US2895075A - Electronic devices - Google Patents

Description

y 14, 1959 R. MILLERSHIP 2,895,075

7 ELECTRONIC DEVICES Filed Dec. 12, 1956 1 2 Sheets-Sheet 1 R. MILLERSHIP ELECTRONIC DEVICES July 14, 1959 Filed Dec. 12, 1956 2 sheets -sheet 2 15 FIG.8.

FIG.7.,

wnnn-wnnnnnnnnnnn-w United St ws Patent 2,895,075 ELECTRONIC DEvitiEs iRonald Millership, London, England, assignoito Elliott Brothers (London) Limited, London, England, 'a British company H Application December 12, 1956, Serial No. 627,796 Claims priority, application Great Britain December 12, 1955 22 Claims. (Cl. 315-39) This invention relates to improvements in electronic devices and is particularly concerned with improvements in devices of the kind (hereinafter referred to as being of the.kind specified?) adapted to be inserted into a waveguide to extract energy therefrom and to provide an indication of the magnitude of the energy propagated through the waveguide. and comprising anfevacu'ated envelope, which may or may notcontain a vapour or gas at a low pressure, in which is disposeda cathode arranged axially within a cylindrical anode to provide a co-axial transmission line, the cathode. extending b'eyond'at least one end of the anode and a transformer associated with such extension of the cathode adapted to transform the mode of the energy propagated through the waveguide to a mode for propagation along the coaxial transmission line provided by the anode-cathode structure.

, In such devices it is desirable that the minimum amount of energy should be reflected back along the waveguide and also that the minimum amount of energy should be reflected back from the end of the co-axial line remote from the input waveguide. vIt has been proposed to achieve the latter by extracting the energy from the device after it is passed along the coaxial line by the provision within the device of a further transformer which is adapted to transform the mode of the energy propagated along the co-axial line into an appropriate mode for transmission along a further waveguide and to' associate with the device and this further transformer such a further waveguide which is suitably arranged to absorb the energy with the minimum of reflection after it'has been propagated through the coaxial line. Such'known devices suffer from the disadvantage that they require to be associated with a further waveguide as referred to above and the task of replacing a device is made tedious and time consuming by the necessity of removing the further waveguide from its association with the device before the latter can be'removed from the first mentioned waveguide along which the energy to be measured is being propagated.

it is an object of the present lnvention to provide an improved electronic device of the kind specified which :shall not require to be associated with a further waveguide, which may readily be inserted into or removed from a wave-guide along which the energy to be measured ;is to be propagated, and which shall be economic ,to

manufacture. I

The present invention broadly stated comprises an electronic device of the kind specified wherein the cathode is surrounded by a body of lossy dielectric material at a location spaced from the transformer in the direction .in which the energy is to be propagated along the coaxial line constituted by the anode cathode structure.

Preferably the material is arranged to produce the minimum reflection along the .co-axial line towards the transformer.

In a preferred embodiment of the present invention the :cathode extends beyond the cylindrical .anode in the direction in which energy is to be propagated along the co-axial line and the envelope is surrounded by a sleeve oflossy dielectric material which has one end contained substantially in the plane containing the end of the anode remote 2,895,075 Patented July 14, 1959 ICC . 2 from the transformer and extends away therefrom in the direction of propagation of energy along the co-axial line.

It is preferred to taper the sleeve at its said one end and advantageously the radial thickness of the sleeve increase gradually from the said one end towards its other end.

The term lossy dielectric material as used herein is defined as meaning a material having a large magnetic and/ or electric loss angle.

In order that the invention may be clearly understood some'embodiments thereof will now be described by way of example reference being made to the accompanying drawings in which:

Fig.1 is a part-sectional part-elevational view of a device according to the invention showing it associated with a waveguide through which the electromagnetic energy to be measured is to be propagated,

Fig. 1A is a section taken on the line IAIA of Fig. 1, I Fig. 2 is a plan view of an element shown in Fig. l,

and

-Figs. 3 to 8 are fragmentary sectional views illustrating modifications of the device of Fig. 1.

In the first example illustrated in Fig. 1 the device comprises a hollow tubular cathode 1 which extends coalxially through a cylindrical anode 2, the axial length of the'cathode 1 being greater than that of theanode 2 so that the cathode 1 is surrounded by the anode 2 for only a part of its length intermediate its ends. The cathode 1 and the anode '2 constitute a .co-axial transmission line and are enclosed in an evacuated glass envelope formed in twoco-axial substantially clindrical parts indicated at 33; and. 3b. The anode 2 Which. is shown in elevation in Fig. 1, is supportedlwithin the envelope by means of a thin metal sleeve 4 which is in electrical contactwith the anode 2 and has an annular flange 5 which is slightly dished at its periphery and which is connected at its periphery to a surrounding annular element 5a by four equi-angularly spaced radial arms 5b (as can be seen more clearly in Fig. 2) which are sufliciently flexible to permit the annular element 5a to move slightly in the axial. direction relative to the annular flange 5. The flange 5 extends between the adjacent ends of the parts 34 and 3b which, are sealed on to the flange 5, the latter together with the annular element 5a providing an electrical connection externally of the envelope for the anode Q4. One end of the cathode 1 which extends beyond the one end of the anode 2 in the envelope part 3b extends .through a transformer 6 of known construction and is electrically connected thereto and is located and sup ported thereby. This end of thej cathode 1 is sealed into a glass seal (not shown) which closes the end of the envelope. part 3b remote from the part 3a. The other end of the cathode 1 extends for some distance beyond the other end of the anode 2 within the envelope part 3a and is.;supported and located by .a spider element 7. This end of-the cathode 1 is pinched on to the end of a heater ,coil finot shown) which extends through the cathode 1 throughout the length thereof and which is electrically connected .bymeans of the lead 8 to the metal cap 9 which covers theclosed end of the envelope 3b. The pinched end .of the cathode 1 is secured to an element 10 which is connected by means of a spring 11. to a similar element 12, secured to a pin 13 which extends through the closed endof the envelope part 3a. The elements 10 and 12 are electrically conducting and are electrically connectedto each other by a flexible lead 14 so that the cathode 1 is electrically connected to the pin 13. The spring 11 accommodates any variation in the length of the cathode 1 which occur in use due, for example, to temperature variations.

LA: metal'sleeve 15, e.g. of copper, of hollow frusto- 'conical'for'm', having at its smaller end an internal diam.

eter slightly greater than the external diameter of the envelope part 3a, is slipped over this part with its smaller end leading until the plane containing the smaller end is substantially coincident with the plane containing the end of the anode 2 remote from the transformer 6. The axial length of this sleeve is such that in this position its larger end extends a short distance beyond the closed end of the envelope part 3a. The space between the inner surface of the sleeve 15 and the outer surface of the envelope part 3a is then filled with a lossy dielectric material indicated at 16. This material is preferably composed of ferromagnetic dust in a binding medium such as polymerised resin which may, or may not, be expanded. A material which has been found to be especially suitable is a suspension of fine carbonyliron dust in a binding medium such as that sold under the trade name of Marco Resin, in equal proportions by weight. This suspension of fine conducting particles in a binding agent constitutes a dielectric material having a high dielectric constant and large magnetic and electric loss angles, whose properties can be controlled by variation in the proportions of magnetic material present in the'dielectric material and by variations in the particle size of the magnetic material together with a selection of magnetic material having suitable conductivity and magnetic properties. The lossy dielectric material 16 maybe introduced into the space between the sleeve 15 and the envelope part 3a in a fluid or semi-fluid state, and then caused or allowed to set or it may be introduced in a finely divided powdered form and caused to assume a coherent solid state. The larger diameter end of the sleeve 15. is then closed with a metal disc 17 having a central aperture which receives the outer end of "the pin 13 which is then electrically connected thereto, e.g. by solder. The disc 17 is in electrical contact with the sleeve 15 so that the latter is in electrical contact with the cathode 1 and the end of the coiled heater remote from the lead 8.

Four fins 18 (of which only two can be seen in Fig. 1) are secured to the outer surface of the sleeve 15 for the purpose of dissipating heat and are arrangedto extend radially from the sleeve 15 being disposed at 90 intervals around the latter. The outer longitudinal edges of the fins 18 extend substantially parallel to the axis of the cathode 1 and the axial length of the fins 16 is such that they extend from the larger diameter end'of the sleeve 13 to within a short axial distance of the flange 5. The fins are cutaway as at 19 adjacent to the smaller diameter end of the sleeve 15 and they are secured to or 1 formed integrally with an annular member 20 adjacent to the flange '5. The face of the member 20 remote from the fins 18 is recessed slightly as at 23 to receive a washer 24 of insulating-material which stands ,above this face of the disc and bears against the annular element'Sa. The recessed face of the-member 20 is formed witha shallow radial groove 21 of relatively smallwidth. A cup-shaped nut-member 25 is provided having an aperture 26 formed in its base of a diameter to permitfthe member 25 'to be slipped over the fins 18 but such that it will engage the-annular member 20. The cylindrical wall of'this member 25 is threaded internally soas to be capable of engaging an annular member '27 which is threaded externally and which forms part of ach'oke block indicated generally at 28. The choke block 28 surrounds a part of -the length of the rectangular-section waveguide 29 through which the energy to be measured is to be propagated, and has one wall 30 through which a plug 31 fora co-axial cable extends and-two side walls 32 and 33 which flank the'wider walls of the waveguide 29. The walls 32 and '33 and the associated wallsof the waveguide 29fare formed with circular apertures "to provide passages 34 and 35 respectivelythrough which the envelope part Sb'may extend with'clearance. Secured to the outer face of the wall 32 is an annular m'e'fnber 36 having an'annular'recess 37 on its inner face.

The face of the annular member 27 presented to the wall 33 is formed with an annular recess 38. The axial lengths of the passages 34 and 35 and the radial width of the respectively associated recesses 37 and 38 are selected to be such that when the device is inserted through the passages 34 and 35 so that the plane containing the end of the anode 2 adjacent to the transformer 6 is substantially co-planar with the inner surface of one of the wider walls of the waveguide 29 and the transformer 6 extends through the opposite wall of the waveguide; the passage 34 and the recess 37 will provide an effective short-circuit between the transformer 6 and the associated wall of the waveguide 29 and the passage 35 and the recess 38 will provide an effective short-circuit between the anode 2 and the associated wall of the waveguide.

The outer face of the member 27 is formed with an annular recess 39'having an outer diameter substantially equalto'that of the recess 23. This recess 39 is lined with a cup-shaped washer 40 of insulating material within which isdisposed a metal ring 41 connected by an insulated lead 42 'to the pin 43 of the plug 31 for connecti'ont'o the inner conduct'or of a co-axial cable. The wall of the memberf27 bounding the recess 39 is formed with aradial 'slot 39a to accommodate the lead 42 and the washer 40 is formed with a radial slot 40a which is arrangedas a continuation of the slot 39a so that the lead 42 extends through the slot 40a to the ring 41.

When "it 'is desired to insert a device constructed as desefibed above into the waveguide 29, the device is passed thrdugh'the passages 35 and 34 with the cap '9 leadiii'gffintil the annular element 5a connected to the flahge'Sfisbroiight up against the metal ring 41. The fiiut'nieinber '25 is thentightene'd onto the annular memberf 27 sothattheflang'e 5 and the ring 41 are sandwiched ibetweeh fthe washers '24 and 40. V The flange 5 is then connected electrically to the pin 43. The slight amount of: relativeaxi'al movement which is possible between the annular element '54 and the flange 5 due to the radial arins 5b prevents the seal 'between the envelope parts 3a am 3b and the flange 5 being broken when variations in the axial lengths of the envelope parts 3a and 3b and the 'fi'ns 18 occur due to temperature variations. The dimensions of the various members are such that when the annular e'leiririt'Sdbears against the ring 41 the end of f'the anodel adjacent the transformer 6 is substantiallyco-planar with the inner surface of one'wall of the waveguide and the transformer 6 extends through the fopposite'wa'll of the waveguide 29 to the interior of the latter.

In the operation of the device the electromagnetic energy 'propag'ated along the waveguide 29is transformed into "the appropriate mode and is propagated along the ,co-axial line provided by the anode-cathode structure. v'vill be understood an adjustable matching plunger fmay befp'rovided'in'the'waveguide 29 on the side of the device remote'fromthe source'of the energy'to prevent "reflections. The anode 2 acquires a potential which is a function "of themagnitude of the energy propagated "along thewaveguide 29 and this appears at the pin 43 which may be connected by a coaxial cable to one of the plates ofa cathode-ray tube where thispotential can 'b'e u's'ed to'give'a visualtrace the amplitude of which is a fu'notionof'the magnitude of the energy propagated alongfthe 'wavegide'2 9, The energy propagated along the"co' axialline coristituted'by the anode-cathode structure isfgr'adually' absorbed by the lossy dialectric material '16f'as it lpassesthrough the plane containing the -eridofthe"anode '2'remote f'rom the transformer 6. Due to the fact that the lossy dielectric material '16 comfmences'at 'this'plane and its radial'thickness. gradually increases in the' direction of propagation, the minimum nt of energy isreflected back to'the anode-cathode uctiire, The axial; length 'of'the sleeve of lossy diniatfial isYpreferably 'made such that'it will absorb substantially all of the energy delivered from the anode-cathode structure. Q

It will be readily appreciated that the lossy dielectric material 16 need not necessarily be arranged as described above with reference to Fig. 1. The only essential feature is that it should surround the cathode and should absorb atleast a proportion of the electromagnetic energy after propagation through the anode-cathode structure. Alternative arrangements are illustrated in Figs. 3 to 7 in which thelossy dielectric material is disposed within the envelope part 3a and .in Fig. 8 in which the lossy dielectric material is disposed externally of the envelope part 3a in a manner somewhat similar to that shown in Fig. 1.

In the arrangement illustrated in Fig. 3 the end of the anode 2 remote from the transformer 6 (not shown) is flared gradually outwards as at 2a and the space between the inner surface of the flared portion 2a and an imaginary continuation of the inner surface of the cylindrical part of the anode 2 is filled with the lossy dielectric material 16 which will absorb the energy propagated along the anode-cathode structure with the minimum of reflection.

In the arrangement illustrated in Fig. 4 the anode 2 is again flared outwards as indicated at 2a and in this example the cathode 1 is also flared outwards as at 1a to provide an annular space between the anode 2 and cathode 1 and the parts 2a and 1a which has a constant radial dimension throughout its length. The space bounded by the inner surface of the part 2a, the imaginary extension of the cylindrical part of the anode 2 and a part of the part 1a is filled with lossy dielectric material 16.

In the arrangement illustrated in Fig. 5 the lossy dielectric material 16 surrounds the cathode 1 within the anode 2 and is in the form of a conical plug coaxial with the cathode 1 which has a diameter at its base equal to the diameter of the anode 2 so as to close the end of the latter remote from the transformer 6 (not shown).

' In the arrangement illustrated in Fig. 6 the end of the cathode 1 at a location adjacent to the end of the anode remote from the transformer 6 (not shown) is gradually reduced in diameter and this tapered end is surrounded by a body of dielectric material 16 of gradually increasing thickness such that the outer surface of the material 16 forms a continuation of the outer surface of the cathode 1.

' In the arrangement illustrated in Fig. 7 the lossy dielectric material 16 is in the form of a cylindrical plug which closes the end of the cylindrical anode 2 remote from the transformer 6 and which at its inner end is formed with a conical recess 16a such that the energy propagated along the anode-cathode structure encounters an increasing thickness of the material.

The arrangement illustrated in Fig. 8 is similar in many respects to that illustrated in Fig. l, the frustoconical sleeve 15 of that example being also employed in this arrangement. A short distance from the adjacent end of the anode 2 of the cathode 1 is flared outwards as at la and then merges into a cylindrical body portion 1b which supports the cathode within the envelope. The wall of the flared part 1a is continued externally of the envelope by a frusto-conical metallic sleeve 15a similar to the sleeve 15 and the space bc tween the sleeves 15 and 15a is filled with lossy dielectric material. The cathode 1 is shown in Fig. 8 in elevation with the flared part 1a and the cylindrical body portion 111 shown largely in section.

As will be understood an electronic device according to thisinvention is used to extract energy from and to provide an indication of the magnitude of the energy propagated through a waveguide by inserting the device into the waveguide in the manner illustrated in Fig. 1 so that the energy propagated along the waveguide is transformed 'by the transformer=6and propagated along the co-axial transmission line constituted 'by the cathode 1 and the anode 2. As described the cathode is heated and emits electrons which are-subjected'to the fields of electromagnetic energy propagated along the co-axial transmission line. Due to the electrons reaching the anode 2 the latter acquires a negative potential with respect to the cathode, and owing to the effect of the energy propagated along the transmission line on the flow of these electrons, the magnitude of the potential acquired by the anode is a function of the magnitude of the energy propagated through the waveguide and provides a measure thereof.

What I claim is:

1. An electronic device of the kind adapted to be inserted into a waveguide to extract energy therefrom and to provide an indication of the magnitude of the energy propagated through the waveguide, comprising an evacuated envelope, a cylindrical anode disposed within the envelope, a cathode arranged co-axially within the anode to provide a co-axial transmission line, the cathode extending beyond at least one end of the anode, a transformer associated with such extension of the cathode and disposed wholly within the envelope and adapted to transform the mode of energy propagated through the waveguide to a mode for propagation along the co-axial transmission line and a body of lossy dielectric material surrounding the cathode at a location spaced from the transformer in the direction in which the energy is to be propagated along the co-axial transmission line.

2. A device according to claim 1 wherein the cathode extends beyond the cylindrical anode in the direction in which energy is to be propagated along the co-axial line and said body is in the form of a sleeve surrounding said envelope and having one end contained substantially in the plane containing the end of the anode nemote from the transformer and extending away therefrom in the direction of propagation of energy along the co-axial line.

3. A device according to claim 2 wherein the radial thickness of said sleeve increases gradually from the end thereof nearest said transformer for at least a part of its length.

4. A device according to claim 1 wherein the body of material is disposed within the envelope.

5. A device according to claim 4 wherein the end of the anode remote from the transformer is flared outwards and the body of material substantially fills the space between the inner surface of the flared portion of the anode and an imaginary continuation of the inner surface of the cylindrical part of the anode.

6. A device according to claim 4 wherein the end of the anode remote from the transformer is flared out- 'wards, the cathode, which for the major part of its length is tubular, has its corresponding end similarly flared to provide an annular space between the anode and the cathode which has a constant radial dimension throughout its length and said body of material substantially fills the space bounded by the inner surface of the flared part of the anode, an imaginary continuation of the cylindrical part of the anode and a part of the flared part of the cathode.

7. A device according to claim 4 wherein the body of material is in the form of a substantially conical plug which is disposed within the anode and surrounds and is co-axial with the part of the cathode, the larger diameter end of the plug closing the end of the anode remote from the transformer.

8. A device according to claim 4 wherein the end of the cathode at a location adjacent to the end of the anode remote from the transformer is gradually reduced in diameter and the body of material surrounds this tapered end of the cathode in a gradually incneasing thickness such that the outer surface of the material forms a continuation of the outer surface of the cathode. 9. A device accordingto claim 4 wherein the body of material is in the form of a cylindrical plug disposed within the anode and which closes the end thereof from the transformer, the inner end of the plug being formed with a conical recess such that the energyprop'agated along the anode-cathode structure encounters an increasing thickness of the material.

10. A device according to claim 1 wherein the envelope is in two parts and the anode is supported within the envelope by a thin metal sleeve having an annular flange which extends between adjacent ends of said envelope parts said adjacent ends being sealed on to said flange.

11. A device according to claim 10 wherein said flange is slightly dished.

12. A device according to'claim 10 wherein said flange is connected to a surrounding annular element by arms which are sufficiently flexible to permit slight axial movement of said annular element relative to said flange.

13. A device according to claim 1 for use in association with a waveguide of rectangular cross-section and having associated therewith a choke block comprising two side walls adapted to flank the Wider walls of the waveguide and each formed with a passage through which the envelope extends with clearance, and an annular member secured to the outer face of each side wall and formed on its inner face with an annular recess, the length of the passage in each side wall and the radial widthof the annular recess in the associated annular member being selected to be such that when the device is inserted through the passages so that the plane containing the end of the anode is substantially co-planar with the inner surface of one of the wider walls of the waveguide and the transformer extends through the opposed wider wall of the waveguide, one passage and annular recess provide an effective short-circuit between the transformer and the associated wider wall of the waveguide and the other passage and annular recess provide an effective short-circuit between the anode and the associated wider wall of the waveguide.

14. An electronic device of the kind adapted to be inserted into a waveguide to extract energy therefrom and to provide an indication of the magnitude of the energy propagated through the waveguide, comprising an evacuated envelope, a cylindrical anode disposed within said envelope, a cathode disposed coaxially within said anode to provide a co-axial transmission line and extending at each end beyond said anode, at least that part of said envelope surrounding the extension of the cathode beyond one end of the anode being of substantially uniform circular cross-section, a transformer disposed wholly within said envelope and associated with the extension of the cathode beyond the other end of the anode and adapted to transform the mode of energy propagated through said waveguide to a mode for propagation along said co-axial transmission line, a hollow frusto-conical metal sleeve surrounding said part of said envelope with its smaller diameter end contained substantially in a plane containing said one end of said anode, and a body of lossy dielectric material substantially filling the space between said part of said envelope and said metal sleeve.

15. A device according to claim 14 wherein a number of fins are secured to the outer surface of the metal sleeve for the purpose of dissipating heat.

16. A device according to claim 15 wherein the fins are equiangularly spaced about the axis of the metal sleeve.

17. A device according to claim 15 wherein the outer longitudinal edges of the fins extend substantially parallel to the axis of the cathode.

18. A device according to claim 15 wherein the axial length of the fins is such that they extend beyond the smaller diameter end of the metal sleeve towards the transformer.

19. A device according to claim 18 wherein an annular member is secured to or integral with the ends of the 8 fins nearest to' the transformer, this annular member providing a means whereby the device may be coupled to a choke'block.

20. An electronic'device of the kind adapted to be inserted into a waveguide to extract energy therefrom and to provide an indication of the magnitude of the energy propagated through the waveguide, comprising a substantially cylindrical evacuated envelope, a cylindrical anode disposed within said envelope, a cathode disposed co-axially within said anode to provide a coaxial transmission line and extending at each end beyond said anode, a 'transforrn'er'disposed wholly within said envelope and associated with the extension of the cathode beyond one end of said anode and adapted to transform the mode of energy propagated through said waveguide to a mode for propagation along said co-axial transmission line, a hollow frusto-conical metal sleeve surrounding that'part of said envelope in which is disposed the extension of the cathode beyond the other end of said anode, said "metal sleeve being disposed with the smaller diameter end thereof substantially contained in a plane containing said other end of said anode and extending away from said transformer the axial length of said metal being such that the larger diameter end thereof extends a short distance beyond one end of said envelope, a body of lossy dielectric material substantially filling the space between saidmetal sleeve and saidenvelope, a metal disc closing said larger diameter-end of said metal sleeve and an "electrical connection from said metal disc to said cathode.

21. A device'acc'ordin'gto claim 20 wherein said elec trical connection includesa pin'extending through said envelope and electrically connected to said metal disc arids'aid cathode.

22. An electronic device 'of the kind adapted to be inserted into a waveguide to extract energy therefrom and to provide an indication of the magnitude of the energypropagated through the waveguide, comprising an evacuated envelope, acylind'rical anode disposed within said envelope, 'a cylindrical cathode disposed co-axially within said-anode to provide a co-ax-ial transmission line and extending at each end beyond said anode, at least that part of'saidenvelope surrounding the extension of the cathode beyond one endof the anode being of substantially uniform'circular c'ross-section and the exten sion of said cathode within said part of said envelope being flared conically outwards to merge into a cylindrical body portion which supports said cathode within said envelope,-a transformer disposed wholly within said envelope and associated with the extension of said cathode beyond the other end of said anode and adapted to transform the mode'of energy propagated through said waveguide to a mode for propagation along said co-axial transmission line, two similar hollow frusto-conic'al metal sleeves co-axially disposed around said part of said 'e'n'evl'o'pe in spaced relationship with the smaller diameter end of one substantially contained in a plane containing said one end 'of said anode and the smaller diameter end of the other sleeve spaced therefrom on the side remote from said other end of said anode, said other sleeve being arranged'as ac'o-ntinuation of said flared conical "part'of said cathode and a body of lossy dielectric material substantially filling the annular space between the two metal sleeves.

References Cited in the file of this patent UNITED STATES PATENTS 1,971,902 Claviera Aug. 28, 1934 2,122,538 Potter July 5, 1938 2,129,712 Southworth Sept. 13, 1938 2,433,074 Tuller Dec. 23, 1947 FOREIGN PATENTS

Images