JP3205295B2 - Underground object detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground buried object detecting apparatus for detecting an object buried in a shallow ground in a non-contact manner using radio waves of a plurality of frequencies without modulation.

[0002]

2. Description of the Related Art An unmodulated wave is radiated from the aerial of a scanning device that scans the ground horizontally toward the ground, and changes in the reflection coefficient as an integral value near the ground are measured on the ground and in the ground. An underground buried object detection device that detects an object buried in the ground by detecting a change in the reception level of the reflected wave of the underground wave is known, as disclosed in, for example, Japanese Patent Publication No. 2-13756. A plurality of antennas arranged apart from each other receive reflected waves from the ground, and a plurality of reflected wave reception levels obtained by the processing are subtracted to cancel unnecessary reflected waves from the ground, thereby burying underground objects. It detects the reflected wave from. In addition, a method of correcting a change in scanning altitude from the ground in combination with an ultrasonic sensor or receiving a reflected signal from the vicinity of the ground using an independent antenna for each of a plurality of frequencies and receiving sensitivity due to a change in scanning altitude of the scanning device. Underground buried objects were detected by a method that compensates for deterioration of sensitivity and sensitivity deterioration due to the size of the buried objects.

[0003]

In the above-mentioned prior art underground object detecting apparatus, the principle of detection is that the average reflection coefficient near the ground changes due to the presence of the underground object during scanning by the scanning device. However, even when the scanning altitude from the ground changes when the scanning device scans or when the local dielectric constant of the soil changes, the reception sensitivity and the reception signal also change, making it difficult to distinguish it from the buried object. . For this reason, reflected waves from the ground are received by a plurality of antennas spaced apart from each other as disclosed, and unnecessary reflected waves from the ground are subtracted by subtracting a plurality of reflected wave reception levels obtained thereby. In the method of detecting the reflected wave from the underground object by canceling out, it is assumed that the incident of the reflected wave from the ground to the antenna occurs at an equal level regardless of the position of the antenna, and the ground and the antenna If the planes are not parallel, the unnecessary reflected waves are not sufficiently canceled, and the reception level of the reflected waves from the underground buried object is also relatively reduced by the subtraction processing. The S / N ratio is extremely poor for underground objects, and detection of such objects in such a situation requires many conditions and requires extremely complicated processing.

Further, a method of correcting a change in scanning altitude from the ground in combination with an ultrasonic sensor is known. However, the correction effect is reduced in vegetation or the like because the detection accuracy of the ultrasonic sensor deteriorates.

Further, in the conventional buried object detection device, a reflected signal from the vicinity of the ground is received using an independent aerial for each of a plurality of frequencies. Although a method for compensating for the deterioration of sensitivity due to the above is known, in this method, radio waves radiated because antennas corresponding to a plurality of frequencies are spaced apart correspond to the arrangement of antennas of a plurality of frequencies. It will be emitted from the remote location and the resulting received signal will be a reflected signal at a different location on the ground. Therefore, in order to identify a buried object by this method, the scanner must repeatedly scan the scanning device to recognize the mutual relationship between the frequencies, and it is a factor that deteriorates the detection accuracy. I was

Also, in the antenna used in the conventional underground object detecting device, the dielectric constant of the dielectric is small, so that the antenna becomes large and the whole device becomes large. Also, when different frequencies are used for the same device, the antennas must be separated from each other in accordance with the frequency, so that radio waves are not effectively emitted to the buried object.

Further, in the conventional underground object detecting device, the fluctuation of the received signal caused by the fluctuation of the scanning altitude of the scanning device has been corrected by using an ultrasonic sensor. Could not respond to the change.

Therefore, the present invention proposes to solve the above-mentioned problems, and as an antenna unit in which antennas for a plurality of frequencies are integrated, the same pattern from the same point in the antenna unit even when the frequency is different. It is a first object of the present invention to provide an underground object detection device capable of simultaneously emitting an average reflection coefficient change at the same location on the ground by emitting radio waves.

Further, according to the present invention, the antenna is made small by using a dielectric material having a large dielectric constant, and moreover, radio waves of a plurality of frequencies are radiated from the same place, whereby the radio waves are effectively radiated to the buried object, and high accuracy is achieved. It is another object of the present invention to provide a small underground object detection device.

Further, according to the present invention, as a method of correcting a received signal due to a change in scanning altitude of a scanning device, an antenna that radiates radio waves from the same portion of the antenna with the same radiation pattern even when the frequency is different is used, 2 of amplitude and phase
A third object is to provide an underground object detection device that employs an orthogonal vector detection method capable of detecting components and performs a correlation process between different frequencies, thereby enabling correction of a received signal due to the scanning altitude variation. The purpose is.

[0011]

In order to achieve each of the above objects, while scanning a scanning device having an antenna portion almost horizontally on the ground, a radio wave is emitted from the antenna portion toward the ground, and In the underground object detecting device which receives a reflected wave at the antenna part and detects an underground object by analyzing a received signal of the reflected wave, the antenna part includes a plurality of antennas and a plurality of dielectrics. A radio wave of a plurality of frequencies is radiated without modulation from the same portion of the integrated antenna section, and a reflected wave of the radiated radio wave can be received. And

According to a second aspect of the present invention, in addition to the first aspect, the underground object detecting device is characterized in that the antenna unit can radiate radio waves of a plurality of frequencies in the same pattern even if the frequencies are different without modulation. I do.

According to a third aspect of the present invention, in addition to the first aspect, the underground object detecting device is characterized in that the antenna section has a multilayered structure made of a dielectric material having a high dielectric constant.

According to a fourth aspect of the present invention, in addition to the first aspect, non-modulated radio waves of a plurality of frequencies are radiated from the antenna section, and the amplitude and phase of the unmodulated reflected waves of the plurality of frequencies are received by the antenna section. And a correlation processing between the amplitude and the phase is performed between different frequencies to thereby detect an underground buried object having a signal processing unit for suppressing a reflected signal from the ground.

[0015]

According to the present invention, radio waves of a plurality of frequencies without modulation are radiated simultaneously or intermittently from the same portion of the antenna in the same pattern from the antenna in which the antenna and the high dielectric material are integrated. With this configuration, even if the frequency is different, it is effectively radiated to a buried object in the ground, so that the level of the received signal due to the reflected wave from the buried object increases accordingly, and the buried object can be detected reliably. In addition, a small underground object detection device can be realized despite the fact that a plurality of frequencies are radiated, and furthermore, by using the correlation between each frequency of the amplitude and the phase of the received signal, the scanning altitude of the scanning device is changed. Since the fluctuation of the received signal is corrected, the detection accuracy of the buried object can be improved.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention (hereinafter, referred to as “embodiments”)
Example) will be described with reference to the drawings.

FIG. 1 is a block diagram of a device for detecting underground objects (hereinafter referred to as the present device) showing an embodiment of the present invention. The housing of the apparatus shown in FIG. 1 is not directly related to the present invention, and is not shown.

In FIG. 1, 1 is a high-frequency transmitter that generates and outputs high-frequency signals of a plurality of frequencies without modulation, and 2 receives a high-frequency signal reflected from the ground (the ground surface and a buried object). The high frequency receiver 3 detects two components of the phase by the quadrature vector detection method and outputs a signal strength (electric signal) proportional to the reception level of the high frequency signal. An antenna unit that is supplied with a high-frequency signal, emits a radio wave of the high-frequency signal, and receives a reflected wave of the radio wave of the high-frequency signal on the ground,
4 is an output side of the high-frequency transmitter 1 and the high-frequency receiver 2
A circulator 5 interposed between the antenna 3 and the antenna unit 3 couples the antenna unit 3 to the high-frequency transmitter 1 and the high-frequency receiver 2. The circulator 5 detects and processes the reception signal output from the high-frequency receiver 2. A signal processing unit 6 for generating data; a data display unit 6 for displaying detection data output by the signal processing unit 5; a reference signal source 7 for supplying a reference signal to the high-frequency transmitter 1 and the high-frequency receiver 2; Is a scanning device that houses the antenna unit 3.

In the configuration of the above embodiment, the antenna unit 3
May be configured by a transmitting antenna directly connected to the high-frequency transmitter 1 and a receiving antenna directly connected to the high-frequency receiver 2. Further, a configuration may be adopted in which a plurality of antenna units 3 are attached to the scanning device 8.

An outline of the operation of the present apparatus will be described with reference to FIG. The high-frequency transmitter 1 continuously or intermittently outputs high-frequency signals of a plurality of frequencies without modulation, and the high-frequency signals are supplied to the antenna unit 3 via the circulator 4, and are output from the antenna unit 3. Radio waves are radiated from the same place toward the ground in the same pattern. Unmodulated radio waves of a plurality of frequencies radiated from the antenna 3 are reflected by the ground surface and the buried object and enter the antenna 3. The high-frequency signal incident on the antenna unit 3 is received by the high-frequency receiver 2 via the circulator 4, and the high-frequency receiver 2 outputs a reception signal proportional to the reception level of the received high-frequency signal. 2 is supplied to the signal processing unit 5. The signal processing unit 5 detects the amplitude and phase from the received signals of a plurality of frequencies, performs a correlation process, and outputs an embedded object detection signal. The buried object detection signal output from the signal processing unit 5 displays the presence of the buried object on the data display unit 6.

Next, FIG. 2 is a structural view of the antenna unit 3 in the present apparatus, (A) is a front view, (B) is a side view,
FIG. 3C is an explanatory view of attaching a high-frequency power supply coaxial cable to the antenna unit 3, and FIG. 3 is a diagram illustrating the antenna unit 3 of FIG.
(A) is an antenna having a feed point for supplying high-frequency power, (B) and (C) are antennas having slits, and (D) is a conductor for supplying ground.

Referring to FIG. 2 and FIG. In FIGS. 2A and 2B and FIGS. 3A to 3D, 9
Reference numerals a to 9c denote a plurality of dielectric materials having different dielectric constants having a high dielectric constant, 10a to 10c antennas for radiating radio waves or receiving reflected waves, and 11a to 11c for the antennas 10a to 10c.
A rectangular conductor (hereinafter, referred to as a conductor) having a prescribed size that differs according to the frequency forming 10c, 11d is a rectangular GND conductor connected to the ground, 12 is a conductor 11b and a conductor 11c
The slits 13 are defined in the antennas 10a-1
0c and the dielectrics 9a to 9c are feed points for supplying high-frequency power to the outermost one conductor 11a of the multi-layered antenna unit 3 described later. Power is supplied to the feed point 13 by a coaxial cable. And the other outermost conductor 11d of the antenna portion 13 becomes a ground conductor by the coaxial cable. Reference numeral 14 denotes a hole through which a coaxial cable feeding power to the feed point 13 passes. In FIG. 2C, a center conductor of the coaxial cable is connected to the feed point 13 of the conductor 11a, and the GND conductor 11d is provided. Is connected to the ground by the coaxial cable. Here, the connection between the coaxial cable and the feeding point 13 and the GND conductor 11d is performed by soldering or a connector.

The antennas 10a to 10c and the GN
The D conductor 11d and the dielectrics 9a to 9c have a multilayer structure in which they are alternately superposed, and the antennas 10a to 10c
c can radiate radio waves (single radio waves) of different frequencies due to the unidirectional electric field strength, or the antenna 10a
To 10c can receive the reflected wave by the radiated radio wave. Therefore, the antenna unit 3 can simultaneously or intermittently radiate a plurality of radio waves from the same location of the antenna unit 3 in the same pattern, and can receive reflected waves from the ground due to the radiated radio waves. .

Further, the slits 12 are formed in the conductors 11b and 11c, which are the conductors of the antennas 10b and 10c constituting the antenna 3 and are elongated from the center of the four sides to the center of the conductor. It is formed and plays a role of eliminating mutual radio interference caused by the excitation current in the higher-order excitation mode flowing through each of the multilayered conductors 11a to 11c during power supply.

That is, since the excitation current in the main excitation mode flows bypassing the slit 12, the current path becomes equivalently longer, but in the even higher-order excitation mode, the center of the four sides of the conductors 11b and 11c is at the center. Since the value of the current distribution becomes zero, there is no influence of the slit 12, so that the current path does not change before and after the slit is inserted. For this reason, the integer relationship between the main excitation mode and the even higher-order excitation mode is broken, and even when the frequency ratio used is close to the integer relationship, the conductor having the slit 12 and the conductor having no slit 12 are combined. Thus, an antenna in which pattern disturbance due to mutual interference is eliminated can be realized, and the same radiation pattern in a single direction at a wide angle at a plurality of frequencies can be obtained. Here, the size of the slit 12 depends on the frequency to be used, but it is defined to be about 1/3 of the length of one side of each rectangular conductor forming the antenna. In the embodiment, the slit 12 is connected to the antenna 10b. Although it is formed on the antenna 10c, it may be formed on the antenna 10a.

The resonance frequency of the radio wave radiated from each of the antennas 10a to 10c is obtained from λ / 2√εr (λ: waveform, εr: relative permittivity of a dielectric), and a square forming each antenna is obtained. The dimensions of the conductor and the ground conductor have the following relationship.

One side of the conductor 11a <one side of the conductor 11b <one side of the conductor 11c <one side of the GND conductor 11d Further, the conductors 11a to 11c are attached to predetermined positions of the dielectrics 9a to 9c, and the conductor 11c is attached to the GND conductor 11d. Bonded to the back side of the dielectric 9c in order from the lowest frequency of the fundamental wave which facilitates excitation. In addition, the conductors 11a to 1
1c and the GND conductor 11d each use a commercially available double-sided copper-clad laminate.

Next, FIGS. 4 to 7 will be described.

FIG. 4 illustrates the characteristics of the reflected wave from the ground at the antenna 3 when a plurality of radio waves of different frequencies are radiated from the antenna 3. The amplitude of the signal reflected by is determined by the transmission power, the reflection coefficient related to the dielectric constant of the soil, the attenuation corresponding to the propagation distance, the antenna pattern, and the frequency (wavelength).
The phase is determined by the complex term of the reflection coefficient, the propagation distance, and the frequency (wavelength). Here, the propagation distance is twice as high as the altitude of the antenna from the ground surface (hereinafter referred to as altitude), so that the amplitude and phase of the received signal can be expressed as functions of altitude.

Signal reflected from the ground surface

[0031]

(Equation 1)

FIG. 4 shows two types of frequencies f1 and f2 by the present apparatus.
(F1 <f2), the reflected signal reflected on the ground surface
(A) is a typical amplitude change of the received signal with respect to altitude.
(B) shows a phase change of a representative received signal with respect to altitude, and the received signal has a time lag with respect to the base transmission signal, and thus is shown by minus coordinates.

The amplitude monotonically decreases with the altitude, the phase changes linearly with the altitude, and decreases monotonically with the altitude, and the phase changes linearly with a constant cycle with the altitude. It shows the situation.

In FIG. 4, reference numeral 15 denotes an amplitude change and a phase change with respect to the frequency f1, and 16 denotes an amplitude change and a phase change with respect to the frequency f2.

Here, the frequencies f1 and f2 are different frequencies, but the ratio is constant at a single frequency, and the other parameters such as the reflection coefficient, the transmission electric field, and the antenna pattern are the same. Both the amplitude change and the phase change with respect to the altitude of f2 have a fixed relation related to the frequency. For this reason, in a situation where there is no buried object, since the amplitude and phase of each received signal obtained at a different frequency have a strong correlation, the ground surface reflection signal can be suppressed by using this correlation. . On the other hand, when there is a buried object, the reflection signal from the buried object is added to the ground surface reflection signal. Since the reflection characteristics of each frequency for the buried object change depending on the size, shape, etc. of the buried object,
The correlation between the above-mentioned frequencies of the received signal in the buried area deteriorates. The detection processing shown in the present apparatus detects a buried object by detecting a deviation from the correlation between the frequencies.

FIG. 5 is a diagram for explaining signal processing between different frequencies in a reflected wave from the ground received by the present apparatus.
The scanning distance when scanning the antenna at each of the frequencies f1 and f2 (the scanning distance is x-axis and Y-axis if the altitude is the z-axis).
This shows typical examples of the amplitude change and phase change of the received signal with respect to the plane composed of the axes), and the hatched portion indicates the received signal from the embedded object described later. Reference numeral 18 denotes a phase change, 18 denotes an amplitude change and a phase change with respect to the frequency f2, and 19 denotes a hatched portion indicating a received signal by a reflected wave from the buried object.

The correlation in the processing of this apparatus is as follows.
In addition to being obtained by statistically processing the detected signal, it can also be obtained by accumulating the signal detected as a calibration operation in an appropriate place without an embedded object before the operation.

FIGS. 6A and 6B are diagrams for explaining a process of suppressing a reflection signal from the ground surface received by the antenna unit 3 by the present apparatus. FIG. 6A shows the same frequency f1 with respect to the scanning altitude as FIG. (B) is a diagram for explaining the correlation between the amplitude changes of the frequencies f1 and f2,
FIG. 4C shows the phase change between the frequency f1 and the frequency f2 with respect to the scanning altitude when the data obtained in FIG. FIG. 4D illustrates the correlation between phase changes of the frequencies f1 and f2.

In FIGS. 6A and 6B, the frequency f1
The amplitude ratio between the frequency f2 and the frequency f2 is in a fixed relationship, so that the correlation between the two frequencies can be expressed by a single linear expression, and the amplitude A of the reflected signal on the ground surface can be expressed by the following equation.

H: scanning altitude, A1: amplitude of frequency f1, A
2: Assuming the amplitude of the frequency f2, A = A1 (h, f1) −A2 (h, f2) = constant (1) In addition, in FIG. When the regression line is obtained from the phase of the frequency f2 and the slope of the regression line is used as the correction coefficient m, the reception data between the frequency f1 and the frequency f2 is reduced to zero. That is, for example, if the frequency f1 and the frequency f2 have a relationship of f1 = a × f2 (a is a constant), the reflection signal phase θ of the ground surface is expressed by the following equation.

H: scanning altitude, θ1: phase of frequency f1, θ
2: Assuming the phase of the frequency f2, θ = a × θ1 (h, f1) −θ2 (h, f2) = 0 (2) The frequency f1 is obtained from the contents of the above equations (1) and (2). And frequency f2
If the correlation between them is obtained numerically and processed by the signal processing unit 5 and the data display unit 6, the signal reflected by the ground surface can be suppressed.

FIG. 7 is a diagram for explaining a process of extracting a reflection signal from a buried object received from the antenna unit 3 by the present apparatus. FIG. 7A is a diagram for explaining a reflection signal from the buried object.
(B) is a graph of the reflection characteristics from the buried object.

In the diagram shown in FIG. 7A, the reflected signal from the buried object is generally expressed by the following equation.

Er (r, θ '): reflection signal from the buried object, γ: refractive index of the beam, S: scattering cross section of the buried object, G
(Θ ′): antenna pattern, r: distance between antenna and buried object, a: radius of buried object

[0045]

(Equation 2)

Here, in particular, the above equation (3) shows the scattering cross section of the buried object at each frequency, and when this is plotted as a graph, it is plotted as shown in FIG. ), The signal processing unit 5 and the data display unit 6 process and correct the frequency ratio and the like between a plurality of frequencies so that the reflection signal from the buried object destroys the linear relationship of the reflection signal from the ground surface. , And the data is subjected to subtraction, a non-linear signal remains and is extracted as a reflection signal from the buried object. Further, when the antenna is multi-channeled, the shape of the buried object having a size larger than the channel arrangement width can be recognized.

A specific processing flow used in the present apparatus will be described below.

1. 1. Acquisition of calibration data 2. Numericalization of correlation by statistical processing 3. Acquisition of measurement data 4. Correction processing using correlation Data display The amplitude and phase of the received signal of the different frequency are detected, and the correlation processing is performed between the different frequencies, thereby suppressing the ground reflected signal and suppressing the signal-to-noise (S) of the reflected signal from the buried object.
/ N) can be improved.

As described above, in the present invention, a plurality of antennas and a plurality of dielectrics are alternately overlapped and integrated to form an antenna portion, from which a plurality of radio waves can be transmitted simultaneously or intermittently without modulation. At the same time, it is possible to radiate from the same place toward the buried object in the same pattern.

That is, the antenna according to the present invention is an antenna in which a plurality of rectangular conductors each having a different size and emitting a single radio wave are superimposed on each other and a dielectric having a high dielectric constant is divided into a plurality of frequencies. In the multilayered structure, one of the outermost rectangular conductors overlapping the antenna portion is a power supply conductor for supplying high-frequency power, the other outermost rectangular conductor is a GND conductor, and the power supply conductor and the By making the conductor between the GND conductors a parasitic conductor, the same radiation pattern in a wide angle and in one direction can be obtained at a plurality of frequencies.

In the case of performing the above multi-layering, a high-order excitation mode of a plurality of individual rectangular conductors becomes a problem, causing interference between the respective conductors and disturbing the same radiation pattern in a single direction at the above wide angle. . In particular, a problem arises when the frequency ratio of a plurality of frequencies to be used is close to an integer relation. Therefore, in the antenna unit according to the present invention, by providing slits in the rectangular conductor, the path of the current flowing on the rectangular conductor is changed to remove the interference of the even higher-order mode.

In other words, the excitation current in the main mode flows bypassing the slit, so that the current path becomes equivalently longer, but in the even higher-order mode, the value of the current distribution becomes zero at the center of the rectangular conductor side. Therefore, the current path is not changed without being affected by the slit. For this reason, the integer relationship between the main mode and the even higher-order mode is broken, and even when the frequency ratio to be used is close to the integer relationship, the interference between the square conductor having slits and the square conductor having no slits is caused. The antenna which eliminates the disturbance of the pattern due to the antenna can be realized.

On the other hand, the reflected signal from the underground object is detected overlapping with the reflected signal on the ground, and therefore, in order to detect only the signal from the underground object, the reflected signal from the ground is removed. There is a need. In the present invention, the signal processing unit acquires the reflection characteristics on the ground for a plurality of frequencies, detects the amplitude and the phase of each frequency, and numerically calculates the correlation between the amplitude and the phase between the frequencies. , It is possible to suppress the signal reflected by the ground. The underground object detection device including the antenna unit and the signal processing unit described above can reliably detect an underground object.

[0054]

According to the present invention, a dielectric and an antenna are alternately overlapped to constitute an integrated antenna, and high-frequency signals of a plurality of frequencies are unmodulated simultaneously or intermittently from the same location and from the same pattern. Since it radiated toward the buried object at, the reception level of the reflected wave reflected from the buried object was
Even if the frequency changes, the signal can be received at the same level, so the S / N ratio has been dramatically improved compared to the past. The size of the buried object detection device can be reduced. In addition, since a plurality of antennas are attached to the scanning device and scanning is performed, the detection data is signal processed, and the shape of the buried object can be displayed, so it is easy to determine whether the detected buried object is the initial one. Can be determined. Further, the amplitude and phase are detected from the received signal of the reflected wave reflected from the buried object, and the correlation between the amplitude and the phase is performed to correct the fluctuation of the received signal due to the fluctuation of the traveling altitude of the scanning device. Therefore, a remarkable effect that the detection accuracy of the underground object is improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an underground object detecting apparatus according to an embodiment of the present invention.

FIG. 2 is a structural diagram of an antenna unit in the apparatus.

FIG. 3 is a configuration diagram illustrating a configuration of an antenna unit shown in FIG. 2;

FIG. 4 is a diagram illustrating characteristics of a ground reflected wave due to a change in altitude of the scanning device according to the present invention.

FIG. 5 is an explanatory diagram of signal processing between different frequencies of a reflected wave received by the present apparatus.

FIG. 6 is an explanatory diagram for suppressing a reflection signal from the ground surface received from an antenna unit.

FIG. 7 is an explanatory diagram for extracting a reflection signal from a buried object received from an antenna unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... High frequency transmitter 2 ... High frequency receiver 3 ... Antenna part 4 ... Circulator 5 ... Signal processing part 6 ... Data display part 7 ... Reference signal source 8 ... Scanning device 9a ... Dielectric a 9b ... Dielectric b 9c ... Dielectric c 10a ... antenna a 10b ... antenna b 10c ... antenna c 11a ... conductor a 11b ... conductor b 11c ... conductor c 11d ... GND conductor 12 ... slit 13 ... feeding point 14 ... holes 15, 17 ... frequency f1 16, 18 ... frequency f2 19: Received signal from buried object

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-12954 (JP, A) JP-A-8-94765 (JP, A) JP-A-11-202043 (JP, A) JP-A-58-1983 223771 (JP, A) JP-A-5-90803 (JP, A) JP-A-6-252631 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 13/88 G01V 3 / 12

Claims (4)

(57) [Claims] 1. A scanning device having an antenna part emits a radio wave from the antenna part toward the ground while scanning the ground substantially horizontally, and a reflected wave of the radio wave is received by the antenna part, and the reflected wave is In the underground object detection device which is configured to detect an underground object by analyzing the received signal of the above, the antenna unit,
A plurality of antennas and a plurality of dielectrics are integrally formed, and radio waves of a plurality of frequencies are radiated without modulation from the same portion of the integrated antenna portion so that reflected waves of the radiated radio waves can be received. An underground object detection device, characterized in that: 2. The underground object detecting device according to claim 1, wherein the antenna unit is capable of radiating radio waves of a plurality of frequencies without modulation in the same pattern even if the frequencies are different. Underground buried object detection device. 3. The underground object detecting apparatus according to claim 1, wherein the antenna section has a multi-layered structure made of a dielectric having a high dielectric constant. apparatus. 4. An unmodulated radio wave of a plurality of frequencies is radiated from the antenna unit, and an amplitude and a phase are detected from unmodulated reflected waves of a plurality of frequencies received by the antenna unit. The underground object detection device according to claim 1, further comprising a signal processing unit that performs a correlation process between different frequencies and suppresses a reflected signal from the ground.