US1694135A - Antenna for electric wave transmission - Google Patents

Description

Dec. 4, 1928.

1,694,135 A. MEISSNER ANTENNA FOR ELECTRIC. WAVE TRANSMISSION Filed July 15, 1925 Zlwwqntoc fllexand'erjyzsmer m W W $1M Patented Dec. 4, 1928.

UNITED STATES 1,694,135 PATENT OFFICE.

ALEXANDER MEISSNER, OF BERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT FUR DRAHTLOSE TELEGRAPHIE M. B. H., OF BERLIN, GERMANY, A CORPORATION OF GERMANY.

ANTENNA FOB ELECTRIC WAVE TRANSMISSION.

Application filed July:15,1925, Serial No. 43,683, and in Germany July 25, 1924.

An antenna for electric wave transmission through space often consists of a high vertical aerial which is'caused to oscillate at such a wave len th that the total length of the antenna is a out three-quarters of the length of the transmitting wave or else is the multiple of the whole wave length plus one-quarter of the same. Where the antenna oscillates under these conditions, the lower portion thereof which corresponds to about one-' quarter of the wave length above the ground connection does not contribute any substantial portion of the total radiation from the antenna but, on the contrary, the energy issuing therefrom passes to the ground, thereby resulting in ground losses.

The object of the present invention there- 'fore is to eliminate such ground losses. The

means which I provide to attain this object consists in surrounding the lower end of the antenna by a conductive body, preferably in the form of a system of parallel vertical wires forming a screen of the type known as the Faraday cage. This screen is connected with the source of transmission so that the radiation which issues from the lower portion of the antenna is intercepted by the screen and is thereby'absorbed and restored to the transmitting apparatus without substantial losses being incurred.

Referrin to the accompanying drawing, the figure thereon illustrates the schematically preferred form of my invention. In accordance with the present invention, in this and the dotted line running from the point A through B to the base line at C illustrates the relation of the length of the transmitted wave to that of the antenna itself. The portion AB ofthe antenna, as will be understood, is the part thereof which is intended to furnish the active radiation while the portion B-C is employed for the exciting of the antenna as a whole. This portion, however, is the 0 portion which is substantially one-quarter of the wave length that occasions the losses above mentioned. The series of vertical lines indicated by R constitutes a reflecting screen preferably, as there shown, consisting of a circular series of vertical conducting wires which are substantially equal in length to onequarter of the wave length transmitted or substantially one-third of the height of the antenna. This conductive screen R is coufigure the line AC represents the antenna,

pled' to the transmitting apparatus in any suitable way apparent to those skilled in the art.

The illustration represents diagrammaticall the simplest manner in which this may be one, which is by coupling. The Vertical wires of the shield R are grounded, as is the antenna. Since the wires are of the length specified they are tuned, and constitute not merely a shield, but rather a series of tuned oscillators which are coupled to the lower part of the antenna. Because of the mutual coupling of the circuits the energy attempted to be radiated in the part BC of the antenna is induced back into it again.' The action is much like that obtained with reflecting conductors, but differs from reflection in that the phase relations, and therefore the spacing of the conductors from the antenna, is of no direct consequence. Of course, the conductors R cannot be located too remotely from the antenna because otherwise the energy will radiate, and will not be recoverable efficiently.

It will therefore be apparent that since the conductive screen R surrounds the lower portion of the antenna, it will absorb the radiation from a corresponding portion of the antenna which radiation will then be coupled back to the source of transmission and reinforce the same so that it will add to the energy transmitted from the upper or active portion of the antenna;

It is to be understood that the aerial need not necessarily be three-quarters of a wave in length, for my invention is applicable to any aerial which includes a useful radiating portion, and another portion not useful for radiation. r

In the claims which follow, I shall by the term electromagnetically coupled mean that the coupling is by means of an electromagnetic wave. The energy transfer probably takes place by means of both the magnetic and the electric components, but I do not wish to be restricted to this requirement, but merely wish to differentiate from a direct conductive coupling, or a close magnetic coupling by means of transformer coils. By the term electrical length I mean the equivalent length if the conductor were a simple linear one. Thus, if the conductor in question is lengthened or shortened or tuned by any means, then the length is to be considered that length to which it is tuned.

What I claim and desire to protect by Letters Patent is: i

1. An antenna for electric wave transmission through space, comprising an aerial conductor, and a conductive body located adjacent only the lower portion thereof and having' a height equal to substantially one-third of the height of said aerial, said conductive .body being coupled with the aerial to reinforce the energy transmitted therefrom.

2. An antenna for electric wave transmission through space, comprising an aerial conductor, and a conductive screen surrounding only the lower portion of the same, said screen being adapted to absorb the radiation from the adjacent lower portion of the aerial and reiinforce the energy which is being transmitte 3. An antenna for electric wave transmission through space, comprising an aerial conductor having a length substantially equal'to three-quarters of the wave length to be trans-v 5. In combination, means to radiate a wave including an aerial whose length is anodd number of quarter lengths of the wave, and a screen a lesser odd number of quarter waves in length positioned closely to only a portion of the aerial and energized thereb 6. In combination, means to r iate a wave including a grounded antenna whose length is an oddnumberofquarterlengths ofthewave and a grounded screen a lesser odd number of quarter waves in length placedadjacent to, and energized by energy radiated from, only a portion of the antenna.

7. In combination, means to radiate a wave including an aerial whose length is an odd number of quarter lengths of the wave, and a screen a lesser number of quarter waves in length electromagnetically coupled to only a portion of said aerial.

8. In combination, means to radiate a wave including an aerial whose length is an odd number of quarter lengths of the wave, and a screen a quarter wave in length electromagnetically coupled to the lower portion only of said aerial.

9. In combination, means to radiate a wave including an aerial whoseelectrical length is an odd number of quarter lengths ofthe wave to be radiated, and a radiation reventing screen, the total electrical length 0 which is a lesser number of quarter waves, coupled to said aerial.

Signed at Berlin, Germany, this 23rd day of June, 1925.

ALEXANDER MEISSNER.

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