US2008931A - Antenna - Google Patents

Description

July 23, A1935. c. scHULl-:R 2,008,931

ANTENNA Filed April 30, 1954 Patented July 23, 1935v UNITED y STATES PATENT OFFICEy International-Stacey Corporation, Columbus,

Ohio, a corporation of Chio Application April 30, 1934, Serial No. 723,214

7 Claims.

This invention relates to the art of radio broadcasting and transmission of electromagnetic waves through space by means of a radio tower or verticalantenna radiator; and more specifically to a novel high vertical radiator or antenna comprising a self-supporting tower structure insulated from a base and separated therefrom by a grounded condenser; as hereinafter described and claimed.

In the prior art, it has been proposed to eliminate radiation ground losses by surrounding. the lower end of an antenna by a conductive body connected with the source of transmission to reinforce the energy transmitted by mutual coupling; it has also been proposed to improve the electrical conductivity of the ground to avoid ground losses, both in short Wave and long wave radiation. The present invention is not to be confused with these prior proposals, although one of the achieved objects of the present invention is the reduction of ground loss energy. Other advantages and achieved objects include a vertical radiator that is substantially self-supporting without the use of guy4 wires; a vertical tower structure approximating theoretical maximum effectiveness of the height-wave length ratio; a composite apparatus that is simple in construction, takes relatively little space, and is efficient in wave transmission; a four-cornered tower structure having a highly conductive ground screen which functions as an element of a condenser which returns energy to the radiating system.

The preferred embodiment of the present lnvention comprehends a vertical antenna of the self -supporting type comprising a steel mast tower formed from structural steel members. Theoretical considerations of vertical radiators indicate that the maximum effectiveness is obtained when the height of the radiator is 5A, of the emitted wave length. Actual tests on a tower structure of the self-supporting type with a conventional ground system indicate that maximum effectiveness of the structure is not nearly as great as would be expected from these theoretical considerations and that there is no advantage gained by increasing the height beyond of an emitted wave length. The present invention reduces to a negligible amount the power loss'that occurs at the base of the tower structure and permits close approximation of full theoretical advantages of increased tower height.

An illustration of the invention is shown in the accompanying drawing, wherein:

Fig. 1 is a view in sectional elevation;

(Cl. Z50-33) Fig. 2 is a horizontal section taken along the line II-II of Fig. 1.

Referring to the drawing, the numeral I represents a tower formed of structural steel members and reinforcing struts and girders, providing a four-cornered tower with a broad base tapering to a narrow top. The tower proper rests on a metal framework 2 carrying a plurality of copper wires 3 forming a reticulated screen or ,conducting shield, the wires being soldered at all points of intersection with one another. This conducting shield functions also as the top plate of the condenser, as Will be hereinafter described, and is supported upon the four tower insulators 4, which insulators in turn rest upon a second shield, screen or framework 6, this framework B functioning both as a conductor and the bottom plate of the condenser. 'I 'he framework? 6, like the framework 2, is preferably in screen form with soldered intersecting wires of high conductivity; but both frameworks may` be of solid conducting material, if desired. The framework 6 is carried or supported on the preferably concrete foundation piers 5 set in the ground. Buried ground conductors are preferably provided, to which the metal framework 6 is connected at a multiplicity of points along its boundary by means of leads 1.

The elements 3 and tween them the insulators 4, the combination functioning as a, two plate condenser between the tower proper and the ground. The base of the tower covers considerable ground area (a 220 foot tower has legs separated 17 feet) and the lower part of the tower acts as one plate of an electrical condenser, the other plate being the earth. When the tower is operatedat a height greater than of an emitted wave length, the voltage at the tower base runs to quite high values and a considerable current flows in this condenser. High losses therefore result because of the resistance and poor dielectric properties of the ground which forms one plate of this condenser. The localized losses so produced are often'as much as one-half of the power input into the antenna.

By the present invention, however, the ground screen provides a-highly conductive path upon which the electrostatic lines of force from the lower part of the tower terminate, and this screen being placed slightly above the surface of the ground,'shields and prevents the intense electric field from existing at the surface of the ground.

6 thus have interposed be- The conventional ground system which may be either radial or a grid of wires is, -as previously stated, connected to the ground shield or screen at a multiplicity of points.

The elimination of these local base losses permits the use of a self-supporting tower as a vertical radiator in every case where a supported vertical wire would be satisfactory.

What is claimed is:

1. A transmitting antenna system comprising a rigid Vertical tower provided with four supporting corners at its base, foundation piers extending into the ground for supporting the tower, a condenser plate carried by the piers, insulator means resting on said condenser plate, a second condenser plate resting on said insulator means,

both of said condenser plates being located between said tower base and said foundation piers, and means grounding said first condenser plate.

2. A wave antenna structure mounted directly on the ground line including base supportingv means of non-radiating character for electromagnetic waves and extending above the ground line, a condenser mounted on said base supporting means, and a radiating antenna mounted on the condenser, the condenser being suitably grounded.

3. n combination, a Vertical antenna radiator directly mounted on a pair of conducting screens separated by insulator means.

4. A wave antenna tower comprising a plurality of upright members interconnected by rigid structural members, said tower being of pyramidal form with the lower base ends thereof insulated from the ground by insulators, and means below said insulators for reflecting energy normally lost and returning it to the tower.

5. In a radiating tower antenna, a base support, insulators mounted on said support, and a condenser formed by metallic members on the opposite ends of said insulators comprising a grounded electrically conducting metallic plate disposed on the ends of the insulators closer to the ground and a metallic tower structure disposed above said insulators.

6. In a radiating tower antenna, a base support, insulators mounted on said support, a condenser formed by two metallic members on opposite ends of said insulators above the ground line', means for grounding the one of said metallic'members closer to the ground, and a vertical self-supporting metallic tower mounted on said insulators and electrically connected with the second one of said metallic members.

7. In a radiating tower antenna, a base support, insulators mounted on said support, and a condenser formed by metallic members on the opposite ends of said insulators comprising a grounded electrically conducting metallic plate member disposed in a plane substantially perpendicular to the axis of said tower on the ends of the insulators closer to the ground and a metallic tower structure disposed above said in sulators.

CHARLES E. SCHULER.

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