Directional antenna array

Jan. 7, 1941. e. werndl 2,227,563

DIRECTIONAL ANTENNA ARRAY

Filed Aug. 8, 1939 2 Sheets-Sheet 1

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Jan. 7, 1941.

E. WERNDL

2,227,563

DIRECTIONAL ANTENNA ARRAY

Filed Aug. 8, 1939

Sheets-Sheet 2

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Patented Jan. 7, 1941

2,227,563

UNITED STATES PATENT OFFICE

2,227,563

DIRECTIONAL ANTENNA ARRAY

Ernst Werndl, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m.b. H., Berlin, Germany, a corporation of Germany

Application August 8, 1939, Serial No. 289,077 In Germany August 11,1938

Claims. (CI. 250—11)

This invention relates to directional antenna arrays and especially to a plurality of arrays which are separately rotated and simultaneously phased to maintain their combined pattern in 5 any desired direction.

In direction finders operating with loop or other antennas of small dimensions, owing to the dimensions of the antenna the receiving energy is limited and thus often insufficient for direction 10 finding at substantial distances. This drawback can be overcome by operating with a larger number of such receiving antennas. Eventually, still further advantages may hereby be obtained such as an improved characteristic of the entire sys15, tem, or an increased sharpness of the indication. In such cases, especially when operating on relatively short waves, it is material how the received energies are combined, since they are applied to a common receiver. While all antennas situated 20 side by side in the direction of the wave front have the same phase, antennas which are arranged in back of each other in the direction of the ray have phase displacements and have the same phase only when spaced at a distance equal to λ. 25 it is old to provide phase control means in the leads of the individual antenna structures by means of which the phase can be properly set and adapted to the respective operating conditions. However, all phase displacements change 30 if, in order to find a new direction, the antennas are each turned separately, although they remain parallel to one another.

The object of the present invention is to provide an arrangement in which the phases once 35 set for a certain direction of reception are maintained automatically substantially correct also for other directions of reception when turning the receiving antennas and whereby the influencing of the elevation angle and the width of 40 the characteristic can be uniformly assured in a simple manner.

The invention will be described by reference to the accompanying drawings in which Figure 1 is a schematic diagram of one embodiment of the 45 invention; Figure 2 is a perspective view of an element of the invention; and Figure 3 is a view partly in perspective of an arrangement of the invention.

There is shown schematically in Fig. 1 an array 50 of antennas al,· a2, a3, etc., having a directional pattern in one or two directions and connected with a common receiver E by means of shielded leads bi, b2, b3, etc., and across phase control means ci, c2, c3, etc. This may be done as is 55 known with the interposition of a frequency trans formation or any suitable type of phase shifter; for example, that disclosed in the copending application Serial No. 131,838, filed March 19, 1937, entitled “Apparatus for measuring phase angle.” Furthermore, a mechanical or electromechani- 5 cal drive through which all antennas remain parallel and are turned into the desired direction may be considered present as shown in Fig. 3, although not shown in Fig. 1, to avoid complexity.

Fig. 1 illustrates that, in the position of the 10 directional antennas represented by the solid Unp arrows, the antennas a2, a5, aB and a3, aB, aS respectively oscillate in different phases with respect to a wave from the direction Rl, whereas, for instance, the antennas α2, a7 and a5, a 10, etc., 15 operate in equal phase. However, in another case, for the direction R2, the antennas will have the position shown in dash lines and other phase conditions will prevail, i. e., the series al, a2, a3 then at, a5, aS and then a8, aB, alO have the ²⁰same phase as regards the individual antennas but phases of different values as regards the series. Hence, there exists a functional relationship between the individual phase angles and the respective angle of the direction. Moreover, this ²⁵condition will change when tuning to different wave lengths and further depends on the elevation angle of the wave beam.

The described functional dependence can be resolved in a purely mechanical fashion and in 30 a simple manner as will be described so that when taking bearings all phase relations will be controlled simultaneously with a change of direction. This can be achieved through a single setting for a change of direction and also for 35 tuning to different wave lengths and for adjusting to the elevation angle. The individual phase shifting means cl, c2, etc., to this end are so arranged according to Fig. 2 that in each of them the phase will be controlled by the vertical move- 40 ment of a rod 1 actuated as a function of the ordinates of an oblique plane d below them. According to Fig. 3, the phase shift means cl, c2, c3, etc., are disposed in the same plane adjacent one another and, for instance, in the same manner as 45 the antennas in the outer field which are assigned to said means. The control rods I, 2, 3, etc., rest on the oblique plane d. The degree of the inclination of this oblique plane, which can be set by swinging about a horizontal axis xx, 50 determines the differences of the individual phase angles, namely, in the direction of the obliquity of the plane, whilst phase shift means situated in the direction xx have respective phase equality. However, if the oblique plane d is turned 55

2,827,563 about a vertical axis yy synchronously with the antennas when taking bearing by means of any suitable like mechanism e or synchronized motors, then (at proper matching of the electrical and 5 mechancal values) the phases in the individual antenas just follow those laws which correspond to the maintenance of the correct conditions at each bearing angle position. The tuning to another wave length and the correction necessary 10 when changing the elevation angle take place likewise in common for all antennas by a simple change of the inclination of the oblique plane and remain also invariably correct for all bearing angles.

The mechanical structure is not limited to the example of construction shown. More especially, the oblique plane may be replaced by other guide devices which operate by individual action or automatically, or any desired mechanical hy20 draulic, or electromechanical transmission members may be interposed between such device and the individual phase shifting means. The invention not only relates to direction finders but can also be applied to the directed radiation of 25 waves.