US2129714A

US2129714A - Wave type converter for use with dielectric guides

Info

Publication number: US2129714A
Application number: US43795A
Authority: US
Inventors: George C Southworth
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1935-10-05
Filing date: 1935-10-05
Publication date: 1938-09-13
Anticipated expiration: 1955-09-13
Also published as: NL47517C; DE738361C; FR49564E; FR49566E; FR818503A; US2180950A; NL49995C; GB491196A; GB468548A

Description

Sept. 13, 1938. a. c. souTHwoRTH WAVE TYPE CONVERTER FOR USE WITH DIELECTRIC GUIDES Filed Oct. 5, 1935 4 Sheets-Sheet l Im E/vm/a. C. South/worth ATTORNEY Sept. 13, 193 8. G. c. SOUTHWORTH 2,129,714

WAVE TYPE CONVERTER FOR USE WITH DIELECTRIC GUIDES Filed Oct. 5, 1955 4 Sheets-Sheet 2 INVENTOR BYa', S

ATTORNEY Sept. 13, 1938.

v s. c. SOUTHWORTH WAVE TYPE CONVERTER FOR USE WITH DIELECTRIC GUIDES 4 Sheets-Sheet 3 Filed Oct. 5, 1935 ATTORNEY Sept. 13, 1938. G. c. SOUTHWORTH 2,129,714

WAVE TYPE CONV ERTER FOR-USE WITH DIELECTRiC GUIDES Filed Oct. 5, 1935 4- Sheets-Sheet 4 INVENTOR G. C. Sou/wmZ/w ATTORNEY Patented Sept. 13, 1938 UNITED STATES PATENT OFFICE WAVE TYPE CONVERTER FOR USE WITH DIELECTRIC GUIDES Application October 5,

28 Claims.

The principal objectof my invention is to provide new and improved apparatus and a corresponding method by which electromagnetic waves of a certain type under propagation in a dielectric guide may be modified or reshaped so that they will go on as waves of a difierent type. Another object of my invention is to provide for the introduction of conductive baflies or deflectors in a dielectric guide, such baffles being so shaped and proportioned that they will bend the lines of force of incoming electromagnetic waves in the guide and reshape them to'give outgoing waves of another type. All these objects and other objects and advantages of my invention will become apparent on consideration of a limited number of examples of the invention which I have chosen for presentation-in the following specification. It will be understood that this disclosure relates principally to these particular embodiments of the invention and that the scope of the invention will be indicated in the appended claims.

Referring to the drawings, Figures 1, 3, 5 and '1 are longitudinal sections of a 'dielectric guide showing wave shapes of different types; Figs. 2 4, 6 and 8 are respective cross sections; Fig. 9 is a longitudinal section, partly in elevation, showing a converter for changing asymmetric magnetic waves to symmetric magnetic waves; Figs. 10a to 100 comprise a set of cross sections of Fig. 9; Figs. 11a and 11b are a pair of diagrammatic cross sections showing a modification of the device of Fig. 9; Fig. 12 is a longitudinal section, partly in elevation, showing a converter for changing second order asymmetric magnetic waves to first order symmetric magnetic waves; Figs. 13a to 13f comprise a set of cross sections of Fig. '12; Fig. 14 is'a diagram indicating one way in which second order asymmetric magnetic waves may be generated; Fig. 15 is a longitudinal section of a converter for changing electromagnetic waves from asymmetric magnetic type to asymmetric electric type; Figs. 16a to 160 comprise a set of cross sections of Fig. 15; Fig. 17 is a longitudinal section showing a converter for changing asymmetric electric waves to asymmetric magnetic waves; Figs. 18a to 180 comprise a set of cross sections of Fig. 1'7; Fig. 19 is a longitudinal section, partly in elevation, showing a converter for changing asymmetric electric waves to symmetric magnetic waves; Figs. 20 and 21 are cross sections taken on the correspondingly numbered lines of Fig. 19; Fig. 22 is a perspective side view, partly in section, of

a converter adapted to change symmetric electric 1935, Serial No. 43,795

waves to asymmetric electric waves; Figs. 23a to .23 comprise a set of cross sections corresponding to Fig. 22; Fig. 24 is a longitudinal section showing a converter for changing asymmetric magnetic waves to symmetric magnetic waves; Figs. 25a to 250 comprise a set of cross sections of Fig. 24; Fig. 26 is a perspective side view, partly in section, showing a converter for changing symmetric electric waves to asymmetric magnetic waves; Figs. 27a to 27 comprise a set of .cross sections of Fig. 26; Fig. 28 is a perspective side view, partly in section, showing a converter for changing symmetric electric waves to asymmetric magnetic waves; Figs. 29a to 29g comprise a set of cross sections of Fig. 28; Fig. 30 is a perspective side view, partly in section showing a converter for changing symmetric electric waves to asymmetric magnetic waves; Figs. 31m to 31f comprise a set of cross sections of Fig. 30; Fig. 32- is a side elevation, partly insection, showing a converter adapted to change symmetric electric waves to symmetric magnetic waves; Figs. 33 and 34 are cross sections indicated by corresponding lines on Fig. 32; Fig. 35 is a perspective view, partly in section, showing a converter for changing symmetric electric waves to symmetric magnetic waves; and Figs. 36a to 36d comprise a set of cross sections of Fig. 35.

The term dielectric guide, as used in this specification, is meant to indicate a wave guide comprising a body of dielectric extending from one place to another place and bounded laterally by a dielectric discontinuity. v Such a dielectric guide functions by the generation therein at the one place of electromagnetic waves and their propagation therein to the other place. A form of dielectric guide which will be convenient for consideration in this connection consists of a cylindrical body of air or empty space as the dielectric,

electric constant of the medium within the guide.

Waves of this character within a dielectric guide I term dielectrically guided waves, and a dielectric guide system is to be understood to mean a system adapted for or utilizing such waves.

Among dielectrically guided wavesthere may be identified different types, that is, waves of different characteristic field pattern. Thus, if the waves have substantial components of electric force parallel to the axis of the guide they are called electric, but if they have substantial components of magnetic force in that direction they are called magnetic. If the lines of force electric .guide with the thickness of the sheath greatly exaggerated to facilitate the disclosure. In these figures continuous lines represent lines of electric force, and dotted lines represent lines of magnetic force. It will readily'be appreciated, from what has been said, that symmetric electric waves are represented in Figs. 1 and 2; symmetric magnetic waves in Figs. 3 and 4;

asymmetric electric waves in Figs. 5 and 6, and" asymmetric magnetic waves in Figs. 7 and'8. All these are, in a sense, first order waves. Certain waves of second order will be mentioned in connection with Figs. 12 to 14.

The present invention has to do in great measure with the provision of a method and apparatus for converting one type of wave into an-' other type of wave. Such a conversion may be useful when one has a generator associated with the dielectric guide at the transmitting end so waves of one type are produced and it is desired to transmit waves 'of a different type; or when waves of one type are received through a dielectric guide and it is more convenient toreceive another type, into which, accordingly, the first type may be converted. For specific example, it may be desirable to generate a wave of a certain type because. of the relatively high efficiency of available generators of that type of wave, and then to convert it to'another type of wave that has lesser atteniiation or, that can be transmitted over a dielectric guide having a cut-off frequency too high to sustain a wave of the type originally generated. In any such case a wave converter of the present invention may be employed.

Asymmetric'magnetic waves coming from the left of the dielectric guide D of Fig. 9, with their lines of force directed up and down as viewed in this figure, are caught and bisected by the intermediate edge I ID of the two pipes l l l and I I2, each with kidney-shaped cross section at their place of junction with the main guide D. Going on to the right, each of these two pipes is gradually brought to a circular section as in Fig 100. Then continuing on to the right, each circular pipe has a baflle which begins with a horizontal edge at H3 or H4 and twists in helical form Bldegrees, the upper one to the right and the lower one to the left. Thus the lines of force which are directed alike along a vertical diameter of the main guide D at I I3 and H4 are directed oppositely across the same diameter at H5 and H6. These lines are then launched from the open ends of the two circular pipes at H5 and H6 into the enlarged circular pipe D, and they link together, giving the trans verse circular lines of force which are characteristic' of the symmetric magnetic waves.

Whereas two branch pipes were shown linking the guide D on the left with the guide D on the right in Fig. 9, four such pipes may be employed as indicated in Figs. 11a and 11b. The electric lines of force of the asymmetric magnetic waves will be received in these four pipes with the directions indicated by the arrows in Fig. 11a. The baflles with helical twist will turn the lines of force 90 degrees clockwise in the upper pipe; 90 degrees counter-clockwise in the lower pipe; 180 degrees in the right-hand pipe, and no rotation in the left-hand pipe. These component lines of force, thus directed, as in Fig. 11b, will be launched forth and .will link up to give the transverse'circular lines of force characteristic of the symmetric magnetic type of waves.

For the output of the system of Fig. 9, or of Fig. 11, it may be desirable to provide a screen of radial wires, like those shown at H15 in Fig. 250, which will purify the outgoingwave to the symmetric magnetic type. Since the lines of electric force of the outgoing symmetric magnetic waves will cut the radial wires of the screen I05 each at a right angle, there will be no tendency to develop electromotive forces in those radial conductors; there will be no loss of energy this way the screen I05 may be called a purifier for the symmetric magnetic waves passing through it.

Before explaining the conversion effected by the apparatus of Fig. 12, I direct attention to the fact that the waves considered hereinbefore may be thought of as being of first order type. But it is possible to generate waves in dielectric guides with more elaborate or 'cornplex grouping of the lines of force in what may properly be called wave types of, higher order. The waves of asymmetric magnetic type of the first order may be generated by an oscillator connected to--two diametrically opposite points within a dielectric guide at the left, as shown in Fig. 9. But if the oscillator is connected to points a quadrant distance around thecircumference, as shown in Fig. 14, the oscillatory currents will develop lines of force as shown in that figure,,corresponding to what may properly be called asymmetric magnetic waves of the second order.

Let such waves be generated in the dielectric guide of Fig. 12 coming from the left, and let four helical baffles I20 be introduced in the guide having the shapes indicated by the successive cross sections of Figs. 13a. to 131. That is, the upper and lower baflles have a 90-degree counterclockwise twist and the right and left baflles have a 90-degree clockwise twist. In this way the lines of force of the waves of second order asymmetric magnetic type incoming on the left are broken up and 'bent around and reconnected so as to give the outgoing waves of symmetric magnetic type on the right.

Asymmetric magnetic waves coming'from the ammm left in Fig. 15 have their lines of electric force in cross section.

caught between the opposedconductors I'0I and I02 and gradually reshaped until they are launched to the right as asymmetric electric waves. The conductors I M and L02 close at the right to form two pipes each of kidneyshape Within each suclg bfpe is an adjustable piston I03 by which an'bptimum conversion with impedance match may be obtained. Successive cross sections are represented in Figs. 16a to 1801.

Another converter to operate either way between asymmetric electric waves and asymmetric magnetic waves is shown in Figs. 17 and 18a to 180. Incoming asymmetric electric waves from the left fix the ends of their lines of force upon the left-hand ends of the opposite kidney-shaped electrodes I06 and I01. These electrodes going from left to right are spread apart and opened out into part cylindrical shells, and the lines of force are stretched out between them so that on the right they are launched forth as asymmetric magnetic waves.

Asymmetric electric waves coming from the left in Fig. 19 have their lines of force picked up by the two kidney-shaped electrodes 46 'having the cross section shown in Fig. 20. The conductors from these kidney-shaped electrodes are gradually deformed, going from left to right, as indicated in Fig. 19, until they make a coaxial conductor system as shown at 44 and 43. Then the inner and

outer conductors

44 and 43 are connected, respectively, at the middle points of the two intersecting parts of the figure-0 frame shown at in Figs. 19 and 21 In this frame it will be seen that when the currents circulate clockwise in the upper member they also circulate clockwise in the lower member. Thus from this frame circular lines of electric force are detached and launched forward to the right as symmetric magnetic waves in the dielectric guide/ Referring to Fig. 22, it is assumed that waves of symmetric electric type, such as diagrammed in Figs. 1 and 2, are propagated along the dielectric guide D from the left and it is desired to convert these into asymmetric electric waves outgoing in the guide D on the right. Beginning at and continuing at 55 the inner metallic guide shell in continuation of shell D is opened along one side and beveled and bent aside and its cross section contracted smoothly and gradually as shown in the sections of Figs. 23a to 23f,

' until it ends in the kidney-shaped cross section shown at 56 in Fig. 23c. Opposite the point 55 an inside coaxial conductor'begins with a circular cross section as at 51. This is beveled gradually and bent to one side until it ends in the kidney-shaped cross section 58 opposite '56. The. cylinder D begins to expand as a frustrum of a cone at 55 and is continued to the right as at D from the place 56-58, with increased diameter. The electric lines of force of the incoming symmetric electric waves approaching from the left are in part radially disposed, with their outer ends to some extent; tied to the shell D. On arriving at the end 51 of the-inner conductor they break and their inner ends attach to the shell 51 and they go on as coaxial conductor waves. The ratio of the inner and outer radii, as indicated at Fig. 231)., is chosen at such a value as to give a proper impedance match between the dielectric guide D on the left and this coaxial conductor system having the inner conductor 51. Going on to the right, the lines of force are gradually redirected, extending across between the two conductors 55" and 51',

and eventually, withtheir principalucomponent parallel to a horizontal plane, they are launched from the

ends

56, 58 into the part of the guide D as asyimnetricgelectric waves. To get a good impedance match throughout, it is desirable to make the diameter at D somewhat greater than at D.

The system of Fig. 22 has been described as for conversion from symmetric electric to asym-' metric electric, going from left to right. It will readily be apparent that the system may be employed for converting from asymmetric electric to symmetric electric, going from rightto left.

In general, a wave type converter will be reversible; that is, if it converts from one type to another type going from left to right, it will conmethod or apparatus of each such claim may be employed either way.

Referring to Figs. 24 and 25a to 250, the lines of electric force of asymmetric magnetic waves coming from the left are received on the conductors I54 which lie in a plane transverse to the axis of the dielectric guide D. These lines of force acting on the intermediate parts I54 of these conductors generate series-assisting electromotive forces in the circumferential parts I52 and I53 between which the parts I54 are connected. Also, these currents in the parts I52 and I53 are directed alike around the guide axis. From these circumferential segments, such as I52 and I53, the lines of force are detached and radiated on along the guide core, linking together in the form of the desired symmetric magnetic waves. A sieve of radial wires I05 is provided on the right to purify the symmetric magnetic waves, in other words, to block-any component at that place which may be present corresponding to the input asymmetric magnetic waves which might tend to break through on the output side. A sieve of horizontal wires I06 at the left purifies the incoming waves against other components than those belonging to the asymmetric" on the coaxial inner conductor 59 as coaxial conductor waves with their lines of electric force extending radially between the two conductors 59 and D. Each of these two conductors is split, one on one side and theother on the other side, as in Fig. 270. The gap 60 in the outer shell may be filled with dielectric material as at 6|. Going on to the right, the two splits are made wider and wider until in cross section each is about a semicircle, whereupon the inner member is expanded to the same size as the outer member; the corresponding cross section is shown in Figs. 27d and 27e. Finally, the two half shells are fused together giving an outgoing shell on the right of simple cyl ndrical contour. It will readily be seen that the radial lines of force which extend outwardly from the inner member at 59 become pushed over more and more past the edges of the cylindrical shell until eventually they stretch across horizontally from one side to the other and are launched to the right as the latter group of figures representing successive cross sections. In view of the explanation that has gone before, it is believed that the transition will be readily apparent by noticing the arrows in the cross sectional views which indicate the electric lines of force of the progressively converted waves.

Yet another converter between the same two types is shown in Figs. 30 and 31a to 311. Here the incoming symmetric electric waves from the left are converted into coaxial conductor system waves with radial lines of force as shown in Fig. 31a. The central conductor is split as one goes from left to right and given a spiral cross section, with the outer end of the spiral connected eventually to the shell of the dielectric guide. 'I'hen going on from left to right, the inner part of the spiral is gradually cut away and the transverse lines of electric force of the waves are brought more and more to an approximately horizontal direction, until finally the wave is launched at the right as an asymmetric magnetic wave.

For effecting conversion of waves from sym metric electric type to symmetric magnetic type, the system of Figs. 32, 33 and 34 may be employed. Here the incoming symmetric electric waves from the left are received on the coaxial conductor system having the central core and the outer shell D which is the shell of the dielectric guide. Thus at 5| the lines of force extend radially between these two conductors. The conductor 5| ends at the right in two arms bent around as shown in the cross section of Fig. 33. The radial lines of force coming from the left are deflected by the extensions 52-53 and radiated therefrom to the right in the form of symmetric magnetic waves. The sieve of radial wires 54' blocks any superposed remnant of the symmetric electric waves and permits the passage to the right of only the purified resultant symmetric magnetic waves.

Fig. 35 shows apparatus for the conversion of symmetric electric waves to symmetric magnetic waves. Symmetric electric waves of the character indicatedv in Figs. 1 and 2 are to be thought of as coming along the dielectric guide D of Fig. 35 from the left toward the right. At 15 there are flat members arranged side by side to form a cylindrical contour. The radii of the shell D and of the compositecylinder 15 are appropriate to match the impedances of the dielectric guide D on the left to the combination D'|5 considered as a coaxial conductor.

Going on from left to right, each strip or plate I5 is given a progressive helical twist and at the same time is made wider; also, going from left to right over this same stretch from D to D, the diameter of the enclosing metallic sheath is increased gradually. Eventually at the right, that is, at 15', each strip 15 has been twisted 90 degrees so that in a cross section at 15' each section is radial. At their ends 15', where the members extend radially, they merely touch the inside wall of the metallic sheath D, but are spaced slightly therefrom.

The lines of force of the symmetric electric waves approaching from the left have substantial radial components and these are caught between the members I5.and D and extend radially as indicated in Fig. 36a. Progressing from left to right these lines of fgrce gradually lose their connection to the surrounding shell D-D and attach themselves each to the next adjacent segment in a circumferential direction until all the lines of force extend consecutively from one or another member 15 to the next member 15' in one direction around the guide. These various elemental lines of force then link together end to end as they are detached from the right-hand ends of the members 15 and progress to the right waves of another dielectrically guided type, re-

ceiving them as lines of force on a conductor system, guiding these lines on such conductor system so as to reshape them to the desired type, and detaching them from said conductor system to be propagated within the guide.

2. The method of converting electromagnetic waves in a dielectric guide from one dielectrically guided type to another which consists in receiving the one type waves on conductive baffles disposed and arranged to bend the lines of force and reshaping them so that they will be discharged from said baffles in the shape of the other type of waves.

3. The method of converting waves of one type to another type in a dielectric guide system which consists in catching the ends of the lines of force of the incoming waves on conductive baflles, bending said lines of force on said baifles and discharging them therefrom with their ends linked together to form waves of the other type.

4. In combination, a dielectric guide and conductive baffles therein adapted to engage the ends of lines of force of incoming dielectrically guided waves of one type in said guide and to deflect and reconnect such lines of force and detach them from the bailles in the shape of lines of force of another type of waves.

5. In combination, a dielectric guide and conductive bailles therein adapted to cut into the lines of force of incoming'dielectrically guided waves of,a certain type, said baffles being bent as one goes along them in the direction of wave transmission so as to reshape the lines of force on them and discharge them in the direction of the outgoing waves to form such waves of a different desired type.

6. A converter to change electromagnetic waves in a dielectric guide from one dielectrically guided type to another comprising a plurality of helical baflles side by side to act on different parts of the incoming wave front and rotate their lines of force so that at the discharge ends of the baiiles they will link together to form waves of the desired output type.

7. In combination, a dielectric guide, means to convert incoming dielectrically guided waves of one type therein to outgoing waves substantially of another type, and a screen across the guide on the output side to purify the waves of the outgoing type.

8. In combination, a dielectric guide,awavetype converter therein adapted to deliver symmetric magnetic waves on its output side, and a screen of radial wires on the output side to purify such waves.

9. In combination, a dielectric guide, andmeans therein to convert incoming dielectrically guided waves of one type to outgoing waves of another type, said guide having a diiferent diameter each way from said means, the greater diameter being associated with the wave type'oi higher cut-ofi frequency.

10. In a dielectric guide system, a converter for changing asymmetric magnetic Waves to symmetric magnetic waves consisting of a main guide for the incoming asymmetric magnetic waves, a plurality of smaller parallel branch guides, respective helical bailles in said branch guides adapted to rotate the lines of electric force so that at the discharge ends of the said baflles they will link together in sequence in coaxial circles, and an outgoing dielectric guide connected around such discharge ends.

11. A converter to change asymmetric magnetic waves to symmetric magnetic waves in a dieleclines of electric force of the incoming waves and discharge them so that they will link together in coaxial circles to form symmetric magnetic waves.

12. In combination, a dielectric guide, helical battles therein side'by side adapted at their ends one way to receive respective groups of lines of force of second order asymmetric magnetic waves and rotate those lines of force so that at the discharge end they will be directedjn sequence around the axis so as to link together and form coaxial circular lines of force of symmetric magnetic waves.

13. In combination, a dielectric guide, and means therein to convert electromagnetic waves from one to the other of the two types, asymmetric magnetic and asymmetric electric, such means consisting of two conductors inside the guide with opposed kidney-shaped cross sections at one end and opening out to opposed arc-shaped cross sections at the other end.

14. In combination, a dielectric guide, means core and a cylindrical conductive shell, said core being graded trough-like into a semi-cylindrical shell, and said cylindrical shell being beveled to an opposite semi-cylindrical shell, and the resultant two semi-cylindrical shells being fused together.

16. The method of operating a dielectric guide system which comprises generating dielectrically guided waves of a first type, converting said waves to dielectrically guided waves of a second type, and propagating said waves of the second type along a dielectric guide.

1'7. In a dielectric guide system, the method 1 which comprises generating dielectrically guided waves of a certain type, distorting said waves to produce dielectrically guided waves of another type, and propagating said waves of another type along a dielectric guide.

18. In a dielectric guide system, a generator of dielectrically guided waves of a first type, means in the vicinity of said generator for progressively modifying said waves to produce dielectrically guided waves of a second type, a dielectric guide and means for applying said waves of said second verting one type of dielectrically guided wave into another comprising a pair of metallic members within the guide, said members being oi. progressively different cross-section along the guide, sub.- stantially arcuate and peripheral at one point and more nearly axial and oval at another point.

21. In a dielectric guide system, means for converting one type of dielectrically guided wave into another comprising a metal-sheathed section of guide and a metallic core therein which progressively along the section of guide is coaxial at one point, eccentric at another and joined to the sheath at another, whereby symmetric waves at the one point and asymmetric waves at the lastmentioned point are inter-convertible.

22. In combination, a cylindrical metalsheathed dielectric guide carrying dielectrically guided waves of the symmetric magnetic type and a purifier of waves of that type comprising a multiplicity of radial conductors electrically connected at the axis of said guide to each other and at their peripheral ends to the sheath.

23. In combination, a metal-sheathed dielectric guide carrying dielectrically guided waves of a certain type and means for attenuating said waves comprising a plurality of conductors lying in planes containing the axis of said guide and interconnected to provide a plurality of closed transverse loops.

24. In combination with a dielectric guide, means for purifying dielectrically guided waves of a certain type therein comprising a screen of conductors that are substantially orthogonally disposed with respect to the electric field of said waves.

25. In combination with a dielectric guide, means for attenuating dielectrically guided waves of a certain type therein comprising a plurality of conductors disposed obliquely with respect to the lines of electric intensity of said Waves and connected to form a plurality of conductive loops for the circulation of current.

26. In combination with a metal-sheathed structure and means for transmitting dielectrically guided waves therethrough, a screen of parallel wires extending across said structure in the path of said waves.

27. In combination with a wave guide and means for propagating dielectrically guided waves therealong, a screen comprising a multiplicity of parallel conductors extending across said guide in the path of said waves and interconnected to form a plurality of electrically closed circuits.

28. In combination, a wave guide, means within the guide to generate dielectrically guided waves having a substantial component of a certain type of waves, and a sieve across the guide consisting of conductors extending transversely to the lines of force of waves of that type, whereby undesired components will be suppressed.

GEORGE C. SOUTHWOR'HI.