JP2011095167A - Electromagnetic wave generation device and radar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave generation device capable of generating a stable electromagnetic wave without widening the band of a transmission system including an antenna and a high frequency circuit, and without increasing the whole circuit scale, and to provide a radar including the device. <P>SOLUTION: A driving voltage application circuit 40 applies a prescribed high voltage induced in a secondary coil N2 of a transformer 41 between a positive electrode 51 and a negative electrode 52 of a magnetron 50 as a driving voltage. In a positive electrode current control circuit 30, a transistor Q31 is switched on by rise of a pulse signal to be inputted into an input terminal IN, and FET Q40 is switched on, and a current flows in a primary coil N1 of the transformer 41, and the induced voltage in the secondary coil N2 of the transformer 41 is applied to the negative electrode 52 of the magnetron 50. An application current when the transistor Q31 is switched on has an approximately proportional relation to a positive electrode current of the magnetron 50, and the positive electrode current is controlled corresponding to a resistance value of a temperature-sensitive resistive element RT. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave generator using a magnetron and a radar equipped with the electromagnetic wave generator.

  Electromagnetic wave generators that generate electromagnetic waves such as microwaves using magnetrons are used in various radars, microwave heating devices, microwave power transmission devices, and the like.

  For example, a pulse modulated radar is composed of a magnetron that oscillates and outputs a microwave, a magnetron driving circuit that drives the magnetron, an antenna that transmits and receives the microwave, a receiving circuit, and the like.

  Further, in the microwave power transmission device, the plurality of microwave generation devices have the phases of the generated microwaves aligned so that the microwaves transmitted from the plurality of microwave generation devices can be received and taken out as power. It is required that

  Patent Document 1 discloses a microwave generator using a magnetron that controls the phase of the oscillation output of the magnetron. Here, the structure of the microwave generator of patent document 1 is demonstrated with reference to FIG.

  In FIG. 1, a high voltage is applied between the anode and the cathode of the magnetron 11 by the high-voltage direct current stabilized power supply 12 to cause an anode current to flow, whereby the magnetron 11 oscillates at a natural oscillation frequency. The reference signal generator 13 generates a reference signal having a frequency close to the natural oscillation frequency of the magnetron 11 and is supplied to the distributor 15 through the variable phase shifter 14. The distributor 15 distributes the inputted reference signal to the circulator 16 and the mixer 17.

  The circulator 16 injects the input reference signal into the magnetron 11 and outputs the microwave radiated from the magnetron 11 to the directional coupler 18. The microwaves through the directional coupler 18 are sent to a feeding system such as a horn antenna.

  The mixer 17 mixes the reference signal from the distributor 15 and the microwave from the attenuator 19, and the low-pass filter (LPF) 20 removes unnecessary harmonic components, so that the reference signal and the microwave are mixed. The frequency difference signal is output. An analog / digital converter (A / D) 21 obtains a value corresponding to the frequency difference.

  The anode current control calculator 22 calculates an anode current control signal for reducing the value corresponding to the frequency difference (frequency error), and converts the control value into an analog control signal by the digital / analog converter (D / A) 23. The voltage is converted and supplied to the high-voltage DC stabilized power supply 12.

The high-voltage DC stabilized power supply 12 increases or decreases the anode current of the magnetron 11 according to this control signal, and controls its oscillation frequency.
Thus, the oscillation frequency is stabilized by controlling the anode current of the magnetron by feedback control.

Japanese Patent No. 3697504

  The microwave generator shown in FIG. 1 is configured to accurately align the phases of microwaves transmitted from a plurality of microwave generators, for example, when microwaves are transmitted by a phased array antenna. Is.

  On the other hand, in various radars and microwave heating devices that use microwaves, if the fluctuation range of the oscillation frequency of the magnetron is large, the transmission system including the antenna and the high-frequency circuit must have broadband characteristics, and high gain and high SN ratio In order to obtain this, the overall size will be increased. Therefore, it is desirable that the frequency of the microwave be stable even in various radars and microwave heating devices that use microwaves.

  However, in the circuit configuration in which the oscillation frequency and phase of the magnetron are controlled by the PLL as shown in FIG. 1, the directionality for detecting the frequency of the circulator and the output microwave that are required for injection locking of the magnetron. A coupler is required, which increases the circuit scale. There is also a problem that loss occurs in the directional coupler and circulator.

  Accordingly, an object of the present invention is to provide an electromagnetic wave generator that generates a stable electromagnetic wave and a radar equipped with the same without increasing the bandwidth of a transmission system including an antenna and a high-frequency circuit without increasing the overall circuit scale. It is to provide.

  The inventor has found that the above-mentioned instability of the oscillation frequency of the magnetron is due to the temperature change of the magnetron, and that the self-oscillation frequency of the magnetron changes according to the temperature of the magnetron under a constant anode current. I found it.

Therefore, an electromagnetic wave generator of the present invention includes an anode and a cathode, and applies a drive voltage between the anode and the cathode, and a magnetron that generates an electromagnetic wave having a predetermined oscillation frequency by an anode current flowing through the anode. An electromagnetic wave generator comprising a drive voltage application circuit,
The drive voltage application circuit includes a temperature detection element that detects the temperature of the magnetron or the environment of the magnetron, and an anode current control unit that controls the value of the anode current according to the temperature. It is characterized by.

  The anode current control unit lowers the value of the anode current when the temperature is higher than the predetermined temperature, for example, with respect to the value of the anode current that generates an electromagnetic wave having the predetermined oscillation frequency at a predetermined temperature. If the temperature is lower than the predetermined temperature, the value of the anode current is increased.

  With this configuration, a change in oscillation frequency due to a temperature change of the magnetron is suppressed by controlling the anode current. Therefore, an electromagnetic wave having a stable frequency is generated.

  The temperature detection element is a temperature-sensitive resistance element whose resistance value changes according to temperature, and changes the anode current by an energization current.

  For example, the resistance value of the temperature detecting element increases as the temperature increases.

  As a result, the anode current can be controlled according to the temperature simply by providing the temperature-sensitive resistance element at a position where the anode current of the magnetron changes due to the energization current, and the entire circuit can be configured with a very simple circuit.

  For example, the drive voltage application circuit includes a transformer having a secondary coil connected to the magnetron, and a transformer drive element that applies a pulse voltage to the primary coil of the transformer, and the temperature detection element is the transformer drive element. Arranged in the main current path.

  For example, the drive voltage application circuit includes a transformer having a secondary coil connected to the magnetron, and a transformer drive element that applies a pulse voltage to the primary coil of the transformer, and the anode current control unit includes: A pre-stage drive circuit that applies a pulse voltage to the control terminal of the transformer drive element is provided, and the temperature detection element is provided in a main current path of the pre-stage drive circuit.

  Further, for example, the anode current control unit is suitable for temperature / anode current relationship setting means for setting a relationship between the temperature of the magnetron and the anode current suitable for the temperature, and for the temperature detected by the temperature detection element. The anode current is obtained by the temperature / anode current relationship setting means, and the drive voltage application circuit is controlled.

The radar according to the present invention, the electromagnetic wave generator, an antenna that emits the electromagnetic wave and receives an echo signal reflected by the target, a target detection circuit that detects the target based on the echo signal, Prepare.
With this configuration, it is possible to detect a target with an electromagnetic wave having a stable frequency without increasing the overall circuit scale.

  According to the present invention, it is possible to configure an electromagnetic wave generator that generates stable electromagnetic waves and a radar including the same without widening the transmission system including the antenna and the high-frequency circuit without increasing the overall circuit scale. .

It is a figure which shows the structure of the microwave generator of patent document 1. FIG. It is a figure which shows the relationship between the temperature of a magnetron, and an oscillation frequency. It is a figure which shows the relationship between the anode current of a magnetron, and an oscillation frequency. 1 is a circuit diagram of a microwave generator 101 according to a first embodiment. It is a figure which shows the attachment position etc. of the temperature sensitive resistance element in the microwave generator. It is a circuit diagram of the microwave generator 102 which concerns on 2nd Embodiment. It is a circuit diagram of the microwave generator 103 which concerns on 3rd Embodiment. It is a block diagram of the radar which concerns on 4th Embodiment.

<< First Embodiment >>
The microwave generator according to the first embodiment will be described with reference to FIGS.
FIG. 2 is a diagram showing the relationship between the magnetron temperature and the oscillation frequency. The horizontal axis is the magnetron temperature, and the vertical axis is the oscillation frequency. The straight line A and the straight line B represent the change of the oscillation frequency with respect to the temperature change as a primary straight line for two types of magnetrons having different output powers.

  Here, the anode current of the magnetron was measured to be constant. Thus, a linear function relationship is observed between the oscillation frequency of the magnetron and the temperature. That is, the oscillation frequency linearly decreases as the temperature rises. Although the oscillation frequency varies depending on the characteristics of the magnetron, the oscillation frequency change coefficient with respect to the temperature change is common.

  The relationship shown in FIG. 2 is that the resonance cavity (cavity) of the magnetron is thermally expanded / contracted according to the temperature, and the oscillation frequency varies according to the thermal expansion / contraction of the resonant cavity of the magnetron. Inferred to be the cause.

  FIG. 3 is a diagram showing the relationship between the anode current of the magnetron and the oscillation frequency. The horizontal axis is the magnetron anode current, and the vertical axis is the oscillation frequency. The straight line in FIG. 3 represents the relationship of the oscillation frequency with respect to the anode current as a primary straight line.

  Thus, a linear function relationship is observed between the oscillation frequency of the magnetron and the anode current. That is, the oscillation frequency linearly decreases as the anode current increases. The reference value (for example, 5 [A]) of the anode current varies depending on the characteristics (rating) of the magnetron, but the change coefficient of the oscillation frequency with respect to the anode current change is negative.

  Thus, in the temperature characteristics of the oscillation frequency of the magnetron, the change coefficient of the oscillation frequency with respect to the temperature change is negative, and the change coefficient of the oscillation frequency with respect to the anode current change is negative. Therefore, the present invention makes it possible to suppress changes in the oscillation frequency due to changes in the temperature of the magnetron by controlling the anode current. That is, the anode current is controlled according to the temperature.

FIG. 4 is a circuit diagram of the microwave generator 101 according to the first embodiment.
The microwave generator 101 includes a magnetron 50, a drive voltage application circuit 40, and an anode current control circuit 30. The magnetron 50 generates a microwave having a predetermined frequency by self-oscillation when a driving voltage (anode voltage) is applied between the anode 51 and the cathode 52. The configuration of the output part of the generated microwave is not shown.

  The drive voltage application circuit 40 includes a transformer 41 for generating a high voltage having a primary coil N1 and a secondary coil N2, and an FET Q40 that is a transformer drive element that applies a pulse voltage to the primary coil N1 of the transformer 41. And a resistance element R40 connected to the FET Q40. One end of the primary coil N1 of the transformer 41 is connected to a positive power source Vdd. The secondary coil N2 of the transformer 41 is composed of two coils, and a heater power supply Vhh is connected so that the heater voltage is energized to the heater which is the cathode 52 of the magnetron 50 via the two secondary coils N2. Yes.

  The drive voltage application circuit 40 applies a predetermined high voltage induced in the secondary coil N <b> 2 of the transformer 41 as a drive voltage between the anode 51 and the cathode 52 of the magnetron 50.

  The anode current control circuit 30 includes a temperature-sensitive resistance element RT that is a temperature detection element and a pre-stage drive circuit 31. The front-stage drive circuit 31 includes transistors Q31 and Q32, which are front-stage drive elements, a capacitor C31, and resistance elements R31 and R32.

  The temperature sensitive resistance element RT is a positive temperature coefficient thermistor whose resistance value changes according to the temperature of the magnetron 50 or the ambient environment temperature of the magnetron 50. The temperature sensitive resistance element RT is provided in the main current path of the pre-stage drive circuit 31.

  Resistor elements R31, R32 and capacitor C31 slow the rise of the pulse voltage for FET Q40 so that magnetron 50 oscillates normally.

The operation of the microwave generator 101 shown in FIG. 4 is as follows.
A rectangular wave positive pulse signal having a predetermined pulse width is applied to the input terminal IN of the anode current control circuit 30. When the voltage of the input terminal IN becomes high level due to the rise of the pulse signal, the transistor Q31 is turned on, the gate voltage of the FET Q40 rises, and a current flows through the primary coil N1 of the transformer 41. A voltage is generated in the secondary coil N2 of the transformer 41 in a direction that cancels a change in current flowing in the primary coil N1, and a negative voltage is applied to the cathode 52 of the magnetron 50. Since the anode of the magnetron is at zero potential (because it is grounded), an anode current flows by applying a voltage between the cathode and the anode of the magnetron 50.

  When the voltage of the input terminal IN becomes low level due to the fall of the pulse signal, the transistor Q31 is turned off, the transistor Q32 is turned on, the gate voltage of the FET Q40 falls, and the current of the primary coil N1 of the transformer 41 becomes Blocked. As a result, the output voltage of the secondary coil N2 of the transformer 41 falls, and the voltage applied to the cathode 52 of the magnetron 50 rises to zero potential. As a result, the oscillation of the magnetron 50 stops.

  The gate bias and the gate voltage are determined so that the FET 20 operates in the active region. Further, since the currents flowing through the primary coil N1 and the secondary coil N2 of the transformer 41 are also in a proportional relationship, the anode current of the magnetron 50 and the drain current flowing in the FET Q40 are in a substantially proportional relationship.

  The transistors Q31 and Q32 of the pre-stage drive circuit 31 constitute a push-pull circuit, and the applied voltage to the input terminal IN is determined so that the transistors Q31 and Q32 also operate in the active region.

  Since the resistance value of the temperature sensitive resistance element RT provided in the main current path of the pre-stage driving circuit 31 is a value corresponding to the temperature of the magnetron 50 or the ambient environment temperature of the magnetron 50, the collector current of the transistor Q31 is the temperature described above. As a result, the drain current of the drive voltage application circuit 40 changes and the anode current of the magnetron changes.

  That is, the temperature sensitive resistance element RT is provided at a position where the anode current of the magnetron 50 is changed by the energization current. Since the temperature-sensitive resistance element RT is a positive temperature coefficient thermistor, the anode current is in a relationship of decreasing as the temperature of the magnetron 50 increases. The temperature resistance coefficient of the temperature sensitive resistance element RT is determined so that the change of the oscillation frequency due to the temperature change of the magnetron is suppressed.

  FIG. 5 is a diagram showing the attachment position of the temperature sensitive resistance element RT in the microwave generator 101. In the vicinity of the magnetron 50, a chassis 60 including the drive voltage application circuit 40 is disposed.

  It is presumed that the oscillation frequency of the magnetron fluctuates due to thermal expansion / contraction of the resonance cavity of the magnetron 50. Therefore, it is preferable to directly measure the temperature of the anode of the magnetron 50. It is difficult to arrange a temperature sensitive resistance element inside. Therefore, one of the favorable positions for attaching the temperature sensitive resistance element RT is the outer surface of the magnetron 50.

  Since the magnetron 50 and the chassis 60 are separate parts, either the magnetron 50 or the chassis 60 is provided so as to be exchangeable as required. At the time of this replacement, the temperature sensitive resistance element RT can be handled together with the magnetron 50, and the circuit board in the chassis 60 and the temperature sensitive resistance element RT are detachably provided with a connector so as to be separable. It is desirable to leave.

  Since the temperature of the magnetron 50 does not fluctuate rapidly during use and gradually changes, the temperature of the chassis 60 disposed in the vicinity of the magnetron 50 approximates the temperature of the magnetron 50. Therefore, the temperature sensitive resistance element RT may be attached to the chassis 60. However, in the case where heating parts 61 and 62 such as a power control transistor and a constant voltage element are attached to the chassis 60, in FIG. 5, so as not to be affected by the heat of these heating parts 61 and 62. What is necessary is just to arrange | position the temperature sensitive resistance element RT in the position away from the heat-emitting components 61 and 62 as shown by area | region A1, A2.

  With the configuration described above, it is possible to generate a microwave with high frequency stability without widening the transmission system including the antenna and the high-frequency circuit without increasing the overall circuit scale.

<< Second Embodiment >>
A microwave generator according to the second embodiment will be described with reference to FIG.
The relationship between the temperature of the magnetron and the oscillation frequency, and the relationship between the anode current of the magnetron and the oscillation frequency are the same as those shown in the first embodiment.

FIG. 6 is a circuit diagram of the microwave generator 102 according to the second embodiment.
The microwave generator 102 includes a magnetron 50, a drive voltage application circuit 40, and an anode current control circuit 30.

  The drive voltage application circuit 40 includes a transformer 41 for generating a high voltage having a primary coil N1 and a secondary coil N2, and a transformer drive element that applies a pulse voltage to the primary coil N1 of the transformer 41. Q40 and a temperature-sensitive resistance element RT which is a temperature detection element are provided. The temperature sensitive resistance element RT is a positive temperature coefficient thermistor whose resistance value changes according to the temperature of the magnetron 50 or the ambient environment temperature of the magnetron 50. The temperature sensitive resistance element RT is provided in the main current path of the FET Q40.

The anode current control circuit 30 includes transistors Q31 and Q32, capacitors C31, and resistor elements R31, R32, and R33, which are front-stage drive elements.
Other configurations are the same as those shown in the first embodiment.

The operation of transmitting the pulse radio wave of the microwave generator 102 shown in FIG. 6 is the same as that of the apparatus shown in FIG. 4 in the first embodiment.
Since the temperature sensitive resistance element RT is inserted in the main current path of the FET Q40, the drain current of the FET Q40 decreases and the anode current of the magnetron 50 decreases as the resistance value of the temperature sensitive resistance element RT increases. .

  Since the temperature sensitive resistance element RT is a positive temperature coefficient thermistor, the anode current decreases as the temperature of the magnetron 50 increases. The temperature resistance coefficient of the temperature sensitive resistance element RT is determined so that the change of the oscillation frequency due to the temperature change of the magnetron is suppressed.

  With the configuration described above, it is possible to generate a microwave with high frequency stability without widening the transmission system including the antenna and the high-frequency circuit without increasing the overall circuit scale.

<< Third Embodiment >>
A microwave generator according to a third embodiment will be described with reference to FIG.
The relationship between the temperature of the magnetron and the oscillation frequency, and the relationship between the anode current of the magnetron and the oscillation frequency are the same as those shown in the first embodiment.

FIG. 7 is a circuit diagram of the microwave generator 103 according to the third embodiment.
The microwave generator 103 includes a magnetron 50, a drive voltage application circuit 40, an anode current control circuit 30, an anode current detection circuit 61, and a temperature sensor 62.

  The anode current detection circuit 61 is connected to the anode 51 of the magnetron 50, detects the anode current, and outputs a voltage corresponding to (in proportion to) the anode current to the anode current control circuit 30. The temperature sensor 62 detects the temperature of the magnetron 50 or the ambient environment temperature of the magnetron 50 and outputs a voltage signal corresponding to the temperature to the anode current control circuit 30.

  In the anode current control circuit 30, the relationship between the temperature of the magnetron 50 and the anode current suitable for the temperature is set in advance as a table, and the drive voltage application circuit so that the optimum anode current flows for the temperature of the magnetron 50. 40 is controlled. This table corresponds to “temperature / anode current relation setting means” of the present invention.

  The anode current is controlled by controlling the gate voltage of the FET Q40 of the drive voltage application circuit 40. That is, the gate voltage is determined such that a predetermined drain current that is substantially proportional to the anode current of the magnetron 50 flows when the FET Q40 is turned on.

<< Fourth Embodiment >>
FIG. 8 is a block diagram of a radar according to the fourth embodiment. In FIG. 8, the magnetron drive circuit 72 and the magnetron 50 constitute any of the microwave generators 101 to 103 shown in the first to third embodiments.

  In FIG. 8, the trigger circuit 71 gives a trigger signal to the magnetron driving circuit 72 and the instruction unit 80 at a constant cycle. Each time the magnetron driving circuit 72 receives a trigger signal, it drives the magnetron 50 to generate microwave pulsed radio waves. This signal is transmitted from the antenna 75 via the circulator 73 and the antenna driving unit 74.

  A reception signal received by the antenna 75 is input to the mixer 77 via the antenna driving unit 74 and the circulator 73. The mixer 77 mixes the local signal from the local oscillator 76 and the received signal to generate an intermediate frequency signal, the intermediate frequency amplification circuit 78 amplifies the signal, and the detection circuit 79 detects the intermediate frequency signal and indicates the instruction unit. Give to 80.

  Based on the detection signal from the detection circuit 79, the azimuth signal from the antenna drive unit 74, and the trigger signal from the trigger circuit 71, the instruction unit 80 performs signal processing and PPI display for displaying an echo of the target in PPI. . Elements other than the microwave generator correspond to the “target detection circuit” of the present invention.

  With this configuration, a target can be detected with a microwave having a stable frequency without increasing the overall circuit scale.

N1 ... Primary coil N2 ... Secondary coils Q31, Q32 ... Transistor Q40 ... FET
R31, R32, R33, R40... Resistive element RT... Temperature sensitive resistance element 30... Anode current control circuit 31. ... Microwave generator

Claims (11)

A magnetron comprising an anode and a cathode, and generating an electromagnetic wave having a predetermined oscillation frequency by an anode current flowing through the anode;
A drive voltage application circuit for applying a drive voltage between the anode and the cathode;
An electromagnetic wave generator comprising:
The drive voltage application circuit includes a temperature detection element that detects the temperature of the magnetron or the environment of the magnetron, and an anode current control unit that controls the value of the anode current according to the temperature. An electromagnetic wave generator characterized by the above.   The electromagnetic wave generation device according to claim 1, wherein the temperature detection element is attached to a chassis that includes the drive voltage application circuit therein and is disposed in the vicinity of the magnetron.   The electromagnetic wave generator according to claim 1, wherein the temperature detection element is attached to the magnetron.   The electromagnetic wave generator according to claim 3, wherein the temperature detection element is detachably disposed with respect to the drive voltage application circuit.   The anode current control unit reduces the anode current value when the temperature is higher than the predetermined temperature with respect to the anode current value that generates the electromagnetic wave having the predetermined oscillation frequency at a predetermined temperature. 5. The electromagnetic wave generator according to claim 1, wherein when the temperature is lower than the predetermined temperature, the value of the anode current is increased.   6. The electromagnetic wave generation according to claim 1, wherein the temperature detection element is a temperature-sensitive resistance element whose resistance value changes according to temperature, and changes the anode current by an energization current. apparatus.   The electromagnetic wave generation device according to claim 6, wherein the resistance value of the temperature detection element increases as the temperature increases. The drive voltage application circuit includes a transformer having a secondary coil connected to the magnetron, and a transformer drive element that applies a pulse voltage to the primary coil of the transformer,
The electromagnetic wave generator according to claim 6 or 7, wherein the temperature detection element is disposed in a main current path of the transformer driving element. The drive voltage application circuit includes a transformer having a secondary coil connected to the magnetron, and a transformer drive element that applies a pulse voltage to the primary coil of the transformer,
The anode current control unit includes a pre-stage drive circuit that applies a pulse voltage to a control terminal of the transformer drive element, and the temperature detection element is arranged in a main current path of the pre-stage drive circuit. The microwave generator of Claim 6 or Claim 7.   The anode current control unit includes a temperature / anode current relationship storage unit that stores a relationship between the temperature and the anode current that generates the electromagnetic wave at the predetermined oscillation frequency, and a temperature detected by the temperature detection element. 6. The electromagnetic wave generator according to claim 1, further comprising: a current setting unit that determines the corresponding anode current based on a temperature / anode current relation storage unit. An electromagnetic wave generator according to any one of claims 1 to 10,
An antenna for emitting the electromagnetic wave and receiving an echo signal reflected by the target;
A target detection circuit for detecting the target based on the echo signal;
A radar comprising:

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