JP3002090B2 - Radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus using a magnetron, and more particularly to a method of generating a tuning instruction signal for performing a tuning operation.

[0002]

2. Description of the Related Art In a radar device using a magnetron,
In order to obtain radar video with maximum sensitivity, measures have been taken to tune the local oscillation frequency to the magnetron oscillation frequency, but in order to enable tuning operation even when there is no reflected wave from the target at all. Conventionally, for example, a configuration shown in FIG. 4 is used to generate a tuning instruction signal by using a reflected wave in the apparatus.

In FIG. 4, most of the pulse-modulated output of the magnetron 1 is supplied from the output port of the circulator 2 to the antenna 5 via the waveguide 4 and the antenna 5
It is radiated from the radar to the space of the radar coverage. The reflected wave (radar video signal) from the target received by the antenna 5 enters the mixer 7 via the waveguide 4, the circulator 2, and the diode limiter 6, where the local oscillation frequency of the local oscillator 8 changes the intermediate frequency band. After the frequency conversion into a signal of the following formula, unnecessary signal components are removed by the band-pass filter 9, the signal is detected by the detector 11 and a video signal is output.

In the above-described operation of forming a video signal, part of the output of the magnetron 1 leaks to the isolation port of the circulator 2 and the diode limiter 6
And a component B input from the circulator 2 to the antenna 5 is reflected by the antenna 5 and again passes through the circulator 2 and is input to the diode limiter 6 at the diode limiter 6. 7
The frequency is converted into a signal in the intermediate frequency band by the local oscillation frequency of the local oscillator 8, filtered by a narrow band-pass filter 10, detected by a detector 12, and a tuning instruction signal is output.

If the oscillation frequency of the local oscillator 8 is adjusted so that the level of the tuning instruction signal becomes maximum, a video signal can be obtained with the maximum sensitivity. The adjustment of the oscillation frequency of the local oscillator 8 based on the tuning instruction signal may be performed manually or automatically using a microcomputer.

[0006]

However, in the conventional method of generating a tuning instruction signal from a composite wave of the leak component A of the circulator and the reflected component B at the antenna, the components A and B
And a time difference corresponding to the length of the waveguide 4 occurs (FIGS. 5A and 5B). Therefore, the diode limiter 6
The amplitude of the combination of the two is shown by the diagonal lines in FIG. 5 (3), but varies in a complicated manner due to the relative phase difference between the two components, and an optimal tuning instruction signal cannot be obtained. May not be performed.

That is, in such a case, if the output spectrum of the magnetron 1 has a center frequency f _C as shown in FIG. 6A, the signal waveform and the spectrum of the component A and the signal B are the same as those of the magnetron. is a similar to the spectrum of the composite wave is likely to will have a different center frequency f _C 'larger than the center frequency f _C as shown in Figure 6 (b). On the other hand, the signal waveform and spectrum of the reflected wave from the target are similar to those of the magnetron 1.

Therefore, there is a problem that the local oscillation frequency at which the tuning instruction signal is maximized does not match the local oscillation frequency at which the video signal is maximized, and the video signal cannot be acquired with the maximum sensitivity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a radar apparatus provided with means for bringing the waveform and spectrum of a signal for generating a tuning instruction signal closer to the output signal waveform and spectrum of a magnetron. To provide.

[0010]

To achieve the above object, a radar apparatus according to the present invention has the following arrangement. That is, the radar device of the present invention performs an operation of generating a tuning instruction signal for tuning the local oscillation frequency to the oscillation frequency of the magnetron by using a reflected wave or the like in the device in parallel with the output operation of the video signal. In the radar apparatus, an inductive window (iris) for obtaining a stable reflection intensity is mounted on a waveguide of an antenna output section of the circulator.

[0011]

Next, the operation of the radar apparatus of the present invention configured as described above will be described. In the present invention, an inductive window (iris) capable of obtaining a stable reflection intensity is attached to the antenna output section waveguide of the circulator, and a reflected wave of the inductive window is provided.
A tuning instruction signal is generated by a composite wave of the leak component of the circulator and the reflection component at the antenna. The inductive window is such that the signal strength of the reflected wave is larger than the signal strength of the other two components. And the composite wave is determined mainly by the reflection component of the inductive window.

Therefore, the signal waveform of the composite wave for generating the tuning instruction signal is close to the output signal waveform of the magnetron, and the spectrum of the composite wave is close to the output spectrum of the magnetron. As a result, the video signal output is maximized, and an accurate tuning operation can be performed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a radar device according to one embodiment of the present invention. The same components as those of the related art (FIG. 4) are denoted by the same reference numerals. Hereinafter, a description will be given mainly of a portion according to the present invention.

In the present invention, an inductive window (iris) 3 is mounted on the waveguide of the antenna output section of the circulator 2. The iris 3 is set so that a reflected component C having a signal intensity larger than that of the component A and the component B is stably obtained, and the insertion loss is minimized.

The tuning instruction signal leaks from the isolation port of the circulator 2 and is input to the diode limiter 6 through the component A (FIG. 2 (1)). The signal sent from the circulator 2 to the antenna 5 is reflected by the antenna 5. The component B (FIG. 2 (2)) which passes through the circulator 2 again and is input to the diode limiter 6, and is reflected by the iris 3 provided on the antenna output waveguide of the circulator 2 and is input again to the diode limiter 6 through the circulator 2. It is generated by a composite wave with the component C (FIG. 2 (3)).

Since the signal strength of the component C is set to be sufficiently larger than that of the other two components as described above, the composite wave is mainly determined by the reflection component of the iris 3 ( FIG. 2 (4)). That is, the composite wave that generates the tuning instruction signal has the same signal waveform and spectrum as those of the magnetron 1 (FIGS. 3A and 3B).

On the other hand, the reflected wave (radar video signal) from the target is such that the output of the magnetron 1 is radiated from the antenna 5, received again by the antenna 5, and input to the diode limiter 6 through the circulator 2. Therefore, the amplitude waveform and spectrum of the reflected wave from this target are similar to the output amplitude waveform and spectrum of the magnetron 1.

Accordingly, the band-pass filter 9 for obtaining a video signal output and the band-pass filter 1 for obtaining a tuning instruction signal
If the local oscillation frequency is adjusted so that the center frequency of 0 is equal and the tuning instruction signal is maximized, the video signal output is maximized. That is, a perfect tuning operation can be performed using only the reflected wave (component C) in the device.

[0019]

As described above, in the radar apparatus of the present invention, an inductive window (iris) for obtaining a stable reflection intensity is attached to the antenna output waveguide of the circulator.
Since the tuning instruction signal is generated by the reflected wave of the inductive window, the signal waveform and the spectrum of the composite wave for generating the tuning instruction signal can be made close to the output signal waveform and the spectrum of the magnetron, and the tuning instruction signal is generated. Maximize the video signal output at the local oscillation frequency to maximize,
That is, there is an effect that an accurate tuning operation can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a radar device according to an embodiment of the present invention.

FIG. 2 is a time chart illustrating a tuning operation performed by the radar device of the present invention.

3A and 3B are comparison diagrams of a spectrum, in which FIG. 3A shows an output spectrum of a magnetron, and FIG. 3B shows a spectrum of a synthetic wave.

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

FIG. 5 is a time chart illustrating a tuning operation performed by a conventional radar device.

6A and 6B are comparison diagrams of a conventional spectrum, in which FIG. 6A shows an output spectrum of a magnetron, and FIG. 6B shows a spectrum of a composite wave.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetron 2 circulator 3 inductive window (iris) 4 waveguide 5 antenna 6 diode limiter 7 mixer 8 local oscillator 9,10 bandpass filter 11,12 detector

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01S 7/03 G01S ^7/ 28-7/285

Claims (1)

(57) [Claims] 1. A radar apparatus which performs an operation of generating a tuning instruction signal for tuning a local oscillation frequency to an oscillation frequency of a magnetron using a reflected wave or the like in the apparatus in parallel with an operation of outputting a video signal; A radar device comprising: an inductive window (iris) capable of obtaining a stable reflection intensity mounted on a waveguide of an antenna output section of a circulator.