US2018273A

US2018273A - Short wave reflector

Info

Publication number: US2018273A
Application number: US650635A
Authority: US
Inventors: Lux Heinz
Original assignee: Telefunken AG
Current assignee: Telefunken AG
Priority date: 1932-01-13
Filing date: 1933-01-07
Publication date: 1935-10-22
Anticipated expiration: 1952-10-22

Description

0a. 22-, 1935. H, LUX 2,018,273

SHORT WAVE REFLECTOR Filed Jan. '7, 1935 INVENTOR HE/l/Z LUX w ww 'A1TORNEY Patented Oct. 22, 1935 UNITED QTATE r error:

SHORT WAVE REFLECTOR Germany Application January 7, 1933, Serial No. 650,635 In Germany January 13, 1932 3 Claims.

This invention relates to an improved reflector arrangement for short electromagnetic waves.

It is known in the prior art that electric waves may be so concentrated. or focussed by the aid of metallic reflectors that the aggregate radiation will be confined to a solid sector. If the reflector has the shape of a paraboloid of rotation or of a parabo-loidal cylinder in whose focus or focal line the radiator is disposed, and if the laws of optical reflection are assumed to hold good, it

can be expected that those radiations as are reflected from the mirror or reflector are orientated parallel. At all points of the solid or space traversed or filled by the radiations the parallel radiation formed into a beam by the reflector is superposed upon the direct radial radiation issuing from the radiator and upon the dispersion caused by marginal diffraction. The more perfect the beam formation is, the more will the parallel radiations, especially at relatively great distance, predominate inasmuch as these decrease at the ratio of (where r=distance from the transmitter), while for broadcasting there holds the law To insure a thoroughly focussed or absolute beam, also for relatively little distances from the transmitter, it is therefore necessary that the direct radiation which goes beyond the confines of the sector considered as permissible should be suppressed. In the drawing there are shown diagrammatically two forms of reflectors in which Fig. 1 illustrates a reflector with an oppositely mounted screening reflector and Fig. 2 illustrates 40 a reflector with an oppositely mounted screening reflector having an aperture. Referring now to Fig. 1 there is shown a means that has been suited to the said end which consists of the disposition of an oppositely directed reflector. l denotes the meridian section of a reflector of the form of a paraboloid of rotation, 2 its focus, and 3 an oppositely mounted accessory reflector designed to collect the entire radial radiations. It will be evident that the said accessory reflector will screen oil also part of the radiations that have already been directed parallel; and similarly also such portion of the direct radiation as falls within the desired sector is lost.

The present invention has the object of eliminating or at least lessening these two drawbacks of the screening reflector, in other Words,

the purpose thereof is to screen as little as possible of the paralleled radiations, and to prevent the wasting of such direct radiations as fall in side the desired sector. For this purpose, the screening reflector has a shape according to this 5 invention as shown in Fig. 2. Referring to the latter figure, i denotes again the meridian section of a reflector having the form of a cylinder or a paraboloid of rotation whose focus is located at 2. 3 and 4 are the meridian sections of the 10 screening reflector of the invention having the form of the zone of a surface of rotation or of parts of the shell of a cylindrical surface. The aperture 5 between 3 and 4 is chosen so large that the sector whose apex is located at 2 and which 15 is laterally bounded by the borders of 5, is. equal to, or smaller than, the desired or permissible radiation sector. In this manner, not only a larger portion of the directed radiation is utilizable, but also the useful part of the radial 20 radiation is utilized. glhe width of the screening reflectors 3 and 4 is so chosen that they are bounded by a line connecting 2 with the ends of the mirror 5 (indicated by dotted lines in the drawing Fig. 2) or slightly beyond the same. 2

I claim:

1. A short wave system for reflecting radio waves comprising a reflector in the form of a parabolic surface of rotation, an accessory refiector being oppositely directed with respect to 30 said first mentioned reflector so as to shut off the undesired part of the direct radiations of said radio waves, a source of radio waves at the focus of said first reflector and between said two reflectors, said accessory reflector having an aper- 35 ture and located centrally and in front of the said first reflector so that a useful part of the radial radiation from said source is utilized.

2. A short wave system for reflecting radio waves comp-rising a reflector in the form of a parabolic surface of rotation, a second reflector being oppositely directed with respect to said first mentioned reflector and having an aperture centrally located in front of said first reflector, a source of radio waves between said two reflectors, the aperture of said second reflector being so chosen that the unscreened sector having its apex located at the focus of the first reflector is laterally bound by a border which is equal to the desired radiation sector.

3. A short wave system for reflecting radio waves comprising a reflector in the form of a tioned reflector for shutting off the undesired part of the direct radiations of said radio waves, a source of radio Waves at the focus of said first reflector and located between said two reflectors,

two arcs of a spherical shell whose radius centers at the focus of said first mentioned reflector and is centrally located in front of the said first reflector so that a useful part of the radial radiation is utilized.

HEINZ LUX.