KR102145558B1 - Ultrawideband v-fed antenna for deep ground penetrating radar - Google Patents

Abstract

The present invention relates to an ultra-wideband V-fed antenna for a deep ground penetrating radar, and more specifically, to an ultra-wideband V-fed antenna for a deep ground penetrating radar, which comprises: a V-shaped unit folded around a feeding unit towards a front side (the direction of a main beam, and the direction into the ground for a ground penetrating radar) to form an angle against a horizontal dipole shaft; and a first horizontal dipole unit and a second horizontal dipole unit which are folded on both end units of the V-shaped unit towards the external side to be placed in parallel to the horizontal dipole shaft. When receiving a signal from a reception side of a bistatic ground penetrating radar antenna, the ultra-wideband V-fed antenna for the deep ground penetrating radar is able to receive a higher level of a reflection wave signal generated in a discontinuous surface underground at a great depth. The present invention has effects of improving the detecting performance of a target in a great depth of a ground penetrating radar system in which, when the whole length of an arm of the antenna is determined in accordance with an antenna operation frequency and an operation mode, the length, the included angle, and the width of an arm of the V-shaped unit, and the length and width of the first horizontal dipole unit and the second horizontal dipole unit are determined by an optimization technique for improving the ultra-wideband operation of the antenna and the direct wave ratio to the underground reflection wave.

Description

Ultra-wideband V-FED ANTENNA FOR DEEP GROUND PENETRATING RADAR for high-depth ground transmission radar

The present invention relates to an ultra-wideband V-feeding type antenna for a high-depth surface transmission radar, and more particularly, an angle with respect to the horizontal dipole axis by folding forward (in the direction of the main beam and the underground direction in the surface transmission radar) around the power supply unit. It is composed of a V-shaped V-shaped part and first and second horizontal dipoles folded in the outer direction at both ends of the V-shaped part and positioned parallel to the horizontal dipole axis, so that a bistatic ground penetrating radar (GPR) is called. In the case of receiving at the receiving side of the above, the present invention relates to an ultra-wideband V-feeding type antenna for a high-depth surface transmission radar capable of receiving a reflected wave signal generated from a deep-depth underground discontinuity at a larger level.

In general, it is a non-destructive test for imaging underground structures or analyzing electrical properties in the basement. After radiating ultra-wide electromagnetic wave pulses in the frequency band of 10 MHz to several GHz to the basement, it receives a signal that is reflected from the discontinuity surface and returns it. There is a Ground Penetrating Radar (GPR) technique that analyzes. The GPR system is divided into a ground contact type and a ground separation type according to the operation type of the antenna.

The ground contact type is used to detect abnormalities or discontinuities with a relatively deep depth (1m to 10m), but since it is applied to the ground, a flat antenna with relatively low directionality is used. As such a ground-contact type GPR antenna, a dipole antenna and a Bowtie antenna are typical.

The ground-separated type is used for safety diagnosis of pavements and bridges with a relatively shallow depth (0.3-1m), and is operated apart from the ground, thus providing a high degree of structural freedom in implementation, and a high-directional antenna is used to suppress unwanted radiation in the air. Used. As such a ground-spaced GPR antenna, a V-shaped antenna is mainly used to obtain the characteristics of high directivity in air, such as a horn antenna and a resistive V-dipole.

FIG. 1 is a schematic diagram illustrating the flow of radio waves transmitted and received by a general ground-contact type bistatic GPR antenna, and FIG. 2 is a graph showing signals received from a reception antenna of a ground-contact type bistatic GPR antenna.

1 and 2, the system dynamic range is a ratio of the largest signal amplitude (usually direct wave) and the minimum recognizable amplitude (noise level or higher), and is meaningful as a major index of system performance. The direct wave 12 of FIG. 1 is confirmed in a time interval of 0 to 5 nanoseconds in FIG. 2, and the ground-reflected wave 14 of FIG. 1 is confirmed in a time period after that in FIG. 2, especially around 15 nanoseconds. Since a large reflected signal is identified, it appears that there is a distinct discontinuity at that depth. The dynamic range of the system excluding the antenna has its own value for each GPR system, and under this premise, the ratio of the signal size of the underground reflected wave (14) and the direct wave (12) is large in order to detect a signal of a smaller level in GPR survey. Must be received. That is, it is preferable that the signal of the ground reflection wave 14 used to analyze the structure of the underground is as large as possible, and the direct wave 12 signal, which is a signal other than that, is received as small as possible. For high-depth GPR survey from an antenna point of view, excellent coupling between the antenna and the underground medium, minimizing direct coupling between the transmitting and receiving antennas, and the high-directed radiation characteristics of the antenna itself are required.

However, the ground-contact type GPR antenna of the prior art has excellent coupling characteristics between the antenna and the underground medium, so that the direct coupling between the transmitting and receiving antennas is small, but has a disadvantage of having omnidirectionality in the magnetic field plane.

In addition, the ground-spaced GPR antenna of the prior art has excellent directivity, but it is difficult to couple with an underground medium due to the V-shaped antenna arm structure, and thus, direct coupling between the transmitting and receiving antennas increases.

[Patent Document 1] Korean Utility Model Registration Publication No. 20-0188711 (Name of invention: Antenna structure of underground buried object detection device using GPR system) [Patent Document 2] US Patent Publication No. US2018/0329051 A1 (Name of invention: Large resistive vee dipole antenna combined with vee dipole array)

Accordingly, the present invention is to solve the problems of the prior art described above, and an object of the present invention is to improve the detection depth for the underground discontinuous surface of the ground-contact type ground transmission radar having high directivity while being easy to couple with the underground medium. It is to provide an ultra-wideband V-feed type antenna for the high-depth surface transmission radar.

In order to achieve the above object, the ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to an embodiment of the present invention includes a transmission antenna and a reception antenna in close contact with the ground. A feeding type antenna, wherein the transmitting antenna and the receiving antenna include a V-shaped V-shaped portion that is folded downward (in a direction of a main beam) around a feeding portion to form an angle to a horizontal dipole axis; And first and second horizontal dipole portions that are folded in an outer direction at both ends of the V-shaped portion and positioned parallel to the horizontal dipole axis.

In the ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to the embodiment, in order to improve the ultra-wideband operation of the antenna and the direct wave ratio to the ground reflected wave, the length of one arm of the V-shaped portion (a), The included angle α and the width W1, and the length La and the width W2 of each of the first and second horizontal dipole portions may be determined by an optimization technique.

[Here, L represents the total length of one arm of the antenna determined according to the antenna operation frequency and operation mode]

In the ultra-wideband V-feed type antenna for a high-depth surface transmission radar according to the above embodiment, when operated as a ground-contact type surface transmission radar antenna, a permittivity corresponding to the underground medium for a space including the angle of the V-shaped portion And it may be configured by inserting a dielectric having a conductivity.

The ultra-wideband V-feed type antenna for a high-depth ground transmission radar according to the above embodiment is configured to load a plurality of impedance elements having an impedance value calculated by using the antenna design parameter as an input variable at an internally set point of the antenna. Can be.

The ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to the above embodiment is to suppress unnecessary radiation into the air by packaging the antenna periphery in a metal or non-metal box, and then filling a radio wave absorber inside the packaging box. Can be configured.

According to the ultra-wideband V-feeding type antenna for a high-depth ground transmission radar of the present invention, a V-dipole-shaped V-shaped portion which is folded forward (main beam direction) around the feeder to form an angle with respect to a vertical dipole axis; And first and second vertical dipoles of the same length, which are folded in the outer direction at both ends of the V-shaped part and positioned parallel to the vertical dipole axis, so that coupling of the antenna to the underground medium is easy, and transmission/reception As the direct coupling between antennas is small and the directivity is excellent, when receiving from the receiving side of the bistatic GPR, it is possible to receive the reflected wave signal generated from the deep underground discontinuity at a higher level. have.

1 is a diagram schematically showing the flow of radio waves of a transmission/reception antenna constituting a general bistatic GPR.
FIG. 2 is a graph showing signals received from the receiving antenna of FIG. 1.
3 is a diagram showing the shape and arrangement of a transmission antenna and a reception antenna in a general ground-contact type GPR antenna.
4 is a view showing the shape and arrangement of a transmission antenna and a reception antenna in the ultra-wideband V-feed type antenna for a high-depth ground transmission radar according to an embodiment of the present invention.
FIG. 5 is a diagram showing a form and arrangement of a transmission antenna and a reception antenna used in a general ground-separated GPR in a ground-contact type to compare performance with the antennas of FIGS. 3 and 4.
6 is a graph showing signals for each target depth obtained through a reception antenna of a general ground-contact type GPR.
7 is a graph showing signals for each target depth obtained through a reception antenna in an ultra-wideband V-feed type antenna for a high-depth ground transmission radar according to an embodiment of the present invention.
8 is a graph showing signals obtained through a reception antenna when a transmission antenna and a reception antenna in a general ground-separated GPR are configured in a ground-contact type.

In describing the embodiments of the present invention, when it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification. The terms used in the detailed description are only for describing the embodiments of the present invention and should not be construed as limiting. Unless explicitly used otherwise, expressions in the singular form include the meaning of the plural form. In this description, expressions such as "comprising" or "feature" are intended to refer to certain features, numbers, steps, actions, elements, some or combination thereof, and one or more other than those described. It should not be construed as excluding the presence or possibility of other features, numbers, steps, actions, elements, any part or combination thereof.

In each of the systems shown in the drawings, the elements in some cases each have the same reference number or a different reference number, suggesting that the elements represented may be different or similar. However, elements may have different implementations and operate with some or all of the systems shown or described herein. The various elements shown in the figures may be the same or different. Which is referred to as the first element and which is referred to as the second element is arbitrary.

In the present specification, "transmitting", "transmitting" or "providing" data or signals by one component to another component means that one component directly transmits data or signals to another component, as well as It includes transmitting data or signals to other components through at least one other component.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

4 is a view showing the shape and arrangement of a transmission antenna and a reception antenna in an ultra-wideband V-feed type antenna for a high-depth ground transmission radar according to an embodiment of the present invention.

In the ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to an embodiment of the present invention, as shown in FIG. 4, the central point f where the V-shaped portions 110 of the two antenna arms meet (feeding unit ), and a transmission antenna 100 configured to infiltrate an electromagnetic wave into the lower part of the ground and a reception antenna 200 for receiving a radio wave reflected from the ground by penetrating the ground from the transmission antenna 100 and returning.

Both the transmission antenna 100 and the reception antenna 200 include a V-shaped portion (V) and first and second horizontal dipole portions (A, A').

The V-shaped portion V is folded downward (in the direction of the main beam) around the power feeding portion f to form a predetermined angle with respect to the horizontal dipole axis b, and has a V shape. In order to improve the ultra-wideband operation of the antenna and the ratio of the direct wave to the underground reflected wave, the length (a), the included angle (α), and the width (W1) of one arm of the V-shaped part (V) may be determined by an optimization technique.

The first and second horizontal dipole portions A and A'are respectively folded in the outer direction at both ends of the V-shaped portion V and are positioned parallel to the horizontal dipole axis b. In order to improve the ultra-wideband operation of the antenna and the ratio of the direct wave to the ground reflected wave, the length (L-a) and the width (W2) of each of the first and second horizontal dipole portions may be determined by an optimization technique. Here, L denotes the total length of one arm of the antenna determined according to the antenna operation frequency and operation mode.

On the other hand, the ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to an embodiment of the present invention is a space including the included angle α of the V-shaped part (V) when operated as a ground-contact type surface transmission radar antenna. It can be constructed by inserting a dielectric having a dielectric constant and conductivity corresponding to the underground medium for (S).

Meanwhile, in the ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to an embodiment of the present invention, a plurality of impedance elements having an impedance value calculated using an antenna design parameter as an input variable are placed at a set point inside the antenna. It can be configured to load.

On the other hand, the ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to an embodiment of the present invention packs a metal or non-metal box around the antenna, and then fills a radio wave absorber inside the packaging box so that radio waves are unnecessary into the air. It can be configured to suppress radiation.

Hereinafter, the operation of the ultra-wideband V-feed type antenna for a high-depth surface transmission radar according to an embodiment of the present invention comprising the above components will be described with reference to the drawings.

In an embodiment of the present invention, a virtual experiment of a ground-contact type bistatic GPR having a broadside-based transmission/reception antenna configuration was performed, and an ultra-wideband bow tie antenna, which is a general ground-contact type GPR antenna as shown in FIG. 3, is used as a transmission antenna 10. And the results of the virtual experiment used as the reception antenna 20, and a ground-contact type using an ultra-wideband horn antenna, which is a general ground-spaced GPR antenna as shown in FIG. 5, as a transmission antenna 10' and a reception antenna 20'. It was compared with the virtual experiment results.

First, in the antenna configuration for the virtual experiment of FIGS. 3, 4 and 5, the length of one antenna arm is L, the distance between the V-shaped parts of the two antenna arms is h, and the V-shaped part of the two antenna arms is The included angle is expressed as α, and in the virtual experiment, all α has a fixed value of 45 ^o .

In the virtual experiment, a circular perfect conductor target (underground target) with a predetermined radius was placed inside the underground medium at depth (d). 7 shows the change of the received signal obtained by the receiving antenna 200 of the present invention according to the change of the depth (d) (30cm ~ 1.5m).

In addition, in order to compare with the results of the virtual experiment of the present invention, according to the change of the depth (d), the case of using an ultra-wideband bow tie antenna, which is a general ground-contact type GPR antenna (shown in FIG. 3) and a general ground-separated GPR, When the ultra-wideband horn antenna, which is an antenna, is configured in a ground-contact type (shown in FIG. 5), changes in received signals obtained from each of the receiving antennas 20 and 20' are shown in FIGS. 6 and 8, respectively.

It is assumed that both the antenna according to the present invention (see FIG. 4) and the general ground-spared GPR antenna (see FIG. 5) are designed so that the separation distance h from the ground has a parameter value of 5.1 cm. For the hypothetical experiments, it is assumed that the electrical properties of the underground medium have a dielectric constant of 10 and an electrical resistivity of 100 Ωm, and a monocycle pulse signal with a peak voltage of 2 V and a center frequency of 750 MHz is applied to the transmitting antenna.

6, 7 and 8, received signals obtained from the receiving antenna 200 of the present invention, a general ground-contact type GPR receiving antenna 20, and a general ground-spaced GPR receiving antenna 20' are all 0 nsec. The direct wave is received at a nearby time, and afterwards, a reflected signal of an underground target corresponding to a depth (d) of 30cm to 1.5m from around 7nsec to around 32nsec is received.

6 and 8, in the case of using the general ground-contact type GPR receiving antenna 20, the coupling property between the antenna and the underground medium is excellent, so that compared to the case of using the general ground-separated GPR receiving antenna 20' The size of the wave signal appears relatively small. In the case of using a general ground-separated GPR receiving antenna (20'), the magnitude of the direct wave signal increases compared to the case of using the general ground-based GPR receiving antenna (20). Appear large.

Table 1 below shows the peak value and depth (d) of the obtained direct wave signal at 1.5m when a general ground-contact type GPR antenna is used and when the ground separation distance (h) of a general ground-based GPR antenna is used by varying It shows the peak value of the target reflected wave signal and the ratio of the two peak values.

[Table 1]

Referring to [Table 1], in the case of a general ground separation type GPR antenna, it is observed that the magnitude of the direct wave peak value increases as the ground separation distance (h) increases, and overall, for all ground separation distances (h) It was confirmed that it was much larger than the peak value of the direct wave in a general ground-contact type GPR antenna. Due to the high directivity of the general ground-spaced GPR antenna, the size of the reflected signal itself at a deep depth (d=1.5m) is observed to be larger than that of the general ground-contact type GPR antenna, but the difference is as remarkable as the direct wave. Since it does not appear as a result, the ratio of the reflected wave to the direct wave, which is a quantitative indicator of the acquired data quality, is observed to have a smaller value for the ground-spared GPR antenna.

As shown in Figs. 6 and 7, when the antenna of the present invention is used (see Fig. 7), the peak value of the direct wave signal is similar to the case of using a general ground-contact type GPR antenna (see Fig. 6). Confirmed. This is considered to be because the coupling characteristics between the antenna and the underground medium deteriorated by the V-shaped portion V of the antenna of the present invention are supplemented by the first and second horizontal dipole portions A and A'.

In addition, the peak value (attached value at d=30cm) of the antenna of the present invention is slightly smaller than that of a general ground-contact type GPR antenna, but the deeper the underground target, the larger the peak value of the reflected signal. It was confirmed to appear.

Table 2 below shows the peak value of the obtained direct wave signal and the peak of the target reflected wave signal at a depth (1.5m) when the distance (h) from the ground of the general ground-contact type GPR antenna and the antenna of the present invention are used while varying. Value, and the ratio of the two peak values.

[Table 2]

Referring to Table 2, in the case of the antenna of the present invention, when the separation distance (h) from the ground is small (h ≤ 5.1cm), the magnitude of the direct wave peak value appears similar to that of the ground-contact type GPR antenna, and then As the separation distance (h) increases (h ≥ 6.37cm), it is observed that the magnitude of the peak value of the direct wave increases significantly. In the case of h ≤ 5.1cm, the first and second horizontal dipoles (A, A') complement the coupling characteristics between the antenna and the underground medium well, deteriorated by the V-shaped part (V), but h ≥ 6.37cm In the case of, it is determined that the specific gravity of the V-shaped portion V increases and the mode of the first and second horizontal dipole portions A and A'weakens.

Due to the high directivity of the V-shaped portion (V) of the antenna of the present invention, the size of the reflected signal at a deep depth (d=1.5m) is observed to be larger than that of a general ground-contact type GPR antenna.

Therefore, when these results are summarized, the ratio of the reflected wave to the direct wave, which is a quantitative index of acquired data quality, is limited to the case where the separation distance (h) from the ground is small (h ≤ 5.1cm). It is observed to have a larger value than that of the close-fitting GPR antenna.

Specifically, as an embodiment of the present invention, when the distance h = 3.8cm of the V-shaped part is set, the size of the direct wave (2.61mV) is the size of the direct wave (2.65mV) in the ground-contact type GPR antenna. ), but it is confirmed that the size of the deep underground target reflected wave signal (1.20mV/0.93mV) increases by 29%, and when h=2.5cm is set, the ratio of the reflected wave to the direct wave is 2.5 compared to the ground-contact type GPR antenna. Since it is increased by dB, it can be seen that it has a remarkable effect compared to the conventional ground-contact type GPR antenna.

According to the ultra-wideband V-feeding type antenna for a high-depth ground transmission radar of the present invention, a V-dipole-shaped V-shaped portion which is folded forward (main beam direction) around the feeder to form an angle with respect to a vertical dipole axis; And first and second vertical dipoles of the same length, which are folded in the outer direction at both ends of the V-shaped part and positioned parallel to the vertical dipole axis, so that coupling of the antenna to the underground medium is easy, and transmission/reception Since direct coupling between antennas is small and has excellent directivity, it is possible to receive a reflected wave signal generated from a deep underground discontinuity surface at a higher level when receiving from the receiving side of the bistatic GPR.

The ultra-wideband V-feed type antenna for a high-depth ground transmission radar according to an embodiment of the present invention has a length (L) of one arm of the antenna so that the transmitting antenna and the receiving antenna meet the frequency and operation mode required for electromagnetic pulse radiation. It is determined, and based on this, the length (a), the included angle (α) and the width (W1) of one arm of the V-shaped part, and the first and second arm of the V-shaped part in order to improve the ultra-wideband operation of the antenna and the direct wave ratio to the underground reflected wave. The length (La) and width (W2) of each of the horizontal dipoles can be adjusted by an optimization technique, and if necessary, an impedance loading technique can be applied to each antenna arm. The impedance loading technique receives an antenna design parameter, that is, the length or width of the antenna as an input variable, and loads an impedance element having an impedance value calculated through a predetermined equation for each arbitrary point inside the antenna at a corresponding point inside the antenna. It may be implemented in the form of empirically, or by loading impedance elements having arbitrary values empirically into points inside the antenna. By applying the impedance loading technique, it is possible to minimize waveform distortion of the electromagnetic wave pulse signal applied to the antenna due to internal ringing of the antenna.

According to the ultra-wideband V-feeding type antenna for a high-depth surface transmission radar according to an embodiment of the present invention, when the transmitting/receiving antenna is operated as a ground-contact type GPR, the underground medium for a space including a V-shaped part included angle It can be configured to improve the coupling characteristics between the antenna and the underground medium by inserting a dielectric having a dielectric constant and conductivity corresponding to and, packaged around the antenna in a metal or non-metal box, and filled with a radio wave absorber inside the packaging box. Thus, it is possible to suppress unwanted radiation of radio waves into the air.

In the drawings and specification, the best embodiments have been disclosed, and specific terms are used, but these are only used for the purpose of describing the embodiments of the present invention, and are used to limit the meaning or the scope of the present invention described in the claims. Was not done. Therefore, those of ordinary skill in the art will appreciate that the true technical scope of the present invention can be modified according to the technical spirit of the appended claims and other equivalent embodiments are possible. Therefore, it will have to be decided.

100: transmitting antenna
200: receiving antenna
f: power supply
V: V-shaped part
A: first horizontal dipole portion
A': second horizontal dipole portion
L: length of one arm of the antenna
h: the distance of the V-shaped part from the ground
d: depth
a: length of one arm of the V-shaped part
α: The included angle formed by the V-shaped part

Claims (5)

As an ultra-wideband V-feed type antenna for a high-depth ground transmission radar including a transmitting antenna 100 and a receiving antenna 200 in close contact with the ground,
The transmitting antenna and the receiving antenna are
A V-shaped V-shaped portion (V) folded downward (in the direction of the main beam) with respect to the power supply portion (f) to form an angle with respect to the horizontal dipole axis (b); And
Including; first and second horizontal dipole portions (A, A') folded in the outer direction at both ends of the V-shaped portion and positioned parallel to the horizontal dipole axis,
The width W2 of the first and second horizontal dipole portions A, A'is formed in a form gradually increasing from both ends of the V-shaped portion, and an ultra-wideband V-feed type antenna for a high-depth surface transmission radar. .
The method of claim 1,
In order to improve the ultra-wideband operation of the antenna and the ratio of the direct wave to the underground reflected wave, the length (a), the included angle (α), and the width (W1) of one arm of the V-shaped part, and the first and second horizontal dipole parts, respectively. Ultra-wideband V-feed type antenna for high-depth ground transmission radar that determines the length (La) and width (W2) by an optimization technique.
[Here, L represents the total length of one arm of the antenna determined according to the antenna operation frequency and operation mode]
The method of claim 1,
When operated as a ground-contact type surface transmission radar antenna, an ultra-wideband V-class for a high-depth surface transmission radar constructed by inserting a dielectric having a dielectric constant and conductivity corresponding to the underground medium into the space including the included angle of the V-shaped part. Typical antenna.
The method of claim 1,
An ultra-wideband V-feed type antenna for a high-depth ground transmission radar configured to load a plurality of impedance elements having an impedance value calculated using an antenna design parameter as an input variable at an internally set point of the antenna.
The method of claim 1,
An ultra-wideband V-feed type antenna for a high-depth surface-transmission radar, which is configured to suppress unnecessary radiation of radio waves into the air by packing a metal or non-metallic box around the antenna, and then filling a radio wave absorber inside the packaging box.

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