US 2219941 A
Description (OCR text may contain errors)
Oct. 29, 1940. H. ROCHOW HIGH FREQUENCY ARRANGEMEN T Filed Dec. 4, 1934 712 VGJZOZ' #47/75 Roman Patented Oct. 29, 1940 UNITED STATES PATENT OFFICE HIGH FREQUENCY ARRANGEMENT Application December 4, 1934, Serial No. '755,917 In Germany December 12, 1933 2 Claims.
It is well known that if the parts of an oscillatory circuit which determine its frequency, for example, inductance coils and condensers, are subjected to the influence of temperature variations, under intense Operating conditions undesirable changes in frequency occur. In order to avoid the disadvantages caused by this, it has been suggested to construct the inductance coils or condensers in such a way that such changes are automatically compensated by beat-sensitive compensation devices. Thus it has been proposed to vary the distance of the rotor set from the stator setof a condenser according to the temperature in such way that capacity variations do not occur in the circuit connected to the condenser. It is also well-known to construct inductance coils in such a way that extension in one dimension counteracts contraction in another dimension.
According to the present invention it is proposed to construct the screening devices for high frequency apparatus or for parts thereof from a material which is insensitive to temperature. In particular it is proposed to employ ceramic material with a metallic coating The improved arrangement, like the known arrangements described above, is intended for use with apparatus in which it is desired to maintain a very high constancy of frequency. The oscillatory circuit elements however are not themselves maintained constant, but the invention is directed to keeping constant the space capacity of the housing in which the high frequency apparatus is contained.
The accompanying drawing is an elevation, partly in section, of a screening device constructed according to one embodiment of the invention.
The walls A and the base plate B of the housing for the apparatus C- consist of ceramic material insensitive to temperature, namely a material that has recently come on the market under various names. Parts A, B are coated inside and out with metal D; for example they are metalized with copper or silver. Owing to the fact that the ceramic material is insensitive to temperature the space capacity determined by the metal screening remains constant in spite of fluctuations of temperature.
The whole apparatus may be housed in this way or screening devices may be used for individual elements or groups of elements, such, for example, as coil units. In this connection difiiculties have arsen hitherto on account of the fact that while maintaining as large a diameter of coil as possible it is necessary to keep the overall dimensions of the unit, that is the coil and container, as small as possible. It thus follows that the distance of the container from the turns of the coil must be made as small as possible. But the nearer the screening device is to the coil the greater are the attenuation losses of the coil. Owing to limitations of space, certain attenuation losses must be allowed for. But further difiiculties arise, if the 15 attenuation losses are not constant due to the fact that the distance of the screening device from the coil changes on account of temperature variations, Thus by employing the present invention the great advantage results that a screening device is obtained which is insensitive to temperature.
The invention can of course be applied to all kinds of high frequency apparatus.
What is claimed is:
1. An arrangement for enclosing oscillatory elements of an electrical circuit comprising a substantially heavy walled casing and a removable closure for said casing, said casing and closure being of ceramic material having a Very small temperature coefficient or expansion, the outer portion of said casing and closure being metallized, and means for electrically connecting together said metallized casing and said metallized closure, whereby electrical effects upon the oscillatory elements due to change in dimensions of the casing are prevented.
2. An arrangement for enclosing and shielding oscillatory elements of an electrical circuit comprising a casing of ceramic material having a very small temperature coefficient of expansion, said 40 casing being provided with a metallized surface, whereby electrical effects upon the oscillatory elements due to change in dimensions of the casing are prevented.