Dielectric constant measurement method and short circuit standard

Abstract

The present invention has a step in which a dielectric spectroscopy system (200) measures the reflection coefficient and the admittance of calibration standard bodies (P1, P2), a step in which the dielectric spectroscopy system (200) measures the reflection coefficient of a shirt-circuit grease (Ps), and a step in which the dielectric spectroscopy system (200) measures the reflection coefficient of an object being measured. The present invention furthermore has: a step in which the dielectric spectroscopy system (200) calculates the admittance of the object being measured on the basis of the reflection coefficient and admittance of the calibration standard bodies (P1, P2), the reflection coefficient of the short-circuit grease (Ps), and the reflection coefficient of the object being measured; and a step in which the dielectric spectroscopy system (200) calculates the dielectric constant of the object being measured on the basis of the admittance of the object being measured.

Description

[Technical field]

[0001] The present invention relates to a dielectric constant measuring method and a short standard used for measuring the dielectric constant. [Background technology]

[0002] Testing blood glucose levels and other constituent concentration tests requires the sampling of blood, which places a heavy burden on patients. For this reason, non-invasive constituent concentration measuring devices that do not require blood sampling have been put to practical use.

[0003] As a non-invasive element concentration measurement device, a method using electromagnetic waves in the microwave to millimeter wave band has been proposed. This method has the advantage that there is less scattering in the body and the energy of one photon is low compared to optical methods such as near-infrared light.

[0004] As a method using electromagnetic waves in the microwave to millimeter wave band, a method using a resonant structure disclosed in Non-Patent Document 1 has been proposed. In Non-Patent Document 1, a measurement sample is brought into contact with a device with a high Q value, such as an antenna or a resonator, and frequency characteristics around the resonant frequency are measured. Since the resonant frequency is determined by the complex dielectric constant around the device, the component concentration can be estimated based on the resonant frequency shift by predicting the correlation between the resonant frequency shift and the component concentration in advance.

[0005] As another method using microwave-millimeter wave electromagnetic waves, dielectric spectroscopy has been proposed as disclosed in Patent Document 1. In dielectric spectroscopy, electromagnetic waves are irradiated into the skin of a human or animal, and the electromagnetic waves are absorbed according to the interaction between the blood components to be measured, for example, glucose molecules and water, and the amplitude and phase of the electromagnetic waves are observed. A dielectric relaxation spectrum is calculated from the amplitude and phase of the observed electromagnetic waves relative to the frequency. The dielectric relaxation spectrum is generally expressed as a linear combination of relaxation curves based on the Cole-Cole equation, and a complex dielectric constant is calculated.

[0006] The complex dielectric constant correlates with the amount of blood components such as glucose and cholesterol contained in blood. A calibration model can be constructed by measuring the correlation between the change in complex dielectric constant and the component concentration in advance, and the component concentration can be calibrated based on the change in the measured dielectric relaxation spectrum. Regardless of which method is used, it is expected that the measurement sensitivity will be improved by selecting a frequency band that is highly correlated with the target component, so it is necessary to measure the change in dielectric constant in advance using broadband dielectric spectroscopy.

[0007] Among dielectric spectroscopy, the method using a coaxial probe (open-ended coaxial probe or open-ended coaxial line) as shown in Non-Patent Documents 2, 3 and Patent Document 2 can use easily available samples such as water to calibrate the measuring instrument. In addition, it is possible to measure the dielectric constant of the sample by contacting the sample to be measured with the probe end without requiring special processing of the material. For this reason, it is suitable for measuring samples such as living organisms, fruits, and soil, whose electrical properties are to be evaluated without processing them. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2013-32933 A [Patent Document 2] Patent No. 6771372 [Non-patent literature]

[0009] [Non-Patent Document 1] M. Hofmann, G. Fischer, R. Weigel, and D. Kissinger, “Microwave-Based Noninvasive Concentration Measurements for Biomedical Applications”, IEEE Trans. Microwave Theory and Techniques, Vol.61, No.5, pp. 2195-2203,2013 [Non-Patent Document 2] J P. Grant, R N. Clarke, G T. SYymm and N M. Spyrou, “A critical study of the open-ended coaxial line sensor technique for RF and microwave complex permittivity measurements”, J. Phys.E: Sci. Instrum,Vol.22, pp. 757-770,1989 [Non-Patent Document 3] TP Marsland, and S. Evans“Dielectric measurements with an open-ended coaxial probe”, IEE Proceedings, Vol. 134, No.4,1987 Summary of the Invention [Problem to be solved by the invention]

[0010] However, when measuring the dielectric constant using a coaxial probe, the measurement accuracy of the dielectric constant depends on the S11 parameter (reflection coefficient) of the calibration standard measured in advance and the short standard, which is a calibration standard having conductivity. Therefore, if the measurement surface of the probe has an uneven shape, the measurement error of the short standard may become large, resulting in a problem of reduced measurement accuracy of the dielectric constant.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dielectric constant measuring method capable of improving the measurement accuracy of the dielectric constant and a short standard body used for the dielectric constant measurement. [Means for solving the problem]

[0012] A dielectric constant measurement method of one embodiment of the present invention is a method for measuring the dielectric constant of a measurement object, comprising the steps of: a dielectric spectroscopy system measuring the reflection coefficient and admittance of at least two calibration standards; a dielectric spectroscopy system measuring the reflection coefficient of a conductive short standard; a dielectric spectroscopy system measuring the reflection coefficient of the measurement object; a dielectric spectroscopy system calculating the admittance of the measurement object based on the reflection coefficients and admittance of each calibration standard, the reflection coefficient of the short standard, and the reflection coefficient of the measurement object; and a dielectric spectroscopy system calculating the dielectric constant of the measurement object based on the admittance of the measurement object, wherein the short standard is a viscous gel.

[0013] A short standard according to one embodiment of the present invention is a short standard used when measuring the dielectric constant of a measurement object using a dielectric spectroscopy system, and is in the form of a viscous gel and has an admittance that is nearly infinite. Effect of the Invention

[0014] According to the present invention, it is possible to improve the measurement accuracy of the dielectric constant of a measurement object. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram showing the configuration of a dielectric spectroscopic sensor and its peripheral devices in which a dielectric constant measuring method according to the present embodiment is adopted. [Diagram 2] FIG. 2 is an explanatory diagram showing the configuration of the measurement probe. [Diagram 3] FIG. 3 is a flowchart showing a process procedure of the dielectric constant measuring method according to this embodiment. [Figure 4A] FIG. 4A is an explanatory diagram showing a state in which the short-circuit grease is pressed by a measurement probe. [Figure 4B] FIG. 4B is an explanatory diagram showing a state in which the short-circuit grease is pressed by the measurement probe. [Figure 5A] FIG. 5A is an explanatory diagram showing a state in which a measurement probe is brought into contact with a metal plate that is a short-circuit standard, and shows a state in which there are no irregularities on the contact surface. [Figure 5B] FIG. 5B is an explanatory diagram showing the state in which the measurement probe is brought into contact with the metal plate that is the short-circuit standard, and shows the state in which the contact surface has projections and recesses. [Figure 6A] FIG. 6A is an explanatory diagram showing a state in which a measurement probe is brought into contact with short-circuit grease, which is a short-circuit standard body, and shows a state in which there are no irregularities on the contact surface. [Figure 6B] FIG. 6B is an explanatory diagram showing the state in which the measurement probe is brought into contact with short-circuit grease, which is a short-circuit standard body, and shows a state in which there are projections and recesses on the contact surface. [Figure 7] FIG. 7 is a graph showing the change in frequency and phase of the reflected wave when the calibration standard is air and the short-circuit standard is short-circuit grease. [Figure 8] FIG. 8 is a graph showing the change in frequency and phase of the reflected wave when the calibration standard is air and the short standard is a metal plate. [Figure 9] FIG. 9 is a graph showing the change in dielectric constant of each sample with respect to the change in frequency when short-circuit grease is used as the short-circuit standard body. [Figure 10] FIG. 10 is a graph showing the change in dielectric constant of each sample with respect to the change in frequency when a metal plate is used as the short-circuit standard. [Figure 11] FIG. 11 is a block diagram showing the configuration of a dielectric spectroscopy sensor and its peripheral devices in which a dielectric constant measuring method according to a modified example of the present embodiment is adopted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Description of the embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a dielectric spectroscopic sensor and its peripheral devices in which a dielectric constant measurement method according to this embodiment is adopted. In the dielectric constant measurement method according to this embodiment, two calibration standards P1 and P2 and a short-circuit grease Ps are prepared, and a dielectric spectroscopic sensor 100 measures a reflection coefficient ρ1 of the calibration standard P1, a reflection coefficient ρ2 of the calibration standard P2, and a reflection coefficient ρs of the short-circuit grease Ps. Furthermore, a dielectric spectroscopic system 200 measures a reflection coefficient ρm of a measurement target. The dielectric spectroscopic system 200 can be, for example, a general-purpose computer system including a CPU (Central Processing Unit, processor), a memory, a storage (HDD: Hard Disk Drive, SSD: Solid State Drive), a communication device, an input device, and an output device.

[0017] For example, air or water can be used as the calibration standards P1 and P2. Alternatively, organic solvents such as alcohols can be used as the calibration standards P1 and P2. When using an organic solvent, it is advisable to select one whose dielectric constant frequency characteristics are known.

[0018] As the short-circuit grease Ps, a liquid metal type grease made of a material having conductivity close to that of a metal and properties close to that of a liquid at room temperature can be used. As the short-circuit grease Ps, for example, a liquid metal type grease containing at least one of Hg, Ga, In, Sn, Cu, and Al can be used. As the short-circuit grease Ps, other than a liquid, metal particles having a diameter of about several μm to several tens of μm may be placed in a container to give it fluidity. The short-circuit grease Ps has an admittance that is almost infinite. That is, the short-circuit grease Ps has an impedance of almost 0Ω. The short-circuit grease Ps is an example of a short-circuit standard body. The short-circuit standard body may be a material other than the short-circuit grease Ps as long as it has an admittance that is almost infinite and is a gel-like material having viscosity.

[0019] Fig. 2 is an explanatory diagram showing an example in which a coaxial measuring probe 10 is used as a dielectric spectroscopy sensor 100 used to measure a reflection coefficient. Fig. 2 shows a plan view and a cross-sectional view of the measuring probe 10. As shown in Fig. 2, the measuring probe 10 is concentric in plan view. Note that, in this embodiment, an example in which the measuring probe 10 is used as the dielectric spectroscopy sensor 100 will be described, but it is also possible to use a substrate-type sensor as the dielectric spectroscopy sensor 100.

[0020] 2, the measurement probe 10 has a conductive internal conductor 11 at the center, and a dielectric 12 is provided around the internal conductor 11 so as to be concentric with the internal conductor 11. A conductive external conductor 13 is provided around the dielectric 12 so as to be concentric with the dielectric 12. A fringe 14 is provided on the lower end surface of the measurement probe 10. The upper end surface of the measurement probe 10 is connected to a dielectric spectroscopy system 200 shown in FIG.

[0021] The fringe 14 is made of metal and ensures contact with samples such as the calibration standards P1 and P2 and the short circuit grease Ps. The fringe 14 serves to disperse pressure applied to the samples.

[0022] In the dielectric constant measuring method according to this embodiment, the admittance ym of the object to be measured is calculated by the following procedure. Furthermore, the dielectric constant εm of the object to be measured is calculated based on the calculated admittance ym. The admittance ym and the dielectric constant εm are numerical values ​​represented by complex numbers consisting of a real part and an imaginary part. The procedure for calculating the dielectric constant εm will be described below with reference to the flowchart shown in FIG.

[0023] 3, the dielectric spectroscopy system 200 applies a voltage of a predetermined frequency between the inner conductor 11 and the outer conductor 13 shown in FIG. 2 with the fringe surface of the measurement probe 10 in contact with the above-mentioned calibration standard P1, and measures the reflection coefficient ρ1. Next, with the fringe surface in contact with the calibration standard P2, a voltage of a predetermined frequency is applied between the inner conductor 11 and the outer conductor 13, and measures the reflection coefficient ρ2.

[0024] For example, when the calibration standard P1 is air, a voltage of a predetermined frequency is applied between the inner conductor 11 and the outer conductor 13 with the fringe surface placed in the air. The reflected wave at this time is transmitted to the dielectric spectroscopy system 200. The dielectric spectroscopy system 200 measures the reflection coefficient ρ1 of the calibration standard P1 based on the detected reflected wave. The reflection coefficient ρ2 of the calibration standard P2 can also be measured in a similar manner.

[0025] In step ST2, the dielectric spectroscopy system 200 applies a voltage of a predetermined frequency between the inner conductor 11 and the outer conductor 13 while the fringe surface of the measurement probe 10 is in contact with the short-circuit grease Ps, and measures the reflection coefficient ρs.

[0026] Specifically, as shown in Fig. 4A, short-circuit grease Ps is placed on the upper surface of the installation stand 20, and the fringe surface 14a of the measurement probe 10 is brought into contact with the short-circuit grease Ps. Furthermore, the fringe surface 14a presses the short-circuit grease Ps from above. As a result, as shown in Fig. 4B, the short-circuit grease Ps is deformed into a flat shape, and the short-circuit grease Ps comes into contact with the entire lower end surface of the measurement probe 10.

[0027] In this state, a voltage of a predetermined frequency is applied between the inner conductor 11 and the outer conductor 13 shown in Fig. 2. The reflected wave at this time is transmitted to the dielectric spectroscopy system 200. The dielectric spectroscopy system 200 calculates the reflection coefficient ρs of the short circuit grease Ps based on the detected reflected wave.

[0028] In step ST3, the dielectric spectroscopy system 200 applies a voltage of a predetermined frequency between the inner conductor 11 and the outer conductor 13 while the fringe surface of the measurement probe 10 is in contact with the surface of the object to be measured, and measures the reflection coefficient ρm. Note that hereinafter, the reflection coefficients ρ1, ρ2, ρs, and ρm may be referred to as "S11 parameters".

[0029] In step ST4, the dielectric spectroscopy system 200 acquires the admittances y1 and y2 of the calibration standards P1 and P2. The admittances y1 and y2 can be known from the materials of the calibration standards P1 and P2. Since the short-circuit grease Ps is a conductor, the admittance ys is almost infinite.

[0030] If the admittance of the object to be measured is ym, the following equations (1) and (2) hold.

[0031]

number

[0032]

number

[0033] "y1, y2, ys, ym" in equation (1) are linear maps of admittances, and are indicated by the same symbols as the admittances y1, y2, ys, and ym. In equation (2), "G0" is the conductance of the measurement probe 10 in a vacuum, and "C0" is the capacitance of the measurement probe 10 in a vacuum.

[0034] In step ST5, the dielectric spectroscopy system 200 substitutes the respective values ​​measured or acquired in the processes of ST1 to ST4 described above into the above formula (1).

[0035] In step ST6, the dielectric spectroscopy system 200 calculates the admittance ym of the measurement object based on the formulas (1) and (2). That is, since the admittance ys of the short circuit grease Ps can be set to "ys = ∞", the following formulas (3), (4), and (5) can be obtained from the above formulas (1) and (2).

[0036]

number

[0037]

number

[0038]

number

[0039] By substituting equation (4) into equation (5), we obtain the following equation (6).

[0040]

number

[0041] In step ST7, the dielectric spectroscopy system 200 calculates the dielectric constant εm of the measurement object by the above formula (6). As described above, the dielectric constant εm is a numerical value represented by a complex number.

[0042] As is clear from the above formulas (1) to (6), the dielectric constant εm of the measurement object is calculated based on the S11 parameters (reflection coefficients ρ1, ρ2, ρs) of the calibration standards P1 and P2 and the short circuit grease Ps. Therefore, if the S11 parameters cannot be measured accurately, the error in the dielectric constant εm increases, and high-precision measurement cannot be performed.

[0043] For this reason, when a metal having no viscosity, such as a conductive metal plate or metal piece, is used as the short standard body, the S11 parameter is measured with the fringe surface in contact with the surface of the short standard body 35 as shown in Fig. 5A. However, due to the metal processing accuracy and the shrinkage of the dielectric 12 provided in the measuring probe 10, unevenness may exist on the bottom end surface of the measuring probe 10.

[0044] 5B, for example, a gap 36 occurs between the bottom surface of the fringe 14 and the bottom surface of the measurement probe 10. In such a case, the presence of the gap 36 makes it impossible to measure the reflection coefficient of the short standard with high accuracy.

[0045] That is, in the above-mentioned formula (1), the measurement accuracy of the reflection coefficient ρs decreases, and therefore the measurement accuracy of the dielectric constant εm of the measurement object decreases.

[0046] In contrast, in the dielectric constant measurement method according to the present embodiment, a viscous gel-like short-circuit grease Ps is used as the short-circuit standard body. Therefore, when the lower end surface of the measurement probe 10 is flat, the lower end surface adheres closely to the short-circuit grease Ps without any gaps, as shown in FIG. 6A.

[0047] 6B, even if the bottom end surface of the measurement probe 10 has irregularities, the viscous gel-like short-circuit grease Ps fills the gaps created by the irregularities, so the bottom end surface of the measurement probe 10 can be tightly attached to the short-circuit grease Ps without any gaps. As a result, the measurement accuracy of the reflection coefficient ρs can be improved, and the dielectric constant εm of the measurement object can be measured with high accuracy.

[0048] FIG. 7 is a graph showing the relationship between the frequency of the voltage generated between the internal conductor 11 and the external conductor 13 of the measurement probe 10 and the phase of the reflected wave generated by the application of the voltage, where curve Q1 is a graph when air is used as the calibration standard, and curve Q12 is a graph when the short-circuit grease Ps adopted in this embodiment is used as the short-circuit standard.

[0049] FIG. 8 is a graph showing the relationship between the frequency of the voltage generated between the inner conductor 11 and the outer conductor 13 of the measurement probe 10 and the phase of the reflected wave, where curve Q11 is a graph when air is used as the calibration standard, and curve Q12 is a graph when a conventionally used short-circuiting metal plate is used as the short-circuiting standard instead of short-circuiting grease Ps.

[0050] As can be seen from curves Q11 and Q12 in Figure 8, with the conventional method, almost no phase difference occurs between the calibration standard and the short-circuit standard, and the characteristics of air that is close to a free single reflection and a short-circuit that is close to a fixed single reflection cannot be accurately measured.

[0051] In contrast, as can be seen from curves Q1 and Q2 in Figure 7, when short-circuit grease Ps is used as the short-circuit standard body, the phase is inverted by approximately 180 degrees between curves Q1 and Q2, indicating that good measurement results were obtained.

[0052] This is because even if the underside of the measurement probe 10 is not flat but has projections and recesses, the short-circuit grease Ps is present so as to fill in the spaces of the projections and recesses as shown in FIG. 6B.

[0053] Fig. 9 is a graph showing the results of measuring the dielectric constant of water and a glucose aqueous solution with a concentration of 5 [g / dL] using short-circuit grease Ps as a short-circuit standard. Fig. 10 is a graph showing the results of measuring the dielectric constant of water and a glucose aqueous solution with a concentration of 5 [g / dL] using a conductive metal plate as a short-circuit standard.

[0054] Curves q1 and q11 in Figures 9 and 10 show the theoretical value of the dielectric constant of water, curves q2 and q12 show the measured value of the dielectric constant of water, and curves q3 and q13 show the measured value of the dielectric constant of an aqueous glucose solution.

[0055] In the conventional method shown in FIG. 10, the dielectric constant q12 of water and the dielectric constant q13 of the glucose aqueous solution are almost the same, with almost no difference being obtained. Also, there is a discrepancy between the theoretical value q11 of the dielectric constant of water and the measured value q12. In contrast, when the method of this embodiment shown in FIG. 9 is employed, the measured value q2 of the dielectric constant of water is almost the same as the theoretical value q1. Also, in this embodiment, as shown by the symbol q3, the change in the dielectric constant of the glucose aqueous solution with respect to the change in frequency can be confirmed.

[0056] That is, in the dielectric constant measuring method according to this embodiment, by using the viscous gel-like short-circuit grease Ps as the short-circuit standard body, it is possible to perform dielectric spectroscopy measurement with high accuracy.

[0057] As described above, the dielectric constant measurement method according to this embodiment is a method for measuring the dielectric constant of a measurement object, and includes the steps of: the dielectric spectroscopy system 200 measuring the reflection coefficients ρ1, ρ2 and admittances y1, y2 of at least two calibration standards P1, P2; the dielectric spectroscopy system 200 measuring the reflection coefficient ρs of a conductive short standard; the dielectric spectroscopy system 200 measuring the reflection coefficient ρm of the measurement object; the dielectric spectroscopy system 200 calculating the admittance ym of the measurement object based on the reflection coefficients ρ1, ρ2 and admittances y1, y2 of each calibration standard, the reflection coefficient ρs of the short standard, and the reflection coefficient ρm of the measurement object; and the dielectric spectroscopy system 200 calculating the dielectric constant εm of the measurement object based on the admittance ym of the measurement object, wherein the short standard is a viscous gel.

[0058] In this embodiment, even if there are irregularities on the lower end surface of the measurement probe 10, by using a viscous gel-like short standard body, it is possible to fill the short standard body into the gap caused by the irregularities, and the reflection coefficient ρs of the short standard body can be measured with high accuracy.

[0059] Therefore, the dielectric constant εm of the object to be measured can be calculated with high accuracy using the above-mentioned equations (3) to (6), and the measurement accuracy of the dielectric constant εm can be improved.

[0060] By using the short-circuit grease Ps, which is a liquid metal type grease, as the short-circuit standard body, the admittance can be made almost infinite, and the measurement accuracy of the dielectric constant εm of the measurement object can be improved.

[0061] By using a liquid metal type grease containing at least one of Hg, Ga, In, Sn, Cu, and Al as the short-circuit standard, the electrical conductivity can be increased, and the measurement accuracy of the dielectric constant εm of the object to be measured can be further improved.

[0062] By using air, water, or an organic solvent as the calibration standards P1 and P2, the reflection coefficients ρ1 and ρ2 of the calibration standards P1 and P2 can be easily measured, which reduces the effort required to measure the dielectric constant of the measurement object.

[0063] [Description of Modifications] Next, a modified example of the above-mentioned embodiment will be described. Fig. 11 is a block diagram showing the configuration of a dielectric spectroscopic sensor and its peripheral devices in which a dielectric constant measurement method according to the modified example is adopted. In the dielectric constant measurement method according to the modified example, three calibration standards P1, P2, and P3 and short-circuit grease Ps are prepared, and the reflection coefficient ρ1 of the calibration standard P1, the reflection coefficient ρ2 of the calibration standard P2, and the reflection coefficient ρs of the short-circuit grease Ps are measured by the dielectric spectroscopic sensor 100. Furthermore, the reflection coefficient ρm of the measurement object is measured by the dielectric spectroscopic system 200.

[0064] By calculating the reflection coefficients using the three calibration standards P1 to P3, even if the conductance G0 and capacitance C0 shown in equation (2) are unknown values, it is possible to calculate the conductance G0 and capacitance C0 based on the reflection coefficients of each of the calibration standards P1 to P3.

[0065] That is, in the dielectric constant measuring method according to the modified example, even if the conductance G0 and the capacitance C0 of the measuring probe 10 are unknown, it is possible to measure the dielectric constant εm of the measurement object.

[0066] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0067] 10 Measuring probe 11 Inner conductor 12 Dielectrics 13 Outer conductor 14. Fringe 20 Installation stand 35 Short-circuit standard 36 void 100 Dielectric Spectroscopy Sensor 200 Dielectric Spectroscopy System P1, P2, P3 calibration standards Ps Short circuit grease

Claims

1. A method for measuring a dielectric constant of a measurement object, comprising the steps of: a dielectric spectroscopy system measuring a reflection coefficient and an admittance of at least two calibration standards; the dielectric spectroscopy system measuring the reflection coefficient of a short standard having a nearly infinite conductive admittance; measuring a reflection coefficient of the measurement object by the dielectric spectroscopy system; the dielectric spectroscopy system calculating an admittance of the measurement object based on the reflection coefficient and admittance of each calibration standard, the reflection coefficient of the short standard, and the reflection coefficient of the measurement object; The dielectric spectroscopy system calculates a dielectric constant of the measurement object based on an admittance of the measurement object, The dielectric constant measuring method, wherein the short standard body is in a viscous gel state.

2. The short circuit standard is a liquid metal type grease. The dielectric constant measuring method according to claim 1 .

3. The short circuit standard is a liquid metal type grease containing at least one of the group consisting of Hg, Ga, In, Sn, Cu, and Al. The dielectric constant measuring method according to claim 2 .

4. The calibration standard is one of air, water, and an organic solvent. The dielectric constant measuring method according to any one of claims 1 to 3.

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