JP2008232957A - Magnetron drive circuit and radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar system having improved distance resolution by easily realizing a drive circuit for magnetron which is driven to output from a magnetron a transmission pulse which has a waveform close to a rectangular form, with the rise and fall being steeper than conventionally, before and pulse width is narrow, in other words, by restraining the occurrence of spurious noise, when driving the magnetron as compared with the conventional types. <P>SOLUTION: The magnetron drive circuit for oscillating magnetron by applying the magnetron to a drive pulse comprises a pulse transformer for driving for generating the drive pulse; and a pulse transformer for reference for generating a reference pulse, where the drive pulse is clipped by the reference pulse. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetron driving circuit for driving a magnetron that outputs a microwave and a radar apparatus using the same.

  A pulse modulated radar (hereinafter referred to as pulse radar) includes a magnetron for outputting a microwave, a magnetron driving circuit for driving the magnetron, an antenna, a receiving circuit, and the like. FIG. 4 is a circuit diagram showing a schematic configuration of a conventional magnetron driving circuit. As shown in FIG. 4, the conventional magnetron driving circuit 100 uses a driving pulse transformer 101. One terminal of the primary winding 102 of the driving pulse transformer 101 is directly connected to the power supply V and grounded via a capacitor 105, and a switching FET 106 is provided on the other terminal. Further, an absorption resistor 104 is connected between both terminals of the primary winding 102. One terminal of the secondary winding 103 of the driving pulse transformer 101 is grounded, and the other terminal is connected to the cathode (not shown) of the magnetron.

  In the magnetron driving circuit 100 having the above configuration, the switching FET 106 is turned on in response to an output from a drive circuit having a predetermined pulse width. Then, a driving pulse having the pulse width is generated in the secondary winding 103 of the pulse transformer 101. When this driving pulse is applied to the magnetron, the magnetron oscillates with a very high output and outputs a microwave (transmission pulse). A target can be detected by emitting this transmission pulse through an antenna outside the figure.

Here, the pulse radar is a radar that obtains the distance to the target based on the time from when the transmission pulse is transmitted to the target until the echo that is reflected back to the target is received. If c is the speed of light and Δt is the time from transmission to reception, the distance D to the target is
D = c × Δt ÷ 2
It becomes.

What is necessary for judging the performance of the radar is not only the distance resolution but also the maximum detection distance, the azimuth resolution, the minimum detection distance, and the like. Distance resolution is a limit indicating how far two targets on a straight line in the same direction can be separated and recognized as two targets when viewed from the radar side that transmits the transmission pulse. Is the minimum distance R. Since the radio wave propagates a distance of about 300 m per 1 μs, it travels back and forth a distance of 150 m between 1 μs. Therefore, as a relationship between the pulse width τ (μs) of the transmission pulse and the distance resolution R,
R = 300τ / 2 = 150τ (m)
The distance resolution is determined by this pulse width. For this reason, the narrower the pulse width of the transmission pulse, the better the distance resolution and also the ability to detect up to a short distance.

  However, although the above-described pulse waveform assumes an ideal rectangle, since the magnetron has a capacitive component, the generated pulse waveform is not rectangular. Accordingly, in order to obtain a rectangular pulse waveform in the conventional magnetron driving circuit 100, it is necessary to make the rising edge of the driving pulse steep. However, if the rising edge is steep, an overshoot that passes the operating point of the magnetron occurs as shown by region A in FIG. This overshoot causes unnecessary radiation.

  Similarly, in order to obtain a rectangular pulse waveform and oscillation due to residual energy such as an electron cloud after driving is a cause of unnecessary radiation, it is necessary to make the driving pulse fall steep. In the conventional magnetron driving circuit 100, the absorption resistor 104 as described above is added so that the residual energy of the driving pulse transformer 101 is made zero in a short time, and the falling is steep. However, since the absorption resistor 104 becomes an extra load when the transmission pulse rises, the value of the absorption resistor 104 cannot be increased too much. Therefore, as indicated by region B, the falling edge of the transmission pulse cannot be made so steep.

  Therefore, in order to solve the above problem, in the magnetron driving circuit (not shown) described in Patent Document 1, the residual energy of the driving pulse transformer 101 is provided without providing the absorption resistor 104 on the primary side of the driving pulse transformer. The active damper which is a residual energy absorption circuit which absorbs is provided. Furthermore, a non-linear load circuit that is turned on at approximately 80% of the operating voltage driven by the magnetron is provided on the secondary side of the driving pulse transformer 101.

  However, even in the magnetron driving circuit described in Patent Document 1, overshooting still occurs at the rising edge of the driving pulse, causing unnecessary radiation. In addition, it takes time to absorb the residual energy even when the driving pulse falls, causing unnecessary radiation.

The present invention was created in order to solve the above-described problems, and its purpose is to output from a magnetron a transmission pulse having a waveform that has a rising edge and a falling edge that are steeper than those of a conventional rectangle and has a narrow pulse width. It is to realize a magnetron driving circuit more easily. That is, an object of the present invention is to provide a radar device that suppresses generation of unnecessary radiation when driving a magnetron, and has a good distance resolution.
JP 2003-87099 A

  In order to solve the above problems, a magnetron driving circuit for oscillating the magnetron by applying a driving pulse to the magnetron according to the present invention, a driving pulse transformer for generating the driving pulse, and a reference for generating a reference pulse And a driving pulse transformer, wherein the driving pulse is clipped by the reference pulse.

  Furthermore, the above-described magnetron driving circuit is characterized in that the secondary side of the reference pulse transformer is connected to the secondary side of the driving pulse transformer via a diode while having a pure resistance as a load.

  Furthermore, the above-described magnetron driving circuit is characterized in that the rising and falling timings of the driving pulse and the reference pulse are substantially equal.

  In order to solve the above problems, a radar apparatus according to the present invention includes a magnetron driving circuit including a driving pulse transformer that generates a driving pulse and a reference pulse transformer that generates a reference pulse. The magnetron is oscillated by applying the driving pulse clipped by the pulse to the magnetron.

(Embodiment 1)
A magnetron driving circuit 1 according to the first embodiment will be described with reference to FIG. The main feature of the magnetron driving circuit 1 is that a reference pulse transformer 11 for generating a reference pulse is added to the conventional magnetron driving circuit 100. The primary and secondary configurations of the reference pulse transformer are the same as those of the conventional magnetron driving circuit 100 except for the presence or absence of a capacitive component such as a magnetron. Details will be described below.

  FIG. 1 is a diagram showing a magnetron driving circuit 1 according to the first embodiment. The magnetron driving circuit 1 includes a driving pulse transformer 101 and a reference pulse transformer 11. The driving pulse transformer 101 includes a primary winding 102 and a secondary winding 103. Hereinafter, the side on which the primary winding 102 is provided is referred to as a primary side, and the side on which the secondary winding 103 is provided is referred to as a secondary side. One terminal of the primary winding 102 is directly connected to the power supply V and grounded via the capacitor 105, and a switching FET 106 is provided at the other terminal. One terminal of the secondary winding 103 is grounded, and the other terminal is connected to the secondary side of a reference pulse transformer 11 described later via a diode 18 and to the cathode (not shown) of the magnetron. Connected.

  On the primary side of the driving pulse transformer 101, the switching FET 106 is turned on in response to an output from a drive circuit having a predetermined pulse width. Then, a driving pulse having the pulse width is generated on the secondary side of the pulse transformer 101.

  Similarly, the reference pulse transformer 11 includes a primary winding 12 and a secondary winding 13. Hereinafter, the side provided with the primary winding 12 is referred to as a primary side, and the side provided with the secondary winding 13 is referred to as a secondary side. One terminal of the primary winding 12 is directly connected to the power source V and grounded via a capacitor 15, and the other terminal is provided with a switching FET 16. Further, one terminal of the secondary winding 13 is grounded, and the other terminal is grounded via a pure resistor 17 and connected to the secondary side of the driving pulse transformer 101 via a diode 18. .

  On the primary side of the reference pulse transformer 11, the switching FET 16 is turned on in response to an output from a drive circuit having a predetermined pulse width. Then, a reference pulse having the pulse width is generated on the secondary side of the pulse transformer 11. In this embodiment, the output waveforms from the drive circuit on the primary side of the drive pulse transformer 101 and the reference pulse transformer 11 are equal.

  With the configuration described above, the driving pulse generated on the secondary side of the driving pulse transformer 101 is clipped by the reference pulse generated on the secondary side of the reference pulse transformer 11. When the clipped driving pulse is applied to the magnetron, the magnetron oscillates at a very high output and outputs a microwave (transmission pulse). This microwave is emitted through an antenna outside the figure, and the target can be detected with high accuracy.

  Hereinafter, the relationship between the reference pulse and the driving pulse to be clipped will be described with reference to FIGS. 2 and 3 are conceptual diagrams showing pulse waveforms in the magnetron driving circuit 1 of the present embodiment. The lower diagram of FIG. 2 shows an output waveform from the drive circuit, that is, an input waveform to the switching FET 16 provided on the primary side of the reference pulse transformer 11. The input waveform to the switching FET 16 is the same as the input waveform to the switching FET 106 shown in FIG. Therefore, the rising point and the falling point of the driving pulse generated on the secondary side of the driving pulse transformer 101 and the reference pulse generated on the secondary side of the reference pulse transformer 11 are equal.

  In the upper diagram of FIG. 2, the solid line indicates the waveform of the reference pulse generated on the secondary side of the reference pulse transformer 11, and the dotted line indicates the drive generated on the secondary side of the driving pulse transformer 101. Pulse. This driving pulse is the same as the conventional driving pulse shown in FIG.

  The reference pulse voltage is also set to be equal to the operating voltage (operating point) of the magnetron. Furthermore, since a pure resistor 17 having no capacitive component is connected to the load connected to the secondary side of the reference pulse transformer 11, the waveform of the reference pulse generated on the secondary side of the reference pulse transformer Is close to a rectangle.

  FIG. 3 shows the waveform of the driving pulse after clipping applied to the magnetron. In the magnetron driving circuit 1, the diode 18 is provided in the forward direction from the secondary side of the reference pulse transformer 11 toward the secondary side of the driving pulse transformer 101. Therefore, when the reference pulse voltage becomes higher than the driving pulse voltage, the diode 18 is turned on. As a result, the current flows until the potential difference between the reference pulse voltage and the drive pulse voltage almost disappears, so that a drive pulse having a waveform clipped by the reference pulse is generated as shown in FIG. When this driving pulse is applied to the magnetron, the magnetron oscillates and outputs a transmission pulse.

  With the configuration as described above, it is possible to output from the magnetron a transmission pulse having a waveform whose rise and fall are close to a rectangle with a steeper shape than before and whose pulse width is narrow. Furthermore, it is not necessary to provide an absorption resistor or the like that absorbs the residual energy of the driving pulse transformer 101 on the primary side of the driving pulse transformer 101, and the load when outputting the transmission pulse can be reduced.

  If the reference pulse that can be clipped at the rise and fall of the drive pulse can be generated, the effect of the present invention can be exhibited. That is, even if the pure resistor 17 is not used as the secondary load of the reference pulse transformer 11, the effect of the present invention can be exhibited if a capacitance component smaller than the magnetron is used.

It is a figure which shows the magnetron drive circuit of this Embodiment 1. FIG. It is a conceptual diagram which shows the pulse waveform in the magnetron drive circuit of this Embodiment 1. It is a conceptual diagram which shows the pulse waveform in the magnetron drive circuit of this Embodiment 1. It is a figure which shows the conventional magnetron drive circuit. It is a conceptual diagram which shows the pulse waveform in the conventional magnetron drive circuit.

Explanation of symbols

1,100 Magnetron driving circuit 11 Reference pulse transformer 12, 102 Primary winding 13, 103 Secondary winding 15, 105 Capacitors 16, 106 Switching FET
17 Pure resistance 18 Diode 101 Driving pulse transformer

Claims (4)

In a magnetron driving circuit that oscillates the magnetron by applying a driving pulse to the magnetron,
A driving pulse transformer for generating the driving pulse;
A reference pulse transformer for generating a reference pulse,
A magnetron driving circuit, wherein the driving pulse is clipped by the reference pulse. The magnetron driving circuit according to claim 1,
A magnetron driving circuit characterized in that the secondary side of the reference pulse transformer has a pure resistance as a load and is connected to the secondary side of the driving pulse transformer via a diode. The magnetron drive circuit according to claim 1 or 2,
2. A magnetron driving circuit according to claim 1, wherein rising and falling timings of the driving pulse and the reference pulse are substantially equal. In a radar apparatus including a magnetron driving circuit,
The magnetron driving circuit is
A driving pulse transformer for generating a driving pulse;
A reference pulse transformer for generating a reference pulse,
A radar apparatus, wherein the magnetron is oscillated by applying the driving pulse clipped by the reference pulse to the magnetron.