JPS6288981A - Survey radar equipment for underground buried body - Google Patents

Abstract

PURPOSE:To survey the direction of an underground buried body from the relation between the direction of a transmitted electric field and reflected wave intensity by applying two kinds of AC voltages to mutually orthogonal dipole antennas, and varying its amplitude and changing the electromagnetic field direction of a radiant linear polarized wave. CONSTITUTION:Alternating currents 13 and 14 of frequency (f) which are in phase of 180 deg. out of phase with each other are flowed to the two orthogonal half-wave dipole antennas 11 and 12. The amplitudes of the currents 13 and 14 are denoted as I1 and I2. Those antennas 11 and 12 are set so that the plane containing the antennas 11 and 12 is parallel to the ground surface, and a radio wave is radiated into the ground. When the radio wave is radiated from above a buried pipe 7, the electric field E on the ground surface of the buried pipe is almost horizontal. The ratio of the currents I1 and I2 is varied at each point while the antennas 11 and 12 are moved to change the electric field direction of the transmitted ratio wave. The reflected wave intensity in each electric field direction is stored and the buring direction is found automatically from the currents I1 and I2 with which the reflection intensity is maximum, so that the antennas need not be moved over a wide range unlike before.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is a four-purpose detection radar installation, particularly suitable for detecting the depth, size, and burial direction of tubular buried objects. This invention relates to a buried object detection radar device.

[Background of the invention]

``Ground Radar System'' (4th Child Communication Society Journal, 83/6)
, VoL J66-B, A6, p-7
13) There is power.

In this conventional example, the buried/robust probe radar device emits radio waves from the ground into J1, determines the presence or absence of the probe by the ejection of reflected waves from the sample, and detects the reflected waves from the radiation. The depth of the probe 1J body was determined by the time taken.

Figure 7 shows the +4 configuration of the conventional buried proboscis detection radar. A high frequency is oscillated at oscillation-61, and radio waves are radiated from the antenna 6 into the pond. - The reflected wave from the d accessory 7 is received again by the antenna 6 and sent to the display device 5 through the receiver 1S device (amplifier) 3. On the other hand, in the controller 4,
The time difference between transmission from oscillator 1 and reception of the reflected wave, and
Determine the depth of the buried object from the radio wave propagation speed and display it on the display.
Decide the display point on 95. Also, what about the size of the buried object and the horizontal position of the antenna? Directly in the horizontal direction, 1 was moving the target while repeating transmission and reception to find it.

Using a conventional birth chamber, the antenna was moved completely above the dot-dash point in Fig. 7, and the diameter was 30 (7) and the depth was 60 (7) in Fig. 7.
The results of exploring the conduit (displayed in binding 45) are shown in Figure 8 (b).
). In the display of FIG. 8(b), the horizontal axis indicates the horizontal position along the one-point jet line 8, and the vertical axis indicates the depth. As is clear from the figure, although the cross-sectional position and size of the conduit 7 can be obtained from 10 in the figure, it is not possible to know how the conduit 7 is buried.

In order to obtain the four installation directions of the conduit using a conventional device, Fig. 8(a)
By repeating transmission and reception with (e) on each - & line, and comparing the display results shown in Fig. 8 (b) obtained by moving on each broken line, it is determined that it is necessary to change the entire length of the burial direction. In order to obtain high accuracy in all directions, it is necessary to make the four-turn interval as shown in 8.9 of FIG.

As a method of performing such two-dimensional antenna i hyperactivity with equal constraints, there is a method of arranging a large number of antennas two-dimensionally on the ground surface and performing transmission and reception with each antenna element. Although this method does not require direct movement, there are problems such as the antenna structure becoming tired and complicated, and the antenna itself increasing in size.

Furthermore, an aperture synthesis method is used as a signal processing method for determining the position of an exploration object with high precision. This is calculated by calculating the distance between the antenna and the reflector from the time from the radio wave emission to the reception of the reflected wave, and calculating the distance between the antenna and the reflector as the antenna moves. J
This method determines the entire position of the reflector based on the changes in the reflector.

However, even in this method, the direction of burying the buried pipe is 1J.
To do this, it is necessary to transmit and receive data two-dimensionally at many points on the earth's surface. Therefore, not only does antenna movement time increase, but also a lot of processing time is required for aperture synthesis.

On the other hand, conventional buried object detection radars use one dipole antenna. However, if the angle between the vertical axis of the ball antenna and the buried pipe axis is other than 0° or 90°, there is a possibility that the reflected wave intensity will decrease and the S/N ratio will decrease.

[Purpose of the invention]

The purpose of the present invention is to easily, in a short time, investigate the depth, position, and @membrane direction of a tubular buried object. It is an object of the present invention to provide a buried object detection radar device that can perform a buried object detection radar system and obtain a high reflected wave intensity with the same electromagnetic wave output as the conventional one.

[Summary of the invention]

Hereinafter, the present invention will be explained from a fundamental point of view.

In the present invention, as shown in FIG. 2, two half-wavelength dipole antennas 11 and 12 that are perpendicular to each other are used. An alternating current 13.14 having a frequency f and having the same phase or a 180° shift is passed through the dipole antenna 11.12. The entire widths of currents 13 and 14 are assumed to be Il and I2, respectively.

The radiation pressure from one half-wave dipole antenna 12 exists only in the θ direction component in the spherical system (r, θ, ψ) with the antenna feeding part as the origin as shown in Fig. 3.
Its value can be expressed as: where: constant: wave number: die ball antenna current. That is, it has only θ dependence and no ψ dependence. Well, t. In equation (1), it can be seen that when θ→o, F is maximum at o-+o, while it is maximum at θ-90°7;).

Now, if we add 4 to the coordinate system (γ, θ, ψ) in FIG. The world is Eψ
This can be expressed as . In the end, the broadcasting world E with antennas 9 and 1o
It can be expressed as a pigeon. This shows that E in equation (3) is a direct wave, and by appropriately setting the ratio of If and 12, the direction of the electric field can be selected in any direction.

As shown in FIG. 4, this antenna/antenna 11.12t radiates radio waves into the ground so that the plane containing the antenna 11.12 is like a thousand lights on the ground surface. - When radio waves are radiated from near the top of the membrane tube 7, the electric field E on the surface of the buried tube is oriented in the horizontal direction, as can be seen from equation (3). At this time, if the angle between the radiated electric field E and the conduit axis is ψ', then so that the radiated power of the radio wave is constant, that is, (8)
The direction of the radiated electric field E, that is, by increasing the ratio eK of Il and I2 while keeping the equation 11"+h"t constant, is
It is possible to change ψ′.

Generally, the reflected wave intensity is ψ/ == o O or ψ
': Maximum at 90°. The value of ψ'-08 is maximum when the radius of the buried pipe is extremely small, and when the diameter of the buried pipe becomes large, it is maximum when ψ'=90°. This is the difference between point Q on the membrane tube 7 in Fig. 4 and E as the horizontal distance of the antenna increases.

Both E decrease, but the decreasing slope is due to the fact that Eψ is larger. In addition, the pipe radius Rs b when the reflected wave intensity changes from the maximum when the angle ψ' between the incident wave electric field E and the buried pipe axis is 0 to the maximum when ψ' = 90° is the wavelength It changes depending on λ, that is, the frequency f. At a frequency of about 300 MHz or more used for nostalgic tube exploration, the tube radius R1- of the upper 0 pi is about 15 or less, as will be described later.

Therefore, on the ground with antenna 11 and 12ffi in Fig. 4, -
It moves in a straight line and transmits and receives at many points. However, at a certain point on the ground, the dipole antenna 11.1
The ratio of 'td self-LII I Iz flowing to 2 is from 1■ to +
■ Change the direction of the transmitted radio wave completely.

From the data obtained in this way, we first determine whether there is a buried pipe or not.
and depth etc. can be obtained using the same conventional methods. 1 of these
・Since the position M of the upper part of the buried pipe is known, find the relationship between the current amplitude ratio 11:I2 of the orthogonal dipole and the reflected wave intensity S at the point M, and find Ir:Iz when S is maximum. Find the burial management installation direction from.

Using the same method as before, for example, if we find that the radius R of the four installation pipes is about 50 cW1, we can determine the direction of burying the antenna 12 from the values of Il and I2 where the reflected wave intensity is maximum. It can be seen that the direction makes an angle with

When the diameter of the conduit is smaller than h as described above, the reflected wave intensity becomes maximum when ψ'=06, and at this time, the buried direction of the conduit forms an angle with the antenna 12. It is the direction.

The reflected wave intensity is maximum at ψ/ −o O to 90
Rsh, which changes with degrees, can be determined by experiment or by direct analysis of the linear number.

Figure 5 shows the reflected wave intensity of the conduit diameter 1β for the cases where the frequency is 300 MHz, ψ′206 and ψ′=90′.
Show your existence. On the No. 24 lightning diameter of 151μ, the reflected wave intensity reaches its maximum at ψ′=90°. Also, the frequency is 500MH2
A similar characteristic for the case of is shown in Figure 6. , 4 When the pipe diameter is 1ocrr1 or more, the reflected wave intensity becomes maximum at ψ'=90'. As the frequency becomes higher, the lower limit value R&h of the pipe diameter at which the reflected wave intensity is maximum at ψ'=90° becomes smaller.

Based on the above, antenna 11.12a - while moving;
At each point, the ratio of the currents I+ and I2 is changed to change the electric field direction of the transmitted radio waves. The reflected wave intensity is memorized for each electric field direction, and the burial direction is automatically determined from the electric field KIt and I2 where the reflected wave intensity is maximum. However, at this time, the pipe radius R determined by the conventional method is R
Fully automatically f! Jm
Then, find the burial direction.

As described above, it is possible to automatically bury the antenna in the M direction ffi = "0" without having to move the antenna over a wide range, which was conventionally necessary to move the antenna in the burying direction 't-1(].

Furthermore, a conventional buried object detection radar device uses one dipole antenna. In this case, when the angle between the buried pipe axis and the antenna is other than 00 or 90', the reflected wave intensity decreases and the SZN ratio decreases, but in the present invention, the reflected wave intensity is always maximized while receiving. Therefore, the problem of the common ratio mentioned above can be solved.

[Invention's human power f! I Reli]

FIG. 1 is a block diagram of a buried proboscis detection radar device of the present invention. The transmission switching devices 15 and 16 have a function of transmitting monocycle pulses 19 and 20'Th of the oscillator 17 and a function of receiving all received waves from the dipole antenna 12. The separate controller 18 instructs the oscillation command and amplitude of the oscillator 17, as well as receiving time meter combination 'ii: 26, wave height: '1!
The calculation device 27 and the aperture synthesis device 28 perform a separate calculation of the total A-timing, etc. 1k.

Amplifiers 21 and 22 take in the received output of the transmission/reception switch 15 and 16 and linearly amplify it. Adder 23, amplifiers 21 and 22
Do the output additional money. The sampling device 24 includes an adder 2
Perform sample full 2 of the output of 3.

The waveform storage device 25 stores the waveform, the reception time tH calculation device 26 calculates the reception time, the waveform storage device 27 calculates the wave height value, the aperture synthesis processing mfi28 performs the aperture synthesis processing, and the waveform storage device 29 calculates the wave height record. , the maximum wave height value meter 'X machine 30 calculates the maximum wave height value, the burying direction calculator 31 calculates the burying direction,
The display device M32 performs display. Explain the operation.

The fundamental frequency f of the radio waves from the antenna 12 is 500MH
Set it to 2. This antenna 12 has a wavelength λ (60crrI
) has a cross dipole shape with 30 crn dipoles intersecting each other. The antenna 12 is placed horizontally with respect to the earth's flame surface.

On the transmitting side, first, the oscillator 17 transmits monocycle pulses 19.20i in response to a signal from the controller 18. The peak value aI+32 of monocycle pulse 19.20 is:
It is controlled by the signal from the 1ilJf distributor 18.

This monocycle pulse 19,20 is applied to the cross dipole antenna 12, and a wave is radiated underground.

The reception jll takes in the evil field component of the reflected wave received by the cross dipole antenna 12 via a switch 15.16, amplifies it with a linear amplifier 21.22, and then sends it to an adder 23
Add with .

This signal is sampled by the sampling device 24, and the time change of No. 1g is recorded in the waveform storage device 25.

Using this stored time-varying waveform of the signal at the receiver 1 and the timing pulse output from the controller 18 at the same time as the pulse transmission, the calculator 26 calculates the time t from transmission to reception of the reflected wave.
, (n is a subscript indicating the transmitting/receiving position)? Gives birth to one baby. after that,
The wave height value calculator 27 calculates the wave direction liMAa of the received signal.

The time t until the reflected wave is received and the peak value A are sent to the aperture forming device 28. Further, the wave height value A is stored in one device 29.

After performing the above processing, at the same transmission and reception point, the transmission pulse amplitude a! + a 2 i' a, 2 +
a22 is constant, and by changing the ratio of aI and a2, the oscillator 17
More pulses are transmitted. This is the parameter β'r4
This corresponds to the expression 0≦β≦π, where K: constant (=m). From Genpukuki 17, β is changed, but the step width Δβ of β is
, the above-mentioned peak value A is stored in all devices 29.

Time t until reception sent to the aperture synthesis device +d28,
and peak value A are one piece of data for one receiving position. After varying β from 0 to π, select the wave height from the wave height data stored in the previous section. The value β when the directivity is maximum is determined by 1530, and is stored in 30 together with the transmitting/receiving position.

The above pulse transmission and signal processing are repeated without moving the antenna 12 over the entire ground surface.

As the antenna changes, the transmitting/receiving position and β at which the received wave intensity becomes maximum at that position are stored in the storage device [30]. Further, the aperture synthesis processing device 28 stores each reception position information, the reflected wave reception time t1 at each reception position, and the wave height value A.

When the antenna movement is completed, the signal is sent from the controller 18 to the aperture synthesis processing device 28, which calculates the depth and size of the buried pipe. Further, the buried/g radius ratio and the transmission/reception position on the upper part of the four-film tube are determined, and the information is sent to the buried direction calculator 31. The position of the upper part of this buried pipe, the transmission/reception position inside the storage device, and the corresponding β are selected by the calculation system [31]. The pipe radius reference value Rab (10 crn since f = 500 MHz) described in the principle of the present invention is stored in the burial direction calculation device, and the pipe radius R obtained by opening threat processing and R+h are compared. However, in the case of Rth, a signal indicating that the antenna 12 is buried in the direction of the angle β is sent to the display device 32.

In addition, when the display device (R) R, th is used in the direction of β+90° with respect to the antenna 12, the display device (
1"Send signal to i32.

As a result, the display device 32 displays, in addition to an image showing the entire depth and size of the buried pipe due to the two-dimensional movement of the antenna.
Buried direction The gold antenna is displayed in angle with respect to Yonago.

〔Effect of the invention〕

As shown above in the examples of the present invention, existing requirements, and support,
Using the present invention, the antenna can be distributed directly over the entire ground surface (
By transmitting and receiving radio waves, it is possible to obtain not only the depth and size of buried objects, but also their direction. This is because conventional buried object detection radar equipment requires a wide range (two-dimensional) to obtain all of the above information.
This eliminates the need for antenna movement and transmission/reception, significantly reducing strain detection time and effort.

Furthermore, by changing the polarization direction of the radio waves and searching for the maximum value of the reflected angle IW, a high S/N ratio can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing a cross dipole used in the present invention, Fig. 3 is a diagram showing a coordinate system, and Fig. 14 is a diagram showing a cross dipole with the ground surface. dipole position i
Figure 1 shows the relationship. Figures 5 and 6 are diagrams showing the relationship between the reflected 7B1 intensity and tube radius, Figure 7 is a diagram showing the structure of a conventional buried object detection radar, and Figure 8 (a) is the antenna 2 transfer position. FIG. 8(b) is a diagram showing the display result when the radar was placed deep in the vE rice. 1...Pulse-1tk device, 2...Transmission/reception switch, 3.
... Receiver, 4... Sub-111 device, 5... Display device, 6... Antenna, 7... Exploration buried object, 8, 9...
・Antenna movement position, 10... Display buried object, 11.1
2...Dipole antenna, 13.14...Antenna applied current, 15.16...Transmission/reception switch, 17...
Pulse oscillator, 18...control device, 19.20...
Antenna applied pulse, 21.22...Linear amplifier, 2
3... Adder, 24... Sampling device, 25.
...Waveform storage device, 26...Reception time calculation device, 27
... Wave height calculation device, 28... Aperture synthesis processing device,
29... Wave height storage device, 3o... Maximum wave height value calculator, 31... Burying direction calculator, 32... Display device.

Claims (1)

[Claims] 1. Antenna section with mutually orthogonal dipole antennas placed parallel to the ground surface, the frequency is the same, the phase is the same or 180° shifted, and the amplitude is a_1,
Application means for applying two types of alternating current waves I_1 and I_2, which are a_2, to each dipole antenna, and causing a composite linearly polarized wave of electric fields of linearly polarized waves in each dipole antenna to be radiated from the antenna part. and receiving means for receiving reflected waves including within the ground surface with respect to the radiation waves of the composite linearly polarized waves, and AC currents I_1 and I_2.
An underground buried object exploration radar device that changes the electric field direction of the radiated linearly polarized wave by changing the amplitudes a_1 and a_2, and searches for the direction of the buried object in the ground surface from the relationship between the transmitted electric field direction and the reflected wave intensity.