RU2645298C2 - Broadband multiport klystron with a multilink filter system - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to multipath klystrons used as power amplifiers of electromagnetic waves of centimeter and millimeter wavelength ranges. Design of low-voltage multipath broadband klystron contains n (n = 1, 2, 3, …, n) passive frequency tunable resonators, located outside the vacuum part of the klystron in the output of microwave energy or in the input and output of microwave energy and containing: passive resonator from a vacuum-dense dielectric microwave window, made in the form of a waveguide-dielectric resonator, which is formed by a section of a waveguide with dielectric filling in the form of a dielectric rod sealed in the waveguide channel, dimensions of the waveguide-dielectric resonator correspond to the condition of approximate equality of its resonant frequency to the upper frequency of the klystron gain band ƒ_B; passive resonator from a rectangular waveguide with dielectric inhomogeneity in the form of a dielectric rod exciting the waveguide and being extension of the dielectric rod sealed in the waveguide channel; passive resonators from tuning pins, one of which is installed in the middle of a wide wall of a rectangular waveguide in the immediate vicinity of the end part of the dielectric rod, and at least one more resonant pin, which is set at a distance S from the axis of the first not less than a quarter of the wavelength at the frequency ƒ_B, pins being configured to change their length, allowing the rectangular waveguide with a dielectric discontinuity to be tuned and tuning pins at the resonant frequency of the active resonator or with a specified detuning from this frequency, which provides a predetermined difference in the transmission power of the microwave power in the operating band of the klystron frequencies from the input path to the active resonator input and from the output active resonator to the output path.

EFFECT: expansion of the amplification band without increasing the size and weight of the input and output resonator systems of the low-voltage multipath broadband klystron.

6 cl, 4 dwg

Description

The invention relates to multi-beam klystrons used as power amplifiers of electromagnetic waves in the centimeter and millimeter wavelength ranges in transmitters of radar stations, communication systems and in microwave power sources of other radio equipment operating in pulsed, quasi-pulsed or continuous modes.

The main problem when creating microwave klystron amplifiers is to obtain the maximum gain band at the highest efficiency.

To solve this controversial problem, it is necessary to create approximately the same amplitude of the first harmonic of the induced current in the output oscillator system of the klystron at all frequencies of the working range, which is carried out by the corresponding tuning of the resonant frequencies of the intermediate resonators.

In addition, it is necessary to ensure a minimum or specially specified difference in the transmission coefficient of microwave power from the input path to the active input resonator and from the active output resonator to the output path in a given frequency band.

The fulfillment of the last condition in the output klystron circuit is achieved using additional passive resonators, forming a single filter system with an active single-gap or multi-gap resonator [Pasmannik V.I. Connected loop systems. M .: Fizmatlit., 2005; US patent 3484861 A, IPC H01J 25/16, (IPC1-7): H01J 25/02, publ. 12/16/1969; Patent US 3299312 A, IPC H01J 25/12, publ. 01/17/1967].

To implement these conditions in multi-cavity klystrons, it is necessary to introduce at least two passive resonators into the output of the filter system [Copyright certificate SU 880158 A1, IPC H01J 25/10, publ. 03/07/1992].

A known design of a broadband multi-beam klystron designed to operate in the long wavelength part of the centimeter range [Patent US 3484861 A, IPC H01J 25/16, (IPC 1-7): H01J 25/02, publ. 12.16.1969]. To expand the strip at the input and output of this device, multi-link filter systems are installed located in the vacuum part of the klystron. The disadvantages of this device are the large size and weight, as well as the difficulty of setting up the filter system located in the vacuum part of this device.

Known broadband multi-beam klystron, designed to work in the mid-wave part of the centimeter range [Application for patent for utility model CN 203134747 U, IPC H01J 23/36, publ. 08/14/2013].

It contains a three-link filter system consisting of an output active two-gap resonator and two passive resonators located in the vacuum part of the klystron and made in the form of two resonance chambers separated by diaphragms and equipped with adjustable pins. Moreover, these cameras are configured to tune to the same resonant frequency as the active resonator using two tuning screws. A vacuum-tight window with a dielectric insulator is installed at the output of the second passive resonator. However, the implementation of such a device in the short-wave part of the microwave range is difficult due to its bulkiness, which is associated with the large dimensions of the filter system containing additional passive resonators in the form of two resonant chambers. In addition, this system is very difficult to configure, since its tuning screws are connected to the vacuum part of the device.

The expansion of the gain band in low-voltage multipath klystrons at higher frequencies is constrained by the fact that the dimensions of the resonators and filter systems are reduced in proportion to the wavelength and the magnitude of the accelerating voltage. Therefore, when creating broadband multipath klystrons designed to operate in the frequency range 15–40 GHz, it is difficult to manufacture small-sized structural parts of the filter system with tolerances of 0.5–1.0 μm.

A known design of a multi-beam small-sized low-voltage klystron of 8 mm wavelength range, in which the input and output energy of the device is made of waveguides with a wall thickness of not more than 1 mm, into which ceramic plates are soldered for vacuum density [Vostrov MS, Zakurdaev AD , Polevich G.A. - Multipath small-sized klystron of 8 mm wavelength range // ELECTRONICS, SER. 1, microwave technology, vyp. 4 (511), 2011, S. 3-5]. The waveguides are soldered to a common flange, in which there are communication windows with input and output resonators for input and output of energy. The energy output is combined with a passive resonator, which can be adjusted on cold measurements with a special tuning screw. To expand the gain band, it is necessary to increase the number of passive resonators. However, the mass and size characteristics of the klystron are deteriorating, and the technological difficulties in manufacturing such a resonant system result in a low percentage of suitable devices and their high cost.

Thus, in the known designs of low-voltage multi-beam klystrons operating in the range of 15-40 GHz, the possibilities of expanding the gain band while maintaining small dimensions and the complexity of their manufacture, in comparison with the achieved level, are practically exhausted.

Closest to the claimed invention is the design of a low-voltage multi-beam klystron designed to operate in the shortwave of the centimeter and longwave of the millimeter ranges [Patent RU 2239256, IPC H01J 25/10, publ. 10/27/2004]. The device has input and output units of microwave energy located, respectively, from the input and output active resonators. These nodes are made in the form of waveguides electromagnetically coupled to active resonators through vacuum-tight dielectric microwave windows and resonant diaphragms, which can be placed in electrodynamic communication elements in the form of segments of waveguides. However, the electrodynamic communication elements do not contain elements providing a change in their resonant frequencies and obtaining filter systems tunable in bandwidth combined with microwave input and output. Therefore, such klystrons are substantially narrowband.

Consequently, there is a need to create multi-beam low-voltage klystrons having a filter system at the input and output of the device, which could be relatively simply tuned in the frequency range (equal to or greater than the gain band of the device) in the process of measuring the electrical parameters of the klystron and its components.

The objective of the invention is to expand the gain band without increasing the size and mass of the input and output resonator systems of low-voltage multi-beam broadband klystron.

This is achieved by the fact that the proposed design of a low-voltage multipath broadband klystron contains n (n = 1, 2, 3, ..., n) passive frequency-tunable resonators located outside the vacuum part of the klystron in the microwave energy output or in the microwave input and output energy and consisting of: a passive resonator from a vacuum-tight dielectric microwave window, made in the form of a waveguide-dielectric resonator, which is formed by a segment of a waveguide with a dielectric filling in the form of a dielectric rod, hermetically Formation in the channel waveguide, wherein the dimensions of the dielectric waveguide resonator correspond to the condition of approximate equality its resonant frequencies of the upper frequency band ƒ amplification _in a klystron; a passive resonator of a rectangular waveguide with a dielectric heterogeneity in the form of a dielectric rod, exciting the waveguide and which is a continuation of the dielectric rod hermetically installed in the channel of the waveguide; passive resonators from tuning pins, one of which is installed in the middle of the wide wall of a rectangular waveguide in the immediate vicinity of the end part of the dielectric rod, and at least one other resonant pin, which is installed at a distance S from the axis of the first at least a quarter of the wavelength at a frequency ƒ _in moreover, the pins are made with the possibility of changing their length, allowing you to configure a rectangular waveguide with a dielectric heterogeneity and tuning pins on the resonant frequency of the active resonator or with a given detuning from this frequency, which provides a given difference in the microwave power transmission coefficient in the working frequency band of the klystron from the input path to the input active resonator and from the output active resonator to the output path. The klystron also contains input, intermediate and output active resonators; microwave energy input and output nodes, which include: diaphragms with communication windows located in the input and output active resonators and designed for electromagnetic coupling of these resonators with elements of microwave energy input and output nodes, vacuum-tight microwave insulating windows , segments of rectangular waveguides with dielectric rods exciting the waveguides, and tuning pins located along the wide walls of the waveguides.

In addition, in the most broadband version, the output of microwave energy or the input and output of microwave energy of a low-voltage multi-beam broadband klystron also contains tuning waveguide diaphragms, providing an extension of the matching band of the impedances of the input and output microwave energy of the klystron with external waveguide paths, at least one diaphragm, which is located between the first adjusting pin located in the immediate vicinity of the end part of the dielectric rod, and subsequent adjustments GOVERNMENTAL pins.

In the proposed design, the critical frequencies ƒ _{cr of} electrodynamic coupling elements, which are segments of waveguides with dielectric filling and segments of rectangular waveguides with dielectric heterogeneity, tuning pins and tuning waveguide diaphragms, are lower than the lower boundary frequency of the operating frequency region of the klystron ƒ _н .

In the proposed device, containing inputs / outputs of microwave energy, the presence of communication elements in the form of segments of insulator-filled waveguides with a resonant frequency equal to the upper frequency of the amplification band of the klystron and rectangular waveguides with dielectric heterogeneity, tuning pins tuned to the resonant frequency of the active resonator or with a given detuning from this frequency, which are sequentially arranged tunable passive resonators, and tuning waveguide diaphragms leads to the creation of In the input and output resonant systems of compact broadband waveguide-dielectric filters with transcendental connections, tunable to a given difference in the microwave power transfer coefficient in the working frequency band of the klystron from the input path to the input active resonator and from the output active resonator to the output path.

The first of these passive resonators, from the side of the active resonator, both in the input device and in the energy output device, is the resonator in the form of a segment of a waveguide filled with a dielectric.

The constructive tuning of this resonator to the upper (or close to it) frequency of the klystron gain band is provided by the choice of the waveguide and dielectric rod parameters, and the condition условие _cr <ƒ _n must be fulfilled.

The dimensions of the waveguides are selected so that the operating range of the klystron lies in single-mode regions of the operating frequencies of the waveguides. The critical frequency of a rectangular waveguide is determined by the formula:

where c is the speed of light;

m, n are the vibration mode numbers;

a is the size of the wide wall of the waveguide;

b is the size of the narrow wall of the waveguide.

Since the type of oscillation used is H ₁₀ , then m = 1, n = 0. The critical frequency of a round (as a special case) waveguide filled with a dielectric is determined by the formula:

where χ _mk is the kth root of the derivative of the Bessel function of the first kind of order m;

a is the radius of the waveguide;

n is the refractive index of the medium (dielectric).

Since this waveguide operates on type H ₁₁ having the longest wavelength, then m = 1 and k = 1.

None of the waveguides is transcendent.

To reduce the loaded Q factor of the input and output active resonators, one end of the dielectric rod is located directly near the resonant diaphragm. Thus, the resonators are loaded on waveguides with dielectric filling.

The second passive resonator, both in the input device and in the microwave energy output device, is a rectangular waveguide with a dielectric heterogeneity in the form of a dielectric rod exciting the waveguide.

The constructive tuning of this resonator to the resonant frequency of the active resonator or with a given detuning from this frequency is provided by the choice of parameters of the dielectric rod in a rectangular waveguide.

When a dielectric heterogeneity is used in a rectangular waveguide in the form of a round dielectric rod, the maximum expansion of the working band of the klystron is achieved provided that:

D _c ≤0.8b,

- длина диэлектрического стержня в прямоугольном волноводе, мм;Where

- the length of the dielectric rod in a rectangular waveguide, mm;

D _c is the diameter of the dielectric rod mm;

ε _r is the relative dielectric constant of the rod;

ƒ _в - upper frequency of the klystron gain band, GHz;

b is the size of the narrow wall of a rectangular waveguide, mm

The calculation of the length of the round rod according to the proposed formula for ƒ _in = 17.7 GHz, D _c = 4 mm; ε _r = 9; b = 6.5 mm gives the result l _c = 6.91 mm (very close to the experimental data - l _c = 6.92 mm).

In FIG. Figure 1 shows that the theoretical and experimental dependences of the relative length of a round dielectric rod on the upper frequency of the klystron gain band coincide well.

The final tuning of this “waveguide-dielectric” resonator to the resonant frequency of the active resonator or with a specified detuning from this frequency at the stage of technological tests of the klystron in the operating mode is carried out by changing the length of the tuning pin mounted in the center of the wide wall of the rectangular waveguide and located in close proximity to end part of the dielectric rod.

The third passive resonator in this filter system is a resonant tuning pin, mounted in the center of the wide wall of a rectangular waveguide and located in close proximity to the end part of the dielectric rod, which is designed to tune the "waveguide-dielectric" resonator to the resonant frequency of the active resonator or with a given offset from of this frequency at the stage of technological tests of the klystron in the operating mode.

The fourth passive resonator in this filter system is a resonant pin, which is installed at a distance of at least a quarter of the wavelength at a frequency of ƒ _in from the tuning pin to achieve optimal coupling between the passive resonators. The range and accuracy of tuning the passive filter system to the given frequencies are increased if a second resonant pin is additionally introduced into the design of the passive filter system. Moreover, these resonant pins are installed with an offset of x ₁ , x ₂ relative to the center of the rectangular waveguide and are equally removed from the end part of the dielectric rod, which provides a common-mode form of vibrations of these resonant elements when they are excited by an H ₁₀ wave in a rectangular waveguide. The range of matching of the wave resistances of the input and output of microwave energy of the klystron with external waveguide paths is expanded if at least one tuning waveguide diaphragm is added to the design of the passive filter system, which is located between the first tuning pin located in the immediate vicinity of the end part of the dielectric rod , and subsequent training pins.

Since the passive resonators of the filter system mentioned above are connected in series, their tuning to the given frequencies and selecting the connection between them can be carried out both by varying their location relative to each other, and by changing the length of the resonant elements (pins).

In both the input and output filter systems, tunable passive resonators and tuning waveguide diaphragms are located outside the vacuum and are connected to the active resonator through a vacuum-tight dielectric microwave window in the form of a segment of a waveguide filled with dielectric, which also functions as the first passive resonator, and through the resonant a diaphragm located on the side of the corresponding active resonator.

The use of waveguide-dielectric structures as vacuum-tight dielectric microwave windows, which are simultaneously the basic elements of multi-beam klystron filter systems, allows you to combine the design of a multi-link filter system with small-sized waveguide-dielectric rod-type energy input / output devices in the centimeter and millimeter frequency ranges and allows expand the klystron gain band without increasing the size and mass of these devices.

The foregoing allows us to conclude that there is a "inventive step" in the claimed invention.

The invention is illustrated by drawings, where in FIG. Figure 1 shows the theoretical (dashed line) and experimental (solid line) dependences of the relative length of a round dielectric rod on the upper frequency of the klystron gain band. In FIG. Figure 2 shows a general view of a multipath klystron. In FIG. 3 shows a cross section of a klystron in section AA (rotated) without a tuning waveguide diaphragm. In FIG. 4 shows a cross section of a klystron in section AA (rotated) with a tuning waveguide diaphragm.

With reference to FIG. 2, FIG. 3 and FIG. 4 are indicated:

1 - cathode-grid node

2 - input active resonator,

3 - output active resonator,

4 - node input energy;

5 - node output energy;

6 - intermediate resonator;

7 - collector;

8 - channels for the passage of electron beams;

9 - resonant diaphragm;

10 - segments of the input and output rectangular waveguides;

11 - segments of dielectric-filled waveguides;

12 - dielectric rods;

13 - channels of communication windows along a microwave field in rectangular waveguides, combined with segments of waveguides filled with a dielectric;

14 - tuning pins;

15 - the first resonant pins;

16 - second resonant pins;

17 - frequency tuning mechanisms;

18 - pole tips of the magnetic system.

19 - tuning waveguide diaphragm.

The work of multi-beam klystron is as follows.

In the cathode-grid unit (1), under the influence of accelerating voltage, a multipath electron beam is formed, which is passed through channels for the passage of electron beams (8), made in the input (2) intermediate (6) and output (3) active resonators. Further, the rays are focused by a longitudinal magnetic field, the configuration of which is determined by the pole tips (18) of the magnetic system. After the passage of the resonators, the electron beams are scattered on the collector (7).

An input microwave signal is supplied to a segment of a rectangular waveguide (10), which is part of the energy input unit (4), and excites in it an electromagnetic field of an H ₁₀ type wave, which, in turn, excites a multi-link broadband filter system from passive resonators containing segments of the input and output rectangular waveguides (10) with dielectric rods (12), segments of insulator-filled waveguides (11), communication channels through a microwave field in rectangular waveguides (13), combined with segments of a wave filled with dielectric odov, adjusting pins (14), the first resonant pins (15), the second resonant pins (16); tuning waveguide diaphragms (19), resonant diaphragm (9) and input and output active resonators. In the input filter system of a multipath klystron, when the input signal is applied, both waves of the main type H ₁₀ propagate in the segment of the rectangular waveguide (10) associated with the load, and waves of the main type H ₁₁ excited in the segment filled with the dielectric waveguide (11), which connected through the resonant diaphragm (9) to the input active resonator (2). Under the action of the longitudinal component of the microwave electric field of a standing wave of type H ₁₀ in the input active resonator (2), a longitudinal microwave electric field of a standing wave of type H ₁₀ appears, which modulates the electron rays passing through the resonators in speed in the microwave gap. The input filter system provides excitation in the input active resonator of a longitudinal microwave electric field of a standing wave of type H ₁₀ in the microwave gap of approximately the same intensity at all frequencies of the working range of the klystron or with a given amplitude-frequency dependence. The formation of dense electron bunches occurs during the sequential passage of intermediate resonators by electron beams (6), where the additional modulation of the electrons in speed occurs, and of drift tubes in which the modulation of electrons in density occurs. To create approximately the same amplitude of the first harmonic of the induced current in the output klystron oscillatory system at all frequencies of the working range using the frequency tuning mechanisms (17), the resonant frequencies of the intermediate resonators are adjusted accordingly (6). Passing through the gap of the output active resonator (3), electron bunches fall into the braking phase of the microwave field and, as a result of braking, give them their kinetic energy. Since the design of the output filter system of a multi-beam broadband klystron is completely identical to the input one, electromagnetic waves are transmitted from the output active resonator through the energy output unit (5) to the load with a given transmission coefficient or close to 1 in the entire working range of the broadband klystron.

Combining the design of the filter system with the energy input and output nodes of the multi-beam klystron leads in the centimeter and millimeter wavelength ranges to expand the gain band of this device without increasing its size and mass.

Information sources

1. Pasmannik V.I. Connected loop systems. M .: Fizmatlit, 2005.

2. Patent US 3484861 A, IPC H01J 25/16, (IPC 1-7): H01J 25/02, publ. 12/16/1969.

3. Patent US 3299312 A, IPC H01J 25/12, publ. 01/17/1967.

4. Copyright certificate SU 880158 A1, IPC H01J 25/10, publ. 03/07/1992.

5. Patent application for utility model CN 203134747 U, IPC H01J 23/36, publ. 08/14/2013.

6. Vostrov M.S., Zakurdaev A.D., Polevich G.A. - Multipath small-sized klystron of 8 mm wavelength range // ELECTRONICS, SER. 1, microwave technology, vyp. 4 (511), 2011, S. 3-5.

7. Patent RU 2239256, IPC H01J 25/10, publ. 10/27/2004.

Claims (13)

1. A broadband multipath klystron containing input, intermediate and output active resonators, microwave energy input and output nodes, which include: diaphragms with communication windows with active input and output resonators, vacuum-tight microwave dielectric windows, sections of rectangular waveguides with dielectric rods exciting the waveguides and tuning pins located along the wide walls of the waveguides, characterized in that it contains n (n = 1, 2, 3, ..., n) passive frequency-tuned resonators located behind the limits of the vacuum part of the klystron in the output of microwave energy or in the input and output of microwave energy and containing: a passive resonator from a vacuum-tight dielectric microwave window, made in the form of a waveguide-dielectric resonator, which is formed by a segment of a waveguide with dielectric filling in the form of a dielectric rod sealed in the channel of the waveguide, and the dimensions of the waveguide-dielectric resonator correspond to the condition of the approximate equality of its resonant frequency to the upper frequency of the gain band to Istron

; a passive resonator of a rectangular waveguide with a dielectric heterogeneity in the form of a dielectric rod, exciting the waveguide and which is a continuation of the dielectric rod hermetically installed in the channel of the waveguide; passive resonators from tuning pins, one of which is installed in the middle of the wide wall of a rectangular waveguide in the immediate vicinity of the end part of the dielectric rod, and at least one other resonant pin, which is installed at a distance S from the axis of the first at least a quarter of the wavelength at a frequency

moreover, the pins are made with the possibility of changing their length, allowing you to configure a rectangular waveguide with a dielectric inhomogeneity and tuning pins to the resonant frequency of the active resonator or with a given detuning from this frequency, which provides a given difference in the transmission coefficient of microwave power in the working frequency band of the klystron from the input path to the input active resonator and from the output active resonator to the output path. 2. The broadband multipath klystron according to claim 1, characterized in that the output of microwave energy or input and output of microwave energy contain tuning waveguide diaphragms, providing an extension of the matching band of the impedances of input and output microwave energy of the klystron with external waveguide paths, at least at least one diaphragm, which is located on the wide wall of the waveguide between the first training pin located in the immediate vicinity of the end part of the dielectric rod, and the subsequent training pins. 3. A broadband multipath klystron according to claim 2, characterized in that the tuning waveguide diaphragms, at least one, which is located on a wide wall of the waveguide between the first tuning pin located in the immediate vicinity of the end part of the dielectric rod and the subsequent tuning pins, has the size along the wide wall of the waveguide is smaller than the size of the wide wall of the waveguide and does not have electrical contact with the narrow walls of the waveguide. 4. A broadband multipath klystron according to claim 1, 2, or 3, characterized in that the dielectric rod sealed in the waveguide channel and the dielectric rod exciting the waveguide and which is a continuation of the dielectric rod sealed in the waveguide channel section. 5. Broadband multipath klystron according to claim 1, or 2, or 3, or 4, characterized in that the resonant pins, which are installed at a distance S from the axis of the first at least a quarter of the wavelength at a frequency

are located with an offset from the axis of the wide wall of the waveguide. 6. A broadband multipath klystron according to claim 1, 2, or 3, characterized in that the dielectric rod sealed in the waveguide channel and the dielectric rod exciting the waveguide and which is a continuation of the dielectric rod sealed in the waveguide channel section corresponding to the conditions:

D _c ≤0.8b, Where

- the length of the dielectric rod in a rectangular waveguide, mm; D _c is the diameter of the dielectric rod mm; ε _r is the relative dielectric constant of the rod;

- the upper frequency of the gain band of the klystron, GHz; b is the size of the narrow wall of a rectangular waveguide, mm

Images