JP2592490Y2 - Pulse type radar device - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a magnetron, a CFA
The present invention relates to a pulse type radar device provided with microwave power such as described above, and particularly to an improvement of a limiter unit for protecting a receiving unit.

[0002]

2. Description of the Related Art FIG. 4 shows an example of the configuration of a transmission / reception unit in a conventional pulse type radar device. In FIG. 1, reference numeral 1 denotes a magnetron pulse drive power supply including a heater power supply, and 2 denotes a magnetron, which constitutes a transmission unit. The magnetron 2 operates when a heater voltage is applied between the heater terminal H and the cathode terminal K, and a negative high voltage pulse is applied to the cathode terminal K and to the grounded anode terminal A. Reference numeral 3 denotes a circulator that functions as a transmission / reception switching unit, 4 denotes an antenna, 5 denotes a limiter, and a limiter diode 6 is incorporated as a main component. Reference numeral 7 denotes a receiving unit, which includes a receiving circuit such as a mixer, a local oscillator, and an intermediate frequency amplifier circuit.

Hereinafter, the same reference numerals in the drawings indicate the same or corresponding components.

A microwave driven by a pulse drive power supply 1 and generated by a magnetron 2 is transmitted by a circulator 3 toward an antenna 4 and radiated to the outside as radar waves by the antenna. The microwave reflected by the illuminated target is received by the antenna 4, guided to the limiter 5 by the circulator 3, and further sent to the receiving unit 7, where the signal is processed for a video indicator.

Here, the limiter 5 generates a direct reflected wave of the microwave generated by the antenna 4 at the time of the transmission pulse operation or a microwave power leaking from the circulator 3 and coming out to the receiving section 7 (such a direct reflected wave). This is provided to protect the receiving unit 7 from waves and leaked microwave power collectively (hereinafter referred to as “leakage power”), and a limiter diode is used as a functional component. Limiter 5
Is composed of, for example, a waveguide system, a waveguide, a pair of metal poles standing on upper and lower inner wall surfaces thereof, and a limiter diode inserted between the metal poles.

In general, the leakage power generated during the operation of the microwave power tube has sufficient energy to destroy the circuit elements of the receiving unit 7, but when this power enters the limiter 5, the limiter diode 6 is short-circuited. State.
As a result, the leakage power is reflected and its transmission is blocked, so that the receiving unit is protected. Needless to say, a normal received radio wave reflected by a target and received with a time delay according to the distance to the target is extremely weak compared to the leakage power. It passes through the limiter without affecting it and is sent to the receiver.
The same operation is performed in the case of a strip line type limiter.

[0007] The limiter thus helps protect the receiver, but the withstand power of the limiter diode is typically several kW.
Therefore, the mere insertion of a limiter as described above can only be used for a radar apparatus having a transmission power of up to several kW. Therefore, in a higher power radar device,
As a means for increasing power durability, a method is used in which a current (bias current) is applied to a limiter diode in synchronism with the pulse operation of a microwave power tube to forcibly short the diode. .

[0008]

In the conventional pulse type radar apparatus as shown in FIG. 4, the transmission power is limited to a low level in view of the power durability of the limiter diode. In the method of flowing a bias current, although the withstand power can be increased, there is a problem that a special power supply for supplying the current needs to be provided, and a circuit becomes complicated because it is necessary to take a timing with a transmission pulse. Was.

The present invention has been made to solve such a problem and to provide a limiter section having high power durability with a simple circuit configuration.

[0010]

In order to achieve the above object, the present invention provides a magnetron, a CFA (Crossed).
A transmitting unit using a microwave power tube such as a Field Amplifier) as a transmitting tube, an antenna, a receiving unit,
In a pulse-type radar device including a transmission switching unit that switches connection of the antenna to the transmission unit or the reception unit, a limiter is provided between the transmission switching unit and the reception unit.
A limiter configured to insert a limiter mainly composed of a diode, and to allow a part or all of a pulse current flowing through the transmission tube or a secondary current of the pulse current to flow through the limiter diode, Is provided.

In one embodiment, the limiter section is
A plurality of distribution paths configured by a demultiplexer and a combiner are provided in a path between the transmission / reception switching unit and the reception unit, and the limiter is inserted into each of the distribution paths, and each of the limiters A limiter configured to flow a part or all of a pulse current flowing through the transmission tube or a secondary current of the pulse current by a current transformer into the diode separately is provided.

Further, as another embodiment, in each of the pulse-type radar devices described above, an STC (sensitivity-time c.c.) is connected in parallel with the limiter diode.
A capacitive circuit is provided for the control circuit.

[0013]

1 is a block diagram showing an embodiment of a pulse type radar apparatus according to the present invention. In the figure, 5A is a limiter having a built-in limiter diode 6 like the limiter 5 described above.
One of the pair of metal poles to which the limiter diode 6 is connected is provided electrically floating from the waveguide so that current can flow through the limiter diode.

Between the anode terminal A of the magnetron 2 and ground, and between the same electrode terminal and one terminal of the limiter diode 6;
Resistor 1 and resistor 2 and limiter diode 6 respectively
In series, the series circuit of the switch SW and a capacitor C1 is provided.

When a pulse voltage is applied to the magnetron 2 by the pulse drive power supply 1, the magnetron oscillates a microwave, but at the same time, a pulse current (anode current) flows through the anode A. This pulse current flows by shunting the resistors R1 and R2. When the current passing through R2 flows through the limiter diode 6, the diode is electrically short-circuited (the resistance values of R1 and R2 are limited by the limiter diode). 6 is set so as to allow a current to flow stably to short-circuit.

As described above, when a bias current is forcibly supplied to the limiter diode from the outside to cause a short-circuit state, a better short-circuit state can be obtained as compared with a case where no bias current is present (self-bias). Therefore, the blocking characteristic with respect to the leakage power is improved, and the withstand power characteristic of the limiter is substantially improved (it is possible to increase the limiter more than twice as much as the case of the self-bias).

The above-mentioned effect can be obtained even in a conventional pulse type radar device in the case of a system in which a bias current is applied to a limiter diode. However, the present invention additionally has the following effects. It has another advantage as mentioned.

FIG. 5 is a waveform diagram for explaining the state of the magnetron in a pulse operation. In the figure, (a) is the anode voltage applied to the magnetron, (b) is the anode current,
(C) is the pulse waveform of the microwave output, (d) is the leakage power passing through the limiter 5A in the case of the present invention,
(E) shows each pulse waveform of the leakage power passing through the limiter 5 in the case of the conventional device. Magnetron and CF
In a microwave power tube such as A, when a microwave output operation (oscillation or amplification) starts, a large spike-like leakage power that passes through a transmission / reception switching unit such as a circulator is generated. Such leakage power at the rising portion cannot obtain sufficient attenuation due to a delay in the operation of the limiter diode, and passes with a waveform as shown in FIG.

Now, when a pulse voltage such as (a) is applied to the anode, as shown in the current pulse waveform of (b), a current called a "dark current" appears at the leading and trailing edges of the pulse. Occurs. This dark current is generated when the voltage pulse rises and falls (normal microwave oscillation and
When the current pulse is used as in the present invention, the dark current flows through the limiter diode 6 prior to the generation of the spike-like leakage power. Since the short-circuiting can be performed, the passage of the spike-like leakage power is prevented, and the waveform of the passing power becomes as shown in (d), and the receiving unit 7 is well protected.

In FIG. 1, when the capacitor C1 is connected to the limiter 5A by the switch SW, the limiter
Since a capacitive circuit is added in series with the diode 6, a recovery time of the limiter operation corresponding to the capacitance can be provided. Such an additional circuit is provided for the purpose of automatically suppressing the receiver gain during the time when sea surface reflection from a close distance occurs in a marine radar or the like, so-called STC.
It can be used as a circuit.

FIG. 2 shows the structure of another embodiment of the present invention. In the figure, reference numeral 8 denotes a current transformer for transforming a current pulse. In this embodiment, the resistor circuit portion in the embodiment of FIG. 1 is replaced with a transformer coupling circuit. By supplying the secondary current of the current transformer to the limiter diode 6 of the limiter 5A, the same effect as in the case of FIG. 1 can be obtained.

FIG. 3 is a block diagram showing another embodiment of the present invention. In the figure, reference numeral 9 denotes a duplexer for distributing received power, and 10 denotes a combiner for recombining the distributed received power.

Each distribution path between the duplexer and the combiner includes:
A limiter 5A having a limiter diode 6 similar to that described above is provided. In the present embodiment, the microwave reception power that has passed through the circulator 3 is split into two by the splitter 9, passes through the limiters 5 </ b> A of the respective distribution paths, is synthesized by the synthesizer 10, and is sent to the receiver 7. By providing such a distribution path, the leakage power described above is also divided into two and passes through each limiter 5A, so that a total of twice the power can be handled, and the pulse power of twice the transmission power can be handled. It can be used for radar equipment. In the present embodiment, the case where the number of distribution paths is two has been described. However, it is needless to say that the number of distribution paths can be further increased and power consumption can be further increased. The same is true for a strip line.

In the above description, the case of the magnetron and the CFA is exemplified as the microwave power tube. However, in the case of a straight-line type microwave power tube such as a klystron or a traveling wave tube, they are also operated by a beam power / pulse modulation method. The present invention can be used by operating the beam current and flowing the beam current to the limiter diode 6.

[0025]

As described above, in the pulse-type radar device of the present invention, the limiter is configured by a limiter diode, a pulse current flowing through the microwave power tube, or a current transformer of the pulse current. By supplying part or all of the secondary current, a special power supply for supplying the bias current required in the conventional device and a special circuit for timing the transmission pulse Is unnecessary, and the power withstand characteristics of the limiter can be improved with a simple configuration.

Further, since the use of the pulse current of the microwave power tube as described above also uses the dark current at the same time, it is effective for the large spike-like leakage power as described above. The limiter effect is produced, and the power withstand characteristics of the limiter are substantially improved.

In the above configuration, when a capacitive circuit is added in series with a limiter diode, it can be used as an STC circuit.

Further, when a plurality of distribution paths are provided, each of the distribution paths is provided with a limiter similar to the above, and a pulse current is supplied to the limiter diode in the same manner as described above, the power consumption is further increased. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a transmission / reception unit of an embodiment of a pulse type radar device of the present invention.

FIG. 2 is a configuration diagram of a transmission / reception unit of another embodiment of the pulse type radar device.

FIG. 3 is a configuration diagram of a transmission / reception unit of still another embodiment of the pulse-type radar device.

FIG. 4 is a configuration diagram of an example of a transmission / reception unit of a conventional pulse type radar device.

FIG. 5 is a waveform diagram for explaining a pulse operation.

[Description of sign]

 REFERENCE SIGNS LIST 1 pulse drive power supply, 2 magnetron 3 circulator 4 antenna 5, 5 A limiter 6 limiter diode 7 receiver 8 current transformer 9 duplexer 10 synthesizer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (3)

(57) [Scope of request for utility model registration] 1. A transmitting unit using a microwave power tube such as a magnetron or a CFA as a transmitting tube, an antenna, a receiving unit,
A pulse type radar device comprising: a transmission / reception switching unit configured to switch connection of the antenna to the transmission unit or the reception unit. A limiter mainly including a limiter diode between the transmission / reception switching unit and the reception unit. A limiter unit configured to be inserted and configured to allow a part or all of a pulse current flowing through the transmission tube or a secondary current of the pulse current by a current transformer to flow in the limiter diode. Pulse type radar device. 2. A method according to claim 1, wherein the limiter is provided with a plurality of distribution paths configured by a demultiplexer and a combiner in a path between the transmission / reception switching section and the reception section, and the limiter is provided in each of the distribution paths. Insert, into each limiter diode of each of the limiters,
The pulse current flowing through the transmission tube or a secondary current of the pulse current by a current transformer is partially or entirely replaced with a limiter unit configured to flow separately. The pulse type radar device as described in the above. To wherein the limiter diodes in series, ST
3. The pulse type radar device according to claim 1, wherein a capacitive circuit is provided for the C circuit.