JP2001027677A - Antenna for underground search radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna for an underground search radar which can search underground while moving in a narrow space. SOLUTION: An antenna body 46 with an antenna element 71 is mounted to the vicinity of an open end of a bottomed antenna housing 45 of aluminum. A supporting plate 75 having conductors 77 and 78 for earthling to prevent unnecessary radiation of electromagnetic waves is set between a bottom 57 and the antenna element 71 in a storage space 70. A balun 79 connected to the antenna element 71 is fixed in a flat posture onto the supporting plate 75, and a connector 47 is set to a side wall 58 of the antenna housing 45. A connector 126 for cable is made detachable to the connector 47 and a flexible cable 53 is connected to the connector 47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for radiating or receiving electromagnetic waves when exploring the position of a buried object such as a pipe buried in soil or in the ground including in a wall of a building. The present invention relates to an underground exploration radar antenna and an underground exploration radar using the same.

[0002]

2. Description of the Related Art FIG. 18 is a sectional view of a prior art underground survey radar antenna 31, and FIG. 19 is a simplified plan view of the prior art underground survey radar antenna 31 shown in FIG. . The bow-tie antenna main body 32 has a pair of substantially triangular conductive antenna elements 34 on the surface of a plate 33 made of a dielectric material.
Rises obliquely and is connected to the balun 36. A connector 39 is fixed to the bottom plate 38 of the aluminum antenna housing 37. The balun 36 is connected to a lower portion of the connector 39. Thus, a bowtie antenna is configured.

The electromagnetic wave from the antenna element 34 is
A magnetic body 41 such as a ferrite is fixed in the antenna housing 37 in order to remove unnecessary electromagnetic fields and prevent interference of the electromagnetic fields toward the soil below. The antenna element 34 is connected via a resistor 42 to an antenna housing 37 surrounding the outside of the antenna element 34.

In the prior art underground survey radar antenna 31 shown in FIGS. 18 and 19, a tip 35 of an antenna element 34 is raised, and a balun 36 is further placed thereon.
And the connector 39 are arranged in the upper and lower parts of FIG. Therefore, the underground exploration cannot be performed by inserting the prior art antenna 31 into a small gap. Further, the antenna housing 37
The antenna 3 is also provided by the magnetic body 41 provided therein.
1 will increase in thickness and weight.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna for an underground exploration radar capable of reducing the size and the weight thereof, and an underground exploration radar using the same. It is to provide.

[0006]

The present invention according to claim 1 comprises (a) a bottomed antenna housing made of a conductive material and having a storage space open to the soil, and (b) an antenna housing. And (c) a support plate disposed between the bottom of the antenna housing and the antenna element in the storage space of the antenna housing, wherein: an electrically insulating substrate; (D) a support plate having a grounding conductor formed on at least one surface substantially all over; and (d) the whole shape is flat, fixed to the support plate in the flat position, and one end is an antenna. An underground radar antenna comprising: a balun connected to an element; and (e) a connector fixed to a side wall of the antenna housing and connected to the other end of the balun.

According to the present invention, an antenna element 71 is arranged in the storage space 70 of the conductive antenna housing 45, for example, near the open end of the antenna housing.
In the storage space between the bottom 57 of the antenna housing and the antenna element 71, a support plate grounded by a grounding conductor is arranged. On this support plate, a flat, for example, rectangular parallelepiped balun 79 is fixed in its flat posture, so that the height of the storage space, that is, the height of the antenna housing can be reduced. Is possible.

Further, according to the present invention, the connector 47 connected to the balun is fixed to the side wall 58 of the antenna housing and is not mounted on the bottom of the antenna housing opposite to the antenna element. Can be lowered. Thus, even in a narrow space, underground exploration can be performed using the present antenna.

The present invention according to claim 2 is characterized in that the antenna element is a pair of conductors extending along an axis on a common straight line.

According to the present invention, a pair of conductors 71a1, 7a
1a2; 71b1 and 71b2 extend with an axis on a common straight line 72, thereby constituting an antenna element. One end of these conductors close to each other is used as a feeding point, and a transmission signal is sent to this feeding point. Then, an electromagnetic wave is generated, and a reflected wave reflected by an underground object, for example, a pipe or the like is received by the antenna, and is output as a reception signal from the feeding point. An antenna having such a configuration is
It has a relatively wide band, excellent directivity, and prevents interference between the conductor, the antenna housing, and the grounding conductor of the support plate, and reduces the adverse effects of electromagnetic fields reflected on the side opposite to the concealed portion such as soil. , Can be suppressed. This antenna has a simple configuration, is easy to manufacture, and can achieve excellent effects such as miniaturization, and the obtained reception signal does not include a vibration waveform,
Ringing can be sufficiently suppressed. Further, in connection with the bow tie antenna, the magnetic material such as the ferrite described in FIGS. 18 and 19 is not required, the radiation of unnecessary electromagnetic waves is suppressed, an unwanted electronic circuit is removed, and the conductor and the antenna housing are connected to each other. Can be prevented from interfering with electromagnetic waves.

According to a third aspect of the present invention, there is provided the underground survey radar antenna according to the first or second aspect, a handle attached to the antenna housing, a flexible cable, and one end of the cable, the connector being connected to the connector. A cable connector that can be attached to and detached from the cable, connected to the other end of the cable, generates a transmission signal, generates electromagnetic waves toward the soil, drives the antenna for underground survey radar, and And an arithmetic processing means for receiving and performing arithmetic processing.

According to the present invention, the aforementioned underground radar antenna 44 is used as a transmitting and receiving antenna,
An electromagnetic wave is generated from the antenna toward the soil, a reflected wave from an underground object is received, and a transmission signal is given to the antenna in this way. Can detect the position of an underground object, for example, the distance from the ground surface and the distance from the antenna, and further, based on the distance and the output of the antenna movement position detection means for detecting the position where the antenna has moved, determine It is also possible to detect the three-dimensional position of the buried object.

The underground radar can be used as a transmitting antenna and a receiving antenna. Although the transmitting antenna and the receiving antenna may be separated from each other, a single antenna may be switched and used by a switching circuit, or a single antenna may be used by using a directional coupler, a bridge, or the like. Transmission and reception may be performed by the

Further, according to the present invention, a detachable flexible cable is connected to the connector, so that a small underground survey radar antenna is used to perform movement for underground survey in a narrow space. Can be.

[0015]

FIG. 1 is a side view of an antenna 44 for an underground survey radar according to an embodiment of the present invention. The antenna 44 basically includes an antenna housing 45 and an antenna body 46 attached to a lower portion of the antenna housing 45, and a connector 47 is fixed to the antenna housing 45.

FIG. 2 is a cross-sectional view showing a state where an underground exploration is performed using the antenna 44. In a state where the antenna body 46 is arranged facing the soil 48 including the wall of the building, the antenna body 46 is moved and scanned in a relatively narrow work space 49, and the soil 48 is scanned.
Underground buried object, for example, the pipe 50 can be detected. A base end 52 of a handle 51 is fixed to the antenna 44, and an operator grasps the handle 51 by hand and moves the antenna 44 in the work space 49 to perform scanning. A flexible cable 53 is detachably connected to the connector 47 by a cable connector 126, and is connected to the arithmetic processing means 54. Thus, underground exploration can be performed. The space 49 is formed between the soil 48 and an obstacle 55 such as a fence, and has a height h1 of the space 49.
Is relatively small, but can be scanned by the antenna 44 of the present invention.

FIG. 3 is a front view of the antenna 44 for the underground survey radar. In this embodiment, the antenna 44 for underground exploration radar includes a transmitting antenna 44a and a receiving antenna 4a.
4b. In the following description, the suffixes “a” and “b” of reference numerals may be omitted, and may be collectively indicated only by numerals.
An electromagnetic wave is generated from the transmitting antenna 44a to the soil 48, and the reflected wave reflected by the tube 50 is received by the receiving antenna 44b.
And the like can be detected.

FIG. 4 is a sectional view taken along section line IV-IV in FIG. 1, and FIG. 5 is a sectional view taken along section line VV in FIG. The antenna housing 45 includes a housing body 56 and a bottom 57, and is made of a conductive material, for example, a metal such as aluminum. Antenna housing 4
5 has a substantially rectangular parallelepiped shape as a whole. The housing main body 56 includes a pair of long side walls 58 and 59, a total of three short side walls 61, 62 and 63, and a height direction (FIG. 1).
Mounting seats 64 and 65 formed at the corners at the upper end, which is one end of the upper and lower sides (up and down directions). At the upper end of the housing body 56, a rectangular flat bottom plate 57 is
By this, it is detachably fixed to the housing body 56.

The antenna main body 46 includes a housing main body 56.
, That is, in the present embodiment, near the open end at the lower end in FIG. The antenna body 46 basically includes a dielectric plate 68 made of a synthetic resin such as polycarbonate, and an antenna element 7 provided in a storage space 70 of the plate 68.
1 is included. The antenna element 71 includes a conductor 71 a such as a metal foil such as copper printed on the surface of the plate 68.
1, 71a2; 71b1, 71b2 are configured to extend with axes on common straight lines 72a, 72b extending left and right in FIG. Conductors 71a1, 71a2; 71b1, 7
The mutually separated ends of 1b2 are electrically connected to the housing main body 56 via the resistors 73 and 74.

Each storage space 70 of the antenna housing 45
Inside, between the bottom 57 and the antenna body 46, the support plate 7
5 are arranged.

FIG. 6 is a cross-sectional view showing a part of the support plate 75a. The support plate 75a is formed on at least one surface of a substrate 76a made of an electrically insulating material such as a synthetic resin, for example, in this embodiment, on both upper and lower surfaces of FIG. , 78. Antenna body 4 on substrate 76a of support plate 75a
On the surface opposite to 6a, that is, the surface on the bottom 57 side,
A substantially rectangular parallelepiped balun 79 having a flat overall shape is arranged.

FIG. 7 is a plan view of the balun 79a, and FIG.
Is a side view of the balun 79a. Balun 79a is
The first to third terminals p are provided on a pair of opposing side walls 82 and 83, respectively.
1 to p3 and fourth to sixth terminals p4 to p6 are provided to protrude, respectively. Between the first and second terminals p1 and p2,
A central third terminal p3 is arranged. A sixth terminal p6 is arranged at the center between the fourth and fifth terminals p4 and p5. The length L2 and the width W2 between the side walls 82 and 83 of the covering member 81 are:
The value exceeds the thickness d2 (L2> d2, W2> d
2). The balun 79a is disposed in a flat posture on the support plate 75a, that is, protrudes from the grounding conductor 77 by a small thickness d2. First, second and sixth terminals p1, p
2 and p6 are soldered to and electrically connected to the grounding conductor 77, whereby the balun 79a is connected to the grounding conductor 7
7, and is therefore fixed to the support plate 75a. Third terminal p
3 is connected to the strip line 85 separated from the grounding conductor 77 by soldering.

The fourth and fifth terminals p4 and p5 pass through the through holes 88 and 89 formed in the substrate 76a from the through holes 86 and 87 where no grounding conductor 77 is formed. 4th
In the vicinity of the insertion hole 88 through which the terminal p4 is inserted, a through hole 90 is formed in the other grounding conductor 78, and the same applies to the other fifth terminal p5. The fourth terminal p4 is connected to one conductor 71a2 of the antenna element 71a at a connection point 91, and the fifth terminal p5 is connected to the other conductor 71a1 at a connection point 92. These connection points 91 and 92 are connected to the conductors 71a2 and 7
1a1 are arranged near the mutually adjacent ends.

FIG. 9 is an example of an electrical configuration of the balun 79a. The electrically coupled coils 94, 95,
96 is connected to the above-described first to sixth terminals p1 to p6. The balun has an input 50Ω unbalance and an output 200Ω balance, and is used, for example, at 750 kHz to 1.5 GHz.

Referring to FIG. 5, a connector 47a includes a right cylindrical outer conductor 98, a right cylindrical inner conductor 99 coaxial with the outer conductor 98, and a space between the outer conductor 98 and the inner conductor 99. And a flange 101 fixed to the outer conductor 98 is fixed to and electrically connected to the long side wall 58 of the housing main body 56. The inner conductor 99 is electrically connected to the strip line 85 by soldering with the conductor 102.
When the antenna housing is small or the third terminal p3 is sufficiently long, the strip line 85 is not necessarily required. That is, p3 may be directly connected to the conductor 102.

FIG. 10 is a partially exploded perspective view showing a state in which the support plate 75a is attached to the housing main body 56. The grounding conductors 77 and 78 on both surfaces of the support plate 75a
Electrical connection is ensured by the soldering of No. 04. A bolt insertion hole 106 is formed in the support plate 75a, and the bolt 107 is removably screwed into a screw hole 108 formed in the mounting seat 64 through the bolt insertion hole 106. As a result, the grounding conductor 77 is electrically connected to the mounting seat 64, and thus to the housing body 56, and the grounding conductor 78 is connected via the conductor 104 to the bolt 107.
Is electrically connected to the mounting seat 64 via

Another antenna element 71b has a configuration similar to that of the above-described antenna element 71a.

FIG. 11 is a block diagram showing the overall electrical configuration of the underground search radar 11 using the underground search radar antenna 44 shown in FIGS. On the ground,
In order to probe the tube 50, electromagnetic waves are emitted from the transmitting antenna 46a toward the soil 48 as indicated by the reference numeral 14. Electromagnetic wave 1 radiated from transmitting antenna 46a
4 is reflected by the tube 50, and the reflected wave 15 is received by the receiving antenna 46b.

The arithmetic processing means 109 includes a transmitting circuit 16, a receiving circuit 17, a processing circuit 18, a display means 21, and an input means 2.
2 and a memory 23.

The transmission antenna 46a receives signals from the transmission circuit 16 at, for example, 100 MHz to 700 MHz in FIG.
A pulse transmission signal having the waveform shown in (1) is provided. The reception antenna 46b derives a reception signal that is a reflected wave from the tube 13 shown in FIG. FIG. 12 (1) from the transmitting antenna 46a.
The time difference ΔW between the emission of the electromagnetic wave shown in FIG. 2 and the reception signal shown in FIG. 12B by the receiving antenna 46 b corresponds to the distance of the tube 50 from the antenna 1. Therefore, it corresponds to the depth of the tube 50 of the soil 48. The processing circuit 18 calculates the time difference ΔW. By moving the moving body 19 on the ground surface of the soil 48 as indicated by the arrow 20 and traversing the pipe 50 at the ground surface, an original image of a cross section of the soil 48 including the pipe 50 in the vertical plane is obtained. And can be displayed on the display means 21.

The display means 21 is realized by, for example, a liquid crystal or a cathode ray tube. Input means 22 such as a keyboard is connected to the processing circuit 18, and a memory 23 for storing the images and the like is connected. The moving body 19 may be provided with wheels, and can travel on the ground surface of the soil 48. By measuring the moving amount of the moving body 19 by the moving distance measuring means and detecting the depth of the pipe 50 at each moving position, a sectional image of the soil 48 can be obtained.

FIG. 13 is a sectional view showing an experiment conducted by the present inventor. The antenna 44 for underground exploration radar is
Immersed in water 111 inside. Antenna 11 with arrow 11
When moving to the side wall 113 as shown in FIG.
The distance between the two was measured.

FIG. 14 is a diagram showing the results of an experiment conducted on the antenna 44 for underground exploration radar of the present invention using the experimental apparatus shown in FIG. In FIG. 14A, the distance between the antenna 44 and the side wall 113 is a distance D1 to a distance D.
When changing between the two, an image was obtained by the display means corresponding to that distance. The image of the antenna 44 according to the present invention is relatively clear. On the other hand, in the prior art shown in FIGS. 18 and 19, a similar experiment was performed with reference to FIG.
Image was obtained.

FIG. 15 is a waveform diagram showing waveforms cut out from the time portion near the direct wave from the image of the present inventor in FIG. When an electromagnetic wave is given to the antenna 44 and received, an electric signal obtained from the antenna 44 is
It has the waveform shown in FIG. As a result, according to the antenna 44 of the present invention, it was confirmed that the overshoot 116 and the undershoot 117 immediately after signal reception were relatively small. On the other hand, FIG.
In the prior art shown in FIG. 19 and FIG.
Have a relatively large amplitude and cause ringing.
Such ringing did not occur in the antenna 44 of the present invention. Thus, it was confirmed that the use of the antenna 44 of the present invention allows an embedded object to be accurately detected.

FIG. 16 is a plan view of a balun 121 according to still another embodiment of the present invention. This balun 121 is
It can be used instead of the balun 79 described above.

FIG. 17 shows the balun 121 shown in FIG.
FIG. 3 is a diagram showing an electrical configuration of the embodiment. Electromagnetically coupled coil 1
22 and 123 are connected to first to sixth terminals p1 to p6.

[0037]

According to the first aspect of the present invention, the antenna element is disposed, for example, near the open end of the conductive antenna housing, and between the bottom of the antenna housing and the antenna element in the storage space of the antenna housing. A support plate with a grounding conductor that removes unnecessary electromagnetic fields and prevents electromagnetic wave interference is arranged, and a balun with a flat overall shape is fixed to this support plate in its flat attitude, that is, the balun is supported. The antenna housing can be lowered, thinned, and thinned along the board in a state of lying down.

Further, according to the present invention, the connector is fixed to the side wall of the antenna housing, and is not fixed to the bottom of the antenna housing. The entire configuration of the radar antenna can be reduced in thickness. Thus, a small underground radar antenna is realized. Therefore, the antenna of the present invention can be easily inserted and moved in a narrow space to perform an underground exploration operation.

According to the second aspect of the present invention, since the antenna element is composed of a pair of conductors having an axis on a common straight line, the antenna element has a wide band, is excellent in directivity, and is described in relation to the prior art. An antenna for an underground exploration radar that can reduce the size of the configuration compared to a bow-tie antenna and suppress the generation of undesired electromagnetic waves without requiring a magnetic material such as ferrite is realized. . Furthermore, the ringing of the reflected wave can be suppressed,
As a result, the resolution of the underground object can be improved.

According to the third aspect of the present invention, underground exploration can be performed by using a small underground exploration radar antenna, so that the present antenna is arranged and moved in a narrow space,
Exploration of buried objects such as underground can be performed. Since a flexible cable is detachably connected to the connector of the antenna for underground exploration radar by the cable connector, the antenna and the arithmetic processing means are connected via the flexible cable to perform the underground exploration. The operation of moving the antenna can be performed, and the weight of the antenna to be moved can be reduced. The flexible cable is detached from the antenna housing by the cable connector, so that it is easy to carry, and when the present antenna breaks down, it can be used by replacing it with a new antenna, and the operability is good.

[Brief description of the drawings]

FIG. 1 is a side view of an antenna 44 for an underground survey radar according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state where an underground exploration is performed using an antenna 44.

FIG. 3 is a front view of an antenna 44 for an underground radar.

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1;

FIG. 5 is a cross-sectional view taken along the line VV of FIG. 1;

FIG. 6 is a cross-sectional view showing a part of a support plate 75a, which is cut away.

FIG. 7 is a plan view of the balun 79a.

FIG. 8 is a side view of the balun 79a.

FIG. 9 is a diagram showing an electrical configuration of a balun 79a.

FIG. 10 is a partial exploded perspective view showing a state in which a support plate 75a is attached to a housing body 56.

11 is a block diagram showing an overall electrical configuration of the underground search radar 11 using the underground search radar antenna 44 shown in FIGS.

FIG. 12 is a waveform chart for explaining the operation of the underground search radar 11.

FIG. 13 is a cross-sectional view showing an experiment performed by the present inventor.

14 is a diagram showing the results of an experiment conducted on the underground radar radar antenna 44 of the present invention using the experimental device shown in FIG.

FIG. 15 is a waveform chart showing an experimental result when using the device shown in FIG. 13 of the present inventor.

FIG. 16 shows a balun 12 according to still another embodiment of the present invention.
1 is a plan view of FIG.

FIG. 17 is a diagram showing an electrical configuration of the balun 121 shown in FIG.

FIG. 18 is a cross-sectional view of a prior art underground radar radar 31;

FIG. 19 is a simplified plan view of the prior art underground radar antenna 31 shown in FIG.

[Explanation of symbols]

 44 Antenna for underground exploration radar 45 Antenna housing 46 Antenna body 47 Connector 48 Soil 49 Working space 50 Tube 56 Housing body 57 Bottom plate 66, 67 Bolt 68 Dielectric plate 70 Storage space 71 Antenna element 73, 74 Resistance 75 Support plate 77,78 Grounding conductor 79 Balun 81 Coating member 85 Strip line 86,87,90 Through hole 98 Outer conductor 99 Inner conductor

Claims (3)

[Claims] (1) an antenna housing having a bottom that is made of a conductive material and has a storage space open to the soil, and (b) an antenna element disposed in the storage space of the antenna housing. c) A support plate disposed between the bottom of the antenna housing and the antenna element in the storage space of the antenna housing, the support plate being formed on substantially the entire surface of at least one of the surfaces of the electrically insulating substrate and the substrate. A support plate having a grounding conductor; (d) a balun having a flat overall shape, fixed to the support plate in the flat position, and one end connected to the antenna element; and (e) an antenna housing. And a connector to which the other end of the balun is connected, the antenna being used for an underground exploration radar. 2. The antenna for underground survey radar according to claim 1, wherein the antenna element is a pair of conductors extending along an axis on a common straight line. 3. An underground radar antenna according to claim 1 or 2, a handle attached to the antenna housing, a flexible cable, and a cable connector connected to one end of the cable and detachable from the connector. And connected to the other end of the cable to generate a transmission signal, generate electromagnetic waves toward the soil, drive the antenna for underground survey radar, and receive and process the received signal of the reflected wave. And a processing means.