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Publication numberUS2342721 A
Publication typeGrant
Publication dateFeb 29, 1944
Filing dateOct 10, 1941
Priority dateJan 20, 1940
Publication numberUS 2342721 A, US 2342721A, US-A-2342721, US2342721 A, US2342721A
InventorsRudolf Boerner
Original AssigneeRudolf Boerner
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Parabolic reflector
US 2342721 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Feb. 29, 1944. Y BOERNER 2,342,721

PARABOLIC REFLECTOR Filed 0G12. 10, 1941 /n venl'or: I

Patented Feb. ze, 1944 UNITED PARABOLIC REFLECTOR Rudolf Boerner, Berlin, Germany; vested in the Alien Property Custodian Application Qctober 10, 1941, Serial No. 414,479 In Germany January 20, 1940 (Cl. Z50-11) 3 Claims.

This invention relates to the directional transmission of intelligence and is more particularly concerned with arrangements of .the kind having a parabolic reector and a radiator in the focus thereof.l

According to the invention a convex mirror, that may be of parabolic or hyperbolic shape or may be of the globular, cylindrical or any similar type, is disposed in front of the radiator arranged in the focus, as will be understood from the following description and the acccnipanying` drawing,l in which Fig. 1 is a diagrammatic sectional View of a prior arrangement, Fig. lo is a diagrammatic sectional View showing one embodiment of the invention, Fig. 2 is a graph which illustrates radiation conditions, Fig. 3 is a diagrammatic sectional view of an arrangement similar to that shown in Fig. 1b, Fig. 4a is a diagrammatic sectional View illustrating an improvement upon the arrangement shown in Fig. 1b, Fig. 4b` is a diagram of the radiation pattern produced by the arrangement according to Fig. 4a.

In many cases, as when transmitting secret communications, the radiation-collecting effect should as far as possible be small, that is to say, should be quasi optical, in order on the one hand to reduce the listening range and on the other hand to enable the use of small sending power. The customary reflectors, being somewhat large in depth have a great collecting effect. Also, the use of such large reflectors meets with difficulties which for economical reasons make it desirable to restrict the collecting effect.

In prior arrangements the direct radiation in the case of parabolic reiiectors is either collected with the aid of a separate wave channel or is directed against the reflector in order to underso total reflection.

For instance, as shown in Fig. 1a,a sof-called calotte A, formed as a concave mirror of semiglobular or other suitable shape, is arranged to utilize the direct radiation in a manner to light up the reflector B and thereby to prevent the direct rays and the reflected rays from interfering outside the reflector. A calotte so arranged does not improve the directivity rand is suitable only in the case of reflectors having a large focal distance and a small depth. In the case of all the other reflectors the efliciency is impaired in the mid-zone by a so-called shading eifect due to the screening property of the calotte A.

The novel system shown in Fig. 1b has a refleeting calotte formed as a sort of convex opti cal mirror C by which the direct rays from a radiator S, located in the focus of reflector B, are guided in a special manner. In fact, the rays .are reflected by mirror C and then by reflector B so that the rays outgoing from the reflector are not parallel to its axis but converge or run toward it. As a result, the directivity of the radiation characteristic is increased by values up to While the detrimental shading effect of concave mirrors, such as mirror A, Fig. la, is obviated.

Another advantage due to mirror C is that the l secondary maxima arising in the case of higher maxima of reflection are reduced, as can be seen in Fig. 2.

Instead of one radiator S a number of radiators or groups thereof may be provided. For instance, Fig. 3 shows two radiators Sl, S2.. F denotes the focus of reflector B.

As shown in Fig. 4a an additional radiator S may be arranged within mirror C in order to produce an additional directive beam. This is not possible in prior devices.

The latter arrangement is particularly suitable for producing radiation patterns to be followed by ships, the broad directional beam serving to give a presignal.

What is claimed is:

1. A directional wave transmitter comprising a concave parabolic reflector, a source of radio frequency energy located at the reiiector focus, the arrangement being such that Waves radiating from the source will be reflected in parallel beams, a shield located on the reflector axis beyond the focus in position to intercept outwardly directed waves from said source, and means for projecting a substantial portion of said intercepted energy into the axial zone beyond saidv in claim 1, in which the reflector extends axially beyond the mirror surface.

3'. An arrangement according to claim 1, wherein the said convex mirror surface is a parabolic reector.


Referenced by
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US2458885 *Dec 15, 1944Jan 11, 1949Bell Telephone Labor IncDirective antenna system
US2471284 *May 25, 1945May 24, 1949Bell Telephone Labor IncDirective antenna system
US2480143 *Sep 11, 1946Aug 30, 1949Standard Telephones Cables LtdDirective antenna system
US2483575 *Jul 26, 1944Oct 4, 1949Bell Telephone Labor IncDirectional microwave antenna
US2530079 *Apr 3, 1945Nov 14, 1950Riblet Henry JDirective antenna system
US2531455 *Dec 7, 1942Nov 28, 1950Sperry CorpDirective antenna structure
US2542844 *Aug 14, 1943Feb 20, 1951Bell Telephone Labor IncMicrowave directive antenna
US2671854 *Sep 6, 1945Mar 9, 1954Julius HalpernConical scanning antenna
US2689304 *Sep 16, 1949Sep 14, 1954Fairchild Engine & AirplaneScanning device
US2755374 *Jun 26, 1952Jul 17, 1956Ott WalterReflecting system
US2759182 *Mar 24, 1945Aug 14, 1956Bell Telephone Labor IncDirective antenna systems
US2831187 *Jun 23, 1945Apr 15, 1958James R AtkinsonRadio direction finding system
US2942264 *Mar 31, 1958Jun 21, 1960Ryan Aeronautical CoCoaxial antenna
US2942265 *Mar 31, 1958Jun 21, 1960Ryan Aeronautical CoEnclosed coaxial antenna
US2976535 *Mar 24, 1949Mar 21, 1961Bell Telephone Labor IncCosecant squared antenna-reflector systems
US3045239 *Dec 14, 1949Jul 17, 1962Westinghouse Electric CorpParabolic feed system
US3133284 *Mar 2, 1959May 12, 1964Rca CorpParaboloidal antenna with compensating elements to reduce back radiation into feed
US3209361 *Jan 14, 1963Sep 28, 1965Webb James ECassegrainian antenna subreflector flange for suppressing ground noise
US3218643 *Mar 1, 1961Nov 16, 1965Peter W HannanDouble-reflector antenna with critical dimensioning to achieve minimum aperture blocking
US3231892 *Jun 26, 1962Jan 25, 1966Philco CorpAntenna feed system simultaneously operable at two frequencies utilizing polarization independent frequency selective intermediate reflector
US3231893 *Oct 5, 1961Jan 25, 1966Bell Telephone Labor IncCassegrainian antenna with aperture blocking compensation
US3826911 *Jul 2, 1973Jul 30, 1974Raytheon CoCatoptric lens arrangement
US3965455 *Apr 25, 1974Jun 22, 1976The United States Of America As Represented By The Secretary Of The NavyFocused arc beam transducer-reflector
US5003321 *Sep 9, 1985Mar 26, 1991Sts Enterprises, Inc.Dual frequency feed
U.S. Classification343/838
International ClassificationF21V7/04
Cooperative ClassificationF21V7/04
European ClassificationF21V7/04