US2663822A - Ultrahigh-frequency electric discharge tube - Google Patents

Description

Dec. 22, 1953 G. DIEMER ET AL 2,663,822

ULTRAHIGH-FREQUENCY ELECTRIC DISCHARGE TUBE Filed Nov.. l, 1951 5 Sheets-Sheet l INVENTORS Gesinus Diemer Klaus Rpdyhuis Dec. 22, 1953 e. DIEME'R ETAL 2,663,822

ULTRAHIGH-FREQUENCY ELECTRIC DISCHARGE TUBE Filed NOV. 1, 1951 5 Sheets-Sheet 2 Gesinus Diemer Kloos RWW By 7/1 Agent Patented Dec. 22, 1953 ULTRAHIGH-FREQUENCY ELECTRIC DISCHARGE TUBE Gesinus Diemer and Klaas Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn., as

trustee Rodenhuis, Eindhoven,

Application November 1, 1951, Serial No. 254,274

Claims priority, application Netherlands November 4, 1950 Claims.

This invention relates to circuits comprising electric discharge tubes which are suitable for short operation at short and ultra-short wavelengths, i. e. wavelengths of several metres down to approximately one centimetre and which comprise at least a cathode, a, control grid and an output electrode. The last-named electrode in a normal triode, tetrode or pentode is the anode; for the centimetric range'it is substantially only triodes that enter into account.

In order to make such tubes serviceable, for example as amplifiers, at as short a wavelength as possible, vefforts have been directed towards minimizing the capacity between the input electrode and the common electrode on the one hand and between the common electrode and output electrode on the other hand. At wavelengths that are not excessively short the cathode is usually the common electrode. With tubes comprising disc-shaped electrode leads suitable for ultra-short waves, the control grid is usually the common electrode. .The capacity between the different electrodes depends not only upon the surface area of the electrodes and their relative spacing but also upon unavoidable parasitic capacity.

If that part of the capacity between the electrodes which is directly proportional to theactive surface is termed the effective capacity, it is well known that the effective capacity of a sim-' ple flat arrangement equals wherein 0=the active electrode surface and d=the spacing. For more intricate arrangements the effective capacity may be computed as the sum of a number of terms or in an integral form. That fraction of the total capacity that is not constituted by the effective capacity as defined will hereinafter be termed the ballast capacity."

In view of the necessity for maximum reduction of the tube capacities it is first essential to minimize the ballast capacity. However, for each electrode arrangement there is a minimum which may not be passed owing to the capacity of the wiring and supply conductors. For tube constructions comprising fiat electrodes and lead-through discs sealed into the wall of the tube, this minimum is lower than for tubes with a concentric arrangement and pin-shaped elec trode leads. I

As a rule the effective capacity must be comparatively high, since in particular the cathode two ratios and the product' thereof are equal to 2 I 7 surface must usually not be loaded above a given current density and the surface area must satisfy the desired power requirement.

According to the present invention in a circuit comprising an electric discharge'tube for short and ultra-short waves, the tubes including at least a cathode, a control grid'and an output electrode, the product of the ratios of the effective capacity and the ballast capacity between the input electrode and common-electrode and between the common electrode and the output electrode lies between and l, each of these ratios has a value between /2 and 2. The product of the two ratios preferably equals or approximately equals unity. In the optimum each of the two ratios equals unity. h I

The power gain attainable with the tube'in'the' case of complete matching is a maximum if the each other and unity respectively. 'Ifthe' two ratiosare each 2 or /2 the attainable power gain is 25% lower than the maximum, again with complete matching. This holds if the 'ohmic dampings preponderate relatively to the electronic dampings as is usually the case at very high frequencies. If the electronic damping is comparatively high, the power decrease is "reduced. The feedback due to the self-inductance of the grid wires of the tube should be small and in absolute value substantially equal the feedback due to the capacity between the anode and cathode.

V The'reasoning behind the choice of the aforesaid ratios and this product may be explained as follows; The maximum attainable power gain depends upon the mutual conductance of the tube, which generally has a complex value for high frequencies. Furthermore the power gain depends upon the input damping, the output damping and the feed-back in the tube. As a rule, the power gain with a non-excessive feed-t back will approximately be inversely proportionalto the product of the inputand output-damping, expressed as conductances, and substantially directly proportiona1 to the square of the absolute value of the mutual conductance. At very high frequencies the input-.-' and output-damping's largely depend upon the respective total capacity, effective and ballast capacity together; since the charging and discharging of these capacitances must take place through the series-resistors formed by the supply conductors and does not appreciably depend vupon the size of the electrode.

surfaces.

The correctness of the aforesaid criteria may be conformed from the considerations in an article by Knol and Van der Ziel in Philips Research, vol. 4, pages 168 to 178, 1949. Referring to Formula 'zfiiaheielhffer thfih 'wiiihiifii power ain amt; at an arbitrary four teri'rriha l network in the case of optimum tuning and matching at the input and output side and an arbitrary given feedback, it holds that vihiil'it rg R input resistance efl"ect1ve part of I input with open output f ack resistance=eective part of I input With shorteircu ited input V R foward resistairoe iafi'h'ti i 'e ears of --1 outpu phase angle, i'ortvard admittance Alithe'aaiifiitttifiees mhs'is't f an electronic and a nonelectmnic srq'the "1 tter'eqnsistm '0; the ohiiiieibs'ses. The ei" ron 'c l part 'i invariably prapoitiaiiai ta th attire. serrate the to the eet'fife'capaity. iThe'non electrbnic parts are rae rtfionei to t e iif'theto'tal capacity.

I the an; aid'forinula'eveiything is expressed"? the ra-t etten the stream-capa gmair has a maxim'irm if it t? i i d, "ba la t eapa ty a l'fii iictiofn 36f this rat'i'o eau'ai ifinity. a p p H V artertharthe i ivenffiient ay be 'inoi'e clearly shes 'vfil 310w gee f ame is "the afcco'iiipanyi'ng rasm'esieiveafbyiwey 'o'f sesame, in w ich; I --Y'fig 1"f"". '71 mattresses-t ase s stem orekiiewh'eaiibieeentadeahu 13$. 2 and {S are longitudinal sections of the elitiiod s nergies? s eet/i1 t ibes comprising dlscaha' semieaamu members and e; a triode cbifiiirrsiiie ms fhja'pe'd lea'd oiit members for us'acetriirie'summarises. a

frhe'fdrfiieiisiefis 6f t e 'ioubi'pjeiitoee shown in FEE, 1; "afi' a'r irofn l the "shale given. For sash,

fientoife ljdi'iotes thqtxwasra 231 's send- 1 gridlanaf'ttnescree' rid. The suppressor grid 4 ei eoilfstrated asia ape srea fsereenena is coiifri'ion ts fb tifitehtbae In thise-Tectrole system, it may be taken that the ballast capacity is present only at the ends dsystem and in the wiring, from which it can be deduced that for the reduced grid the efieetive capacity=2.05 pf, and the ballast capacity=3.25 pf. For the reduced anode the efiective "capacity is L55 pf, andtheballastpapacityf -lzfl pf gthe two ratios between effective capacity and ballast capacity then being and and the-product 0:95; 7

For the known tube the ballast capacities-are the same and the efiective capacities for :grid'and anode are $.16 and 4:5- pf. respectively, so that the ratios'are and a d the productfit. V p

'In the k' ip' n tats shewn i'n-FigQ-E; aeyiindrrcal ensue block are se'ied "to a Qi'iddisc fttfby means of a conical glass head 9. A glass u eehstjitutes thejdiht petween diesels and a oathd'debylin jl-"a. By inefans oflass beads two hest'er supeiy eon'aiietors1&4 a d a- "cathodesueei semester is aie' sea lejd 11; "the base 13. The exhaust tube is designates fifties filament '1"! and the cathode 8. The active surface of the cathode carries a thin iiifide layer (not shown). The cathode I8 is Welded with thec aid of foil [9 tothe flanged ame I. llts 'fia'rigj'e 'is emits-ea between two-s same rings- '22 and 23' iaiidfo'entred 'bya 2e au ts-sting ith the" 'supei 'emauc'tor 1"6. rh catu'oee is electric-any separated fr'om the vpyimesa;{ i y means at an insulating ring 25. ine 'fdohTstiiifcftionis diain'iieatbeether by means of foui""'spiings 26 extendme from ring 2'! and strained by cylinder 23. The cerairi'ic'i ine 22 bears ees eripir asrestr g' "on "the oathod'e s d' H or "grid 11 mg 30*which has secured thereto rrautyfdrem "wires. By means is sue-melt: tamer-mes! are secure three 5161s preview at ape lest: in rme'fz. Ks's'tated this construction isk'llown; it is 'fg ive n to .permit direct contrast with a cerrespthuin tube; for use according "to inventive 'shoiva in' Fig. 3. in Fig. 3 the cathbd'e Quee s ano euiscsa're' design'ated 31, e2; 33 respective'1yf34 'be'ing'a' cylindrical anode. :Ifhegrid ring 375 rests with its w'irewound-side es aeams theerii disc. A porous tungsten hood containing. a supply of bariumstrontium oxide 38 is designated 31. The cathode is connected to the cathode disc through foil 39. This tube is shown in lesser detail than the tube shown in Fig. 2, since there is no necessity to describe points following known tube-technique.

In the following table constructional data and properties are given for the known tube shown in Fig. 2 and for the tube shown in Fig. 3.

Ratio between effective and ballast capacity:

Cathode-grid Grid-anode Product of ratios between effective and ballast capacity. Attainable power gain at wave length. Supplied power Corresponding anode cur- 10 X7.5 cms rent and mutual con- 50 um ductance.

The capacities stated in the table are those of the tube without the capacities through the glass of the bulb. It is obvious that in the tube shown in Fig. 3 the total capacity between cathode and grid is materially lower. Moreover, the cathodegrid spacing through the bulb wall is simpler than through the foil shown in Fig. 2. The mutual conductance of the tube shown in Fig. 3 is one fourth of that shown in Fig. 2 and notwithstanding that, the power gain at the same wavelength similarly corresponds to the power supplied. This equally-satisfactory operation, despite the larger cathode-grid spacing and the low mutual conductance, is for the major part due to the favourable ratio between effective capacity and ballast capacity,

What we claim is:

1. An electric discharge tube comprising a cathode, an output electrode, and a common electrode interposed between said cathode and output electrode, said common electrode and said cathode electrode having active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said cathode and said common electrode, the ratio of said capacitances being between and 2, said output electrode and said common electrode having active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said output and common electrode, the ratio of the latter capacitances being between /2 and 2, said electrodes further being spaced from each other a distance at which the product of said ratios is between and 4.

2. An electric discharge tube comprising a cathode, an output electrode, and a common electrode interposed between said cathode and output electrode, said common electrode and said cathode electrode having'active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said cathode and said common electrode, theratio of said capaQitances being between and 2, saidou'tput electrode and said common electrode having active surface portions spaced apart a distance at which there is a given effective, capacitance and a given ballast capacitance between said output and common electrode, the ratio of the latter capacitances being between /2 and 2, said electrodes further being spaced from each other a distance at which the product of said ratios is unity.

3. An electric discharge tube comprising a cathode, an output electrode, and a common electrode interposed between said cathode and output electrode, said common electrode and said cathode electrode having active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said cathode and said common electrode, the ratio of said capacitances being approximately unity, said output electrode and said common electrode having active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said output and common electrode, the ratio of the latter capacitances being approximately unity, said electrodes further being spaced from each other a distance at which the product of said ratios is approximately unity.

4. An electric discharge tube comprising a cathode, an output electrode, a common electrode interposed between said cathode and output electrode, said common electrode and said cathode electrode having active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said cathode and said common electrode, the ratio of said capacitances being between /2 and 2, said output electrode and said common electrode having active surface portions spaced apart a distance 'at which there is a given effective capacitance and a given ballast capacitance between said output and common electrode, the ratio of the latter capacitance being between /2 and 2, said electrodes further being spaced from each other a distance at which the product of said ratios is between A and 4, and terminal wires for said common electrode, said terminal wires having a self-inductance at which feed-back introduced thereby equals the feed-back introduced through inter-electrode capacitance between the cathode and output electrode.

5. An electric discharge tube comprising a cathode comprising ahollow body of refractory metal having a cavity therein, one wall of said body adjoining said cavity being porous, and a supply of alkaline earth oxides in said cavity, an output electrode, and a common electrode interposed between said cathode and output electrode, said common electrode and said cathode electrode having active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said cathode and said common electrode, the ratio of said capacitances being between and 2, said output electrode and said common electrode having active surface portions spaced apart a distance at which there is a given effective capacitance and a given ballast capacitance between said output and common electrode, the ratio of the latter capacitance being between and 2. said electrodes Iurther being spaced from each other a distance a: which the product bf said r'atid's is between /4 and 4;

GESINDS DIEMER.

Number Name Number mms 2,121,589 2,131,204 2,353,?42 2,353,743 2,391,923 2 1 1 3.? 2,416,565

Name Date H1111 at al Feb. 8, 1933 Espe i June 21 1938 Walfic-hmidt Sept. 22, 1938 Jury 1'3, 1944 McA'r'tnur July 18, 194 jsgerstrom, Jr. "Jim 1, 1946 Bggs Nov. 19, 1946 Bg'gs Feb. 25, 1947

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