US2036002A - High frequency cable system - Google Patents

Description

March 31, 1936. L, WALTER 2,036,002

HIGH FREQUENCY CABLE SYSTEM Filed Jan. '7, 1933 3 Sheets-Sheet l INVENTOR- LUDWIG WALTER ATTORNEY- Marcia w l 1936., L. WALTER HIGH FREQUENCY CABLE SYSTEM Filed Jan. '7, 1933 3 Sheets-Sheet 2 INVENTOR- LUDWIG WALTER BY 7% m ATTORNEY- L' TE i2 HIGH FREQUENCY CABLE SYSTEM Filed Jan. 7, 1933 3 Sheets-Sheet 5 INVENTOR- LUDWIG WALTER BY .wg /a/ ATTORNEY- Patented Mar. 31, 1936 UNITED STATES PATENT OFFICE Ludwig Walter, Berlin, Germany, assignor to Telefunken Gesellschaft fur Drahtlose, Telegraphic in. b. H., Berlin,

tion of Germany Germany, a corpora- Application January 7, 1933, Serial No. 650,645 In Germany January 9, 1932 5 Claims.

This invention relates to an improved high frequency cable system, by means of which an effective change of circuits can be made without impairing the eificiency of the system.

The object of this invention is to provide a circuit arrangement adapted to unite at will the various radio frequency downleads of a system which comprises a plurality of such energy-feed leads, with any of the various energy-feed leads of another system of similar nature. Such a scheme may be used, for instance, in receiving equipments for radio intelligence transmission on short waves. Where these are of relatively large size, they usually contain a comparatively large number of aerials and-also a plurality, but mostly dissimilar number, of receivers, and there arises apractical requirement to connect any one of the receivers with any desired antenna. The connecting link between the antennae and the receivers, as is well known in the art, is effected by way of radio frequency energy-feed leads or downleads, and these mustbe so disposed and proportioned that an optimum propagation of the waves will be assured. A similar scheme could be carried into practice'also in transmitter plants.

Another object of this invention is to provide an improved coupler device adapted to connect the concentric radio frequency downleads from the antenna to the receivers, whereby the joining both of the external as Well as of the internal conductor isaccomplishable in the simplest possible manner by a mere manipulation of the outer conductor. The essential feature consists in that by the closure of look, by means of which the two tubular outers are joined with each other, there is exerted at-the same time the requisite contact pressure between the abutting inner conductors.

Another object of this invention is to provide an improved high frequency cable for use in the improved antenna system wherein the inner conductor is disposed internally within the outer conductor by means of improved insulating'elements or bodies being spaced apart from one another so as to minimize the capacity of the cable.

Still another object of this invention is to provide the high frequency cable with improved insulated disks having radial slots for retaining the central conductor within the outer metallic sheath.

In change-over antenna switching arrangements of the kind suggested in the prior art for the said purpose, optimumconditions could not be preserved in all junctions thus-established, for instance, because dummy leads or parts of leads were unavoidable, and these act-like concentrated (lumped) capacities becoming a source of disturbance in the tuning of the downleads. The problem of providing an arrangement that will measure up to all requirements is aggravated still further on account of the fact that the feed-leads in the majority of cases consist of concentric radio frequency energy-feed or downlead cables of the kind known in the art. In a scheme of this sort each internal conductor must be perfectly shielded in reference to all of the other conductors comprised in the arrangement,in order that no spurious coupling may be permitted between them. Finally, this demand must be made that each junction between an aerial and a receiver should contain a minimum number of contacts, preferably but one, seeing that each contact represents a potential source of trouble in the case of incoming currents of a small value as here concerned.

In order that all of these requirements may be fulfilled, according to the present invention, all of the feedleads of one system, and similarly those of the second system, are separately conveyed in the arrangement in such a way that from the ends of the leads of one system to the terminals of the leads of the second system connecting leads may be establishable of a kind that will be of the same, or nearly the same, length between any point of one system and any point of the other.

One practical embodiment of this basic idea resides in that the ends or terminals of one system terminate upon the circumference of a circle or at the corners or apexes of a regular polygon, and that similarly the ends of the second system are located along a second circle or polygon being disposed co-axially in reference to the first system. All that will then be necessary and governing is to choose the distance between the two circles or the two polygons compared with the diameter in such a way that the demand-of approximately equal length between any point of one system to any point of the other will be satisfied.

For establishing connection between the two systems, according to this invention, flexible junction wires are used, the length of which must exceed by a certain amount the intervening distance between the two circles of the systems, the

said junction wires being passed through the air along an arc-from one system to the other.

High frequency cables are known in the prior art of a kind in which, man outer sheath or casing or shell serving as a protection against mechanicaldamage, one-or moreconductors are disposed in such a way that they are spaced apart from one another and from the outer shell by the aid of rings or of beads made of insulator material. Similar cables have been used also in the form of concentric radio frequency energy lines or leads (downleads) in which the outer tubular shell and an inner lead coaxially arranged therein serve as conductors of the current.

In such radio frequency cables it is of advantage, in order that the same may be of low capacity, to mount the insulating rings or disks supporting the internal conductor spaced a certain distance apart. Several means have been disclosed in the art in order to insure constancy of distance between the insulating pieces in the interior of the cable. Now, the present invention discloses novel means adapted to the said end, which are of a nature to insure a particularly low capacity for the cable inasmuch as distinct spacer elements or pieces for the insulating bodies are avoided, and this makes for greater convenience and simplicity in the construction of the cable. According to the invention, the insulating pieces of the radio frequency cable are spaced apart from one another by continuous wires attached thereto. These spacer wires could also be used as current conductors in the cable.

Referring now to the drawings,

' Fig. 1 is a front elevation of the improved cable system;

Fig. 2 is a plan view of the lower portion of my improved cable system;

Fig. 3 is a detailed longitudinal cross-section of the improved coupler device;

Fig. 4 is a side elevation of Fig. 3 showing the bayonet joint for establishing a firm coupling between the conductors;

. Fig. 5 is a cross-section of the cable showing the method of preventing rotation of the cable when turning the cap nut, the section being taken on line A-A of Fig. 3;

Fig. 6 is a longitudinal cross-section of the improved high frequency cable;

Fig. 7 is a cross-sectional view of Fig. 6;

Fig. 8 is a cross-sectional view similar to Fig. 7 except a plurality of central conductors are shown located within the outer conductor;

Fig. 9 is a longitudinal cross-section of the improved high frequency cable with suitable insulating spacers;

Fig. 10 is a cross-sectional view of Fig. 9, and

Fig. 11 is a cross sectional view similar to Fig. 10 except a plurality of central conductors are shown located within the outer conductor and retained by means of insulated disks having radial slots.

An exemplified arrangement according to the invention is shown by Figs. 1 and 2, wherein there is shown arranged a suitable frame or rack in the form of a top circle I to which the downleads 2 of one system, say, the part of the leads coming from the receivers, are brought, the same. being secured thereon in such a way that their terminal heads 3 are directed downwardly. Below the circle, upon the floor or ground, and also in the shape of a circle of more or less large diameter, there is an assembly or bank of vertical concentric pipe pieces which represent the terminal parts of the downleads 5 of the second system and which, for instance, may be brought down from the antennae. The said pipe pieces have at their upper ends inwardly directed terminal heads 8. Connection between the upper and the lower systems is established by means of the flexible junction or coupling pieces indicated at I, the latter consisting likewise of concentric energy-feed cables and being designed to be fitted with their suitably shaped terminals into the terminal couplings or sockets of the upper and the lower lead systems.

A detailed description of the coupling will be given later.

By choosing a form of construction for the terminals of the upper and the lower annular system, conditions can be made so that the flexible connector wires or radio frequency cables, no matter what the particular junction, will have substantially only one general downward curvature with only a single elbow or bend at the lower end. This fact is of special importance on the ground that the connectors, owing to their concentric construction as energy-feed leads, are capable of being flexed only along a definite and minimum'radius. In spite of a great number of possible couplings inside the systems, they will experience only a minimum amount of mechanical stress as a result of the particular disposition thereof as hereinbefore described/ Ihe upper ends of the flexible connector leads in the switching or antenna coupling arrangement, that is to say, at the terminal ends brought from the receiver equipments, may permanently stay connected once they have been fitted or joined thereto, in fact, it is only the lower ends that have to be disengaged for the change of connections, and the practical result is that the downleads as a whole comprise only one disengageable contact point. If in this arrangement all of the proportions are properly chosen, and if the flexible conductor pieces are so placed as to cover the shortest possible distance, it will be seen that no tangling will occur even where the number of leads is large.

One exemplified embodiment of the coupling device is shown in Fig. 3 wherein the two outer conductors H and Ila terminate in tubular bushings l2- and I211. The inner conductors i3 and l3a terminate in head pieces l4 and Ma. These latter are held inside the terminal bushings I 2 and 12a of the outer conductors by the aid of conical insulating pieces 15 and 15a. The said head or inner conductor terminal pieces l4 and Ma protrude in a tipor dome-like fashion from the face of the said insulating pieces. To unite the two energy-feed leads they are placed adjacent to each other with their anterior faces so that the tips of the head pieces l4 and Ma of the inner conductors, and the edges of the tubular bushings l2 and 12a of the outer conductors come to abut against one another, with a certain amount of clearance being provided for the latter, For establishing firm coupling a sort of bayonet joint [0 as shown in Fig. 4, is used, constituted by the cap nut it which is held rotatably upon the ferrule 20a of the tubular bush 12a. of the energy-lead and whose segmental projections ll come'to engage over corresponding segments I8 on the ferrule 20 of tubular bushing E2 of the respective other lead, the said segments ll and I8 being wedge-shaped (conical) in the direction of rotation so that by approximately rotation of the cap nut IS the connection is effected with an incidental tightening (pulling) of the downleads. action that the requisite pressure is produced whereby the abutting head pieces M and Ma of the inner energy leads are pressed together so that a safe connection is established also between the inner conductors.

It is by virtue of this tightening In order that when turning the cap nut for the purpose of joining the energy feed-leads, one of the leads may be prevented from participating in such rotation, the end faces of the terminal bushings are furnished with tooth rims H), as shown in Fig. 5. When the two leads are fitted together, the said teeth will come to inter-engage. Thus, if one of the leads is fixedly mounted with its terminal bushing secured in place, then the second mobile lead can be brought to a point at close proximity thereto in any desired position without it being necessary to first turn it into a definite position in reference to the fixed conductor.

The spacing of the insulator elements of the high frequency cable inside the tubular shell is secured in an extremely simple manner by the insulator disks threaded upon the inner conductor being prevented from being shifted out of position by pinched or squashed points in the conductor bilaterally of the disks.

An arrangement of such insulator disks is shown by way of example in longitudinal crosssection Fig. 6, and the cross-section view Fig. '7. The outer conductor of the radio-frequency cable, for instance, consists of the leaden sheath or shell 3|, the inner one consisting of the co-axial wire 32, the latter being held in position by the aid of insulator disks 33 consisting of a suitable sort of insulation material, such as glass, porcelain, etc, and being spaced suitable distances apart. Upon both sides or faces of the insulator disk 33 is a squash 34 in the conductor 32, so that the latter is unable to work its way through the bore of the disk 33, because the latter is just adapted to the gauge of the wire.

Instead of just one inner conductor, it would be feasible to arrange also a plurality thereof in the radio frequency cable as shown by way of example in the cross-sectional view Fig. 8. In this instance, in addition to the central conductor 32, there have been passed three additional conductors 35, 36, 31, through suitable holes formed in the insulator disks. In this case, these wires 35, 36, 31, could constitute thus the outer of a concentric energy-feed line (downor uplead), shell 3| in that instance serving solely as a protector. But it is also feasible to accommodate only two or three conductors in the interior of the tubular shell 3|. A cable containing a plurality of such conductors could, for instance, serve for the feeding or supply of several circuits or as a three-phase transmission line. The spacing apart of the insulation disks may be secured and insured, where a plurality of conductors are concerned, by squashes provided in all of the conductors, though, if desired, securing by a single set of squashes, say in the central conductor, may sufiice.

The manufacture of a cable of the kind here disclosed is particularly simple. For instance, first a chain comprising the inner conductor with insulator disks threaded thereon may be formed, whereupon, in an uninterrupted operation, the leaden sheath or shell 3| is formed by pressure around the same.

An embodiment of such a cable is shown in Fig. 9 in longitudinal section and in cross-section by way of example. The cable consists of the outer tubular conductor 5| and the inner co-axial conductor 52. The tubular conductor 5| most preferably consists of a leaden sheath or shell which constitutes at the same time the protector of the cable against mechanical damages. Threaded upon the inner conductor 52 are the insulator pieces 53, by the aid of which co-axial position inside shell 5| is secured and preserved. The insulator disks 53 consist of a suitable insulation material such as glass, porcelain, steatite, and the like. In order to insure proper spacing between the said insulator disks 53, wires 54, 55, 56, are attached thereto, connection being accomplishable in any desired way. It is conven ient to provide the insulator disks 53 with slots, and to press-fit the spacer wires 54, 55, 56, op tionally consisting of copper into the said grooves.

As shown in Fig. 10, the securing of the spacer wires 54, 55, 56, is effected directly upon the circumferences of the insulator disks 53. As a consequence, these wires 54, 55, 56 come to make direct contact with the outer lead shell 5| so that they serve conjointly with the latter for the carrying and conduction of the current, with the result that they promote the conductivity of the outer conductor.

However, it is also possible to press-fit the spacer wires 54, 55, 55, into slots formed in the insulator disks 53 being of greater depth, in a Way shown, for instance, in Fig. 11 in cross-section, with the result that the spacer wires do not make contact with the outer shell. In this instance, for example, the wires 54, 55, 56, conjointly could constitute one conductor, while 52 represents the second conductor, the outer shell in that case serving solely for mechanical protection. In a cable comprising a plurality of such inner conductors, the latter could serve also for the supply of a plurality of different circuits, say, as a three-phase current transmission cable.

A cable of the kind hereinbefore described may be manufactured particularly conveniently by that the insulating disks threaded or alined upon the conductor 52 are first press-fitted together with the wires 54, 55, 56, whereupon the leaden shell or case 5| is press-fitted around the chain or rosary thus produced in an uninterrupted process.

In cables of the kind as described it is of advantage to provide the inner conductor, i. e., the central conductor 52 and the wires 54, 55, 55, when they do not make contact with the outer shell, with a suitable coat of varnish or other insulation means. In this way, the risk of a short-circuit being produced between the conductors as a result of a compression of the lead shell between two insulation bodies due to mechanical damage to the cable, is obviated.

Although this invention has been described and shown in a particular form and arrangement of parts, it should be understood it is capable of embodiment in other and different forms and not limited to those shown, except as such limitations are clearly imposed by the appended claims.

I claim:

1. A switching arrangement adapted to insure at will connection between the radio-frequency downleads of a short wave system comprising a plurality of leads forming a first system, a corresponding plurality of leads forming a second system and a flexible coupling lead for joining said first and second systems, with this characteristic feature that the terminal points of the downleads of the first system and similarly the leads of the second system are each placed in a circle, one system being located above the other so that from any terminal point of one system and each terminal of the other system it will be possible to accommodate practically equal lengths of said flexible coupling leads.

2. An antenna switching arrangement comprising a plurality of concentric energy feed cables arranged in a circular manner on a frame, wherein the junction leads connecting an upper and lower system consist of a plurality of flexible concentric cables each of which terminates with a terminal socket fitted thereon, with this characteristic feature that the junction leads between the terminal sockets of the flexible concentric cables connecting the upper and lower systems is arranged to insure the formation of a general downward curvature at the lower end of the junction lead which will be substantially in the shape of an elbow.

3. An antenna short wave switching arrangement comprising a plurality of concentric conductors, said conductors divided into an upper and lower system, the lower system located near the ground, the conductors being arranged to 4. An antenna short wave switching arrangement comprising a plurality of concentric conductors, said conductors divided into an upper and lower system, the lower system located near the ground, the conductors being arranged to form the periphery of a regular polygon, the upper system arranged above said lower system, forming a regular polygon with a periphery similar to said lower system, a flexible connection joining said systems, said flexible connection comprising concentric conductors having detachable end terminals with a bayonet joint locking means for detaching said flexible conductor from said upper and lower systems.

. 5. An antenna short wave switching arrangement comprising a plurality of concentric conductors, said conductors divided into an upper and lower system, the lower system located near the ground; the conductors being arranged to form the periphery of a regular polygon, the upper system arranged above said lower system, forming a regular polygon with a periphery similar to said lower system, a flexible connection joining said systems, said flexible connection comprising concentric conductors having detachable end terminals witha tooth-like rim and a rotatable cap for detaching said flexible conductor from said upper and lower systems.

- LUDWIG WALTER.

Images