JP2014021028A - Magnetron drive circuit, radar device and magnetron drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten pulse width of pulse-like microwaves to be output by magnetron by improving a fall part of anode voltage in a magnetron drive circuit.SOLUTION: A pulse transformer 70 of a magnetron drive circuit 50 has: a primary side coil 71 to which drive pulse voltage Vd is applied; and secondary side coils 72, 73 which are serially inserted into an anode voltage input line 30 of a magnetron 20. The pulse transformer 70 generates anode voltage Vp to the secondary side coils 72, 73 according to the drive pulse voltage Vd. A thyristor 91 of the magnetron drive circuit 50 turns on in a fall period of the anode voltage Vp to connect the anode voltage input line 30 with an anode 21 of the magnetron 20.

Description

  The present invention relates to a magnetron driving circuit for modulating a microwave output from a magnetron, a radar apparatus using the magnetron driving circuit, and a magnetron driving method.

  A conventionally known pulse modulation radar apparatus obtains a distance to a target based on a time from when a pulsed microwave is transmitted until it is received. In such a radar apparatus, in order to output a pulsed microwave from the magnetron, a pulse is applied to the anode of the magnetron by a magnetron driving circuit as described in, for example, Japanese Patent Application Laid-Open No. 2008-232957. Conventionally, a high voltage (hereinafter referred to as an anode voltage) is applied.

  Among the radar devices that output such pulsed microwaves, for example, in a river radar device that monitors a ship traveling in a river, in order to accurately grasp the position of a cargo ship or a container ship, It is necessary to accurately detect the distance to the mark. As described above, depending on the application of the radar apparatus, there is a demand for high distance resolution, and it is necessary to modulate the microwave with a shorter pulse.

  However, the magnetron generally has a structure in which the anode surrounds the cathode and the filament, and has a capacitive component when viewed from the magnetron driving circuit. Therefore, even if an anode voltage is applied to the magnetron by the magnetron driving circuit, the voltage waveform is distorted.

  For example, in Patent Document 1 described above, a reference pulse transformer is provided on the primary side of a driving pulse transformer for applying an anode voltage to the magnetron, and the driving pulse generated on the secondary side of the driving pulse transformer is reduced. Waveform shaping is performed.

  When a magnetron is connected to a magnetron driving circuit to which the technique described in Patent Document 1 is applied, for example, it is considered that a circuit configuration as shown in FIG. 6 is obtained. In FIG. 6, an anode voltage is applied to the magnetron 20 between the filament 22 and the anode 21 connected to the common potential through the anode voltage input line 30.

  The anode voltage is generated by the secondary coil 152 of the pulse transformer 150 inserted in series with the anode voltage input line 30. A drive pulse voltage generation circuit 75 is connected to the primary coil 151 of the pulse transformer 150. An anode voltage is generated in the secondary coil 152 in accordance with the drive pulse voltage applied to the primary coil 151 of the pulse transformer 150.

  A waveform shaping circuit 170 for shaping the waveform of the anode voltage is connected to the primary side of the pulse transformer 150. By shaping the waveform of the voltage applied to the primary coil of the pulse transformer 150 by this waveform shaping circuit 170, the waveform of the anode voltage becomes close to a rectangle and the occurrence of unnecessary radiation and the like is suppressed. The anode voltage input line 30 in FIG. 4 is connected to the filament 22 of the magnetron 20 and the heater power supply 40 that supplies power to the filament 22.

  However, the waveform shaping circuit 170 described in Patent Document 1 is provided on the primary coil 151 side of the pulse transformer 150 and is generated in the secondary coil 152 via the pulse transformer 150. Anode voltage waveform shaping is performed. Therefore, when the pulse width is shortened, it becomes difficult to perform waveform shaping by the waveform shaping circuit 170 due to the charge accumulated in the magnetron 20. Therefore, for a radar device that requires a very short pulse width of 100 ns or less, such as a river radar device, for example, applying the technique described in Patent Document 1 makes the fall of the anode voltage steep. Have difficulty.

  An object of the present invention is to improve the falling portion of the anode voltage and shorten the pulse width of the pulsed microwave output from the magnetron in a magnetron driving circuit used in a radar device that requires high distance resolution. .

  The magnetron drive circuit according to the present invention includes a transformer and a switching element. The transformer has a primary side coil to which a drive pulse voltage is applied and a secondary side coil inserted in series with the anode voltage input line of the magnetron. This transformer applies an anode voltage to the magnetron by a secondary coil. The switching element is connected between the anode voltage input line and the magnetron anode. This switching element is turned on during the fall period of the anode voltage.

  In the magnetron driving circuit of the present invention, the switching element is turned on during the falling period of the anode voltage, whereby the anode voltage input line is connected to the anode by the switching element. At this time, the charge on the anode voltage input line in which the secondary coil of the transformer is inserted flows to the anode potential through the switching element. In this way, the electric charge of the anode voltage input line rapidly decreases, so that the waveform of the falling portion of the anode voltage is improved and the falling becomes steep.

  A radar apparatus according to the present invention includes a magnetron having an anode voltage input line, an antenna that radiates microwaves oscillated from the magnetron, and a magnetron driving circuit that drives the magnetron. The magnetron driving circuit includes a transformer and a switching element. The transformer has a primary side coil to which a driving pulse voltage is applied and a secondary side coil inserted in series with the anode voltage input line, and applies an anode voltage to the magnetron by the secondary side coil. The switching element is connected between the anode voltage input line and the anode of the magnetron, and is turned on during the fall period of the anode voltage.

  In the radar apparatus of the present invention, the switching element is turned on during the fall period of the anode voltage of the magnetron, so that the anode voltage input line is connected to the anode of the magnetron by the switching element. At this time, the charge on the anode voltage input line in which the secondary coil of the transformer is inserted flows to the anode potential through the switching element. By rapidly decreasing the charge on the anode voltage input line, the waveform of the falling portion of the anode voltage is improved, and the fall becomes steep. Therefore, the pulse width of the microwave radiated from the antenna is shortened.

  In the magnetron driving method according to the present invention, a driving pulse voltage is applied to a primary coil of a transformer having a secondary coil inserted in series with an anode voltage input line of the magnetron, and an anode applied to the secondary coil is applied to the magnetron. An anode voltage generating step for generating a voltage, and a switching step for turning on a switching element connected between the anode voltage input line and the anode of the magnetron during the anode voltage falling period in the anode voltage generating step. .

  According to the magnetron driving method of the present invention, the switching element is turned on during the falling period of the anode voltage in the switching step, whereby the anode voltage input line is connected to the anode by the switching element. At this time, the charge on the anode voltage input line in which the secondary coil of the transformer is inserted flows to the anode potential through the switching element. In this way, the charge of the anode voltage input line rapidly decreases, so that the waveform of the falling portion of the anode voltage generated in the anode voltage generation step is improved, and the anode voltage falls steeply.

  According to the present invention, the pulse width of the pulsed microwave output from the magnetron can be shortened by improving the falling portion of the anode voltage.

A radar apparatus using a magnetron drive circuit according to an embodiment of the present invention. 1 is a circuit diagram of a magnetron driving circuit according to an embodiment of the present invention. The voltage waveform diagram for demonstrating operation | movement of a magnetron drive circuit. The wave form diagram which shows an example of the anode voltage in the magnetron shown in FIG. The wave form diagram which shows an example of the microwave transmitted from the magnetron of FIG. The circuit diagram of the conventional magnetron drive circuit.

  Hereinafter, a magnetron driving circuit according to an embodiment will be described with reference to FIGS. As shown in FIG. 1, the magnetron drive circuit 50 is used in, for example, the radar apparatus 10.

(1) Outline of Configuration of Radar Device The radar device 10 includes an antenna 11, a transmitter 12, a transmission / reception switch 13, a receiver 14, a local oscillator 15, a signal processor 16, and a display 17. . The magnetron 20 is used for the transmitter 12. When the transmission / reception switch 13 is switched to the transmitter 12 side, a pulse signal is radiated from the antenna 11 in accordance with the pulsed microwave output from the magnetron 20.

  When the transmitter 12 is off, the transmission / reception switch 13 switches from the state in which electromagnetic waves are transmitted from the transmitter 12 to the antenna 11 to the state in which electromagnetic waves are transmitted from the antenna 11 to the receiver 14. A reception signal received by the antenna 11 is given to the receiver 14. The receiver 14 includes a high frequency amplifier, a mixer, an intermediate frequency amplifier, and a detector, and the receiver 14 separates a desired signal and amplifies the received signal. A local oscillation signal necessary for converting the received signal from a high frequency to an intermediate frequency by the receiver 14 is supplied from the local oscillator 15 to the mixer of the receiver 14.

  The reception signal output from the receiver 14 to the signal processor 16 includes unnecessary signals such as clutter. After signal processing such as removal of these unnecessary signals is performed by the signal processor 16, display regarding the target is performed on the display 17.

  As will be described later, by reducing the pulse width of the pulsed microwave output from the magnetron 20 by the magnetron driving circuit 50, the distance resolution of the received signal processed in the signal processor 16 is improved, and the distance is increased. Close targets can be distinguished and displayed on the display 17.

(2) Magnetron Drive Circuit and its Peripheral Configuration FIG. 2 shows an outline of the connection relationship between the magnetron 20, the magnetron drive circuit 50 and the high voltage power supply 60 constituting the transmitter 12 shown in FIG. 1 and the configuration of the magnetron drive circuit 50. . The magnetron 20 is the same as the conventional magnetron 20 shown in FIG.

(2-1) Magnetron The magnetron 20 includes a cathode (not shown) and a cylindrical anode 21 disposed around the cathode. The magnetron 20 is an anode-divided magnetron in which the anode 21 is divided into a large number. The cathode of the magnetron 20 is heated by the filament 22. A heater power supply 40 for heating the filament 22 is connected to the filament 22 by a power supply line. A power supply line connecting the heater power supply 40 and the filament 22 is used as the anode voltage input line 30. The output of the magnetron 20 is supplied to the antenna 11 via the microwave output circuit 23.

(2-2) Anode voltage input line The anode voltage input line 30 includes a first power supply line 31 having one end 31 a connected to one end 22 a of the filament 22 and the other end connected to the other end 22 b of the filament 22. And a second power supply line 32 having 32a. The other end 31 b of the first power supply line 31 is connected to one end 43 a of the secondary side coil 43 of the transformer 41. The other end 32 b of the second power supply line 32 is connected to the other end 43 b of the secondary coil 43. There is a capacitor 33 inserted between the other end 31b of the first power supply line 31 and the common potential, and a capacitor 34 inserted between the other end 32b of the second power supply line 32 and the common potential. is there.

(2-3) Heater Power Supply The heater power supply 40 is connected to the primary coil 42 of the transformer 41 described above. When a heater voltage is applied from the heater power supply 40 to the primary side coil, a voltage is generated in the secondary side coil 43, and a current flows through the filament 22 via the first power supply line 31 and the second power supply line 32. Generates heat.

(2-4) Magnetron Drive Circuit The magnetron drive circuit 50 includes a pulse transformer 70, a drive pulse voltage generation circuit 75, a gate pulse voltage generation circuit 80, and a switching circuit 90. The pulse transformer 70 includes a primary side coil 71, a first secondary side coil 72, and a second secondary side coil 73. A drive pulse voltage generation circuit 75 is connected to the primary coil 71 of the pulse transformer 70, and the drive pulse voltage Vd is applied from the drive pulse voltage generation circuit 75. The first secondary coil 72 of the pulse transformer 70 is inserted in series with the first power supply line 31. Further, the second secondary coil 73 of the pulse transformer 70 is inserted in series with the second power supply line 32. The first secondary coil 72 and the second secondary coil 73 generate an anode voltage Vp having the same magnitude according to the drive pulse voltage Vd. The drive pulse voltage generation circuit 75 is connected to a high voltage power supply 60 and is given a high voltage.

  The switching circuit 90 includes a thyristor 91 as a switching element, and the gate pulse voltage generation circuit 80 outputs a gate pulse voltage Vg to the switching circuit 90 in order to control the thyristor 91. The thyristor 91 has an anode connected to the same common potential as the anode 21 of the magnetron 20. In addition to the thyristor 91, the switching circuit 90 includes a transformer 93, resistors 92, 94, 96, and diodes 95, 97. The resistor 92 is connected between the cathode of the thyristor 91 and the anode voltage input line 30.

  The primary coil 93a of the transformer 93 is connected to the gate pulse voltage generation circuit 80, and the gate pulse voltage Vg is applied. One end of the secondary coil 93 b of the transformer 93 is connected to the cathode of the thyristor 91, and the other end is connected to the gate of the thyristor 91 via a resistor 94 and a diode 95. A resistor 94 and a diode 95 are connected in series between the other end of the secondary coil 93b and the gate of the thyristor 91 so that the thyristor 91 operates reliably. A resistor 96 and a diode 97 are connected in parallel with the thyristor 91. The resistor 96 has a resistance value large enough to apply the anode voltage Vp to the filament 22.

(3) Operation of Magnetron Drive Circuit In the magnetron drive circuit 50, a pulsed negative high voltage as shown in FIG. 3 is applied to the primary coil 71 of the pulse transformer 70 as the drive pulse voltage Vd. However, the anode voltage Vp generated in the anode voltage input line 30 by the secondary coils 72 and 73 of the pulse transformer 70 is distorted as shown in FIG. The slope of the rise and fall of the anode voltage Vp is reduced. Therefore, discharge from the capacitive component starts from time T1 when the drive pulse voltage Vd falls, and the potential of the anode voltage Vp becomes 0 at time T2 when the discharge ends. During the period t3 during which discharge from this capacitive component is performed, the gate pulse voltage Vg is set to the high level H to turn on the thyristor 91.

  When the thyristor 91 is turned on, the anode voltage input line 30 is connected to the common potential to which the anode 21 of the magnetron 20 is connected, and the anode voltage Vp falls rapidly. FIG. 4 shows waveforms of the anode voltage Vp1 when the thyristor 91 is operated and the anode voltage Vp2 when the thyristor 91 is not operated. As shown in FIG. 4, when the thyristor 91 is turned on, the fall of the anode voltage Vp1 is improved. FIG. 5 shows a transmission waveform Vs1 when the thyristor 91 is operated, and a transmission waveform Vs2 when the thyristor 91 is not operated. As can be seen by comparing the two transmission waveforms Vs1 and Vs2, when the switching circuit 90 is provided and the charge of the anode voltage input line 30 is discharged by the thyristor 91 at an appropriate timing, the pulse width is shortened by about 20%.

<Features>
(1)
The pulse transformer 70 includes a primary coil 71 to which a drive pulse voltage Vd is applied, and secondary coils 72 and 73 inserted in series in the anode voltage input line 30 of the magnetron 20. Primary side coil 71 and secondary side coils 72 and 73 are insulated. Therefore, although safety is high, it takes time to discharge from the capacitive component on the magnetron 20 side, the falling period of the anode voltage Vp of the magnetron 20 becomes long, and it is difficult to shorten the pulse width. Therefore, the thyristor 91 (switching element) is turned on during the falling period t3, and the anode voltage input line 30 is connected to the common potential via the resistor 92. Since the anode 21 of the magnetron 20 is connected to the common potential, the anode voltage input line 30 is connected to the anode 21 via the resistor 92 and is accumulated between the anode voltage input line 30 and the anode 21. Charge is discharged rapidly. As a result, the pulse width of the anode voltage Vp applied to the magnetron 20 is shortened, and as a result, the pulse width of the pulsed microwave output from the magnetron 20 is also shortened. As a result, the pulse width of the pulsed transmission signal emitted from the radar apparatus 10 is shortened, and the distance resolution of the radar apparatus 10 is improved.

  As the anode voltage Vp, for example, a high voltage of several kV is used. Therefore, a thyristor is suitable as a switching element that can withstand such a high voltage. In addition, the thyristor is suitable for performing an operation of discharging electric charges only during the falling period t3 shorter than several hundred ns because of its high response speed.

(2)
When the anode voltage input line 30 is connected to the common potential by the thyristor 91 (switching element), power is consumed by the resistor 92 (damping resistor), so that problems such as voltage fluctuations can be prevented.

<Modification>
(1)
Although the case where one thyristor 91 is connected has been described in the above embodiment, a plurality of thyristors may be connected in series in order to obtain a withstand voltage when the anode voltage of the magnetron 20 is large.

(2)
In the above embodiment, the thyristor 91 is taken as an example of the switching element, but other switching elements such as an insulated gate transistor can also be used.

(3)
In the above embodiment, the case where the anode voltage input line 30 is connected to the common potential via the resistor 92 when the thyristor 91 is turned on has been described. However, a capacitor may be inserted in series with the resistor 92. In some cases, a capacitor can be used instead of the resistor 92.

DESCRIPTION OF SYMBOLS 10 Radar apparatus 20 Magnetron 30 Anode voltage input line 50 Magnetron drive circuit 70 Pulse transformer 91 Thyristor 92 Resistance

JP 2008-232957 A

Claims (6)

A transformer having a primary side coil to which a driving pulse voltage is applied and a secondary side coil inserted in series with an anode voltage input line of the magnetron, and applying an anode voltage to the magnetron by the secondary side coil; ,
A switching element connected between the anode voltage input line and the anode of the magnetron and turned on during a fall period of the anode voltage;
A magnetron driving circuit comprising: The anode voltage input line is
A first power line having one end connected to one end of the filament of the magnetron and the other end;
A second power supply line having one end connected to the other end of the filament of the magnetron and the other end connected to the other end of the first power supply line via a voltage generator;
Including
The secondary coil of the transformer is
A first secondary coil inserted in series with the first power line;
A second secondary coil inserted in series with the second power supply line;
including,
The magnetron drive circuit according to claim 1. A damping resistor connected in series to the switching element;
The magnetron drive circuit according to claim 1 or 2. The switching element is a thyristor whose on / off is controlled by a gate pulse signal that rises during a fall period of the drive pulse voltage.
The magnetron drive circuit according to any one of claims 1 to 3. A magnetron having an anode voltage input line;
An antenna that radiates microwaves oscillated from the magnetron;
A magnetron driving circuit for driving the magnetron;
With
The magnetron driving circuit is
A transformer having a primary coil to which a driving pulse voltage is applied, and a secondary coil inserted in series with the anode voltage input line, and applying an anode voltage to the magnetron by the secondary coil;
A switching element connected between the anode voltage input line and the anode of the magnetron and turned on during a fall period of the anode voltage;
A radar apparatus. Anode voltage generation that applies a drive pulse voltage to the primary coil of a transformer having a secondary coil inserted in series with the anode voltage input line of the magnetron, and generates an anode voltage to be applied to the magnetron in the secondary coil Steps,
A switching step of turning on a switching element connected between the anode voltage input line and the anode of the magnetron during a fall period of the anode voltage in the anode voltage generation step;
A magnetron driving method comprising:

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