US1664044A - Conductor for high-frequency work - Google Patents

Description

March 27, 1928.

M. OSNOS ET AL CONDUCTOR FOR HIGH PREQUENCY WORK Filed 0621. 20. 1925 wuwtoz MENDEL OSNOS Richard KuMmcH g'fhe'w Patented Mar. 27, 1928.

` UNITED STATES PATENT oFFlcE;

MENDEL OSNOS AND RICHARD .KUMMICH, OF BERLIN, GERMANY, ASSIGNORS TO e GESELLSCHAFT FR DRAHTLOSE TELEGRAPHIE IB. H., OE BERLIN, GERMANY, A

CORPORATION OF GERMANY.

CONDUCTOR FOR HIGH-FREQUENCY WORX.

Application led October 20, 1925, Serial No. 63,617, and in Germany September 5, 1924. l

Our invention relates to inductance devices using a magnetic material and, more particularly, -to a novel form of conductor, especially adapted for high frequency work 5 Where large amounts of heat must be dissipated.

An object of the invention is to providea conductor of the above kind which will be cheap to make and eicient in use.

vOther objects will be apparent from the following description and appended claims when considered with the accompanying drawing in which,

Fig. l illustrates a conductor made according to the invention.

Fig. 2 is a modification, showing the conductor bent upon itself, and

Figs. Sand lc-represent further modilications in cross-section.

The subject matter of the invention 1s a current conductor for high frequency purposes, which may act, for instance, as a choke coil, transformer, frequency changer,

coupling means, and the like'. In short, it 25,1nay be used for all such services for which heretofore the usual transformers or choke coils have been employed such as, for instance, for key work and telephony.

In .the attempt tol utilize iron and other magnetic materials for these purposes, one meets this difliculty that the energy losses become very great for the reason that for a small volume of iron, a high number of ampere turns per centimeter are necessary.

This'holds true particularly for very high frequencies. Incidentally there occurs pronounced-heating of the arrangement, while, on the other hand, it has heretofore not been possible to provide adequate cooling, on the ground that the known coil arrangements constitute concentrated heatlng centers presenting comparatively small cooling sur- In/accordance with the present invention,

the said disadvantage is obviated because vthe iron constitutes the surface of the conductor or the iron covers the latter, and further, the conductor is elongated in shape and arrangeii'ient. rlhis advantage is thereby 5u obtainedfviz that in virtue of the high overload capacity'of the current conductor, a

high number of ampere-turns per cubic centimeter may be used, while at the same time, on account of the arrangement chosen, the length of the magnetic flux pathremains within low limits.

The iron or other suitable magnetic material can be placed upon the surface of the linear conductor by various processes. For instance, it may be deposited by galvanic precipitation or deposition, by the so-called bimetal drawing method, by spraying, etc. However, it is of considerably greater advantage` to continuously wrap around the surface of the conductor a very line, most suitably insulated capillary wire, as this means an extensive subdivision of the eddy current paths and consequently 'a considerable diminution of the losses.

The thickness of the iron wire used, and the number of the layers of iron-Wire turns (provided a plurality of layersis needed), depend 4entirely upon the frequency employed. In order to safeguard the surface from oxidation, it is a recommendable plan to coat the surface with chromium, an amalgam, or some similar means. i

Instead of using a massive or solid conductor in the manner as hereinbefore described which is externally surrounded in the usual manner by air orv another cooling medium, the said conductor could be given the shape of a hollow body through the interior of which there is passed a convenient cooling agent. The massive conductor could also be replaced by this sort of arrangement,

.upon a massive or a cylindrical insulating body, there is first brought a layer or strat-l um of the current-conducting material to be used, whereupon the iron Wrapper, winding, ,or envelope is placed upon said layer.

Referring to the drawing, in Figs.` 1 and 2, a represents the conductorwhich may be copper, provided at its ends with eyes 1 and 2 for securing necessary connecting wires. A coating or covering b of magnetic mate-l rial is shown upon the conductor a. This coating is quite thin and for purposes of illustration is one-tentli of one millimeter in thickness.

In Fig. 2 the conductor is bifilar, that is, it is bent backon itself to save space. 'r

In Fig. 3, the conductor a is shown hollow, the hollow space being denoted by 10.

is practically limited by the amountof energy to be dissipated. Under certain circumstances, it may be siiitable to wind the stretched wire in some constructionally appropriate form so that itoccupies less space. But in this regard, attention must be paid that by such wrapping or winding-as is true of a simple coil--no increase in self-inductance will be produced in the internal conductor. On the contrary, it is necessary to always provide bifilar winding or wrapping. More suitable than the simple stretched length or piece of conductor with lead-in at one end and lead-off at the opposite end is the bifilar arrangement. In other words, there should be at least onelto-andfro arrangement so that no loop field can be 'set up for the conductor.

As a stretched conductor in the foregoing sense, if the frequencies are sufficiently high, there can be used also an iron wire without special wrapper, in view of the fact that the physical effect in such an arrangement is approximately the same asf before described for a current conductor made of non-magnetic material. Y

Having described our invention, we are entitled to all modifications thereof that fall fairly within the spirit and scope of the following claims:

. 1. A high frequency conductor comprising an inner nonmagnetic conducting member, a thin magnetic layer surrounding said conducting member and in direct contact therewith, said layer being designed to provide maximum magnetic permeability irrespec tive of tensile strength and means for neutralizing the'- leakage flux. which passes through said, outer magnetic layer, said neutralizing means being provided in winding said conductor bitilarl fashion.

2. A high frequency conductor comprising an inner nonmagnetic hollow cylindrical conducting member, a thm magnetic layer surrounding said conducting member and in direct contact therewith, said layer being adapted to provide maximum magnetic permeability irrespective of tensile strength, in-

sulating material of fluid forni adapted to cool said Aconductor contained within said hollow cylindrical conducting member, and means for neutralizing the leakage flux which passes through said outer magnetic layer, said neutralizing means being provided in winding said conductor bitlar fashion.

3. A high frequency conductor compris- \ing, an inner nonmagnetic hollow cylindrical conducting member, a thin magnetic layer surrounding said conductor and in direct 'contact therewith, said, layer being designed to providemaximum magnetic permeability irrespective of tensile strength, and means for neutralizing the leakage flux which passes throughl said outer layer, said neutralizing means being provided in winding the conductor bifilar fashion.

MENDEL osNos. RICHARD y KUMMIGH.

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