US2156653A - Ultra short wave system - Google Patents

Description

May 2, 1939.

w. ILBERG ULTRA SHORT WAVE SYSTEM Filed May 22, 1936 lay;-

REFLECTOR INVENTOR WALDEMAR ILBERG ATTORNEY Patented May 2, 1939 UNITED STATES PATENT OFFICE ULTRA SHORT WAVE SYSTEM tion of Germany Application May 22,

1936, Serial No. 81,225

In Germany June 4, 1935 3 Claims.

The present invention relates to direction or bearing finding systems wherein communication is eiiected by means of beams having varying degrees of beam concentration.

In communication with electric wave beams, particularly where decimeter waves are employed, it may often be of advantage to operate during the running of a station consecutively with different beam concentrations. An example of this type of operation is the so-called search reception wherein a directional receiver expects a transmission coming from a transmitter of unknown position. In this case it is best to scan the territory with a receiver having wide beam angles until signals (even if only very weak ones at first) are heard. After the direction has thus been somewhat established, it is best then to go over to a concentrated beam fora distinct and distortionless reception of the transmitter signals. A similar case exists when a field is to be probed by means of a transmitter-receiver apparatus in order to find out whether back radiating or reflecting objects are located in the territory or area. In this case also, use is made first I of a broad beam and the direction of the back radiating object is then exactly determined with a concentrated beam.

For achieving this result, there have been proposed antenna arrangements wherein the beam concentration is varied by variation of the feeding of the individual transmitters.

In accordance with the present invention, use is made of a directional antenna whose beam angle is adjusted to vary the effectiveness of its individual radiators and/or its distance from a suitable reflector.

Figs. 1 and 2 show two practical embodiments of the invention, and Fig. 3 is a curve illustrating different radiation diagrams obtainable by a system such as Fig. 2.

Fig. 1 shows a Christmas tree antenna with the dipole pairs I, l'-8, 8'. Two switches Sam and SChz are provided for enabling the disconnection of the dipole pairs 3, 3 to 8, 8'. Hence the Christmas tree antenna can Work with two or eight dipole pairs, 1. e., two different degrees of beam concentration are obtainable. Of course, more switches can be provided so that the antenna can be operatively connected with from one to eight dipole pairs and thus eight difierent beam concentrations are assured. The transmitter or receiver is connected to the antenna at the end of a transmission line as indicated at S.

By this disconnecting of parts of the multiple antenna its total wave resistance changes, of

course; this might be, if necessary, compensated by disposing auxiliary impedances of suitable value in the feeder line.

A further embodiment of an antenna with various beam concentration would also be one wherein the relative position of a radiator with respect to a reflector is more or less varied.

Fig. 2 illustrates a further example of an antenna arrangement according to the invention. Here, the concentration of the beam is accomplished in one of the coordinates by a suitable reflector, in the other by means of a row of single dipoles. For obtaining lesser concentration in vertical directions, variation is accomplished by disconnecting dipoles, by means of switch Sch, for example, the concentration of the beam in horizontal direction is then lessened by a shifting of the dipole, or the dipole row out of the focal line of the reflector.

In Fig. 2, Sp is a cylindrical parabolic mirror or reflector. D1, D2 and D3 represent a row of dipoles disposed in the focal line. The arrangement as drawn has a definite beam concentration. If the same is to be lessened, dipole D2 is, for instance, used only and moved out of the focal line to position D2. The degrees of beam concentration accomplished by this movement are shown in Fig. 3. Beam B can be emitted or received with the angle 51, and beam B2 with the angle 52.

The embodiments herein cited do not, of course, cover by far the entire field of the invention. Thus, the cited examples can be modified, for example, by adjustment of any desired beam concentration between a circular diagram and the sharpest concentration possible.

What is claimed is:

1. In an antenna system, the combination with a reflector and a plurality of aerials located substantially at the focus of said reflector in a plane coincident with the axis of said reflector, and signaling means connected to said aerials, of means for disconnecting one or more of said aerials without interrupting the continuous reception of or transmission from the other aerials of said system, and means for moving the position of one or more of the remaining aerials in said plane.

2. A beam antenna system having, in combination, a plurality of dipole antennas located end to end substantially in the same straight line and in the focus of a reflector, high frequencytranslating apparatus coupled to said dipole antennas simultaneously, and means for disconnecting at least one of said dipole antennas from said apparatus without interrupting the continuous reception of or transmission from said system.

3. In an antenna system, a reflector, a plurality of aerials located substantially at the focus of 5 said reflector in a plane coincident with the axis of said reflector, translating apparatus coupled to said aerials through feed lines, and switching means serially arranged in one or more of said feed lines for disconnecting only certain of said aerials without interrupting the continued operation of the other aerials.

WALDEMAR ILBERG.

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