Sensor device

1 . A sensor device, comprising:

a pair of antennas;

a measurement circuit that measures the amount of moisture in a medium between the pair of antennas;

a transmission path that connects the pair of antennas to the measurement circuit; and

a radio wave absorption section that is formed in the surroundings of the transmission path,

wherein the radio wave absorption section has an exterior portion of a non-tapered configuration, the exterior portion being formed with a spiral groove, and

wherein the radio wave absorption section comprises, as a component material, at least one of a magnetic material, a conductive polymer, a dielectric polymer or a metamaterial.

2 . The sensor device according to claim 1 , wherein the radio wave absorption section covers the entire transmission path.

3 . The sensor device according to claim 1 , wherein the radio wave absorption section covers a part of the transmission path.

4 . The sensor device according to claim 3 , wherein the radio wave absorption section covers the transmission path between a predetermined position in the transmission path and one end of each of the antennas.

5 . The sensor device according to claim 3 , wherein the radio wave absorption section covers the transmission path between a predetermined position separated from one end of each of the antennas and the measurement circuit.

6 . The sensor device according to claim 5 , wherein the distance from the other end of each of the antennas to the predetermined position does not exceed half a wavelength of a center frequency of electromagnetic waves transmitted and received by the pair of antennas.

7 . The sensor device according to claim 5 , wherein the distance from the other end of each of the antennas to the predetermined position does not exceed a wavelength bandwidth of electromagnetic waves transmitted and received by the pair of antennas.

8 . The sensor device according to claim 1 , further comprising:

an electronic substrate that has a pair of projecting portions,

wherein the pair of antennas and the transmission path are formed at the pair of projecting portions.

9 . The sensor device according to claim 8 , wherein the radio wave absorption section covers a distal end of each of the pair of projecting portions.

10 . The sensor device according to claim 1 , further comprising:

a first intra-probe substrate;

a second intra-probe substrate; and

a measurement section substrate that is orthogonal to the first and second intra-probe substrates,

wherein

the pair of antennas and the transmission path are formed in the first and second intra-probe substrates, and

the measurement circuit is disposed on the measurement section substrate.

11 . The sensor device according to claim 10 , wherein the radio wave absorption section covers a distal end of each of the first and second intra-probe substrates.

12 . The sensor device according to claim 10 ,

wherein electromagnetic waves are transmitted and received between one of both surfaces of the first intra-probe substrate and one of both surfaces of the second intra-probe substrate, and

the radio wave absorption section covers the other surface of the both surfaces of the first intra-probe substrate and the other surface of the both surfaces of the second intra-probe substrate.

13 . The sensor device according to claim 1 , comprising:

a plurality of pairs of the antennas,

wherein the radio wave absorption section covers the transmission path connecting each of the plurality of pairs of antennas and the measurement section.

14 . The sensor device according to claim 1 , wherein the radio wave absorption section is a layer of a radio wave absorption material embedded in a sensor casing.

15 . The sensor device according to claim 1 , further comprising:

a sensor casing,

wherein the radio wave absorption section is disposed in the sensor casing.

16 . The sensor device according to claim 15 ,

wherein a groove is formed in the sensor casing, and

a projection fitted into the groove is formed at the radio wave absorption section.

17 . The sensor device according to claim 15 ,

wherein a projection is formed at the sensor casing, and

a groove fitted onto the projection is formed at the radio wave absorption section.

18 . A sensor device, comprising:

a pair of antennas;

a measurement circuit that measures the amount of moisture in a medium between the pair of antennas;

a transmission path that connects the pair of antennas to the measurement circuit; and

a radio wave absorption section that is formed in the surroundings of the transmission path,

wherein the radio wave absorption section has a rectangular outer shape and a circular inner shape,

wherein the radio wave absorption section includes grooves formed in the rectangular outer shape at a top region and along side regions, and

wherein the radio wave absorption section comprises, as a component material, at least one of a magnetic material, a conductive polymer, a dielectric polymer or a metamaterial.

19 . A sensor device, comprising:

a pair of antennas;

a measurement circuit that measures the amount of moisture in a medium between the pair of antennas;

a transmission path that connects the pair of antennas to the measurement circuit; and

a radio wave absorption section that is formed in the surroundings of the transmission path,

wherein the radio wave absorption section has a circular outer shape and a rectangular inner shape,

wherein the radio wave absorption section includes grooves formed in the circular outer shape at a top region and along side regions, and

wherein the radio wave absorption section comprises, as a component material, at least one of a magnetic material, a conductive polymer, a dielectric polymer or a metamaterial.

20 . The sensor device according to claim 19 , wherein the radio wave absorption section covers the entire transmission path.