US2349942A

US2349942A - Hollow space radiator

Info

Publication number: US2349942A
Application number: US353755A
Authority: US
Inventors: Dallenbach Walter
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-08-22
Filing date: 1940-08-22
Publication date: 1944-05-30
Anticipated expiration: 1961-05-30
Also published as: FR870325A; NL56782C

Description

May 30, 1944.

W. DALLENBACH HOLLOW SPACE RADIATOR Filed Aug. 22, 1940 WA: 75/? cine-Nana,

Patented May 30, 1944 2,349,942 HOLLOW SPACE nAmA'ron Walter Application August 22 In Germany tuned hol- This invention particularly can be used as sending or receiving aerial for oscillation having a wave length less than 1 meter.

- One feature of this invention is the tuned hollow space radiator consisting of surrounding conducting surfaces and open at one side, the hollow space being coupled to an energy conducting device or alike by means of a slit in the back wall of said hollow space radiator. Several of such hollow space radiators are coupled side by side to an energy conducting device, or alike for the purpose of improving the directing effect. The length of these single radiator is equal to the length of a single wave or a multiple of one wave length. It is necessary that the single radiators of such a group be tuned accurately so as to create signals of frequency so a to obtain optimum results.

A further feature of this invention is that the single radiator walls may be placed directly adjacent one another and that they can be coupled electrically through openings of the walls thus providing an automatic adjustment of the different radiators. In this way the adjusting of the single radiators by hand, which is rather dimcult and troublesome, can be avoided. Furthermore the location of the slits in the back walls of the single radiators forming the connections to the energy conducting device is not critical.

Fig. 1 represents a single hollow space radiator consisting of a boxlike device.

Fig. 2 shows a group radiator consisting of several hollow space radiators located adjacent one another and provided with openings in the side walls.

Fig. 3 illustrates a plan view of a set of hollow space radiators forming a group as shown in Fig. 2, and showing the side walls of the single hollow space radiators, each being divided into two portions at the outside, each portion forming a small pocketlike case having a depth of one quarter of a wave length.

Fig. 1 represents the hollow space radiators consisting of a box with parallel walls, the walls having conducting surfaces. The side edges of the box are designated a, b and c, respectively, the front of the box being open. The back wall of the box contains a slit 2 communicating with the interior of an energy conducting device 6; said device may or may not be provided with an inner conductor. The hollow space radiator thus Dallenbach, Berlin, Germany; vested in the Alien Property Custodian e 1940, Serial No. 353,755 August 22, 1939 3 Claims. (Cl. 250-11) is coupled with the energy conducting device and is excited in such way that theelectric vector of the oscillations is perpendicular to the walls having edges be. The intensity of th electrical vector is divided sinusoidal alongthe edge 0 as along the edge has shown in Fig. l by thecurves e and f. A box tuned in'such'a way represents a resonator being equivalent to a Lecher system of a length of one quarter of .a wave length. In. the open front side lfthere is a potential loop, there being. apoteritial node in the back wall at the slit 2. The tuning of the box will not be changed by alteration of the length of the edge a.

Fig. 2 represents another special feature of the invention, this being a group radiator, consisting of several single boxes as shown in Fig. 1. This group radiator is shown with its edge a very much longer than the other edges b and c. In this group radiator box several separating and electrical conducting walls 1 are provided parallel to the sides bc, thus forming a device comprising a set of single radiators built closely together. Every single radiator box in its back wall has a slit 2, for coupling the box to the energy conducting device 6. The wall 1 contain openings 9 for providing a radiation of only one wave length. These openings should be particularly placed close to the back walls 8 of the group box while these openings are shown semicircular, it also may be useful to form these openings 9 rectangularly by leaving off that small piece of a separating wall 1 which is next to the back wall 8, i. e. the rear end of the separating wall being spaced from the back wall. The coupling of the single radiators resulting from these openings 9 in the side walls 1 provides, in all the boxes, equal amplitudes of oscillations even if the excitation of the different slits 2 in the single boxes is not exactly the same. Therefore it is not necessary to place the slits 2 with respect to the energy conducting device, in a mathematically exact position in the current loops. In many cases it is quite sufiicient that the slits 2 be placed near to currents of equal direction, 1. e. having a distance of about one wave length. In some cases it might be necessary to regulate the coupling of the single radiators and therefore it will be useful to provide adjustable openings 9 in the nature of a variable screen. Instead of building only one large box containing separating walls for making a radiator device, one also can put together several single boxes each box comprising one hollow space radiator. The construc-. tion as per Fig. 2 has essential advantages.

Fig. 3 schematically shows a modification of the Fig. 2 arrangement designed to avoid spraying appearing at the edges of the walls as explained in applicants former application filed February 18, 1936, Ser. No. 64,604. In Fig. 3 the edges of the surfaces next to the front side, especially the side walls It and the separating walls I, and also the covers 12 and the grounds l3 (-Fig. 2) are split thus to provide pocket-like small cases ll oil a depth of one quarter of a wave length. Thus, at all edges of the front sides the intensity of the current will be exactly zero, since the spaced wall of each of the pockets form a Lecherconductor one quarter of a wave length, the spaced. walls thereof being connected at the inner ends thereof. According to circuit equations, a Lecher concluctor one fourth of a wave length, short circuited' at the end, has a final resistance that is zero in magnitude, whereas the initial resistance. that occurs at the free end of the box amounts to infinity. Therefore no current can flow in this Lecher conductor of a quarter wave length so that overlapping of the current from the inside of the box on the outer' surfaces is prevented.

-What I claimis:

l. A device 'forradiating ultra short waves particularly of a wave length of less than 1 meter, comprising at least two tuned hollow spaces, defined by a plurality of walls having conducting surfaces, said hollow spaces being closely adjacent one another, the walls between the single hollow spaces having openings therethrough whereby to couple the hollow spaces electrically, said hollow spaces being coupled to an energy conducting device by means of slits in the back walls of the radiator.

2. A device for radiating ultra short waves particularly of a wave length of less than 1 meter, comprising at least two tuned hollow spaces defined by a plurality of, walls having conducting surfaces, said hollow spaces being closely ad- 'jacent one another, the walls between th single hollow spaces having openings therethrough whereby to couple the hollow spaces electrically, said walls at the front edges being provided with pocketlike cases of the depth of one quarter the wav length being resonated.

3. A device for radiating ultra short waves, particularly of a wave length of less than 1 meter, comprising at least two tuned hollow spaces defined by a plurality of walls having conducting surfaces, said hollow spaces being closely adjacent one another and adjacent spaces having one wall in common, the wall between the single hollow spaces having openings therethrough whereby to couple the hollow spaces electrically, said hollow spaces being defined by-a boxlike device with parallel walls, said boxlike device being open at one side and having a breadth substantially longer than the length and depth and being divided by walls in several single radiators.

WALTER. DALLENBACH.