JPH06273514A - Radar system - Google Patents

Abstract

PURPOSE:To protect the detection capacity of radar from deteriorating due to the operational noise generated in a traveling wave tube (TNT) being employed at the transmitting section of a radar system and leaked to the receiving section. CONSTITUTION:The radar system comprises a receiving section 3 and a transmitting section 4 connected with a transmitting/receiving antenna ANT through a circulator 2, where the transmitting section 4 is provided with a TNT 5 having an outputted connected with an attenuator circuit 7 operable only when a signal is received. The attenuator circuit 7 comprises a lambda/4 transmission line 11 inserted into the output line of the TNT 5, first and second transmission lines 12, 13 comprising lambda/4+nlambda/2 (n is an arbitrary integer of 0, 1, 2... transmission lines 15, 17 connected, respectively, with the opposite ends of the line 11 and terminated with PIN diodes 16, 18, and a control circuit 14 for opening the PIN diodes 16, 18 at the time of reception in synchronism with the switching operation of transmission and reception.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more particularly to a radar device having a TWT amplifier circuit using a traveling wave tube (hereinafter abbreviated as TWT) in a final power amplification stage of a transmitter.

[0002]

2. Description of the Related Art Generally, a TW is installed in a final power amplification stage of a transmitter.
In a radar device that includes an amplifier circuit using T and has a transmitter and a receiver connected to a shared antenna via a circulator, operation noise generated in the TWT of the transmitter leaks to the receiver through the circulator, and this operation The noise may deteriorate the radar detection capability of the receiving unit. FIG. 4 is a circuit diagram showing a part of a conventional radar device. A circulator 2 is connected to the antenna connection end 1 of the transmission / reception shared antenna ANT. The circulator 2 supplies a signal from the transmission / reception shared antenna ANT to the reception unit 3 and a signal from the transmission unit 4 to the transmission / reception shared antenna AN.
Supply to T. The transmission unit is provided with a TWT 5, the transmission signal input to the input end 6 is power-amplified by the TWT 5, output to the transmission / reception shared antenna ANT via the circulator 2, and transmitted from here.

However, in this configuration, although the receiving unit 3 and the transmitting unit 4 are not directly connected by the circulator 2, if the TWT 5 is operating at the time of reception, the operating noise generated by the TWT 5 will be generated.
To leak to the receiving unit 3 and reduce the radar detection capability of the receiving unit 3. For this reason, the radar apparatus shown in the figure is provided with a control circuit 8 for turning on and off the electron beam of the TWT 5 as shown by a virtual line, so that the radar circuit is selectively operated in synchronization with switching between transmission and reception. Attempts have been made to configure it. With this configuration, the control circuit 8 turns off the electron beam of the TWT 5 at the time of reception.
The operation of T5 is stopped, so that no operation noise is generated in TWT5, and the operation noise is generated by the circulator 2
Is prevented from leaking to the receiving unit 3.

[0004]

SUMMARY OF THE INVENTION With such a configuration,
It is necessary to control ON / OFF of the electron beam of the TWT 5 by the control circuit 8 in synchronism with the switching of transmission / reception, but normally, the switching of transmission / reception of the radar device is performed at an extremely high speed, so the control circuit 8 must follow this. Control circuit at high speed by
It is required to operate off. Further, during this on / off control, voltage control that matches the operating conditions of the TWT is required in an extremely short time, and the voltage handled is a high voltage. Therefore, the configuration of the control circuit 8 becomes extremely complicated, and the followability to high-speed switching is limited, which makes it difficult to put this type of radar device to practical use. The object of the present invention is to provide T at the time of reception.
It is an object of the present invention to provide a radar device that prevents leakage of WT noise and prevents deterioration of radar detection capability.

[0005]

SUMMARY OF THE INVENTION The present invention provides a TW provided in a transmitter connected to a receiver via a circulator.
The output terminal of T is provided with an attenuation circuit that performs an attenuation operation only when receiving. The attenuator circuit has a λ /
4 transmission lines and λ / 4 + nλ / connected to both ends of this λ / 4 transmission line and terminated with PIN diodes.
2 (n is an arbitrary integer of 0, 1, 2, ...) Transmission lines, and a control circuit for performing a short-circuit operation or an open operation of the PIN diode in synchronization with transmission / reception switching. Composed. For example, the control circuit uses P when transmitting.
The IN diode is short-circuited and opened at the time of reception. Also, the first and second transmission lines are PIN
A plurality of λ / 4 + nλ / 2 transmission lines terminated by diodes are connected in parallel to form a transmission line group.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, in which a receiving section 3 and a transmitting section 4 are connected to an antenna connection end 1 of a transmission / reception shared antenna ANT via a circulator 2.
The transmitter 4 is provided with a TWT 5 and amplifies the power of the transmission signal input to the input terminal 6. Further, the transmission unit 4 is provided with a noise attenuating circuit 7, and the noise attenuating circuit 7 is inserted between the TWT 5 and the circulator 2 to provide a TWT.
5 is operated to attenuate the operating noise generated. That is, in this radar device, the transmission / reception antenna A
The signal received by NT is received by the receiving unit 3 through the circulator 2. Further, the transmission signal input to the input terminal 6 is amplified to the required transmission power by the TWT 5, passed through the noise attenuating circuit 7, and then supplied through the circulator 2 to the transmission / reception shared antenna so that it is transmitted from here. Composed.

The noise attenuating circuit 7 has an isolator 1 inserted in a path from the TWT 5 to the circulator 2.
0 and λ / 4 transmission line 11 and this λ / 4 transmission line 1
1, a first transmission line group 12 connected to the input side end, a second transmission line group 13 similarly connected to the output side end of the λ / 4 transmission line 11, and the first and second transmission lines And a control circuit 14 for opening or short-circuiting the other end of the group. The first transmission line group 12 includes a plurality of λ / 4 transmission lines 15 (15a, 15b, ...) Connected in parallel,
It is composed of a plurality of PIN diodes 16 (16a, 16b, ...) Connected to the other ends of these λ / 4 transmission lines 15, respectively. Similarly, the second transmission line group 13
A plurality of λ / 4 transmission lines 17 (17a, 1) connected in parallel
7b, ...) and a plurality of PIN diodes 18 (18a, 18a, 18a, 18b) connected to the other ends of these λ / 4 transmission lines 17, respectively.
18b, ...). In addition, the control circuit 14
Changes the bias supplied to the PIN diodes 16 and 18 based on a control signal that is input in synchronization with the switching of transmission and reception, here the bias control signal A, and thereby changes the operating impedance of the PIN diodes 16 and 18. The control is performed by changing and opening the other ends of the λ / 4 transmission lines 15 and 17 or short-circuiting the other ends.

The operation of the noise attenuation circuit 14 will be described with reference to the operation timing chart of FIG. In the figure, α is a reception time domain and β is a transmission time domain. The bias control signal A input to the control circuit 14 is the transmission signal B.
Is synchronized with. In the transmission time region β, the bias control signal A input to the control circuit 14 is at a high level, which makes the operating impedance of the PIN diodes 16 and 18 short-circuit impedance. As a result, at the time of transmission, the first and second λ / 4 transmission lines 11 are
It is equivalent to that the transmission line groups 12 and 13 are not connected, and the output power from the TWT 5 is λ without being attenuated.
Sent to the circulator 2 through the / 4 transmission line 11,
Further, it is supplied to the transmission / reception shared antenna ANT and transmitted.

On the other hand, in the reception time region α, the bias control signal A is at a low level, which makes the operating impedance of the PIN diodes 16 and 18 open impedance. This is equivalent to short-circuiting both ends of the λ / 4 transmission line 11 at the time of reception, and the impedance at the input end of the λ / 4 transmission line 11 is short-circuited.
The operating noise generated in WT 5 is reflected at this point and is further absorbed by the isolator 10. Therefore, the operating noise generated in the TWT 5 at the time of reception is the circulator 2
There is no leakage to the receiving unit 3 through, and the detection ability of the receiving unit 3 is not deteriorated. Further, in this configuration, since the TWT 5 can be continuously operated, it is not necessary to control the ON / OFF of the electron beam of the TWT 5, and a complicated circuit for performing the ON / OFF control is unnecessary. .

The first transmission line group 12 and the second transmission line group 12 are theoretically one transmission line and one P, respectively.
Although it can be configured with an IN diode, in practice, it is difficult to put the PIN diode into an ideal short-circuit state during transmission, so a part of the power from the TWT is consumed as a loss in the PIN diode. Therefore, in order to prevent this loss from exceeding the loss rating of the PIN diode, a plurality of transmission lines and the PIN diode are connected in parallel, and the loss is shared by each PIN diode.

Here, the first embodiment in the embodiment shown in FIG.
And a plurality of λ / s configuring the second transmission line groups 12 and 13.
4 transmission lines 15 and 17 are λ / 4 + nλ / 2 (n is 0,
1, 2, ... Arbitrary integer) may be satisfied. That is, in the example of FIG. 1, n is 0, and when n is 1, as shown in FIG.
The length may be 4 + λ / 2. The same applies when n is 3 or more. Further, by slightly shifting the lengths of the respective transmission lines 15 and 17 from the wavelength of the center frequency, it is possible to expect expansion of the band corresponding to the shifted amount.

[0012]

As described above, according to the present invention, since the attenuator circuit that performs the attenuating operation only at the time of reception is provided at the output end of the TWT provided at the transmitter, the noise generated at the TWT at the time of reception is received. Since it can be prevented from leaking to the receiving unit by being attenuated by the attenuating circuit, it is possible to prevent the operating noise of the TWT from leaking to the receiving unit without stopping the operation of the TWT at the time of reception. In addition to avoiding the deterioration, the complicated circuit configuration for controlling the ON / OFF of the TWT becomes unnecessary, the reliability of the radar device can be improved, and the configuration can be simplified. Further, the attenuating circuit has a λ / 4 transmission line and first and second transmission lines respectively connected to both ends thereof and terminated with a PIN diode, and the control circuit opens the PIN diode only when receiving. By doing so, it is possible to perform the attenuation operation only during reception, without complicating the control circuit,
Moreover, it is possible to prevent the leakage of the operation noise of the TWT during reception with a simple control operation. Furthermore, the first and second
By configuring the transmission line of (1) as a transmission line group including a plurality of transmission lines, it is possible to share the loss in the PIN diode with the plurality of PIN diodes and secure the loss rating of the PIN diode.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a radar device of the present invention.

FIG. 2 is a timing diagram for explaining the operation of the noise attenuation circuit.

FIG. 3 is a block diagram showing a modified example of the noise attenuation circuit.

FIG. 4 is a block diagram of a part of a conventional radar device.

[Explanation of symbols]

 2 Circulator 3 Receiver 4 Transmitter 5 TWT 7 Noise Attenuation Circuit 10 Isolator 11 λ / 4 Transmission Line 12 First Transmission Line Group 13 Second Transmission Line Group 14 Control Circuit 15, 17 λ / 2 + nλ / 2 Transmission Line 16 , 18 PIN diode

Claims (4)

[Claims] 1. A radar having a shared antenna for transmission and reception, a transmission unit and a reception unit connected to the antenna via a circulator, and the transmission unit having an amplifier circuit using a traveling wave tube as a final power amplifier. The radar apparatus according to claim 1, further comprising an attenuating circuit provided at an output end of the traveling wave tube for performing an attenuating operation only when receiving. 2. An attenuator circuit is provided with a λ / 4 transmission line inserted in an output path of a traveling wave tube, and a λ / 4 + line connected to both ends of the λ / 4 transmission line and terminated with a PIN diode.
Control for causing the first and second transmission lines consisting of nλ / 2 (n is an arbitrary integer of 0, 1, 2, ...) Transmission line and the PIN diode to be short-circuited or opened in synchronization with switching between transmission and reception. The radar device according to claim 1, further comprising a circuit. 3. The radar device according to claim 2, wherein the control circuit short-circuits the PIN diode at the time of transmission and opens the PIN diode at the time of reception. 4. The first and second transmission lines are respectively P
4. The radar device according to claim 2, wherein a plurality of λ / 4 + nλ / 2 transmission lines terminated by IN diodes are connected in parallel to form a transmission line group.