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Патент USA US2128232

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Aug. 30, 1938.
w. DALLENBACH
2,128,232
ELECTRON TUBE
Filed Jan. 25, 1935
36
Fig". 3b
wlR“E.
A.
'
'
lnventor:
I
‘65 W71”?
'
Patented Aug. 30, 1938
2,128,232
UNITED STATES PATENT OFFICE
2,128,232
ELECTRON TUBE
Walter Dillenbach, Berlin-Charlottenburg, Ger
many, assignor to the ?rm N. V. Machinerieen
en Apparaten Fabrieken “MeaP', Utrecht, Neth
erlands
Application January 23, 1935, Serial No. 3,132
In Germany February 23, 1934
10:
8 Claims. (Cl. ‘250-36)
The present invention relates to an electron this space and, therefore, also the distance from
tube for exciting i. e. generating, amplifying and
control grid and acceleration grid, will then,
receiving ultra-frequency electro-magnetic oscil the
be without in?uence'upon the excitation. The
lations, particularly of oscillations possessing a clearance between the control grid and the ac
wavelength of less than one metre. The elec
celeration grid can, in accordance therewith be
tron tube in accordance with the present inven
made to be so large, that also in connection with
tion belongs to that type of high vacuum elec
high potentials at the acceleration grid the satu
tron tube in which the flow of electrons passing ration of the emission has not yet been attained
over between the cathode and the positive elec
and that, therefore, the control grid still pos
trode, is controlled by means of a grid being po
sesses its controlling properties. Furthermmore,
sitioned in-between. In consequence of the em
it will now be possible to adapt path of trans
ployment of the control-grid in such tubes, the mission and duration of transmission to the
?eld space between the cathode and the positive period of the oscillation to be excited, without ex
electrode is divided into two spaces, 1. e. in a ercising a deleterious in?uence upon the control
‘ control space situated between the cathode and
the grid and an exciting space situated between
the grid and the anode. For the purpose of be
ing able to excite oscillations, the duration of
transmission of the electrons from the cathode
20 to the anode must remain short or, at least com
parable in relation to the period of the oscilla
tion to be excited. In connection with the excita
tion of oscillations possessing a wavelength of less
than one metre and with a clearance between
25 the electrodes practically possible, such high
anode potentials are necessary, that in conse
quence of the magnitude of the anode through
the control grid, the tube will no longer be able
to work in the space charge zone and thus lose
30 its controlling property.
‘
This di?iculty has been obviated in accordance
with the present invention by the fact that for
the purpose of exciting ultra-high frequency elec
tro-magnetic oscillations, particularly such pos—
35 sessing a wavelength of less than one metre, elec
tron tubes are being employed, in which, be
tween the control grid and the anode, a further
grid with a high positive charge has been pro
vided. As a result of the introduction of this
40 so-called acceleration grid, three spaces will be
produced between the electrodes, viz. a control
space between the cathode and the control grid,
an acceleration space between the control grid
and the acceleration grid and an exciting space
45 between the acceleration grid and the anode.
In the acceleration space, the velocity of...the
electrons is raised to such an extent, that they
are made to cross the space, intended for the
excitation of the ultra-high frequency oscilla
50 tions and situated between the acceleration grid
and the anode, at intervals of time which
are short or comparable with .the period of the
oscillation to be excited. It is advisable to keep
high-frequency ?elds away from the acceleration
65 space.
The interval of time of the electrons in
space.
15
The electron tubes in accordance with the pres
ent invention may be provided not only with
plane, but also with concentric and, ?nally, also
with cylindrical electrodes. The arrangement
may, furthermore, be of such a nature, that the
control space limited by the cathode and by the
control grid, may be made to belong to a control
resonator, and the exciting space, limited by the
acceleration grid and the anode, to an exciting
resonator. The acceleration space between the 25.
control grid and the acceleration grid suitably
remains alternating-?eld-free, whereby disturb
ing in?uences upon the excitation will be obvi
ated. If the control resonator and the exciting
resonator are coupled with each other, a reduc 30
tion of the damping of the resonators may be
attained, in consequence of which the arrange
ment as ampli?er will attain a higher ampli?ca
tion, as receiver a higher sensitivity and, ?nally,
it may, in connection with excitation beyond the
commencement of the oscillations, be used as gen
erator.
,
The Figs. 10. and 1b to 3a and 3b represent
three examples of performance of the present in
vention,
Fig. 1b is a longitudinal section through an ar
40
rangement of the invention in which plane elec
trodes are used, and Fig. 1a is a section through
1b along line la, la. Lecher systems have
‘been provided to serve as resonators, said Lecher
systems being open at the ends and consisting of
plane metal bands.
.
Fig. 2b is a longitudinal section through an ar
rangement of the invention in which concentric
and cylindrical electrodes are used, and Fig. 2a is 50
a section through Fig. 2b along line 2a, 2a. The
resonators have been adapted to the electrodes
and are each made to consist of a concentric and
cylindrical Lecher system.
Figs. 3a and 3b are made to show, in cross sec- 55
2,128,282
2
tion as well as in longitudinal section, an ar
rangement, well screened to prevent the escape
of loss radiation, the electrodes of which arrange
ment are also of the cylindrical and concentric
type. Fig. 3a is a cross section along line 3a,
3a of Fig. 3b. The electrodes have been extended
at either end by means of tubes, thus producing
two concentric resonance spaces, the ends of
which have been closed up by short-circuit con
10 densers. The arrangement is, moreover, con
nected with an aerial over an energy line.
In the ?rst instance the present invention will
be described in detail, reference being had to Figs.
la and 1b in connection herewith:
In the electron tube, illustrated in Fig- 1, four
15
plane electrodes have been accommodated with
in the vacuum vessel I, viz. a cathode 2, a con
trol grid 3, an acceleration grid 4 and an anode
5. The heated wire 6 placed within the cathode
20 serves as a source of electrons.
The cathode 2
and the control grid 3 have been extended by
two parallel metallic bands ‘I, 8, so as to form an
open Lecher system. In an identical manner
have the acceleration grid and the anode been
25
continued by metallic bands 9, I0, being parallel
to each other, thus also forming an open Lecher
system. If an open Lecher system of this descrip
tion is excited in the ?rst harmonic, a potential
node will be formed in the central portion of the
30 conductors and potential loops at the ends. The
length of the conductors will then coincide with
half the wavelength of the oscillation. In order
to avoid disturbances of the alternating ?elds,
the metallic bands are made to intersect the vac
uum vessel in the potential node. The walls of
35
the vacuum vessel are, for this reason, fused with
the metallic bands, so as to be vacuum-tight, ap
proximately in the electric centre. Thus one half
of the Lecher system is situated without, i. e.
outside of the vacuum vessel, whereas the other
40 half has been accommodated inside said vacuum
vessel. The battery H is utilized as current
source for heating the hot heating wire 6. With
the aid of the battery I! a bias is produced at
the control grid 3, and through the medium of
45 the batteries 13 and M a suitable potential'is im
parted to the acceleration grid and the anode.
The potential leads are connected in the prox
imity of the potential nodes, i. e. in the proxim
ity of the fusing points, with the metallic bands
50 ‘I, 8 or 9, l0, galvanically joined with the elec
trodes, with the result that leakage losses over
the lead are being avoided. The two Lecher sys
tems ‘i, 8 and 9, l0, have been so arranged rela
tively to each other, that the acceleration space
55 positioned between the control grid 3 and the ac
celeration grid 4, is situated far beyond the res
onance of the oscillation to be excited or to be
ampli?ed. In the instance referred to, the two
Lecher systems extend from the electrodes in op
posite directions.
'
.'
The arrangement speci?ed previously may be
employed for the purpose of exciting, particu
larly, however, for the ampli?cation of oscilla
tions, if the following directions are observed.
The control grid is suitably given a weakly
negative bias in order to avoid an additional
damping of the control resonator. Furthermore,
so as to make low control alternating potentials
do, it is advisable, to select the clearance between
70 the'hot cathode and control grid as narrow as
possible, with the aim of obtaining in the con
trol space, durations of transmission of the elec
trons which are short when compared to the du
75 ration of oscillation. If the duration of trans
mission of the electrons in the control space is
short when compared to the duration of oscilla
tion, the displacement current in the control
space, produced by the controlled electron alter
nating current, and also exercising a damping ef—
feet on the control resonator, will be negligibly
small. With regard to the short duration or
transmission in the control space it will be of ad
vantage to cause the potential of the accelera
tion grid to be so high, that the tube works in 10
the proximity of the upper end of that part of
the static characteristic rising linearly. Experi
ments in connection with a wavelength of 12 cm.
have proved, that at such a selection of the po
tential of the acceleration grid, the dynamic 15
characteristic deviating from the static charac
teristic, presents its maximum slope. Also when
employing the arrangement as rectifier, particu
larly as audion, the recti?cation at the upper bend
of the static characteristic will be more effective
than the recti?cation at the lower bend, in con
sequence of the short duration of transmission of '
the electrons in the control space.
It has further been proved, that the electron
alternating current, produced in the control
space, is ?rst made to acquire a considerable ve
locity in the acceleration space, in consequence
of the high positive potential of the acceleration
grid and subsequently brings about an optimal
excitation,'if the anode potential is selected in
the proximity of the cathode potential. This
means, however, that the electrons must arrive
at the anode at the velocity zero. This relation
exists practically independent of the velocity with
which the electrons enter the excitation space.
By means of experiments it has been ascertained
to be essential with maximum excitation that the
anode potential be selected to be a little less posi
tive than the potential of the cathode. In spite
thereof, however, the majority of the electrons
40
describe a turning movement in front of the an
ode and return to the acceleration grid. This re
versal is a result of the fact, that the electrons
are subjected to lateral deviations through the
medium. of the bars of the acceleration grid 4 45
which impart to them a velocity component par
allel to the grid and reduce the velocity com
ponent vertical to the grid. The reason, why an
electron alternating current, turning back just
in front of theanode, exercises a maximum ex
citation upon a resonator coupled with the ex
citation space, is explained by the fact, that at
this selection of the anode potential the electrons
are the longest time in interaction with the high
frequency ?eld in the excitation space. The cou
pling between the moved electrons and the high
frequency ?eld will then be at its maximum. If
the anode potential is selected so as to be essen-.
tially more positive than the cathode potential,
the duration of transmission will be reduced and
the electrons received by the anode after once
crossing the excitation space. If, however, the
anode potential is selected so as to be essentially
more negative than the cathode potential, the
electrons will be forced to return in a plane be 65
tween the acceleration grid and the anode. Their
duration of transmission in the excitation space
will again be shorter than in the most favour
able case, in which the reversal takes place im
mediately in front of the anode.
70
The optimum of the excitation effect on the
excitation space presenting itself at the selec
tion of the anode potential depends now, on the
one hand, upon the velocity at which the elec—
tron alternating current is made to pass through
3
2,128,232
the acceleration grid 4. If in connection with
plane electrodes and a neglected effect of the
space charges in the excitation space the anode
potential is selected so as to be in the proximity
of the cathode potential, it will be found that
with a change of the acceleration potential the
exciting effect will then become a maximum, if
the electrons, turning back immediately in front
of the anode, are made to cross the exciting
10 space at a simple duration of transmission which
is shorter than half the duration of the period
and approximately equals one third of the dura
tion of period of the ultra-high frequency oscil
lations.
In connection with an arrangement which is
not plane, but, for instance, cylindro-symmetri
cal or, in due consideration of the space charges,
1. e. in case of high current density in front of
the anode, it is necessary to so adjust the sim
20 ple duration of transmission that it deviates
somewhat from one third of the duration of
period of the ultra-high frequency oscillations.
The most simple method is to determine in each
case by means of practical experiments the po
[6 Cl tentials and therewith the duration of transmis
sion, at which maximum excitation, e. g. in case
of an oscillation generator, maximum oscillatory
power presents itself.v
' If to the end, situated outside the vacuum ves
30 sel, of the control resonator ‘i, 8, ultra-high fre
quency alternating potentials are conveyed and
the D. C. potentials of the electrodes are adjusted
in such a manner, that a maximum control ef
fect upon the stream of electrons emanating
from the cathode, will take place, as well as a
maximum excitation of the electron alternating
current passing through the acceleration grid
is conveyed phase-correctly to the control reson
ator, it will be possible to attain a reduction of
the damping of the whole of the oscillatory ar
rangement. If the reduction of damping is ef
fected in the proximity of self-excitation, the 5
arrangements will represent highly sensitive res
onance ampli?ers and are excellently adapted for
receiving ultra-high frequency oscillations.
If
the reduction of the damping property is in
creased up to the self-excitation of oscillations, 10
the. arrangement represents a generator, which
may be used for the emission of oscillations. It
is, however, a matter of course, that the coupling
of the two resonators and the duration of trans
mission of the electrons from the cathode to the 15
entrance into the exciting space are so adapted
to each other, which may be suitably attained by
changing the acceleration potential or by the
suitable selection of the clearance between the
control grid and the acceleration grid, that the 20
controlled stream of electrons enters the excit
ing space with a phase which proves most suit
able for excitation purposes.
An arrangement of suchdescription has been
reproduced in the Figs. 3a and 3b, adapted for 25
transmitting and receiving ultra-short wave 05
ciliations. The electrode system consists in this
instance, identical with that arrangement shown
in Figs. 2a and 2b, of a bar-shaped hot cathode
l5 and the cylindrical and concentric electrodes 30
surrounding the cathode, viz. the control grid It,
the acceleration grid I‘! and the anode l8. All
four electrodes have been extended at either end
by means of metallic conductors, i. e. the cathode
by the rods 25 and 25’, serving for the conveyance
of the heating current, the control grid through
the medium of the two cylindrical tubes 26 and
26' and the acceleration grid by means of the
two cylindrical tubes 21 and 21'. The anode I8
into the excitation space, the output of the excit
ing resonator 9, I 0 will be intensi?ed.
Instead of the plane arrangement represented has likewise been extended at both ends so as to 40
40
in Figs. 1a and 1b, a cylindro-symmetrical ar
form a cylinder, enclosing the previously men
rangement, shown in Figs. 2a and 2b, may be ad— tioned electrodes with their extensions. The
vantageously made use of. In this instance, the space between the tubes 26 and 21 or 26' and 21'
electrode system consists of a wire or bar-shaped has been ?lled up by means of two insulating
45 hot cathode l5 and the other electrodes concen ~ bodies 28 and 28’. With the aid of these insu 45
trically surrounding the cathode i. e. the control lating bodies, the tubes connected with the con
grid Hi, the acceleration grid 11 and the anode trol grid and the acceleration grid have been sup
l8. The cathode l5 and the control grid l6 have ported against each other, whilstv in addition
been extended on the left-hand side through the thereto the acceleration space, extended towards
50 medium of the two metallic tubes 19, 26, so as both sides, is detuned relatively to the natural
to form a cylindrical Lecher system serving as frequency of the resonators provided within the
control resonator. The acceleration grid l1 and tube. The control resonator is limited by the sur
the anode l8 have also been continued so as to face of the rods 25, 25' and of the cathode, as
form just such a cylindrical and concentric Lech
55 er system by means of the two metal tubes 2|,
22.
The arrangement has been ‘accommodated
completely within the vacuum vessel I. The
D. C. leads have been provided in the centre of
the Lecher system in potential nodes. The con
60 trol energy may be conveyed to terminals 23 pro—
vided outside the vacuum vessel and the en
hanced output may be taken from the terminals
24. The represented, cylindrical arrangement is
characterized, when compared to the plane ar
65 rangement, by an inconsiderable damping capa
city, which may be particularly attributed to the
low leakage loss.
The arrangements represented by Figs. 1a and
lb or 2a and 2b are particularly adapted for the
70 ampli?cation of decimetre and centimetre waves.
A coupling between the control resonator and
the exciting resonator has not been provided for
in that case. If, however, the exciting space and
the control space are coupled in such a manner
75 that, for instance, a part of the enhanced output
well as by the interior surfaces of the control grid
l6 and the tubes 26 and 28', the exciting reso 55
nator, on the other hand, being limited by the
exterior surfaces of the acceleration grid l1 and
the two tubes 21 and 21' and by the inner face
of the extended anode l8. The ends of the
Lecher system are provided with short-circuit 60
condensers for the oscillation. The tubes 26 and
26’ are each provided at their free end with a
?ange 29 and 29', forming, together with the
plates 30 and 30’ a short-circuitpondenser each.
In an identical manner has the left end'of the " 65
extended anode tube l8 been provided with a
flange 3| which, in conjunction with the plate 36
also forms a short-circuit condenser.
At the
right side the extended anode has been continued
by the tube 32 and forms, together with the ex 70
tension 33 of the tube 21', an energy line. The
inner conductor 33 of the energy line' further
passes on the right side into the aerial 34, where
as the outer conductor 32 of the energy line, ter
minates in the metal plate 35 serving as counter
76
2,128,282
4
poise. The aerial 34 is thus made to project freely
"beyond the metal plate 35 into the space.
The tube, which has been represented in Fig. 3
does not require a vacuum vessel if, as may be seen
from Fig. 3b, the interspaces between the metallic
parts surrounding the tube, have been closed up
and rendered vacuum-tight by glass-fusings.
Thus the two plates 30 and 3| have been con
nected by means of a glass seam 36 and the right
10 end of the tube 32, 33, serving as energy line, by
means of a glass seam 31, so as to be vacuum
tight. The current and potential leads have been
joined to the electrodes in the proximity of the
short-circuit condenser, for the purpose of keep
15 ing the leakage losses within the smallest possible
limits. In view of the fact that the cylindrical
resonators are excited in the ?rst harmonic, in
connection with which potential nodes are formed
at the ends and a potential loop in the centre, the
total length of, the resonators is to be made to
equal half the wavelength of the desired oscilla
tion. The energy line and the aerial are suit
ably given a length which equals a quarter wave
length of the oscillation. The optimal coupling
25 of the emitter to the exciting resonator is obtained
by means of a proper selection of the space be
tween the cylinders 32 and 33. The closer the
space between the two cylinders, the looser will
be the coupling between the emitter and the ex
citing space. It is advisable to‘ so adjust this
coupling, that the emitter represents for the
resonator of the exciting space an optimal load-‘
ing resistance.
In the represented example of performance, the
.15 condenser plate 30, closing up the control_reso
nator situated in the proximity of the axis, as
well as the peripherally placed exciting resonator,
is eifective in bringing about the coupling of the
two resonators. The closer the space between this
plate 30 and the ?ange 29, the greater the ca
pacity of this short-circuit condenser and, simi
larly, the smaller will be the coupling between
exciting space and control space. It now the hot
cathode I5 is heated and if the other electrodes,
as already mentioned. are given a suitably se
and including two grid electrodes within said
tube, two oscillatory systems, each of said sys
tems containing one of said grid electrodes and
extending in a direction opposite to the other
system, each two other of said electrodes being
connected to one of said systems, each system be
ing .formed of at least two tubular conductors,
one of which is within the other, said grids being
continuations of the conductors belonging to said
systems, and each grid section being spaced frqm 10
and extending substantially coincidental with
each other grid section.
‘
2. An arrangement as in claim 1, said grid
electrodes comprising a control electrode, and
an accelerating electrode, and said other elec
trodes comprising an anode and a cathode, means
to impress a negative potential on said control
electrode with respect to said cathode, means to
impress a- positive potential on said anode with
respect to said cathode, and means to impress
a higher positive potential on said accelerating
electrode with respect to said cathode.
3. An arrangement as in claim 1, said other
electrodes comprising a cathode and an anode,
and lead wires for said electrodes, said wires
being connected to said oscillatory systems at
potential node points.
4. An arrangement as in claim 1, said other
electrodes comprising a cathode and an anode,
short circuit condensers, said condensers sealing
the ends of said oscillatory systems, and means
coupling said condensers to each other, whereby
said systems are sealed against radiation losses.
5. An arrangement as in claim 1, said other
electrodes comprising a cathode and an anode,
and means coupling said oscillatory systems to
each other.
6. An arrangement as in claim 1, said other
electrodes comprising a cathode and an anode,
short circuit condensers, said condensers seal
ing the, ends of said oscillatory systems, an ex
tension on one of said conductors of an oscil
latory system, said extension comprising an en
ergy lead coupled with a radiator.
‘7. An arrangement as in claim 1, .said elec
trodes comprising a cathode and an anode, short
lected continuous potential and, furthermore, if
the control grid is given a weakly negative, the _ circuit condensers, said condensers sealing the
acceleration grid a high positive and the anode a ends of said oscillatory systems, said condensers
weakly positive continuous potential relatively to being each composed of two plates, a plate of
the cathode, the ultra-high frequency alternating one condenser being electrically connected to a
plate of the other condenser, an extension on one
potentials produced at the electrodes in the excit
of said conductors of. an oscillatory system, said
ing space, will be transmitted to the control reso
nator over the coupling channel existing between
29 and 30. In consideration of the fact, that the
extension comprising an energy lead and an
leakage, it possesses a very small natural damp
ing; for this reason it will also be possible, in
connection with a weak coupling with the excit
aerial, and a plate connected to and perpendicu
lar to said extension forming a counterpoise for
said aerial.
8. An arrangement as in claim 1, said other
electrodes comprising a cathode and an anode,
grid, in consequence of which the stream of elec
densers being each composed of two plates, one
control resonator is incapable of emitting loss
ing resonator, for high alternating amplitudes to . short circuit condensers, said condensers sealing
present themselves between cathode and control the ends of said oscillatory systems, said con
' trons, emanating from the cathode, is vigorously
controlled through.
What I claim is:
1. A_ high frequency arrangement comprising
an electron tube having at least four electrodes,
of the plates of a condenser and an electrode
forming a part of the outside walls of said elec
tron tube.
WALTER Dir-[mason
u
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