US2248762A - Directional antennae - Google Patents

Description

u y 1941. E. KRAMAR ETAL 2,248,762

4 DIRECTIONAL ANTENNAE Filed D60. 17, 1938 fife/riots Ernst ffram ar lelma zk 'Jokamzsan funnel) stares P1 nranoTIoNAL ANTENNAE Ernst Kramar and Helmuth Johannson, Berlin,

Germany, assignorsto C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a comp'any Application December 17, 1938, Serial No. 246,30

TE e l- I was A .In Germany December 20, 1937 2 Claims. (01.250 41) Directional antennae are known which are composed of individual antennae arranged either to receive or radiate only the vertically polarized waves, in order to do away with errors in direction finding. For suppressing the horizontal component a number of measures have been adopted which relate in part to the construction of the individual or component antennae and in part to the use of screenings. The best known antenna of this kind is the so-called Adcock antenna that comprises four vertical radiators which are arranged in the angles of a square and are in pairs interconnected crosswise. The operation of these antenna systems resides in the fact that a vertical antenna can receive or radiate such waves only as are vertically polarized, this antenna not responding to waves polarized horizontally. In order to avoid that the horizontal lines interconnecting the vertical antennae have a receiving or radiating efiect, whereby a powerful horizontal component would result, these lines in the case of the known arrangements are provided with a screening or are buried in the ground, in order to increase the screening efiect.

These antenna systems if properly installed operate to perfection. However, it has been found that in certain cases the desired result is not attained. Investigations have shown this to be attributable to the following reasons.

A vertical antenna, in order to receive only vertically polarized waves, must be clear of any neighbouring objects. For instance, if such antenna is mounted on the ground then it does not respond to the vertical component only but will be sensitive also to horizontally polarized waves. This disturbing influence is due to the fact that the electric constants of the ground are not the same in all directions. Every dissimilarity in the electric conductivity of the ground causes the electric lines of force to be in part inclined with respect to the earths surface, thus producing an asymmetric distribution of the lines of force. Therefore, the electric behaviour of a vertical antenna mounted on non-uniform ground is not the same as if such antenna were clear of any neighbouring objects or were stood on ideal ground.

In order to compensate for these drawbacks the invention proposes not to mount the antenna system directly on the ground, this usually being nonuniform, but to arrange it on a plane ground formed of uniform conductive material constituting a large-sized body. Also, in accreasing the conductivity thereof.

cordance with the invention, the said horizontalinterconnectors are embedded in this ground.

The invention thus provides an artificial ground that consists of a homogeneous material and which consequently is free from any dissimilarity. The electric lines of force extend at right angles to such artificial ground, whereby a symmetric distribution of the lines of force is obtained. A Vertical antenna erected on such ground is of the same action as if it were clear of any neighbouring parts. An antenna system of this kind thus will receive none but vertically polarized waves, the horizontal component being completely suppressed. By embedding the interconnectors in this ground the additional advantage is obtained that these are screened to perfection, also this screening being prevented in this way from radiating or receiving.

It may be mentioned here that wire network or the like has been arranged as a ground structure. This means, however, has proved not to present the required uniformity because these wire structures oxidize and thereby fail to the 01' the same conductivity throughout. Apart from this, such wire structures do not constitute a body large enough always to stand the influence of the transmitting oscillations, but are a means that may happen to share in these.

The novel antenna arrangement will be of special advantage if arranged above a receptacle in which an electrically conducting liquid is contained. For instance, a reservoir containing water will be suitable, such being the case especially if salts are dissolved in the water, thus in- Since the liquid may be considered a homogeneous or uniform body the surface of the water will act as a perfectly plane ground incapable of effecting field distortions.

One embodiment of the invention is represented in the accompanying drawing, in which:

Fig. 1 is a diagrammatic sectional elevation of this embodiment, while Fig. 2 is a diagrammatic plan view thereof.

and therefore need not be considered here. The arrangement is simplest if reservoir l is filled with water or another conductive liquid.

To effect the invention will be still simpler, if the earth below the antenna system is given an equal conductivity throughout. For instance, the earth may be continually impregnated with a liquid, such as water, for example. To such end a tubular system may be arranged below the antenna system, in order to supply the liquid in uniform distribution to the earth. The well known drainage tubes will be particularly suitable in this connection.

The invention is applicable to all those antenna systems which are to receive or radiate none but vertically polarized waves. Also there is no limitation as regards the wave length. It is merely necessary to accommodate the dimensions of the ground structure to the wave length employed in the respective case. The invention is of special advantage with short-wave and ultrashort wave systems, as in these cases the artificial ground may be comparatively small.

What is claimed is:

1. A directional antenna system, comprising component antennae, a plane ground common to said component antennae comprising homogeneous electrically conducting material arranged in a pit having lateral dimensions greater than that occupied by said component antennae and supporting said antennae and having such a depth as to give said ground a large mass to substantially prevent self-oscillation, and interconnectors for the component antennae, said interconnectors being embedded in the said homogeneous ground.

2. A directional antenna system, comprising component antennae, a plane ground supporting said antennae and comprising a reservoir containing an electrically conducting liquid.

ERNST KRAMAR. HELMUTH JOHANNSON.

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