US2269075A - Directive antenna system - Google Patents

Description

Jan. 6; 1942. R. BOERNER DIRECTIVE ANTENNA SYSTEM Filed Sept. 24, 1940 B llll llll I .II II Al I I I I K 3---- :l 4 I I lllll I I INVENTOR. #0004, 3 5/?67? ATTOR Patented Jan. 6, 1942 2,269,075 ,7 ANTENNA SYSTEM Rudolf Boerner, Berlin, Germany, ass ignor "to C. 1 Lorenz Aktiengesellschaft, Berlin, Germany, a

company I 1 Application September 24, 1949, Serial No. 358,065 In Germany-October 12,1939

For the directional intercommunication by high frequency radiation antenna combinations are necessary whose radiation characteristics are strongest within a certain angle which should be small as far as possible, whereas in all the other angles the directive characteristic should be zero. However, disturbing secondary maxima arise in addition to that maximum value. The number of such secondary maxima is the greater the larger the number of radiators constituting the respective antenna combination.

Methods are known by which such disturbing secondary radiations may be avoided. For instance, radiators may be arranged beside each other or in a plane in such a manner that their mutual distances are larger than M2, i being the wavelength, and further, that they are fed in accordance with a binomial coefficient law.

By this means the zero values are increased in.

number and the secondary maxima attenuated. The amplitudes of-these, however, do .not disappear completely. Such arrangement comprises reflecting dipoles located in the same height as the main dipoles. I.

In another prior arrangement the radiators are fed with cophasal currents which decrease in intensity in the direction from the mid-antenna toward the outer antennae. In this case the number and strength of the secondary maxima may be diminished by making the mutual distances of the antennae smaller than M It has been found that the secondary maxima which arise with an antenna combination can be avoided with the aid of a suitable auxiliary radiation. For this purpose an additional antenna combination or several such combinations are arranged to act as reflecting antenna systems which if fed at the proper phase, as by radiation, for instance, add to the efficiency of the antenna combination.

The invention described hereafter relates to arrangements of the latter type.

In the drawing, Figs. 1 to 8 are diagrams showing each an embodiment of the invention.

Arrangements as provided by the invention comprise a linear antenna system, that is, a rectilinear row of radiators A, and an auxiliary antenna system composed of radiators B. In the case of Figs. 1 and 2 the radiators B are pro.

vided on both sides of the row of radiators A,

whereas Figs. 3 and 4 show them arranged on only. one side thereof, the other side being occupied by a plane reflector C, as earth, for in-- stance. The radiators B are not located beside the radiators A but are offset with respect to these, thus being arranged in positions that correspond to the gaps between the radiators A. Furthermore, the radiators B are preferably arranged in groups on the circumference of circles which have the radiators A as centre point and whose radius is 1'=0.27 and they are likewise arranged to form a rectilinear row.

Antenna combinations of this construction have a directional effect of fairly constant sharpness and act greatly to suppress the secondary maxima of the radiation characteristics produced by the usual systems comprising radiators disposed in a rectilinear row, and hence can be employed wherever these systems are used, even if these are unsuitable on account of unduly high secondary maxima arising in them.

A good efilciency, better than that of the ordinary systems by values up to 20%, is obtained Also, systems as provided by the invention may be located above each other so as to compose a structure of the 'kind represented in Figs. 5 or 6. This structure comprises dipoles arranged in planes and produces in the two planes of polarization a directive beam free from secondary maxima. One of the reflecting dipole planes may be replaced by an arrangement having a reflecting surface spaced from the midplane by a distance which preferably equals 0.2 to 0.27)., a unilateral directive characteristic free from secondary radiation being obtained in this way.

Furthermore, as shown in Figs. 7 and 8, in the case of a symmetric arrangement a reflect- 40 mg surface D, such as earth, may be located in theplane of symmetry thereof, part of the antenna arrangement thus being replaced by its mirror reflection. The arrangement so obtained is likewise free from secondary radiation and may be useful in connection with broadcast an radiators, and the auxiliary radiators being associated in separate groups with respective ones of the main radiators, the radiators of such groups each being arranged on the circumference of circles having the associated main radiator as a centre point said auxiliary radiators being arranged out of alignment with a line through the associated main radiator normal to said rectilinear rows.

2. An antenna system according to claim 1, wherein the radius of said circles is equal to 0.2m, X being the wavelength.

3. An antenna system comprising a first rectilinear row of main radiators, a second rectilinear row of auxiliary radiators, this second row being arranged on one side of the row of main radia tors, and means defining a reflecting surface located on the other side of said first row, the auxiliary radiators being associated in groups of at least two with individual main radiators, such groups each being arranged on the circumference of circles having its associated main radiator as a centre point.

4. An antenna system having a rectilinear row of main radiators and a rectilinear row of auxiliary radiators which extends along a line parallel to the row of main radiators, the auxiliary radiators being associated in separate groups with respective ones of the main radiators, each such group comprising two of the auxiliary radiators these two radiators forming with their associated main radiator as vertex angle of 90

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