JP2702866B2 - Antenna device for radar search - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device for radar search used when searching for a buried object using an underground radar.

[0002]

2. Description of the Related Art Underground radar systems using the electromagnetic wave reflection method have already been put into practical use for exploring underground buried objects and cavities, and exploring the surface layer of ice, snow, and the like. It is also being applied to geological surveys on continuous surfaces and groundwater, and applications are increasing.

[0003] In the shield method, a method for exploring a face in front of the face using the radar has been developed, and the system is capable of exploring a pile or a buried tree in front of the shield machine while excavating. In this case, since the transmitting / receiving antenna is in close contact with the soil layer on the front of the machine, the coupling loss with the search surface is small.

[0004]

When the coupling loss between the transmission / reception antenna and the search surface is small, that is, when the search surface has a small unevenness, the conventional radar search method can cope with the problem, but the search surface has unevenness (unevenness). In the case of rocks with large rocks, reflection of electromagnetic waves occurs on the surface of the rocks, so that the intensity of electromagnetic waves penetrating through the rocks and penetrating into the rocks becomes small, so that there is a problem that the depth of search is shallow and the search performance is reduced.

[0005] Therefore, as a method for preventing the decrease in the search depth and improving or maintaining the search performance, it has been considered to increase the transmission output of the electromagnetic wave, lower the frequency of the electromagnetic wave, and the like. However, this method has various restrictions when used in an urban area or the like due to the regulation of the Radio Law. In addition, the method (1) has disadvantages in that the size of the antenna for transmitting and receiving electromagnetic waves becomes large and workability is deteriorated, and that the resolution is reduced because the wavelength is long. Therefore, these methods cannot be said to be solutions for improving the search performance. In addition, a method that can secure the search depth and increase the search performance has been desired.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a radar search antenna device capable of improving the search performance by increasing the search depth. It is in.

[0007]

In order to solve the above-mentioned problems, a radar search antenna device of the present invention transmits a radar search electromagnetic wave toward a search area in which an object to be searched is embedded. A receiving antenna for receiving a reflected wave from the object to be detected with respect to an electromagnetic wave transmitted from the transmitting antenna; and a relative permittivity provided between the transmitting antenna and the receiving antenna and the search surface are the same as the search area. And compressed along the irregularities of the exploration area
And a flexible member having a deformable volume shape . 2. The flexible member according to claim 1,
Is a non-foamed urethane resin. Further
And the flexible member according to any one of claims 1 and 2.
Has a relative dielectric constant of 4 to 10.

The antenna device for radar search according to the present invention comprises:
Between the transmitting and receiving antennas and the exploration area in which the object is buried , compress along the irregularities of the exploration area.
It is configured with a flexible member having a deformable volume shape interposed, and the electromagnetic wave transmitted from the transmission antenna is propagated to the search area in which the object to be searched is buried via the flexible member. Further, the electromagnetic wave reflected by the buried object is propagated to the receiving antenna via the flexible member.

Moreover, when this flexible member is pressed against the exploration region in which the object to be inspected is buried, it is compressed along the uneven shape of its surface, so that no air layer is formed near the boundary. In close contact. Since the relative permittivity of this flexible member is substantially equal to that of the exploration region and is substantially equal to the relative permittivity of general rock, electromagnetic waves are transmitted from the flexible member to the exploration region in which the object to be detected is embedded. Can be minimized when the reflected wave enters the flexible member from the exploration region where the object is buried or from the exploration region where the object to be explored is buried.

The flexible member is preferably non-foamed and homogeneous, and the electromagnetic wave is reflected and reflected inside the flexible member.
There is no scattering.

As described above, according to the present invention, the relative permittivity of the transmitting and receiving antennas on the transmitting and receiving sides of the electromagnetic waves is substantially the same as that of the search area, and along the irregularities of the search area.
By providing a flexible member having a volume shape that undergoes compressive deformation, the search depth in the search area in which the object to be searched is buried can be increased without lowering the resolution, and the search performance can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. (1) Configuration of Embodiment FIG. 1 is a perspective view showing the entire configuration of a radar search antenna device according to an embodiment of the present invention.

Referring to FIG. 1, an antenna device according to the present embodiment includes a transmitting antenna 10 for transmitting a predetermined electromagnetic wave for radar search, a receiving antenna 20 for receiving a reflected wave from an object to be searched, a transmitting antenna 10 and a receiving antenna. Antenna 20
A transmission cable 12 and a reception cable 22 connected to
F holding transmission antenna 10 and reception antenna 20
It is configured to include the RP jig 40 and the non-foamed urethane resin 30 provided on the transmitting / receiving side of the electromagnetic wave.

The transmission antenna 10 converts an electric signal input through the transmission cable 12 into a predetermined electromagnetic wave and outputs the electromagnetic wave. The electromagnetic wave is transmitted only to the non-foamed urethane resin 30 shown in FIG. Output.
For example, the electromagnetic wave to be transmitted may be a continuous wave method using a continuous sinusoidal electromagnetic wave or an impulse method using an electromagnetic wave of a predetermined frequency repeatedly transmitted at predetermined intervals. In the case of electromagnetic waves transmitted at predetermined intervals, the center frequency is set to be a predetermined frequency.

The receiving antenna 20 is for receiving a reflected wave from an object to be searched embedded in a search area such as a rock. In the present embodiment, the transmitting antenna 10 and the receiving antenna 20 are arranged adjacent to each other in the FRP jig 40. However, when analyzing rock or the like by surface propagating waves, the transmitting antenna 10 and the The installation position of the antenna 20 may be kept away.

The FRP jig 40 serves as a housing for holding the transmitting antenna 10 and the receiving antenna 20 as described above. Transmission antenna 1
Metals such as stainless steel and other materials may be used as long as they can fix 0 or the like.

The non-foamed urethane resin 30 has a dielectric constant ε _s substantially equal to the relative dielectric constant of general rock, and has a homogeneous composition. Specifically, the relative permittivity ε _s is in the range of 4 to 10.

The non-foamed urethane resin 30 is made of, for example, 2
This is a liquid-reactive urethane gel system in which a polyol component and a polyisocyanate component are reacted.
By reacting and curing each of these components, a gel with high elasticity and tackiness can be obtained. Has the characteristic that appears.

The polyol component is colorless and transparent in appearance, and has a viscosity at 20 ° C. of 70 to 80 cps, 60 cps.
It has a characteristic of a viscosity at 20 ° C. of 20 to 30 cps. The polyisocyanate component is light yellow and transparent in appearance, and has a property that the viscosity at 20 ° C. is 6000 cps and the viscosity at 60 ° C. is 2500 cps. Such a polyol component and a polyisocyanate component are mixed and stirred so as to have a mixing ratio of 100: 33 (weight ratio). The liquid temperature at the start of stirring is 60 ° C, and the curing temperature is room temperature (20 to 25).
C), it has a characteristic that it can be used 10 to 15 minutes after stirring and cures after 12 to 15 hours. In addition, the urethane gel system can change the compressibility and the relative dielectric constant 調整_s by adjusting additives to be added in addition to the above-mentioned two components.

FIG. 2 is a diagram showing a state in which the antenna device shown in FIG. The storage case 50 serves to protect the transmission antenna 10 and the reception antenna 20 and also functions as a water stop box. The antenna device integrated with the storage case 50 is mounted on a search cart or the like (not shown) by a mounting jig 52 shown in FIG. (2) Operation of Embodiment Next, the operation of the antenna device of this embodiment having the above-described configuration will be described. For example, the present antenna device is used for exploration in front of a face, which is an excavation surface of a tunnel, but can also search the underground from the ground surface.

FIG. 3 is a view showing a state in which the antenna device shown in FIG. 1 is pressed against a rock 60, and shows a state in which the antenna device shown in FIG. 1 is viewed from a lateral direction. When exploring a buried object in the bedrock 60, the front surface 32 of the non-foamed urethane resin 30 is entirely covered with the bedrock 6 as shown in FIG.
The antenna device is installed so as to be crimped on the surface of No. 0. Since the non-foamed urethane resin 30 is flexible and can be arbitrarily compressed, the shape of the front surface 32 of the non-foamed urethane resin 30 is deformed along the unevenness of the surface of the bedrock 60. Therefore, the non-foamed urethane resin 30 and the bedrock 60 adhere to each other without forming an air layer near the boundary.

FIG. 4 shows that the non-foamed urethane resin 30 of the antenna device is brought into close contact with the bedrock 60 as shown in FIG.
FIG. 2 is a diagram schematically illustrating a case of searching for a buried object by transmitting and receiving electromagnetic waves, and shows a state in which the antenna device illustrated in FIG. 1 is viewed from above. As an embedded object in the bedrock 60, for example, a steel pipe 62 is considered.

As shown in FIG. 4, the electromagnetic wave transmitted from the transmitting antenna 10 propagates through the non-foamed urethane resin 30 and then enters the rock 60 and is reflected by the steel pipe 62. The reflected wave from the steel pipe 62 propagates in the rock 60,
Receiving antenna 20 after penetrating into non-foamed urethane resin 30
To reach. Generally, the distance from the surface of the rock 60 to the steel pipe 62 can be analyzed by measuring the time delay of the electromagnetic waves transmitted and received in this manner. That is,
By analyzing the electromagnetic waves transmitted and received in this manner, the presence or absence and the position of the buried object (the steel pipe 62 in this case) in the rock 60 can be known.

Further, by bringing the non-foamed urethane resin 30 into close contact with the bedrock 60 as described above, it is possible to minimize the coupling loss between the transmitting / receiving antenna and the search surface. That is, the relative permittivity of the bedrock 60 is in the same range of 4 to 10 as that of general rock, while the non-foamed urethane resin 3
Since the relative permittivity ε _{s of} 0 is also in this range, when the electromagnetic wave passes through the boundary surface between the non-foamed urethane resin 30 and the bedrock 60, there is no sharp difference in the relative permittivity. Therefore, the reflection of the electromagnetic wave from the boundary surface of the rock 60 can be minimized (the relationship between the relative permittivity and the reflection will be described later). Further, since the non-foamed urethane resin 30 is made of a homogeneous material, unnecessary reflection and scattering do not occur inside the urethane resin 30.

As described above, when the antenna device of the present embodiment is used, the reflection on the surface of the rock 60 can be minimized, so that the intensity of the electromagnetic wave transmitted through the rock 60 can be increased. . Therefore, the depth at which the electromagnetic waves reach becomes deep, and the search performance can be improved. In addition, since the exploration performance is improved without changing the intensity and frequency of the electromagnetic wave to be transmitted, there are no inconveniences such as being stipulated by the Radio Law, increasing the size of the antenna, and lowering the resolution. (3) Verification of Example, etc. Relation between Relative Dielectric Constant and Reflection Intensity and Transmission Intensity Next, how the electromagnetic wave output from the transmitting antenna 10 is reflected and transmitted at the interface between layers having different relative dielectric constants is described. explain.

FIG. 5 is a schematic diagram for explaining the reflection and transmission of electromagnetic waves, in which a medium A corresponds to a layer on the side where electromagnetic waves are incident, and a medium B corresponds to a layer on the side where electromagnetic waves pass. doing. The relative permittivity of the medium A is ε ₁ , and the relative permittivity of the medium is ε ₂ .

As shown in the figure, when an electromagnetic wave penetrates perpendicularly to the boundary between two different media, the reflection coefficient R and the transmission coefficient T of the electromagnetic wave at the boundary surface of the electromagnetic wave are expressed by the following equations (1) and (2). It is.

(Equation 1)

(Equation 2) Therefore, the dielectric constant of the dielectric constant epsilon ₁ and the medium B of the medium A epsilon ₂
Are equal to each other, the reflection coefficient R =
0 and the transmission coefficient T = 1. That is, electromagnetic waves are not reflected between layers having the same relative permittivity, but all are transmitted.

In the above-described antenna device of this embodiment, the non-foamed urethane resin 30 corresponds to the medium A, and the bedrock 60 corresponds to the medium B. In addition, since the relative dielectric constant of the non-foamed urethane resin 30 is substantially equal to the relative dielectric constant of the rock 60 composed of general rocks, the reflection coefficient R approaches 0, and conversely, the transmission coefficient. T approaches 1. Therefore, when the electromagnetic wave output from the transmitting antenna 10 enters the bedrock 60 via the non-foamed urethane resin 30, it is transmitted with almost no reflection. Similarly, when the reflected wave from the steel pipe 62 in the bedrock 60 enters the non-foamed urethane resin 30 from the bedrock 60, almost all of the wave passes through and the receiving antenna 3
Reach 0.

Measurement of Electric Constants of Non-Foamed Urethane Resin Next, by measuring electric constants of the non-foamed urethane resin 30, the attenuation characteristics of electromagnetic waves in the non-foamed urethane resin 30 will be examined.

In general, the electrical characteristics of a certain medium have a dielectric constant ε
(F / m), conductivity σ (S / m), magnetic permeability μ (H / m)
Is determined. When the electromagnetic wave having the frequency f propagates through the medium by the distance r, the intensity of the electromagnetic wave is attenuated by exp (-αr). Here, the propagation constant γ = α + jβ, wherein the attenuation constant α and the phase shift constant β are represented by the following equation (3).
And by Equation 4.

(Equation 3)

(Equation 4) Here, ω is an angular frequency, and ω = 2πf between ω and f.
There is a relationship.

Further, the propagation velocity v of the electromagnetic wave in the medium
Is

(Equation 5) It can be seen that the propagation characteristics differ depending on the electrical characteristics of the medium and the frequency f.

Next, the respective electric constants used in the above formulas 1, 2 and 3 will be considered.

The relative dielectric constant ε _s of a certain substance is a value indicating how many times the capacitance C of a capacitor having the same shape becomes larger than that in a vacuum case. Assuming that the capacitance when the space between the parallel plate capacitors is in a vacuum is C ₀ (F) and the capacitance when a certain substance is filled is C (F), C ₀ = ε ₀ S / d. Become.

Here, S is the area of the plate electrode, and d is the distance between the plate electrodes.

Substituting the relationship of ε = ε _s ε _{0 into} the above equation gives C = ε _s ε ₀ S / d.

Therefore, the relative dielectric constant ε _s becomes ε _s = C / C ₀ , and the relative dielectric constant ε _s can be calculated by measuring C and C ₀ with an LCZ meter.

The calculation of the conductivity σ is performed by measuring the specific resistivity ρ,
It can be obtained using the relational expression σ = 1 / ρ.

Assuming that a voltage V is applied to a conductor having a length L and a cross-sectional area S and a current i is flowing, the current density is i / S and the voltage per unit length is V / L. In this case, the ratio between the voltage (V / L) and the current density (i / S) is defined as the specific resistivity ρ. Therefore, the specific resistivity ρ is expressed by the following equation.

Ρ = (V / L) / (i / S) = (V / i) · (S / L) Here, since (V / i) is the resistance R of the conductor, ρ = R · ( S / L). When the conductance G and σ (= 1 / ρ), which are the reciprocals of the resistance R, are used, σ = G · (L / S). Therefore, the conductivity σ can be calculated by measuring the resistance R or the conductance G with an LCZ meter.

FIG. 6 is a diagram showing the measurement results and the calculation results of the above-mentioned electric constants obtained for the non-foamed urethane resin 30 of the present embodiment. FIG. FIG. 3B shows the case of a small hard urethane and the case of a soft urethane having a relatively high compression ratio. In this measurement, a copper plate having a diameter of 50 mm was used as the flat electrode, and the distance d between the parallel electrodes was 5 mm.
0 mm. FIG. 7 shows, for comparison, the measurement results and calculation results of the respective electric constants described above for air and tap water.

When the electrical characteristics calculated based on these measurement results are substituted into the above-mentioned equations (3), (4) and (5) to study the damping characteristics, it is found that in the case of hard urethane, ω = 2πf = 2π × 10 ⁶ (Hz, f = 1 M / Hz) ε = ε _s ε ₀ = 6.08 × 8.854 × 10 ⁻¹² = 5.38 × 10 ⁻¹¹ (F / m) μ = μ ₀ = 1.257 × 10 ⁻⁶ (H / m) σ = 12.0 × 10 ⁻⁶ (S / m) Substituting these into Equation 3 results in α = 9.167 × 10 ⁻⁴ . Substituting this value into the expression exp (−αr) gives
The damping ratio of purely hard urethane (non-foamed urethane resin 30) alone is 9% of the transmitted strength, given that r = 10 m.
Decays to 9.1%. When the same calculation is performed using the respective values shown in FIG. 7B, it can be seen that the attenuation rate of pure tap water alone is 10 m and greatly attenuates to 4.5%.

When the non-foamed urethane resin 30 made of hard urethane is used as described above, the electromagnetic wave transmitted through the bedrock 60 is hardly affected because the non-foamed urethane resin 30 itself has a small attenuation of electromagnetic waves. Absent.

When the phase shift constant β and the propagation velocity v of the hard urethane are determined by the equations (4) and (5), β = 0.0517 v = 1.22 × 10 ⁸ (m / sec) This value is obtained by the approximate expression v = C ₀ / ε _s ^1/2 = 1.2
The result is the same as the result of 2 × 10 ⁸ (m / sec).

For reference, in tap water, β = 0.345,
Although v = 0.18 × 10 ⁸ (m / sec), v = 0.42 × 10 ^{8 in} the approximate expression. This is because the effect of the term (σ / ωε) in Equation 5 is large because the conductivity of tap water is large.

Similarly, when calculation is performed for soft urethane, α = 7.373 × 10 ⁻⁴ β = 0.000643 v = 0.98 × 10 ⁸ (m / sec) By substituting this value of α into the expression of exp (−αr), the attenuation rate of pure soft urethane alone is 10 m, and 9
Decays to 9.3%. It can be seen that almost no attenuation occurs as in the case of hard urethane.

As described above, as a result of examining the case where the non-foamed urethane resin 30 is formed of hard or soft urethane, it becomes clear that the attenuation rate is small, and the transmission / reception antennas 10 and 20 transmit the electromagnetic wave to the transmission / reception side. Even when the urethane foam resin 30 is provided, the intensity of the electromagnetic wave is hardly affected. As for the measurement result of the relative permittivity, the case of hard urethane was ε _s
= 6.08, ε _s = 9.40 in the case of soft urethane (both at f = 1 MHz), and these values are
It can be seen that the relative permittivity of general rocks constituting 0 falls within the range of 4 to 10.

Difference in Received Intensity Due to Presence or Absence of Non-foamed Urethane Resin Next, a description will be given of a result of actually measuring the received strength in the case where the non-foamed urethane resin 30 is present and in the case where it is not.

FIG. 8 is a diagram schematically showing an experimental apparatus used for measuring the reception intensity. This figure shows a configuration for measuring how the reception intensity changes depending on the presence or absence of the non-foamed urethane resin 30 when electromagnetic waves are reflected by the steel pipe 72 in the water tank 70. In the figure, A1 =
1.1 m, A2 = 0.1 m, A3 = 1 m, and the antenna device is disposed on the left side of the water tank.

FIG. 9 (A) shows an example in which the electromagnetic wave (f = 35) is transmitted from the antenna device located at the left end in the configuration shown in FIG.
0 MHz) and observed received waves. FIG. 9A shows the results of an experiment performed on the antenna device of the present embodiment shown in FIG. 1 with the non-foamed urethane resin 30 removed. The horizontal axis indicates the normalized time, which is obtained by converting the time at which the reflected wave is actually observed to an appropriate scale. The vertical axis indicates the reception intensity of the electromagnetic wave, and the reception intensity is represented by a voltage value.

In the figure, R1 is a surface propagation wave directly transmitted and received from the transmitting antenna 10 of the antenna device to the receiving antenna 20, R2 is a reflected wave from the steel pipe, and R3 is a reflected wave from the right end of the water tank 70. Each corresponds. In this case, the reception intensity of the reflected wave from the steel pipe 72 is 0.44.
(V).

FIG. 9B shows a case where the antenna device of this embodiment shown in FIG. 1 is used, and a non-foamed urethane resin is provided between the transmitting antenna, the receiving antenna 20 and the water tank 70. 30 is filled. As shown in the figure, the reception intensity of the reflected wave from the steel pipe 72 is 1.0
(V), which indicates that the reception intensity of the reflected wave is twice or more as compared with the case where the non-foamed urethane resin 30 is not provided.

FIG. 10 is a view schematically showing another experimental apparatus used for measuring the reception intensity. In this configuration, the water tank 7
The transmitting antenna is installed on the right side of the water tank 70, and the receiving antenna is installed on the left side of the water tank 70 facing the antenna. In FIG.
1 = 1.5 m, B2 = 0.1 m, B3 = 1.3 m.

FIG. 11A is a diagram showing a measurement result of the reception intensity of the electromagnetic wave measured by the reception antenna in the configuration shown in FIG. FIG. 3A shows a non-foamed urethane resin 30 between a transmitting antenna, a receiving antenna and a water tank 70.
Are not measured, and the horizontal axis and the vertical axis are the same as those shown in FIG. In this case, the reception intensity of the transmitted electromagnetic wave was 0.97 (V).

FIG. 11B shows a non-foamed urethane resin 30 between the transmitting antenna, the receiving antenna and the water tank 70.
The result of measurement in the case where is filled is shown, and the reception intensity of the transmitted electromagnetic wave in this case was 1.33 (V).

As described above, when the non-foamed urethane resin 30 is not provided, reflection occurs on the surface of the water tank 70, so that the reception intensity of the electromagnetic wave is reduced. On the other hand, when the non-foamed urethane resin 30 is filled, the reflection on the surface of the water tank 70 decreases, and the receiving intensity of the electromagnetic wave by the receiving antenna increases. Therefore, from this experiment, it can be said that by providing the non-foamed urethane resin 30 between the exploration surface and the transmitting / receiving antenna, the intensity of the transmitted electromagnetic wave is increased and the exploration performance can be improved.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention.

For example, in this embodiment, a two-component reactive urethane gel system comprising a polyol component and a polyisocyanate component is used as the non-foamed urethane resin 30.
The present invention is not limited to this, and other members may be used as long as they are non-foamed, flexible, and have a relative dielectric constant in the range of 4 to 10.

In this embodiment, the non-foamed urethane resin 3
Although 0 is used, another material may be used as long as it has appropriate compressibility, is not foamed, and has a relative dielectric constant in the range of 4 to 10.

Further, in this embodiment, the case where the rock 60 is searched is considered, but the search area may be a soil layer or the like. However, in this case, the relative dielectric constant is 10 to 30,
Since it is larger than the relative dielectric constant of the bedrock 60, it is necessary to adjust an additive to be added when forming the non-foamed urethane resin 30.

[0060]

As described above, according to the present invention, the relative permittivity between the transmitting and receiving antennas and the search area in which the object to be searched is embedded is substantially the same as that of the search area , and
The volume shape that is compressed and deformed along the irregularities of the
One by providing a flexible member, exploration by enhancing the strength of the electromagnetic wave generation of the electromagnetic wave reflected at the surface of the search area for the search object is embedded can be minimized <br/>, transmitted The depth becomes deeper, and the exploration performance can be improved. Further, specifically, the flexible member is made of non-foamed
The transmission / reception antenna and the exploration surface
Can be minimized. Further
The relative permittivity of the flexible member is 4 to 10.
It is in the same range as the relative permittivity of general rock,
Abrupt relative permittivity at the interface between the flexible member and the
Since there is no difference, the reflection of electromagnetic waves from the interface is minimized.
It can be kept to a minimum.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall configuration of a radar search antenna device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state where the antenna device shown in FIG. 1 is housed in a storage case.

FIG. 3 is a view showing a state in which the antenna device shown in FIG. 1 is brought into close contact with rock.

FIG. 4 is a diagram schematically illustrating a case where the antenna device according to the present embodiment transmits and receives electromagnetic waves to search for a buried object.

FIG. 5 is a schematic diagram for explaining reflection and transmission of an electromagnetic wave.

FIG. 6 is an explanatory diagram showing measurement results of various electric constants of air and a non-foamed urethane resin.

FIG. 7 is an explanatory diagram showing measurement results of various electrical characteristics of tap water.

FIG. 8 is a diagram showing a configuration for experimenting the reception intensity of electromagnetic waves depending on the presence or absence of a non-foamed urethane resin.

9 is a diagram showing an experimental result of the configuration shown in FIG.

FIG. 10 is a diagram showing a configuration for experimenting on the reception intensity of an electromagnetic wave depending on the presence or absence of a non-foamed urethane resin.

11 is a diagram showing an experimental result of the configuration shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 transmitting antenna 12 transmitting cable 20 receiving antenna 22 receiving cable 30 non-foamed urethane resin 40 FRP jig 50 storage case 60 bedrock

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masafumi Naito 1-7-1, Kyobashi, Chuo-ku, Tokyo Toda Construction Co., Ltd. (56) References JP-A-58-35478 (JP, A) 2-14801 (JP, B2)

Claims (3)

(57) [Claims] 1. A transmitting antenna for transmitting an electromagnetic wave for radar exploration toward an exploration area in which an object is buried, and a reception for receiving a reflected wave from the object for electromagnetic wave transmitted from the transmitting antenna. An antenna, the relative permittivity provided between the transmission antenna and the reception antenna and the search surface is substantially the same as the search area , and
An antenna device for radar search, comprising: a flexible member having a volume shape that is compressed and deformed along irregularities in a search area . 2. The method according to claim 1, The flexible member is a non-foamed urethane resin.
Antenna device for radar exploration. 3. The method according to claim 1, wherein The flexible member has a relative dielectric constant of 4 to 10.
Antenna device for radar exploration.