CN111770601A - Magnetron-based frequency scanning microwave oven - Google Patents

Magnetron-based frequency scanning microwave oven Download PDF

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CN111770601A
CN111770601A CN202010019285.9A CN202010019285A CN111770601A CN 111770601 A CN111770601 A CN 111770601A CN 202010019285 A CN202010019285 A CN 202010019285A CN 111770601 A CN111770601 A CN 111770601A
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magnetron
frequency
signal
injection
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杨阳
黄卡玛
朱铧丞
陈星�
刘长军
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Sichuan University
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Sichuan University
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
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    • H05B6/64—Heating using microwaves
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    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
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Abstract

The invention relates to the microwave field, in particular to a frequency scanning microwave oven based on a magnetron, which solves the problems of relatively low output power and high cost of a solid microwave source in the prior art.

Description

Magnetron-based frequency scanning microwave oven
Technical Field
The invention relates to the field of microwaves, in particular to a frequency scanning microwave oven based on a magnetron.
Background
Microwaves are widely used in daily life and experimental research in subjects such as physics, chemistry, and biomedicine. Microwave ovens are often used for heating or for corresponding treatments using the microwave spectrum effect.
The magnetron is used as one of microwave sources, the output frequency spectrum of the magnetron can be influenced by the anode current of the magnetron, namely clutter and phase noise can be generated or the output frequency spectrum of the magnetron is wider when the anode current is at a smaller value;
the magnetron has the advantages of large output power, high efficiency, small volume, low cost and the like. The magnetron can be widely applied to the fields of military affairs, industry, agriculture, medical treatment and health, household cooking range and the like. The common magnetrons in the prior art all belong to traveling wave magnetrons.
However, in the conventional industry, most common interference sources for interference of the civil unmanned aerial vehicle are high-power solid-state microwave sources, the power is usually 400W-600W, and the solid-state microwave sources are widely applied to numerous fields due to the advantages of stable output, light volume, simplicity, easiness in use and the like. The output power of solid state microwave sources is relatively low and costly;
a new microwave source with low cost and high output power that can replace the solid state microwave source is urgently needed.
Disclosure of Invention
The invention provides a magnetron-based frequency scanning microwave oven, which solves the problems of relatively low output power and high cost of a solid-state microwave source in the prior art.
The technical scheme of the invention is realized as follows: a frequency scanning microwave oven based on a magnetron includes a magnetron including an external injection signal connected thereto through a circulator.
Preferably, the device providing the external injection signal is a low power solid state microwave source;
further, the low power solid state microwave source adjusts the frequency and swept bandwidth of the output signal through injection wave interaction.
Preferably, the injection ratio of the external injection signal to the magnetron signal is 15% -45%.
Preferably, the frequency sweep signal of the low-power solid-state microwave source is used for injection locking of the magnetron, so that the magnetron outputs the frequency sweep signal.
The invention uses the external signal injection frequency locking form, takes the standing wave interaction as the theoretical basis, innovatively uses the magnetron microwave source as a solution idea, uses the sweep frequency signal of the low-power solid microwave source to perform injection locking on the magnetron, can realize large output bandwidth and high emission power by the high-power and high-cost solid microwave source with low cost, and is a microwave source with low cost, high power and high efficiency.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1: a module schematic diagram of the invention;
FIG. 2: a magnetron equivalent circuit;
FIG. 3: an equivalent circuit when the magnetron is locked by an external signal;
FIG. 4: magnetron model in CST particle working chamber;
FIG. 5: high-frequency voltage waveform under free oscillation of the magnetron;
FIG. 6: fourier transform of high-frequency voltage under free oscillation of the magnetron;
FIG. 7: an electronic spoke in a magnetron resonant cavity under free oscillation of a magnetron;
FIG. 8: magnetron output spectrograms of different frequencies when the high-frequency voltage of the external signal is at 20V;
FIG. 9: injecting a magnetron frequency sweep experimental system of a frequency locking theory;
FIG. 10: the relation graph of anode current, power and center frequency under the free state of the magnetron;
FIG. 11: magnetron and swept signal source frequency spectrum;
FIG. 12: magnetron output frequency spectra at different injection ratios;
FIG. 13: the magnetron outputs high-frequency voltage at different injection ratios;
FIG. 14: magnetron output parameters under different injection ratios;
FIG. 15: comparing the frequency-time relationship between the output of the magnetron and external signals at different frequency sweep rates;
FIG. 16: magnetron DPX spectrograms at different sweep periods.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention discloses a frequency scanning microwave oven based on a magnetron, which comprises the magnetron, wherein an external injection signal is connected with the magnetron through a circulator.
Preferably, the device providing the external injection signal is a low power solid state microwave source;
further, the low power solid state microwave source adjusts the frequency and swept bandwidth of the output signal through injection wave interaction.
Preferably, the injection ratio of the external injection signal to the magnetron signal is 15% -45%.
Preferably, the frequency sweep signal of the low-power solid-state microwave source is used for injection locking of the magnetron, so that the magnetron outputs the frequency sweep signal.
Further, the swept frequency signal reaches a full lock state: transient output frequency of magnetron:
Figure RE-GDA0002659108900000031
wherein the content of the first and second substances,
Figure RE-GDA0002659108900000032
wherein
Figure RE-GDA0002659108900000033
Figure RE-GDA0002659108900000034
Where ω is the oscillation frequency of the magnetron, ω0Is the local oscillator frequency, Q, of the resonant cavity0Being the inherent quality factor, Q, of the resonant circuitextIs an external quality factor, V, of the resonant circuitdcIs the magnetron anode voltage, VRFThe magnetron high-frequency voltage is represented by R, equivalent resistance, equivalent inductance, equivalent capacitance, equivalent magnetron power supply G + jB and equivalent load G + jB.
Further, the frequency sweeping signal is swept by a voltage controlled oscillation device of the low-power solid-state microwave source.
The injection frequency locking of the continuous wave magnetron disclosed by the Adler formula means that a low-level high-stability external reference microwave signal is injected into the continuous wave magnetron, the frequency of the signal is positioned near the inherent frequency f0 of the magnetron, the signal is directly injected into the continuous wave magnetron through a circulator, and when the amplitude of the injected signal reaches a certain value, the oscillation frequency of the continuous wave magnetron controlled by high voltage keeps consistent with the frequency of the injected signal.
The invention makes the magnetron output wider frequency spectrum by adjusting the anode current of the magnetron, thereby realizing the broadband interference aiming at the spread spectrum communication system. The invention is based on the classic broadband interference theory, uses the normal distribution curve to carry out fitting simplification on the output frequency spectrum of the magnetron, and uses the mathematical segmentation idea to equivalently convert the whole frequency band into a plurality of narrow-band interference signals, thereby obtaining the broadband interference error rate calculation formula of the magnetron microwave source. The analysis shows that the magnetron broadband interference is the same as the common broadband interference, the bandwidth occupation ratio of the interference signal and the interference power are the same decisive factors influencing the interference effect, and the ideal interference effect can be achieved only when the bandwidth occupation ratio and the interference power are large. On the basis of theoretical derivation, the invention designs a magnetron broadband interference experiment to verify the theory, the injection ratio is adjusted by adjusting the remote control distance in the experiment, the interference signal bandwidth and the injection ratio are adjusted and intercepted by adjusting the anode current of the magnetron, the experimental result is consistent with the theory, and when the anode current of the magnetron is 70 mA-120 mA, the better interference effect is achieved because the magnetron bandwidth is wider and the output power is larger.
In addition, the magnetron can output a wider frequency spectrum by adjusting the current of the filament and the anode so as to realize wider frequency band coverage, and also provides favorable conditions for the magnetron to be used as an interference microwave source; on the other hand, a lot of researches are carried out on the injection frequency locking theory of the magnetron by predecessors, so that the magnetron can realize high-power frequency sweep output through injection of external signals, and further can realize frequency sweep interference aiming at spread spectrum communication systems such as unmanned aerial vehicles and the like.
Effect of wideband interference on spread spectrum communication systems:
1. when the injection ratio is small, i.e. below about-5 dB, a smaller interference bandwidth ratio will result in a higher bit error rate for the disturbed communication system, i.e. in this case a lower interference bandwidth ratio will result in a higher bandwidth ratio. However, the overall bit error rate is low, and the final interference effect is not obvious;
2. when the injection ratio is large, namely about higher than 0dB, the higher the interference bandwidth ratio is, the higher the bit error rate is caused, and therefore, the interference effect is better;
3. the interference bandwidth ratio is kept unchanged, and the influence of the injection ratio on the bit error rate is seen, the fact that the bit error rate of a system is increased along with the increase of the injection ratio is found, the increase trend of the bit error rate is the largest in the interval of-5 dB to 5dB of the injection ratio, but the bit error rate is not infinitely increased along with the increase of the injection ratio and finally tends to be gentle, which means that in an actual situation, an interference signal with extremely large power is not needed, and only the optimal solution is obtained by comprehensively considering two factors of the bit error rate and the injection ratio;
4. when the bandwidth of the interfering signal completely covers the frequency band of the interfered communication system, i.e. full-band interference, the bit error rate limit in this case is 50%.
The magnetron microwave source is used for carrying out broadband interference on the frequency hopping spread spectrum communication system, which is a special form of common partial bandwidth interference or full-band interference, and the main difference is that the power distribution is uneven on an interference frequency band. In order to obtain the best possible interference effect, the transmission power of the magnetron needs to be increased, and the output bandwidth of the magnetron needs to be increased, that is, the communication frequency band covering the interference target is increased as much as possible.
Swept-frequency interference is similar to wideband or partial band noise interference, in that a relatively narrowband signal is swept or scanned over a period of time. The narrowband signal is very narrow in bandwidth, corresponding to a tone, and at any time in the time period, the center frequency of the jammer is a specific frequency, and the only portion of the spectrum that is disturbed falls within a narrowband region around the frequency. However, since the signal is swept, it can interfere with multiple frequencies in a wide range in a short time, and therefore swept interference is also an effective way to interfere with spread spectrum communication systems.
Because of the advantages of the frequency sweep interference when the frequency sweep interference is carried out aiming at the spread spectrum communication system and the characteristics of the magnetron, the magnetron with low cost and high power is used as a microwave source, based on the injection locking theory of the magnetron, the frequency sweep output power and the output bandwidth of the magnetron are extracted by the means of injection through the external signal of the magnetron and the solid microwave source with low cost, usually 40W-60W;
magnetron frequency sweep theory analysis based on injection frequency locking theory
Theoretical analysis of free oscillation process of magnetron: the injection frequency locking of the continuous wave magnetron refers to that a low-level high-stability external reference microwave signal is injected into the continuous wave magnetron, and the frequency of the signal is positioned at the natural frequency f of the magnetron0The signal is directly injected into the continuous wave magnetron through the circulator, and when the amplitude of the injected signal reaches a certain value, the oscillation frequency of the continuous wave magnetron controlled by high voltage keeps consistent with the frequency of the injected signal. Adler equates the model of the magnetron resonant cavity to an RLC circuit model, and analyzes the starting oscillation and external injection processes of the continuous wave magnetron from the angle of circuit analysis, so as to obtain the phase change condition of the magnetron locked by external signal injection, namely the classical Adler formula. Thereafter J.CThe sloter has performed a more detailed analysis of the injection locking process of the magnetron, and other scholars have performed a lot of more intensive research on the basis of the analysis.
As shown in the equivalent circuit model of the magnetron in fig. 2, RLC is an equivalent model of the magnetron resonator, where R is an equivalent resistance, L is an equivalent inductance, C is an equivalent capacitance, G + jB is an equivalent magnetron power supply, and G + jB is an equivalent load.
From fig. 2 it can be derived that:
Figure RE-GDA0002659108900000061
wherein
b＝b0-gtanα (2)
Figure RE-GDA0002659108900000062
Where ω is the oscillation frequency of the magnetron, ω0Is the local oscillator frequency, Q, of the resonant cavity0Is the intrinsic quality factor of the resonant circuit, Qext is the external quality factor of the resonant circuit, VdcIs the magnetron anode voltage, VRFIs a magnetron high frequency voltage. Assuming that the voltage amplitude of the magnetron at the start of oscillation changes exponentially, dividing the frequency into a real part and an imaginary part, the imaginary part of the frequency represents the increasing trend of the exponent:
ω1＝ω-jω2(4)
Figure RE-GDA0002659108900000071
this can result in:
Figure RE-GDA0002659108900000072
let (t) be ω 2, during the magnetron oscillation, equation (1) becomes:
Figure RE-GDA0002659108900000073
separating the real part from the imaginary part in equation (7) can result:
Figure RE-GDA0002659108900000074
Figure RE-GDA0002659108900000075
wherein
Figure RE-GDA0002659108900000076
The formula (3) may be substituted for the formula (8):
VRF(t)＝VRF0(1+ηe-γt) (11)
wherein
Figure RE-GDA0002659108900000077
In addition, the
Figure RE-GDA0002659108900000078
The transient output frequency of the magnetron can be solved by equation (9):
Figure RE-GDA0002659108900000081
in the formula
Figure RE-GDA0002659108900000082
From equation (14), it can be seen that the frequency of the magnetron in stable operation is composed of three parts, which are: omega0Local oscillation frequency of the magnetron resonant cavity; b0/(2C)-Bω0/(2Qext) Is the frequency push-forward effect caused by the electron beam and ω 0tan α/(2QL) is the frequency pull-in effect caused by the load, as can be seen from equations (11) and (13), as time t approaches infinity,the high frequency voltage and frequency of the magnetron can be converged to obtain a convergence value VRF0And ω'.
As shown in the theoretical analysis of the magnetron sweep injection in fig. 3, when there is an external injection signal, the external signal can be equivalent to the load of the magnetron, assuming that the voltage of the external signal is V1The current of the external signal is
Figure RE-GDA0002659108900000083
Frequency of omega1And the external injection signal is equivalent to a current source to simplify calculation. Then:
Figure RE-GDA0002659108900000084
the admittance of the magnetron load is:
Figure RE-GDA0002659108900000085
where ρ is the ratio of the amplitude of the injection signal to the magnetron high frequency voltage, known as the injection ratio, i.e.:
Figure RE-GDA0002659108900000086
in the formula, θ ═ ω - ω1) t represents a phase difference between the high frequency output signal of the magnetron and the external injection signal. Formula (16) may be substituted for formula (15):
Figure RE-GDA0002659108900000087
separating its real part from its imaginary part can yield:
Figure RE-GDA0002659108900000088
Figure RE-GDA0002659108900000091
the following equations (19) and (20) are simplified and solved:
Figure RE-GDA0002659108900000092
Figure RE-GDA0002659108900000093
β＝1+ρω0cosθ/(γQext) (23)
normalizing and simplifying the frequency in equation (22) can be obtained:
Figure RE-GDA0002659108900000094
when the magnetron is locked by an external single-frequency signal, θ is constant, that is, d θ/dt is 0, equation (24) can be simplified as follows:
Figure RE-GDA0002659108900000095
or:
2Qext|1-ω1|≤ρ (26)
this is the well-known Adler condition. Further, solving equation (24) can result in:
Figure RE-GDA0002659108900000096
wherein
Figure RE-GDA0002659108900000097
B＝1-ω1(29)
Figure RE-GDA0002659108900000098
Figure RE-GDA0002659108900000099
From the above analysis, it can be seen that if the external injection signal is a frequency sweep signal, the frequency sweep signal can be regarded as a single frequency signal in a sufficiently short time period. At the frequency omega of the injected signal1When the above condition is satisfied near the center frequency of the free-state magnetron, that is, when D is real in equation (30), the magnetron can be completely locked by the external injection signal, and in this frequency band, the output frequency of the magnetron will change completely with the change of the external signal frequency, if 2Qext |1- ω 1| is slightly larger than ρ, or D is a relatively small imaginary number in equation (30), △ ω is the absolute value of the difference between the center frequency of the free-oscillation magnetron and the external signal frequency, the output of the magnetron will have a series of sideband signals at the integer multiple of △ ω, that is, when the frequency of the external signal moves to this range, the magnetron will be in a quasi-locked state, and when the external signal exceeds the above range, that is, B △ ω is a quasi-locked state>>At time a, the output signal of the magnetron will be irrelevant to the external signal.
In addition, it can be seen from the equation (21) that, for the resonant circuit with high Q value, the high frequency output of the magnetron will be reduced to some extent when the injection ratio is increased; and due to the last item-Due to the existence of gamma t/β, when the power of the external frequency sweeping signal is relatively high, the frequency of the frequency sweeping signal changes frequently, the high-frequency output of the magnetron cannot reach a stable state in a short time, that is, the-gamma t/β term cannot be ignored, and the frequency change of the external signal every time causes the jump of the high-frequency output amplitude of the magnetron, so that the stability of the high-frequency output amplitude of the magnetron is greatly influenced.
Magnetron frequency sweep particle simulation based on injection frequency locking theory
A magnetron particle simulation method, namely particle-in-cell (PIC simulation for short), is a simulation method for researching the interaction of charged particles in electric and magnetic fields. The particle simulation method is gradually perfected after a particle model with a limited size is adopted and can be applied to practical application. The more common magnetron particle simulation software includes MAGIC, CST, CHIPIC, etc. Generally, the particle simulation of the magnetron has one of the following applications: rapidly designing a magnetron by using a three-dimensional electromagnetic particle simulation method; researching the oscillation process of the magnetron by using a particle simulation method; the influence of the structures of all parts of the magnetron on the working state of the magnetron is researched.
Magnetron model building
The invention uses Particle Studio in CST electromagnetic simulation software to simulate the magnetron particles. Because the scanning frequency injection research is carried out by adopting the Songjiang 2M244-M1 continuous wave magnetron, the simulation takes the Songjiang 2M244-M1 continuous wave magnetron as a prototype, and a model is established in a CST particle working chamber for simulation. According to the actual structure of the Panasonic 2M244-M1 magnetron, in order to shorten the simulation time, the structure is simplified when modeling is carried out in CST, only the resonant cavity, the internal structure and the output window of the magnetron are modeled, the actual spiral cathode is replaced by a cylindrical cathode, and the permanent magnet and the pole shoe in the magnetron are replaced by the constant magnetic field in the axial direction of the magnetron, as shown in the structural diagram of the magnetron in CST in FIG. 4.
Due to the working principle of the magnetron, the anode potential of the magnetron is set to be 0V, the cathode potential is set to be-4200V, and meanwhile, a constant magnetic field with the size of 0.19T is added to the axial direction of the resonant cavity of the magnetron. Fig. 5-7 show the outputs of the magnetron operating in the pi mode, and it can be seen that the amplitude of the high frequency voltage of the magnetron model in the free oscillation state is about 100V, and the center frequency is 2.343 GHz.
When 2Qext |1- ω 1| in equation (26) is slightly larger than ρ, or D is a relatively small imaginary number in equation (30), the magnetron will be in a quasi-locked state, which is actually advantageous for magnetron sweep sources in some cases. In the case of the frequency sweep interference, when the frequency of the external signal is in this range, the output spectrum of the magnetron will generate a range of sideband signals outside the range limited by the Adler condition, i.e. the frequency band that the actual interference can cover is slightly wider than the range limited by the Adler condition. As shown in the graph of the output spectrum of the magnetron at different frequencies when the high-frequency voltage of the external signal is 20V in fig. 8, when the frequency of the external signal is slightly higher than 2.351GHz, the magnetron is in a quasi-locked state; and when the frequency of the external signal is at a higher frequency, the magnetron will not be locked by the external signal.
In order to obtain the external quality factor of the simulation model, a group of simulations are carried out when the injection ratio is 30%, the maximum offset of the central frequency of the magnetron is 7MHz, and the maximum offset is brought into an Adler condition, so that the external quality factor of the magnetron model can be reversely deduced to be 50.23. According to the magnetron external quality factor reversely deduced from the data obtained by simulation, the relation between the frequency sweep bandwidth and the injection ratio of the magnetron model in an ideal state is calculated. When the injection ratio is 50%, the sweep bandwidth of the magnetron can reach 23 MHz.
Magnetron simulation and result analysis: since the center frequency f0 in the free state of the magnetron is 2.434GHz, we set the sweep range of the external sweep signal to 2.3GHz to 2.4GHz, and study the relationship between the injection ratio and the magnetron sweep bandwidth by changing the injection ratio.
The output power of the magnetron model in a free state is about 5kW, ten groups of power of a frequency sweeping signal are uniformly arranged from 12.5W to 1250W to control the injection ratio of the ten groups of 5% to 50%, and the output frequency spectrum bandwidth of the magnetron is increased along with the increase of the injection ratio, which shows that the locked bandwidth of the magnetron is widened and the frequency sweeping range is larger and larger at the same time of increasing the injection ratio; for the high-frequency voltage of the magnetron, the amplitude fluctuation is larger and larger along with the increase of the injection ratio, each fluctuation is 40ns and is equal to the sweep interval of an external sweep signal of 40ns, and the output power of the output port of the magnetron is not obviously increased along with the large increase of the injection power.
The sweep bandwidth increases with increasing injection ratio, its trend is with QextThe sweep bandwidth curves of the value estimation are basically consistent, and when the injection ratio is 50%, the sweep bandwidth reaches 21 MHz; the output power of the injection-locked magnetron is always slightly less than that of the magnetronThe sum of the free-state magnetron output power and the injection signal power and as the injection ratio increases, this difference also increases slightly.
Experimental verification of magnetron frequency sweep based on injection frequency locking theory
The experimental scheme is as follows: in order to further verify the theory and simulation result of the frequency sweep external injection, the experimental system of the magnetron frequency sweep designed by the invention and adopting the BJ-26 waveguide system is built as shown in the experimental system of the injection frequency locking theory of the magnetron frequency sweep of the figure 9. The external signal is provided by an external sweep frequency signal solid source, the signal is injected into the magnetron through two circulators, the power of the injected signal can be connected to a power meter for measurement through a coupling end of the 40dB directional coupler, the output of the magnetron is absorbed by the load 1 after passing through the dual directional coupler 1, the circulator 1 and the dual directional coupler 2, and the load 1 selects a water load in consideration of the large output power of the magnetron. In order to protect the signal source from being damaged by the possible reflected power, the system adopts a dual-circulator dual-load structure, and when all power is not absorbed or reflection exists at the load 1, the load 2 can absorb the redundant power as a double fuse. The output power and frequency spectrum data of the magnetron can be measured through the coupling end of the bi-directional coupler 2.
The magnetron uses a loose 2M244-M1 continuous wave magnetron, the rated output power is 1kW, the rated working frequency is 2.45GHz, and the power supply of the magnetron is provided by a DDY10-5K/0V8-S220/F02 high-voltage direct current power supply of Invitrogen company; the external injection signal is provided by a solid microwave source with a frequency sweeping function, the maximum frequency sweeping bandwidth is 100MHz, and the rated maximum output power is 50 dBm; the frequency spectrum in the experiment and the frequency time relationship data of the signal were measured by a Tektronix RSA5126B real-time signal analyzer, and the power was measured by an AV2433 power meter at the midrange 41.
The experimental procedure was designed as follows:
1. starting the magnetron, injecting no external signal, and recording the relation between the anode current of the magnetron in a free oscillation state and power and frequency spectrum by adjusting the anode current of the magnetron;
2. closing the magnetron, starting a frequency sweep signal source, adjusting the power of an injection signal, the frequency sweep bandwidth, the frequency sweep interval and the like, and recording the data;
3. starting a magnetron, fixing the anode current of the magnetron at 120mA, wherein the output power of the magnetron at the moment is 314W, the sweep frequency bandwidth of an external sweep frequency signal is fixed at 100MHz, and measuring the influence of an injection ratio on the sweep frequency bandwidth by changing the injection power of an external signal source;
4. the state of the magnetron and the power of the external frequency sweeping signal are unchanged, and the influence of the frequency sweeping speed on the output of the magnetron is recorded by changing the frequency sweeping speed of the external frequency sweeping signal.
In addition, to compare the difference between the sweep bandwidth calculated by Adler conditional theory and the actual sweep bandwidth, we first performed a cold chamber test on the panasonic 2M244-M1 continuous wave magnetron using a vector network analyzer to obtain its external quality factor.
Ql＝f0/Δf (32)
Q0＝Ql(1+β0) (33)
Qext＝Q0/β0(34)
In the formula QlIs a loaded quality factor, Q0Is a no-load quality factor, QextIs an external quality factor, f0Resonant frequency, △ f, half power bandwidth, β0Is the coupling coefficient.
Cold chamber test results: f. of0Is 2.48GHz, &lTtTtransfer = delta "&gTt & &lTt/T &gTt f is 60MHz, &lTtTtransfer = beta" &gTtβ &lTt/T &gTt0Equal to the standing-wave ratio 12.74, and the external quality factor Q of the magnetron can be obtained by bringing the standing-wave ratio 12.74 into the formulas (32) to (34)extWas 41.15. According to the obtained external quality factor of the magnetron, theoretically, the relationship that the frequency sweep bandwidth of the magnetron changes along with the injection ratio, and when the injection ratio is 50%, the frequency sweep bandwidth can reach 29.6 MHz.
As shown in the graph of the relationship between the anode current, the power and the center frequency in the free state of the magnetron in fig. 10, when the filament current of the 2M244-M1 continuous wave magnetron is 5.33A, the filament voltage is 1.924V and the anode voltage is 4300V, the output power and the center frequency of the continuous wave magnetron vary with the anode current. In the free state, both the power and frequency of the magnetron vary with the anode current. Considering that the power of the external swept solid-state source can only reach 50dBm at maximum, namely 100W, in order to obtain a larger range of injection ratio data, the anode current of the magnetron is controlled to be 120mA, and the output power of the magnetron at the moment is 314W.
FIG. 11(a) is a magnetron spectrum at an anode current of 120mA in a free state, where a center frequency of the magnetron is 2.4366 GHz; FIG. 11(b) is the max-hold mode spectrum of an external swept frequency signal centered at 2450MHz with a swept bandwidth of 100 MHz. The injection ratio was varied to measure the output spectrum of the magnetron and to count the lock bandwidth.
Fig. 12 shows the max-hold spectrum of the magnetron output at the injection ratios of 5%, 15%, 25%, 35% and 45%, respectively, and it can be seen from the graph that the frequency sweep bandwidth of the magnetron is continuously increased with the increase of the injection power. From the amplitude of the spectrum, the frequency spectrum of the frequency band locked by the external signal is obviously higher than that of the frequency spectrum not locked, which shows that the output frequency of the magnetron moves along with the movement of the frequency of the external sweep signal in the locked frequency band. Fig. 13 shows the output high-frequency voltage of the magnetron at different injection ratios, which is the output waveform of the high-frequency voltage of the magnetron at different injection ratios, and as the injection ratio increases, the stability of the output of the magnetron is affected.
FIG. 14 details of magnetron output parameters, magnetron sweep bandwidth and output power as a function of injection ratio for different injection ratios. Compared with the sweep frequency bandwidth in the simulation result, the sweep frequency bandwidth in the experiment result is wider than that in the simulation result, and under the condition of not considering the difference between the simulation model and the actual experiment, due to the existence of the quasi-lock effect, the increase of the sweep frequency bandwidth can be realized under the condition of the same injection ratio. In addition, in consideration of practical significance, the maximum injection ratio is set to 50% at most (25% of injection power ratio) in experiments and simulations, and the maximum locking bandwidth is 37 MHz. For the output power of the magnetron, the actual output power is slightly smaller than the sum of the injection power and the magnetron power in the free state, and as the result of the simulation, the difference slightly increases as the injection ratio increases.
Influence of frequency sweep rate on magnetron frequency sweep output: the equivalent circuit model is used for the magnetron, and whether the frequency sweeping speed influences the output of the magnetron or not needs to be considered due to the existence of distributed inductance and distributed capacitance. In short, it is whether the frequency output of the magnetron can be synchronized with the external signal when the sweep rate of the external injection signal is increased. Therefore, the magnetron power is fixed at 397W, the power of an external signal is fixed at 52.4W, the frequency sweep range is 2430MHz to 2450MHz, the magnetron can be completely locked by the external signal, and the frequency sweep period is changed to observe the frequency of the magnetron output and the time relationship, namely the frequency-time relationship comparison graph of the magnetron output and the external signal under different frequency sweep rates in FIG. 15, wherein the frequency sweep periods T of the comparison graph are 1580 mus, 1050 mus, 630 mus and 90 mus respectively.
Fig. 16 shows magnetron DPX spectrograms at different sweep periods, where the sweep periods T are 1580 μ s, 1050 μ s, 630 μ s, and 90 μ s, respectively. When the sweep period T is in the range of 1580 mus to 90 mus, the output of the magnetron can keep completely consistent with the sweep rate of the external injection signal, and in addition, the frequency of the magnetron can follow the frequency of the external injection signal to change smoothly. Therefore, when the sweep period of the external signal is more than 90 mus, the magnetron can work as a high-power sweep microwave source.
When the frequency-hopping magnetron microwave source interferes the frequency-hopping communication system, the effect is equivalent to that the total power is evenly distributed to the whole frequency-hopping band, and the frequency-hopping communication system with the communication band of 80 MHz-100 MHz, such as an unmanned aerial vehicle for aerial photography, has good interference effect.
Product cost analysis
Product cost analysis
Figure RE-GDA0002659108900000161
Product cost analysis
Figure RE-GDA0002659108900000171
The invention uses the external signal injection frequency locking form, takes the standing wave interaction as the theoretical basis, innovatively uses the magnetron microwave source as a solution idea, uses the sweep frequency signal of the low-power solid microwave source to perform injection locking on the magnetron, can realize large output bandwidth and high emission power by the high-power and high-cost solid microwave source with low cost, and is a microwave oven with low cost, high power and high efficiency.
It is understood that various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention, and it is intended to cover in the appended claims all such changes and modifications.

Claims (6)

1. A magnetron-based frequency scanning microwave oven comprising a heating chamber and a magnetron, characterized in that the magnetron is connected to an external injection signal via a circulator.
2. A magnetron-based frequency scanning microwave oven as claimed in claim 1, wherein: the device providing the external injection signal is a low power solid state microwave source.
3. A magnetron-based frequency scanning microwave oven as claimed in claim 2, wherein: the low-power solid-state microwave source adjusts the frequency and the sweep frequency bandwidth of the output signal through injection wave interaction.
4. A magnetron-based frequency scanning microwave oven as claimed in claim 3, wherein: the injection ratio of the external injection signal to the magnetron signal is 15% -45%.
5. A magnetron-based frequency scanning microwave oven as claimed in any one of claims 1 to 4, characterized in that: and injecting and locking the magnetron by the frequency sweeping signal of the low-power solid-state microwave source to enable the magnetron to output the frequency sweeping signal.
6. An injection frequency locked microwave source according to claim 5, characterized in that: the swept frequency signal reaches a fully locked state: transient output frequency of magnetron:
Figure FDA0002360121110000011
wherein the content of the first and second substances,
Figure FDA0002360121110000012
wherein
Figure FDA0002360121110000013
Figure FDA0002360121110000014
Where ω is the oscillation frequency of the magnetron, ω0Is the local oscillator frequency, Q, of the resonant cavity0Being the inherent quality factor, Q, of the resonant circuitextIs an external quality factor, V, of the resonant circuitdcIs the magnetron anode voltage, VRFThe magnetron high-frequency voltage is represented by R, equivalent resistance, equivalent inductance, equivalent capacitance, equivalent magnetron power supply G + jB and equivalent load G + jB.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113950176A (en) * 2021-10-14 2022-01-18 四川大学 Magnetron anode power supply ripple mixing multi-frequency heating device and method
CN114446740A (en) * 2021-11-18 2022-05-06 电子科技大学 Modular frequency and phase locking structure, frequency and phase locking circuit system and monitoring system thereof

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0447207A2 (en) * 1990-03-14 1991-09-18 Litton Systems, Inc. Injection locked oscillators
GB2425415B (en) * 2005-04-20 2009-01-14 E2V Tech Phase locking magnetrons
CN102904569A (en) * 2011-07-29 2013-01-30 飞思卡尔半导体公司 Oscillator systems having annular resonant circuitry
CN103199855A (en) * 2013-04-02 2013-07-10 四川大学 Multi-path injection lock magnetron coherent power combination microwave source
CN103208406A (en) * 2013-04-02 2013-07-17 四川大学 Artificial intelligent phase modulation injection locking continuous wave magnetron microwave source
CN104241064A (en) * 2014-08-29 2014-12-24 南京三乐微波技术发展有限公司 Magnetron with injected locking frequency of 20 kW/2450 MHz

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0447207A2 (en) * 1990-03-14 1991-09-18 Litton Systems, Inc. Injection locked oscillators
GB2425415B (en) * 2005-04-20 2009-01-14 E2V Tech Phase locking magnetrons
CN102904569A (en) * 2011-07-29 2013-01-30 飞思卡尔半导体公司 Oscillator systems having annular resonant circuitry
CN103199855A (en) * 2013-04-02 2013-07-10 四川大学 Multi-path injection lock magnetron coherent power combination microwave source
CN103208406A (en) * 2013-04-02 2013-07-17 四川大学 Artificial intelligent phase modulation injection locking continuous wave magnetron microwave source
CN104241064A (en) * 2014-08-29 2014-12-24 南京三乐微波技术发展有限公司 Magnetron with injected locking frequency of 20 kW/2450 MHz

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113950176A (en) * 2021-10-14 2022-01-18 四川大学 Magnetron anode power supply ripple mixing multi-frequency heating device and method
CN113950176B (en) * 2021-10-14 2023-05-23 四川大学 Magnetron anode power supply ripple mixing multi-frequency heating device and method
CN114446740A (en) * 2021-11-18 2022-05-06 电子科技大学 Modular frequency and phase locking structure, frequency and phase locking circuit system and monitoring system thereof
CN114446740B (en) * 2021-11-18 2023-04-14 电子科技大学 Modular frequency-locking phase-locking structure, frequency-locking phase-locking circuit system and monitoring system thereof

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