JP-7856968-B2 - Methods, systems, and apparatus

Inventors

• 黒木 太司
• 三宅 正光

Assignees

• 独立行政法人国立高等専門学校機構
• 株式会社三宅

Dates

Publication Date

20260512

Application Date

20220308

Claims (9)

1. The steps include receiving electromagnetic waves transmitted from a transmitting antenna using a receiving antenna installed on or near the ground surface, A method comprising the steps of: using a reactance circuit whose resonant frequency matches or approximates the frequency of electromagnetic waves emitted from a transmitting antenna, and determining the water content below the ground surface according to the received intensity of electromagnetic waves obtained by removing electromagnetic waves in a frequency band different from the frequency of electromagnetic waves emitted from the transmitting antenna from the electromagnetic waves received by a receiving antenna.
2. The method according to claim 1, wherein the entire reactance circuit is located underground.
3. The method according to claim 1, wherein the receiving antenna is a coaxial cable antenna.
4. The steps include transmitting information about electromagnetic waves obtained via a reactance circuit from the first device, The process includes the step of receiving information relating to the electromagnetic waves with a second device, The method according to any one of claims 1 to 3, wherein the step of determining the moisture content is performed by a second device based on the received information regarding electromagnetic waves.
5. The method according to any one of claims 1 to 4, wherein the electromagnetic wave is a radio broadcast wave.
6. The method according to any one of claims 1 to 5, wherein the received intensity is the ratio of the received power obtained via a reactance circuit to the transmission power for transmitting the electromagnetic waves, when the receiving antenna receives the electromagnetic waves.
7. A system comprising a first device and a second device, The first device is connected to a reactance circuit, The reactance circuit is connected to a receiving antenna installed on and near the ground surface, and has a resonant frequency that matches or approximates the frequency of the electromagnetic waves emitted from the transmitting antenna. The first device is The system includes a transmitting means that transmits information about electromagnetic waves obtained by removing electromagnetic waves in a frequency band different from the frequency of the electromagnetic waves transmitted by the transmitting antenna from the electromagnetic waves received by the receiving antenna using a reactance circuit . The second device is A receiving means for receiving information about electromagnetic waves, A system comprising a means for determining the water content below the ground surface based on information about received electromagnetic waves.
8. The first device is The device comprises a rectifier means for rectifying a current generated by receiving electromagnetic waves with a receiving antenna , which has been transmitted through a reactance circuit , and/or an amplifying means for amplifying the current, The system according to claim 7 , wherein the transmitting means transmits a signal based on a rectified and/or amplified current as information relating to an electromagnetic wave.
9. A receiving antenna that receives electromagnetic waves emitted from a transmitting antenna , A reactance circuit whose resonant frequency matches or approximates the frequency of the electromagnetic wave emitted from the transmitting antenna, A transmitting means that uses a reactance circuit to transmit information about electromagnetic waves obtained by removing electromagnetic waves in a frequency band different from the frequency of electromagnetic waves transmitted by a transmitting antenna from electromagnetic waves received by a receiving antenna. A device equipped with the following features.

Description

Applicable under Article 30, Paragraph 2 of the Patent Act. Presented on March 12, 2021, at the 2021 IEICE General Conference by Subaru Iwaki, Kota Iwamoto, Yuto Uchida, Masaya Sakamoto, and Taishi Kuroki. Presented on March 12, 2021, at the 2021 IEICE General Conference by Riku Takamatsu, Subaru Iwaki, Kota Iwamoto, Masaya Sakamoto, and Taishi Kuroki. This invention relates to methods, systems, and apparatus utilizing antennas. Conventional measures have been considered to address natural disasters such as river flooding and landslides caused by localized heavy rainfall. As a method for addressing such natural disasters, for example, it has been considered to monitor the subsurface conditions of levees across their watersheds by measuring elastic waves propagating through the ground and the water content of the ground using sensors (Patent Document 1). Furthermore, the water content of the ground is known to be extremely important information in projects such as irrigation (for example, Patent Document 2). Patent Document 1 describes methods for measuring moisture content, including determining moisture content from the magnitude of pressure within the soil, determining moisture content from the change in impedance between two electrodes buried separately in the ground, and determining moisture content from changes in dielectric constant and inductive components within the soil. Patent Document 2 also describes methods for optically measuring soil moisture content. Japanese Patent Publication No. 2000-46597Japanese Patent Publication No. 2002-65086 This is a schematic diagram of an apparatus according to an embodiment of the present invention.(a) is a schematic diagram of a reactance circuit according to an embodiment of the present invention, and (b) is a schematic circuit diagram of the reactance circuit shown in Figure 2(a).This is a schematic diagram showing the configuration of a radio wave receiving circuit element according to an embodiment of the present invention.This is an example of a graph showing the analysis results of the permeability coefficient S21 in relation to changes in water content.This graph shows the relationship between moisture content and the input impedance of a reactance circuit during resonance.This is a schematic diagram of an apparatus according to an embodiment of the present invention. The embodiments for carrying out the present invention (hereinafter referred to as "embodiments") will be described in detail below. However, the present invention is not limited to the following embodiments and can be implemented in various ways within the scope of its gist. (First Embodiment): Method for Estimating Moisture Content The first embodiment relates to a method for determining the moisture content below the ground surface by receiving electromagnetic waves with an antenna installed on or near the ground surface and according to the received intensity of the received electromagnetic waves. The received intensity is expressed as the received power when the receiving antenna receives electromagnetic waves. Figure 1 is a schematic diagram of an apparatus according to an embodiment of the present invention, and is an apparatus for carrying out the method of the first embodiment. As shown in Figure 1, the apparatus 1 of this embodiment comprises an antenna 2, a radio wave receiving circuit element 3, and a reactance circuit 4. Antenna 2 has the function of receiving electromagnetic waves. Preferably, the electromagnetic waves received by Antenna 2 are transmitted from a predetermined transmitting antenna located at a predetermined distance from Antenna 2. By specifying the received intensity at Antenna 2 for electromagnetic waves transmitted from a predetermined transmitting antenna at a specific intensity and within a specific frequency range, it is possible to estimate the moisture content of a medium such as soil or sand in the ground, or to detect that the moisture content of a medium such as soil or sand in the ground is within a predetermined range. The electromagnetic waves received by antenna 2 are not particularly limited as long waves, but from a practical standpoint, radio waves such as long waves (LF) with wavelengths of 10 to 1 km, medium waves (MF) with wavelengths of 1 km to 100 m, short waves (HF) with wavelengths of 100 to 10 m, very high frequency (VHF) with wavelengths of 10 to 1 m, extremely high frequency (UHF) with wavelengths of 1 m to 10 cm, centimeter waves (SHF) with wavelengths of 10 to 1 cm, millimeter waves (EHF) with wavelengths of 1 cm to 1 mm, and submillimeter waves with wavelengths of 1 to 0.1 mm are preferred. Among these, from the viewpoint of the electromagnetic waves penetrating deep into the water-containing soil, it is preferable that the electromagnetic waves are standard radio waves used for terrestrial television broadcasting, radio broadcasting, and standard frequency time signals. In particular, for AM radio broadcasts and standard frequen