have found that very satisfactory results may be obtained by 50 mounting the radiating portion of my antenna system at the top of a metal pole and coaxial therewith. Such a radiator I have indicated at H as having a length for optimum results.
or half the length of the Wave to be propagated. The antenna pole l2 may be constructed of sections of metal pipe which may or may not be nonferrous. The pole may be held erect in any suitable manner as by being partly sunk in the 5 ground, or by means of hemp or non-metallic guy ropes, not shown. No insulation is necessary between the radiating portion II, the pole l2 and ground. It is desirable, however, that the radiator ll be at least five wave-lengths above the ground or grounded support of the pole so as to minimize distortion of the signals, and also in order that the feeder system l3. may be sufllciently spaced from the ground to avoid phase cancellation.
In order to transfer the signalling energy from the transmitter to the radiator ll without dissipation thereof to ground and also without permitting the pole 12 to become a radiator, I have provided a structure which includes a wire or metallic strip l3 disposed parallel to and insulated from thepole I2. The conductor I3 terminates on a level with the bottom of the radiator H, but is not connected thereto. It passes through a number of insulators l4 and may be kept taut by means of a. weight l5 attached to its lower end. The conductors l9, which are in the output circuit of the transmitter, connect at points l6 and I1 respectively with the metallic pole I2 and with the conductor IS. The connections 16 and I1 are made as nearly as possible on the same level.
Interposed between the pole l2 and the conductor l3 at a suitable point below the connecting points l6 and I1 I make an electrical connection which may, if desired, include an ammeter A, and preferably a hot-wire instrument of this type. It is essential that this connection between the pole l2 and the conductor l3 be made so that the effective length of the .conductor portion a from the connecting point I! to the electrical center of the ammeter shall be and the same effective length shall exist along the pole portion b from the electrical center of the ammeter up to the connecting point Hi. The ammeter A serves to locate its own position 50 When the ammeter A shows a maximum reading it will be understood that the section a of the conductor I3 and b or the pole I! provide an effective insulation of the structure above the feeders with respect to ground and. for the particular radio frequency to which the system is tuned.
It will be apparent to those skilled in the art that the portion of the structure above and including the feeders 19 from the radio transmitter constitute an electrically symmetrical and self-neutralizing part of the system, and that a very high percentage of the output energy from the transmitter is thereby transferred to the portion. 1 I, from which it is radiated.
In certain instances the radiator l I may not be I ta'nt from the ground level, and a conductive loop of sufficient length to produce a voltage maxiline from the transmitter to the antenna proper. Condensers are preferable to loading coils because they may be adjusted while the signal strength is being observed on the ammeter, A.
The advantages to be gained by the very-sim-' ple structural arrangement of my antennasystem will readily appear to those skilled in the art. This disclosure will also suggest modifications of my invention which, however, would not be a departure from the spiritand scope thereof. 'Ihe'applicability of my antenna system to radio reception, as well as to transmission; is also apassess. The particular 'embodimentshownis, therefore, to be understood as merely an example. "Acc drding ly, I do not intend to be limited to the particular structural details herein described; but only as necessitated by the p'fior art and by the spirit of the appended claims.
7 I claim as my invention:
1. A metallic antenna pole electrically grounded at its 'base, in combination with means for reneen g'an upper portion of said pole radiative and the remaining portion thereof non-radiative, means for impressing signalling energy upon said pole "and contraphasally upon thefirst said means, and means for effectively'preventing the dissipation to ground of signalling e'nergy impressed upon said pole, the last said meansconjstituting an electrically conductive path of substantiallya halfwave length at the frequency of said signalling energy along portions of the first said means and of said pole, respectively, and including'acurrent responsive device interconnecting said portions. 2 :The invention set forth in claim 1 in which the'radiative portion of said pole is of approximately half the lengthy of the radio frequency wave to be propagated; v
3. The invention set forth in claim 1 in which the means for rendering different portions of .said pole radiative and non-radiative, respectively, is constituted by a single conductor disposed substantially parallel to and along one side of said pole and approximately coextensive with the non-radiating portion. 7 4. In combination with a radio transmitten -a substantially vertically disposed metallic antenna pole electrically grounded at its base, means extending substantially parallel to said pole for effectively cancelling the radiating effect except from an upper portion thereof which isof substantially half the length of one' of the'waves to be transmitted, separate connections from one point on said means and from anotheripoint of corresponding height on said pole, both being included in the output circuit of said transmitter, and means interconnecting said pole and the first said means such that a voltage loop is'established signalling energy,
thereat for preventing the dissipation of radio frequency energy to ground.
5. An antenna system having a space-energy transfer element of effectively a half-wave length in respect to the signalling frequency for which it is intended, a metallic supporting pole for said transfer element, a conductor disposed parallel to and insulated from said pole, a two-wire transmission circuit connecting a given radio apparatus with said pole and with said parallel-disposed conductor at points substantially equidiso'feffectively a half-wave length, said loop including portions of said pole and of said paralleldisposed conductor extending downwardly from "said points of connection with said transmission pole receives its energy, and an electrical connection between said pole and said conductor at a point substantially one quarter wave-length removed from points on said conductor and on said pole, respectively, whereon signalling energy is impressed.
9. An antenna system comprising an upright metallic pole the base of which is electrically grounded with respect to stray and transient energy, in combination with a conductor disposed parallel to and along one side of said pole for a distance at least greater than a quarter wave length of signalling energy of a frequency at which said system is intended to be operated, means for establishing aconductive path between 'a point on said conductor and said pole, means for establishing a potential point in said conductive path which effectively prevents the dissipation of said energy to ground, a source of energy of the desired frequency, and means coupling said source to the nodal current points of said conductive path.
10. An antenna system comprising an upright metallic pole the base of which is electrically grounded with respect to stray and transient energy, while being effectively insulated from ground with respect to signalling energy of a given frequency, in combination with means including a conductor disposed parallel to and along one side of said pole for a distance at least greater than a quarter wave length of said sig 'nalling energy said means being such that the opposed portion of said pole is renderedno'nradiative of said energy while a portion of said pole. extending above the extreme height of said conductor is rendered radiative, a junction between said conductor and said pole, means for establishing at the said junction a potential node with respect to ground, a source of oscillatory and means coupling said source to said pole and conductor at current nodal points.