DE963704C - Adjustment arrangement for traveling field pipes - Google Patents

Description

ISSUED MAY 9, 1957

/ 7740 Villa / 21 a ^l

is used

The invention is concerned with matching arrangements for traveling wave tubes and in particular with arrangements for matching high-frequency lines of low impedance to the helix with relatively high impedance commonly used in traveling wave tubes. It has been proposed an adjustment arrangement already for traveling wave tubes, which consists of a short part of a coaxial high impedance and whose inner conductor is coupled to the W ^T endel. which has the same high impedance. The opposite end of this coaxial part is short-circuited. The coaxial line lower. Impedance is coupled to the high impedance coaxial part between the ends thereof at the point with the appropriate matching impedance. A good match is achieved by this arrangement. However, the setting is very critical and places high demands on the accuracy of manufacture.

There are already resonance line pieces known, one end of which is short-circuited, while in near the other end a high-resistance consumer is connected and the connecting one Line from the consumer is arranged perpendicular to the resonance line. Furthermore, lines that consist of a conductive surface and a conductor arranged parallel thereto, known.

709 513/202

The invention provides an adjustment arrangement of coaxial lines to the end of the helix, with good broadband adaptation in the production and adjustment is not critical. According to the invention this is achieved by that to adapt a helical line high wave resistance to a line low Characteristic impedance a parallel line arranged perpendicular to the axis of the helical line is used whose first conductor consists of a conductive surface and whose second conductor consists of a arranged parallel thereto, connected at one end to the first conductor line piece consists, and the length of a conductor of this line is chosen so that a resonance line piece arises at the working frequency, one end of which is short-circuited to a voltage node is, while another part of the line section forms a tension bulge and there the coupling takes place on the helix.

The invention will be explained in more detail using the exemplary embodiments in the drawings.

In FIGS. 1 and 2, ι denotes the cathode, 2 denotes the focusing electrode and 3 denotes the anode. These three electrodes are constructed as a unit and are carried by the plate 4, which rests against the bearing 6 of the metal cylinder 5. At the other end of the tube, a further plate 7 is provided which rests in a similar manner on the bearing 8 of the cylinder 5. The plate 7 is normally carries the ^Hochfrequ: nzdurchiührungen. in particular the high-frequency output and, in some exemplary embodiments, also the high-frequency input. Between the two plates 4 and 7, the coil is arranged, which transmits the high-frequency energy from the input 10 via the transmission pieces 12 and 13 to the output line 11. The helix 9 is preferably held with the aid of the dielectric rods 14, 15 and 16, which are arranged at a distance around the helix and extend parallel to the helix axis. These rods 14, 15 and 16 are in turn held at their ends in openings in the conductors 17 and 18 of the transmission parts, as can be seen from FIG. An opening 19, which contains the end of the helix, is attached centrally to these openings. In this exemplary embodiment, this end is connected to the conductor 17. The opening 19 can be significantly smaller than shown in the drawing and can correspond to the inner coil diameter. The rods can be made of any suitable dielectric material such as glass, ceramic or quartz. Instead of the rods, a tube made of one of the materials mentioned can also be used. In Fig. 1 only those parts of a traveling wave tube are shown, which are necessary to understand the inventive concept. The magnetic field, which is directed parallel to the axis, can be generated either by permanent magnets or by the coil 20. The plates 4 and 7 are preferably made of magnetic material in order to promote the flow of lines of force of the magnetic field in the axial direction. The plate 7 carries the collecting electrode 21, which is arranged axially to the helix. The plates 4 and 7 are parts of the transmission arrangement. As can be seen from Fig. 1 and 2, the front transmission part consists of the plate 4 and the conductor 17. The conductor 17 is kept at a suitable distance from the surface of the plate 4, whereby the suitable line impedance is achieved. In these exemplary embodiments, both ends of the conductor are short-circuited with the plate 4, as is shown at 22 and 23. The length of the conductor 17 is approximately half a wavelength or a multiple of the working frequency, as a result of which a resonance part is achieved which has a voltage node at the short-circuited ends and a voltage bulge in the area of the coil end. The input line 10 is a coaxial line, the outer conductor 24 of which is fixed in an opening in the plate 4, and the inner conductor 25 is connected to the conductor 17 as indicated at 26. The high-frequency energy is fed through the input line 10 to the transmission part, on which it is propagated in a transverse waveform and is coupled to the helix 9 in the process. While the one conductor of the transmission part in the embodiment is formed by the plate 4, it goes without saying that it can also be formed by a separate conductor. The coaxial line 10 has a relatively low impedance on the order of 50 ohms, while the helix 9 has a relatively high impedance, for example 300 ohms or more. The coaxial line 10 is coupled in at a suitable point 26 between the voltage node 22 and the voltage bulge 19 and is therefore well adapted. In the same way, a suitable adaptation is achieved by coupling the transmission part 12 to the helix 5 in the tension belly. The transfer part 13 at the exit of the helix is the same as part 12 in this exemplary embodiment A minimum of space in the axial direction is required for coupling between the coaxial lines and the helix. A separate flat conductor can also be provided in place of the plate.

In the embodiment of FIGS. 3 and 4, the strip-shaped conductor I7 _{β of} the transmission part is considerably narrower than the strip 17 of FIGS. 1 and 2. The strip 17, for example, can have a circular, rectangular, triangular, elliptical cross-section. In this exemplary embodiment, the strip 17 is arranged next to the electron beam which flies through the opening 27. The helix g _a is τ it the strip; 17a coupled, and suitable holding devices, similar to that already described, align the helix with the opening 27. The connection of the coaxial line io _fl with the transmission _{conductors 4 a} and 17 ^ is the

hang with the connections described in Fig. ι and 2 similar. The strip-shaped conductors iy _a and iy of FIGS. 1 to 4 are connected at their two ends to the associated conductor. In other exemplary embodiments, for example, the upper end of the transmission strip above the helix 9 can be omitted, as a result of which an open transmission part of approximately a quarter wavelength is achieved. Such a transmission part is shown in FIGS. In this embodiment, the transmission part 28 consists of the flat conductor ₄₆ and a narrower, strip-shaped conductor 29. The strip 29 can be round, triangular, rectangular, oval or of another cross-section and has a length of about a quarter wavelength . In order to hold the end 30 of the strip 29 in place with respect to the plate 4 & 8, additional strips 31 and 32 are arranged at right angles to the strip 29. The ends of the strips 31 and 32 are connected to the plate 4. Their length is about a quarter of a wavelength. The end 30 of the strip 29 is arranged adjacent to the end of the helix, whereby the coupling between the coaxial line 10 ₆ and the helix is achieved.

In the embodiment of FIGS. 7 and 8

is the material of the strip 33 as wide and thick, that although only attached at one end to the plate 4 _C, is parallel to this plate.

The open end is coupled to the helix g _c.

The coupling between the coaxial line 10 and the transmission part takes place at a suitable one Adjustment point between the tension node and the tension bulge.

Fig. 9 shows a longitudinal section of a further embodiment of the invention. The tube consists of the beam generating system 101 and the collecting electrode 102. The beam generating system is arranged either separately or ereinigt ^r with the plate 103 \ which is supported against the bearing 105 of a non-magnetic cylinder 104th Either a permanent magnet or a magnetic coil 106, which generates the required axial magnetic field, is arranged around the cylinder 104. A second plate 107 is arranged at the other end of the cylinder. The helix 108 is located between the two plates 103 and 107 and is held by dielectric rods 109 or a dielectric tube made of a suitable dielectric material, for example glass or quartz. The rods or tubes are held in the openings 110 and the plates 103 un x ¹ 107th The coil 108 is connected to the high-frequency input or output 112 or 113 by the transmission part 114 or 115.

The transmission part 114, for example, forms a parallel line, one conductor of which is formed by the plate 103 and the other conductor is formed by the mast 116. The mast 116 is connected directly to the plate 103 at 117 and the other end is connected or otherwise coupled to the helix 108. If this mast is made approximately equal to a quarter wavelength of the operating frequency or an odd multiple thereof, resonance occurs and a standing wave is created at part 114 with a tension node at 117 and a tension bulge at the end. The outer y ₀ conductor 118 of the high-frequency input line 112 is connected to the plate 103 and the inner conductor 119 is connected to the mast 114. This connection lies between the tension node and the tension bulge, as a result of which a good match of the coaxial line 112 is achieved. The mast is tapered towards the helix, as indicated at 120. The transmission part 115 is the same as the part 114. The propagation of the wave, however, proceeds in the opposite direction. An example of the size and spacing of the mast which is sufficient for satisfactory transmission is the following: The dimension d of the mast 116 can be the same as the diameter of the inner conductor 119. However, this relationship is not critical and the mast can be related to the size of the inner conductor can be varied considerably, as long as the size of the mast and its distance from the plate 103 provides a suitable transmission between the impedances of the coaxial line and the helix. For mechanical reasons, however, d should not be much smaller than 2.5 mm. The distance h is given by the equation

cos h

2h

given, where Z is chosen equal to the impedance of the coaxial line 112 and d according to the above considerations; t is equal to 2/8 at 1.1 ^ ₁ , where /, is the lowest operating frequency. L is preferably chosen to be a quarter wavelength at 1.15 ^ f _1. The dimension of m is not critical. The tapered portion 120 provides a gradual transition from the larger diameter of the mast to the narrow diameter of the helical wire, and its length is again not critical.

In Fig. 10, another embodiment for the mast of the transmission part is shown. It is composed or layered. As can be seen from the figure, the mast consists of a core conductor 121 which is surrounded by a sheath of dielectric material, which in turn is surrounded by a conductive sheath 123. The sheath 123 is connected to the inner conductor 124 of the coaxial line 125. The core 121 is connected to the supply 126, through which a direct current or modulation voltage can be supplied. The upper parts of the three parts 121, 122 and 123 are tapered to achieve a smooth transition. In the embodiment of FIG. 10, the mast is arranged on the front side of the plate IO3 _S , so that the coaxial line _{extends parallel to the helix IO8 β} and on the rear part of the tube the

Input and output line for the high frequency can be arranged. The coil io8 _o extends through the opening of the plate io3 _a and almost reaches the electron source. Experiments have shown that very low levels of radiation emanate from the arrangements of FIGS. 9 and 10, as the curves in FIG. 12 show. This small amount of radiation can, however, be eliminated by a shield, as can be seen from FIGS. 11 and 13. The transmission masts of this embodiment are similar to one of the masts shown in FIGS. 9, 10, 14 and 15. The shield of FIG. 11 consists of a semicircular shield 128 of conductive material which encloses the mast _{6 connected to the plate 10 3 &} 6. The front part of the coil io8 ₆ is shielded by the cylindrical screen 130, which is connected to the shield 128.

It can be seen from the curves of Fig. 12 that the shield of Fig. 11 provides an improvement, but the radiation loss without a shield is negligible. From the mismatch curves of FIG. 12 it can be seen that 2g by the arrangement of FIG. 11 a mismatch of less than 2: 1 is achieved over a bandwidth of 60% of the frequency Z ₁ .

The shield of Fig. 13 consists of a second plate 131 which is arranged on the opposite side of the mast u6 _c . The plate iO3 _r separates the beam generation system ioi _c from the coil 108, .. The plates are connected to one another. The plate 131 is so large that the mast 116 ;. and the spiral end io8 _c can be accommodated. The mast 11 6 _C is arranged on the connection of the two plates, whereby a tension node is created for the transmission part. Each plate is provided with openings; the opening 132 is adapted to the electron beam, the opening 133 is so large that the filament and its holding devices, either rods or tubes, can be accommodated therein. The width of the plate is preferably limited so that a rectangular waveguide is formed _{in connection with the plate io3 c.} The shield of FIG. 13 not only shields against radiation, but offers other advantages in certain types of tubes. The mast n6 _c can for example be formed from a strip of conductive material which is arranged between two layers of dielectric material which _{lie between the plates io3 c} and 131. The distance A _{1 of} the helix end from the plate IO3 _C is preferably given by the expression for this exemplary embodiment

Z =

138

8 Ji ₁

given, where d. is the width of the strip.

In the embodiment of Figures 14 and 15, the mast is replaced by a flat strip 134 approximately one-quarter wavelength of the operating frequency or an odd multiple thereof. The strip 135 is formed by a layer or strip of suitable dielectric material. The strip 134 can be applied and shaped using the printing process, with the undesired portions etched away or cut off. By this strip-shaped conductor which is a small fraction of a quarter wavelength from the conductive plate 103; is remotely located, the electromagnetic waves of the coaxial line H2 _{d are} propagated in a transverse electrical waveform. The width of the strip 134 is preferably large enough to ensure sufficient coupling with the coaxial line. The part which lies between this coupling and the helix is tapered towards this, as indicated at 136, whereby there is a gradual transition to the size of the helix. The distance h for this line across the conductive surface of plate 103; is obtained by the following expression:

Z ₀ =

377 *

2h nd

ι y

fid ^r - ^ d * '"Zh ₁

where h is the distance between the strip and the surface of the plate and d is the width of the strip at the point of coupling with the coaxial line 112,;

In the exemplary embodiments of FIGS. 9 to 15, the plane conductor of the transmission part is the Plate of the tube used. It goes without saying that also separate from this tube plate arranged plates or other flat conductors can be used.

In the exemplary embodiments of FIGS. 16, 17 and 18, the traveling wave tube is equipped with two plates 37 ^{and 1} SS. Plate 137 supports the beam generation system and plate 138 supports at least a portion of input and output lines 140 and 141. Input line 140 is a coaxial line with outer conductor 142 and inner conductor 143 which extends to the front end of the tube. Instead of the coaxial lines, rectangular waveguides or other high-frequency lines can also be used

The input transmission part 144 consists of no the flat conductive plate 145 and a strip-shaped conductor 146. The outer conductor 142 is with of plate 145 and inner conductor 143 connected to conductor 146.

As can be seen from FIGS. 17 and 18, the plate-shaped conductor of each transmission part is provided with a right angle, with which one end of the conductor 146 is capacitively coupled. The arrangement of the transmission parts is more suitable for tubes of smaller diameter than if the transmission part would be formed by straight-line, transverse to the W ^r endel extending lines.

As can be seen from FIGS. 17 and 18, there is the strip-shaped conductor made of three parts, the tapered part 148, with one end of which the Helix and its other end with the inner one

Conductor 143 is coupled, the part 149, which in is arranged at right angles to part 148, and the third part 150, at right angles to part 149 and arranged at a small distance parallel to the flange 147, around a capacitive high-frequency short circuit to build. The part 150 is built up on the flange 147 with the help of the rivets 152, between the two is a thin strip 151 of dielectric material.

Since the parts for the transmission parts at the input and output of the helix are the same, the reference numerals used for the input part in FIG. 17 with the index α are used for the corresponding parts of the output part in FIG.

The only difference in these two parts is the structure. The plate 145 of the input transmission part is through the rods 153, which are arranged between the plates 137 and 138, held. The plate 145 is secured with the help of the bracket 154 held from dielectric material at a distance from the plate 137. Metal or other suitable Materials help hold the dielectric rods 155, which in turn hold the helix

156 set in their position. The bracket 154 is preferably carried by plate 145, although this is also done by plate 137 can.

The operation of the transmission parts of these embodiments is essentially the same as already described. The coupling of the high frequency voltage node is capacitive instead of the direct connection in the exemplary embodiments of FIGS. 9 to 15. The voltage bulge, namely the end of the tapered parts 148 and 14S ₀ , is connected directly to the helical ends. In the case of the transfer member 144, the strip 146 is disposed at the front of the plate 145 and the helix extends through the opening in the plate 145 to the strip 146.

In the embodiment of FIG. 19, the conductor of the transmission part is made up of the strips

157 and 158 formed. The two stripes are parallel and closely adjacent to each other through the thin layer 159 of dielectric material arranged, whereby a good high frequency coupling between the two .Streifen is achieved. The center conductor 160 of the coaxial input line is coupled to the strip 157 and is the tapered End of the strip 158 with the helix 161.

The plane conductor of the transmission part is formed by the plate 162, to which the outer conductor 163 of the coaxial input line is connected. The end of the strip 157 can be connected to an adjacent portion of the plate 162 be connected, but is preferably coupled through the flange 164 by means of the strip 158 and the flange IS8 _a. The flange I58 _a is held parallel to and at a small distance from the flange 164 by the dielectric layer 165. This coupling results in a high frequency short circuit between the transmission conductors 157, 158 and the plate 162 due to the high capacitance. In this exemplary embodiment, the coil and the conductors 158 and 158 _ß are isolated from the rest of the high-frequency line in terms of direct current. With the aid of the supply line 166, a direct current bias or another voltage can be applied to the filament for control or modulation purposes.

Claims (1)

Patent claims: 1. Adaptation arrangement for traveling wave tubes, characterized in that for adaptation a helical line with high wave resistance to a line with low wave resistance a parallel line arranged perpendicular to the axis of the helical line is used whose first conductor consists of a conductive surface and whose second conductor from a parallel to it, connected at one end to the first conductor Line piece consists, and the length of a conductor of this line is chosen so that a Resonance line piece arises at the working frequency, one end of which becomes a voltage node is short-circuited, while another part of the line section has a voltage bulge forms and there the coupling to the helix takes place. 2. Adaptation arrangement according to claim 1, characterized in that the parallel wire line ends near the helix and its length is about a quarter wavelength of the working frequency or one. odd multiple of it amounts to. 3. Adjustment arrangement according to claim 1, characterized in that the parallel wire line extends over the connection point of the Helix extends a quarter of the wavelength of the working frequency and this end briefly closed is. 4. Adaptation arrangement according to claim 1, characterized in that the second conductor at one end with the helical cable and near the other end with the Inner conductor of the coaxial line serving as a high-frequency feed or discharge line and their Outer conductors are connected to the first conductor. 5. Adaptation arrangement according to claim 4, characterized in that the second conductor extends beyond the coupling end by a quarter wavelength of the working frequency and the end is galvanically connected to the first conductor. 6. Adaptation arrangement according to claim 5, characterized in that the second conductor has an opening made axially to the helix for the electrons to pass through. 7. Adaptation arrangement according to claim S, characterized in that the second conductor is arranged offset with respect to the axis of the helical line and the helix to this second conductor is coupled. 8. Adaptation arrangement according to claim 1, characterized in that both ends of the second conductor connected to the first conductor 709 513/202 and the length of this second conductor is about half a wavelength of the operating frequency or an odd multiple thereof amounts to. S 9. adjustment arrangement according to claim i, characterized in that the second conductor is entrained at the point of the tension bulge laterally extending support members is provided, the ends of which are connected to the first conductor are, and the length of these laterally extended support members about a quarter wavelength the working frequency or an odd multiple thereof. 10. Adaptation arrangement according to claim 1, characterized in that the second conductor from a flat strip, one side of which is parallel to the flat surface of the first Conductor is arranged, and the open part of this strip to the helical line an-2o> closed is. 11. Adaptation arrangement according to claim i, characterized in that the first conductor is tapered towards the helix. 12. Adaptation arrangement according to claim 1, characterized in that the cross section of the second conductor and the distance between the first and second conductor are chosen so that that the characteristic impedance of the resonance line is lower than that of the connected line Characteristic impedance corresponds, and the transition of the second conductor is on the cross-section the helical cable gradually tapers. 13. Adaptation arrangement according to claim 1, characterized in that the second conductor consists of two separated by a dielectric Line pieces consists, the inner line piece with the helical line and the outer line piece is connected to the coaxial line. 14. Adaptation arrangement according to claim 1, characterized in that the inner line piece with a feed for an additional voltage is provided. 15. Adaptation arrangement according to claim i, characterized in that the first conductor surrounds the second conductor and the first conductor extends from a tension node to a tension bulge, at the end of which the Helix is connected. 16. Adaptation arrangement according to claim 1, characterized in that the first conductor is separated from the second conductor by a dielectric is separated. 17 ·. Adaptation arrangement according to claim 1, characterized in that the second conductor on the side facing away from the helix of the first conductor is attached and the helical cable passed through a hole in the first conductor and the helical end is connected to the open end of the second conductor. 18. Adaptation arrangement according to claim ι, characterized in that the first conductor consists of two parts which make up the second conductor surround, and that the two parts are adjacent to the junction of the first with the second Conductors are interconnected. 19. Adaptation arrangement according to claim 1. characterized in that the first conductor consists of a pair of flat legs extending into at an angle to each other, the coupling to the inner conductor of Coaxial line takes place through a connection of these legs and one of the legs with the Helical line is capacitively coupled through a dielectric and the end of the other Leg is short-circuited. 20. Adaptation arrangement according to claim 1, characterized in that the second conductor consists of an angle piece and is in a capacitive connection with another conductor, which is connected to the high frequency line. 21. Adaptation arrangement according to claim 1, characterized in that the second conductor in an upper tapered part by a Dielectric is capacitively coupled to the first conductor, the tapered end of which with the Helix is coupled, wherein two tuning elements are arranged on the first conductor. 22. Adaptation arrangement according to claim 2, characterized in that the tapered The end of the second conductor is connected to the first conductor and the connection of the helix at a distance of a quarter wavelength for the working frequency or an odd one Multiples of it takes place. 23. Adaptation arrangement according to claim 21, characterized in that the first and the second conductors are open at the tapered ends and the connection of the coil to the second conductor at a distance of half a wavelength of the working frequency or a multiple of this takes place. 24. Adaptation arrangement according to claim 21, characterized in that the cross section of the tapered conductor into the cross section of the helical conductor via the open end of the first Ladder gradually goes over. 25. Adaptation arrangement according to claim 1, characterized in that the two conductors passed through a sheath and outside the shell are connected to the line of low wave resistance. Documents considered: French Patent No. 1 012 374; "Principles of Radar", Second Edition, 1946; McGraw-Hill Book Company, pp. 8 to 89; H. H. Meinke, "Curves, formulas and data from decimeter wave technology", Munich, 1949, S.DIV / 15. iao 1 sheet of drawings © 609 708/2 * 7 11.56 709513/202 5.57