Dielectric spectroscopy measurement device

Abstract

A sensor unit (1) comprises: an antenna unit (110) in which an end part on the surface side of the substrate that comes into contact with a sample is an open end; an open unit (111) in which an end part on the surface side of the substrate that comes into contact with air is an open end; a short unit (112) in which a signal line and the ground are electrically connected at an end part of the surface side of the substrate; and a dielectric unit (113) in which the signal line and the ground are connected via a dielectric at an end part of the surface side of the substrate. A dielectric constant measurement unit (2) measures the reflection coefficient of each of the short unit (112), the open unit (111), the dielectric unit (113), and the antenna unit (110), and calculates the dielectric constant of the sample.

Description

Dielectric Spectroscopy

[0001] The present invention relates to a dielectric spectroscopic measuring device used for measuring component concentrations and the like.

[0002] As the aging population advances, responding to adult diseases is becoming a major issue. Tests such as blood glucose levels require blood sampling, which places a heavy burden on patients. For this reason, non-invasive constituent concentration measurement devices that do not require blood sampling are attracting attention. One such non-invasive constituent concentration measurement device that uses dielectric spectroscopy has been proposed.

[0003] Furthermore, in order to measure the performance of the device, phantoms that mimic biological tissues are being investigated. For example, a known phantom that mimics biological tissues is a highly hydrated gel phantom made from basic materials such as water, glycerol, agar, sodium chloride, TX-151, and polyethylene powder (Non-Patent Document 1). Also known is a solid phantom made from basic materials such as silicone resin, epoxy resin, polyethylene fine particles, ferroelectric ceramic filler, Aerosil (registered trademark), and carbon fiber. Gaining knowledge from these human-equivalent phantoms is expected to improve the accuracy of measurements taken on humans.

[0004] A conventional dielectric spectrometer uses a coaxial probe that irradiates an object to be measured with electromagnetic waves ranging from microwaves to millimeter waves (see Patent Document 1). The configuration of the dielectric spectrometer using a coaxial probe disclosed in Patent Document 1 is shown in Fig. 15. The dielectric spectrometer comprises a coaxial probe 1000 whose end on the sample side of the object to be measured is an open end, a sensor unit 1001, and a vector network analyzer (hereinafter referred to as VNA) 1002.

[0005] 16 , the sensor unit 1001 includes a coaxial probe 1000, a dielectric substrate 1003, a switch 1004, a load unit 1005, an RF terminal 1006, and a control terminal 1007. The coaxial probe 1000, the switch 1004, the load unit 1005, the RF terminal 1006, and the control terminal 1007 are mounted on the dielectric substrate 1003. The coaxial probe 1000 includes a plurality of coaxial probe units. The probe units include at least one antenna unit 1008, an open unit 1009, and a short unit 1010.

[0006] In microwave and millimeter-wave radio frequency (RF) technology, a known configuration is to integrate an integrated circuit (IC), an antenna, and a sensor on the same dielectric substrate to reduce insertion loss between the IC and the antenna or sensor, and multilayer wiring boards are used to optimize the layout of signal lines and power lines and reduce the board area. Vias and through-holes that penetrate the board are used as structures for transmitting RF signals between layers of a multilayer wiring board.

[0007] Patent Document 1 discloses a pseudo-coaxial line structure in which a plurality of ground vias are provided around a high-frequency signal via formed vertically penetrating from the top layer to the bottom layer of a multilayer wiring board in which conductor layers and insulator layers are alternately stacked. In the example disclosed in Patent Document 1, this pseudo-coaxial line structure is adopted to form an antenna portion 1008, an open portion 1009, and a short portion 1010.

[0008] The antenna section 1008 has a pseudo-coaxial line structure in which the end that comes into contact with the sample to be measured is an open end. The open section 1009 also has a pseudo-coaxial line structure in which the end that comes into contact with air is an open end. The short section 1010 also has a pseudo-coaxial line structure in which the center conductor and ground are electrically connected at the tip. The load section 1005 formed on the dielectric substrate 1003 is composed of a resistor formed between the signal line and ground, and terminates the signal line.

[0009] Furthermore, a switch 1004, an RF terminal 1006, and a control terminal 1007 are mounted on the dielectric substrate 1003. The antenna section 1008, the open section 1009, the short section 1010, and the load section 1005 are each connected to a selection terminal of the switch 1004. This allows the switch 1004 to select one of the antenna section 1008, the open section 1009, the short section 1010, and the load section 1005. The control terminal of the switch 1004 is connected to the control terminal 1007.

[0010] VNA 1002 outputs a control signal to switch 1004 via control terminal 1007. As a result, VNA 1002 switches switch 1004 so that one of antenna section 1008, open section 1009, short section 1010, and load section 1005 is connected to the RF terminal of VNA 1002 via RF terminal 1006. VNA 1002 connects short section 1010, open section 1009, and load section 1005 to the RF terminal of VNA 1002 in that order, and measures the reflection coefficient of each in advance. Furthermore, with the open end of antenna section 1008 in contact with the sample to be measured, VNA 1002 switches switch 1004 so that antenna section 1008 is connected to the RF terminal of VNA 1002 via RF terminal 1006, and measures the reflection coefficient of the sample. Then, VNA 1002 calculates the dielectric constant of the sample based on the reflection coefficient measured in advance and the reflection coefficient of the sample.

[0011] The dielectric spectroscopy described above has the problem that changes in the characteristics of the coaxial probe occur due to fluctuations in environmental temperature and vibrations and stresses applied to the measurement cable, resulting in drift errors in the reflection coefficient and resulting in errors when calculating the dielectric constant of the sample.

[0012] Patent No. 6771372

[0013] “Biological Tissue-Equivalent Phantoms Usable in Broadband Frequency Range”, NTT DoCoMo Technical Journal, Vol.7, No.4, 2006

[0014] The present invention has been made to solve the above-mentioned problems, and has an object to provide a dielectric spectroscopy measuring device that can reduce dielectric constant measurement errors caused by a coaxial probe.

[0015] a switch configured to selectively connect any one of the antenna unit, the open unit, the short unit, and the dielectric unit to a port of the dielectric measurement unit; and the dielectric measurement unit controls the switch to sequentially connect the short unit, the open unit, the dielectric unit, and the antenna unit to a port of the dielectric measurement unit to measure a reflection coefficient for each unit, and calculates the dielectric constant of the sample based on the known dielectric constants of the short unit, the open unit, and the dielectric unit, and the measurement result of the reflection coefficient.

[0016] According to the present invention, since the antenna section, short section, open section, and dielectric section are integrated on the same substrate, it is possible to reduce the measurement error of the dielectric constant caused by the coaxial probe. Since they are on the same substrate, the temperature difference between the antenna section, short section, open section, and dielectric section is reduced, and the calibration accuracy can be improved. Furthermore, this embodiment makes it easy to calibrate the dielectric constant measurement section at any time.

[0017] FIG. 1 is a block diagram showing the configuration of a dielectric spectroscopy measurement apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of a sensor unit according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a sensor unit according to the first embodiment of the present invention. FIG. 4 is a plan view of an antenna unit according to the first embodiment of the present invention. FIG. 5 is a bottom view of an antenna unit according to the first embodiment of the present invention. FIG. 6A is a plan view of a portion of a dielectric substrate in the first embodiment of the present invention, on which a switch, a temperature sensor, an RF terminal, a control terminal, a temperature measurement terminal, and a multilayer wiring board are mounted. FIG. 6B is a bottom view of a portion of a dielectric substrate in the first embodiment of the present invention, on which a switch, a temperature sensor, an RF terminal, a control terminal, a temperature measurement terminal, and a multilayer wiring board are mounted. FIG. 7 is a cross-sectional view of a portion of a dielectric substrate in the first embodiment of the present invention, on which a switch, a temperature sensor, an RF terminal, a temperature measurement terminal, and a multilayer wiring board are mounted. FIG. 8 is a cross-sectional view showing another configuration of a coaxial probe according to the first embodiment of the present invention. FIG. 9 is a cross-sectional view of a dielectric section according to a second embodiment of the present invention. FIG. 10 is a plan view of a dielectric section according to the second embodiment of the present invention. Fig. 11 is a cross-sectional view showing another configuration of the dielectric section according to the second embodiment of the present invention. Fig. 12 is a cross-sectional view showing another configuration of the coaxial probe according to the first and second embodiments of the present invention. Fig. 13 is a cross-sectional view showing another configuration of the coaxial probe according to the first and second embodiments of the present invention. Fig. 14 is a block diagram showing an example of the configuration of a computer that realizes the dielectric constant measuring section according to the first and second embodiments of the present invention. Fig. 15 is a block diagram showing the configuration of a conventional dielectric spectroscopy measuring device. Fig. 16 is a block diagram showing the configuration of a conventional sensor section.

[0018] [First embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows the configuration of a dielectric spectroscopy measurement device according to a first embodiment of the present invention. The dielectric spectroscopy measurement device comprises a sensor unit 1 and a dielectric constant measurement unit 2. The dielectric constant measurement unit 2 may be, for example, a vector network analyzer (VNA). The sensor unit 1 comprises a dielectric substrate 10, a coaxial probe 11, a switch 12, a temperature sensor 13 (temperature measurement unit), an RF terminal 14, a control terminal 15, and a temperature measurement terminal 16.

[0019] 2 and 3 are cross-sectional views of the sensor unit 1. The coaxial probe 11, switch 12, temperature sensor 13, RF terminal 14, control terminal 15, and temperature measurement terminal 16 are mounted on a dielectric substrate 10. However, in FIGS. 2 and 3, the switch 12, temperature sensor 13, RF terminal 14, control terminal 15, and temperature measurement terminal 16 are omitted from illustration.

[0020] The coaxial probe 11 includes multiple coaxial probe sections. As shown in Fig. 1, the probe sections include at least one antenna section 110, an open section 111, a short section 112, and a dielectric section 113. The dielectric section 113 is omitted from Fig. 2 and is shown in Fig. 3.

[0021] Patent Document 1 discloses a pseudo-coaxial line structure in which a plurality of ground vias are provided around a high-frequency signal via formed vertically penetrating from the top layer to the bottom layer of a multilayer wiring board in which conductor layers and insulator layers are alternately stacked. In this embodiment, this pseudo-coaxial line structure is adopted to form an antenna portion 110, an open portion 111, a short portion 112, and a dielectric portion 113.

[0022] The antenna unit 110 has a pseudo-coaxial line structure in which the end that comes into contact with the sample to be measured (upper side in FIG. 2) is an open end. In the antenna unit 110, a land 1100 made of a conductor is formed on the upper surface of the topmost insulator layer 22 of the multilayer wiring substrate 21, and a land 1101 made of a conductor is formed on the lower surface of the bottommost insulator layer 25. The lands 1100 and 1101 are connected by a high-frequency signal via 1102, which is a conductor that vertically penetrates the insulator layers 22 to 25 along the stacking direction of the conductor layers 26 to 30.

[0023] A conductor layer 26 serving as a ground conductor is formed in the same layer as the land 1100 but in an area outside the land 1100. The land 1100 and the conductor layer 26 are separated by a conductor removal area 1103 that is circular in plan view and has no conductor. Similarly, a conductor layer 30 serving as a ground conductor is formed in the same layer as the land 1101 but in an area outside the land 1101. The land 1101 and the conductor layer 30 are separated by a conductor removal area 1104 that is circular in plan view and has no conductor. In the present invention, the plan view is defined as the view of the sensor unit 1 from above (the sample side).

[0024] A plurality of conductor layers 27 to 29 serving as ground conductors are formed inside the multilayer wiring board 21. The layers on which the conductor layers 27 to 29 are formed have conductor removal areas 1105 that are circular in plan view and are areas without conductors and filled with dielectric. A high-frequency signal via 1102 passes through the centers of the conductor removal areas 1103 to 1105. In the antenna section 110, the conductor layers 26 to 30 are connected by a through via (through hole) 1106.

[0025] The insulator layers 22 to 25, the lands 1100 and 1101, the high-frequency signal via 1102 that vertically penetrates the insulator layers 22 to 25, the conductor layers 26 to 30 around the high-frequency signal via 1102, and the through via 1106 that connects the conductor layers 26 to 30 form a pseudo-coaxial line. The high-frequency signal via 1102 and the conductor removal areas 1103 to 1105 are circular in plan view, and the impedance of the pseudo-coaxial line can be designed according to the sample to be measured by the diameter of the high-frequency signal via 1102, the diameters of the conductor removal areas 1103 to 1105 that surround it, and the dielectric constant of the dielectric of the insulator layers 22 to 25.

[0026] The open portion 111 has a pseudo-coaxial line structure in which the end on the side in contact with air (upper side in FIG. 2 ) is an open end. In the open portion 111, an opening 1117 (recess) which is a removed area having a circular shape in plan view is formed in the uppermost conductor layer 26 and insulator layer 22 of the multilayer wiring board 21 so that the lower insulator layer 23, conductor layer 27, and high-frequency signal via 1112 are exposed to the air. A land 1111 made of a conductor is formed on the underside of the lowermost insulator layer 25. A high-frequency signal via 1112 which is a conductor that vertically penetrates the insulator layers 23 to 25 along the stacking direction of the conductor layers 26 to 30 is formed so as to be connected to the land 1111.

[0027] The land 1111 and the conductor layer 30 are separated by a conductor removal area 1113 that is circular in plan view and has no conductor. The high-frequency signal via 1112 and the conductor layer 27 are separated by a conductor removal area 1114 that is circular in plan view and has no conductor. In the open portion 111, the layer on which the conductor layers 28 and 29 are formed has a conductor removal area 1115 that is circular in plan view and has no conductor and is filled with a dielectric. The high-frequency signal via 1112 passes through the centers of the conductor removal areas 1113 to 1115. In the open portion 111, the conductor layers 27 to 30 are connected by a through via 1116.

[0028] The insulator layers 23 to 25, the land 1111, the high-frequency signal via 1112 that vertically penetrates the insulator layers 23 to 25, the conductor layers 27 to 30 around the high-frequency signal via 1112, and the through via 1116 that connects the conductor layers 27 to 30 form a pseudo-coaxial line.

[0029] The short-circuit portion 112 has a pseudo-coaxial line structure in which the center conductor (high-frequency signal via) and ground are electrically connected at the tip. In the short-circuit portion 112, a land 1120 made of a conductor is formed on the underside of the lowest insulator layer 25 of the multilayer wiring substrate 21. The conductor layer 27 and the land 1120 are connected by a high-frequency signal via 1121, which is a conductor that vertically penetrates the insulator layers 23 to 25 along the stacking direction of the conductor layers 26 to 30.

[0030] The land 1120 and the conductor layer 30 are separated by a conductor removal area 1122 that is circular in plan view and has no conductor. In the short section 112, the layer on which the conductor layers 28 and 29 are formed has a conductor removal area 1123 that is circular in plan view and is an area filled with a dielectric and has no conductor. The high-frequency signal via 1121 passes through the centers of the conductor removal areas 1122 and 1123. In the short section 112, the conductor layers 27 to 30 are electrically connected by a through via 1124.

[0031] The insulator layers 23 to 25, the land 1120, the high-frequency signal via 1121 that vertically penetrates the insulator layers 23 to 25, the conductor layers 28 to 30 around the high-frequency signal via 1121, and the through via 1124 that connects the conductor layers 27 to 30 form a pseudo-coaxial line. In the short portion 112, the phase of the incident signal is inverted and the signal is almost totally reflected.

[0032] 3, the dielectric portion 113 has a pseudo-coaxial line structure in which the center conductor (high-frequency signal via) and ground are connected by a dielectric at the tip. In the dielectric portion 113, a land 1130 made of a conductor is formed on the upper surface of the topmost insulator layer 22 of the multilayer wiring substrate 21, and a land 1131 made of a conductor is formed on the lower surface of the bottommost insulator layer 25. The lands 1130 and 1131 are connected by a high-frequency signal via 1132, which is a conductor that vertically penetrates the insulator layers 22 to 25 along the stacking direction of the conductor layers 26 to 30.

[0033] The land 1130 and the conductor layer 26 are separated by a conductor removal area 1133 that is circular in plan view and has no conductor. The land 1131 and the conductor layer 30 are separated by a conductor removal area 1134 that is circular in plan view and has no conductor. In the dielectric section 113, the layer on which the conductor layers 27 to 29 are formed has a conductor removal area 1135 that is circular in plan view and is a region that has no conductor and is filled with a dielectric. The high-frequency signal via 1132 passes through the centers of the conductor removal areas 1133 to 1135. In the dielectric section 113, the conductor layers 26 to 30 are connected by a through via (through hole) 1136.

[0034] The insulator layers 22 to 25, the lands 1130 and 1131, the high-frequency signal via 1132 that vertically passes through the insulator layers 22 to 25, the conductor layers 26 to 30 around the high-frequency signal via 1132, and the through via 1136 that connects the conductor layers 26 to 30 form a pseudo-coaxial line. A dielectric 1137 is formed on the land 1130 and the conductor layer 26.

[0035] Pads 40 to 43 made of conductors and a conductor layer 46 serving as a ground conductor are formed on the upper surface of the dielectric substrate 10. The pads 40 to 43 are separated from the conductor layer 46 by conductor removal areas 47 to 50 that are circular in plan view and have no conductor. Pads 51 to 54 made of conductors and a conductor layer 55 that serves as a ground conductor are formed on the lower surface of the dielectric substrate 10. The pads 51 to 54 are separated from the conductor layer 55 by conductor removal areas 56 to 59 that are circular in plan view and have no conductor.

[0036] The pads 40 and 51 are connected by a high-frequency signal via 60, which is a conductor that penetrates vertically through the dielectric substrate 10. The conductor layers 46 and 55 are connected by a through-hole 64, which is a conductor that penetrates vertically through the dielectric substrate 10. The dielectric substrate 10, the pads 40 and 51, the high-frequency signal via 60, the conductor layers 46 and 55 around the high-frequency signal via 60, and the through-hole 64 connecting the conductor layers 46 and 55 form a pseudo-coaxial line. Figure 4 is a plan view of the antenna unit 110, and Figure 5 is a bottom view of the antenna unit 110. In Figure 5, reference numeral 120 denotes a microstrip line connected to the pad 51 of the antenna unit 110.

[0037] The pads 41 and 52 are connected by a high-frequency signal via 61, which is a conductor that penetrates vertically through the dielectric substrate 10. The dielectric substrate 10, the pads 41 and 52, the high-frequency signal via 61, the conductor layers 46 and 55 around the high-frequency signal via 61, and the through via 64 that connects the conductor layers 46 and 55 together form a pseudo-coaxial line.

[0038] The pads 42 and 53 are connected by a high-frequency signal via 62, which is a conductor that penetrates vertically through the dielectric substrate 10. The dielectric substrate 10, the pads 42 and 53, the high-frequency signal via 62, the conductor layers 46 and 55 around the high-frequency signal via 62, and the through via 64 that connects the conductor layers 46 and 55 together form a pseudo-coaxial line.

[0039] The pads 43 and 54 are connected by a high-frequency signal via 63, which is a conductor that penetrates vertically through the dielectric substrate 10. The dielectric substrate 10, the pads 43 and 54, the high-frequency signal via 63, the conductor layers 46 and 55 around the high-frequency signal via 63, and the through via 64 that connects the conductor layers 46 and 55 together form a pseudo-coaxial line.

[0040] The land 1101 and pad 40, the land 1111 and pad 41, the land 1120 and pad 42, the land 1131 and pad 43, and the conductor layer 30 and conductor layer 46 are connected by solder 65. In this way, the multilayer wiring board 21 having the antenna portion 110, the open portion 111, the short portion 112, and the dielectric portion 113 formed therein is mounted on the dielectric substrate 10.

[0041] Furthermore, a switch 12, a temperature sensor 13, an RF terminal 14, a control terminal 15, and a temperature measurement terminal 16 are mounted on the dielectric substrate 10. Fig. 6A is a plan view of a portion of the dielectric substrate 10 on which the switch 12, the temperature sensor 13, the RF terminal 14, the control terminal 15, the temperature measurement terminal 16, and the multilayer wiring board 21 are mounted, and Fig. 6B is a bottom view of the same portion as Fig. 6A . Fig. 7 is a cross-sectional view of a portion of the dielectric substrate 10 on which the switch 12, the temperature sensor 13, the RF terminal 14, the temperature measurement terminal 16, and the multilayer wiring board 21 are mounted. Note that in Figs. 6A and 6B, the antenna portion 110, the open portion 111, the short portion 112, and the dielectric portion 113 are positioned differently from Figs. 2 and 3 to make the arrangement of each portion easier to understand.

[0042] In this embodiment, a recess 133 is formed on a side surface of the multilayer wiring substrate 21. For example, a support member 134 fixed to the insulator layer 22 of the multilayer wiring substrate 21 supports the temperature sensor 13 so that the temperature sensor 13 is accommodated in the recess 133. The temperature measurement terminal 16 mounted on the dielectric substrate 10 and the temperature sensor 13 are connected by wiring 132. The temperature sensor 13 may be, for example, a thermistor, a thermocouple, a platinum resistor, or an IC (Integrated Circuit) temperature sensor.

[0043] On the other hand, a switch 12, an RF terminal 14, and a control terminal 15 are mounted on the lower surface of the dielectric substrate 10. A pad 51 of the antenna section 110 and a first selection terminal of the switch 12 are connected by a microstrip line 120 made of a conductor. A pad 52 of the open section 111 and a second selection terminal of the switch 12 are connected by a microstrip line 121 made of a conductor. A pad 53 of the short section 112 and a third selection terminal of the switch 12 are connected by a microstrip line 122 made of a conductor. A pad 54 of the dielectric section 113 and a fourth selection terminal of the switch 12 are connected by a microstrip line 123 made of a conductor. The RF terminal 14 and an input terminal of the switch 12 are connected by a microstrip line 124. The control terminal 15 and a control terminal of the switch 12 are connected by a microstrip line 125.

[0044] Next, measurement of the complex dielectric constant of a sample will be described. The dielectric constant measurement unit 2 outputs a control signal to the switch 12 via the control terminal 15. As a result, the dielectric constant measurement unit 2 switches the switch 12 so that one of the short portion 112, the open portion 111, and the dielectric portion 113 is connected to a port of the dielectric constant measurement unit 2 via the RF terminal 14. The dielectric constant measurement unit 2 connects the open portion 111 to the port of the dielectric constant measurement unit 2 and outputs an RF signal, and calculates the reflection coefficient of the open portion 111 (air) based on the voltage amplitude and phase of the reflected wave reflected by the open portion 111 and the voltage of the incident wave measured by the dielectric constant measurement unit 2.

[0045] Similarly, the dielectric constant measuring unit 2 connects the short portion 112 to a port of the dielectric constant measuring unit 2 and outputs an RF signal, and calculates the reflection coefficient of the short portion 112 (the metal constituting the conductor layer 27) based on the voltage amplitude and phase of the reflected wave reflected by the short portion 112 and the voltage of the incident wave measured by the dielectric constant measuring unit 2. Furthermore, the dielectric constant measuring unit 2 connects the dielectric portion 113 to a port of the dielectric constant measuring unit 2 and outputs an RF signal, and calculates the reflection coefficient of the dielectric portion 113 (dielectric 1137) based on the voltage amplitude and phase of the reflected wave reflected by the dielectric portion 113 and the voltage of the incident wave measured by the dielectric constant measuring unit 2.

[0046] Next, with the open end of the antenna unit 110 in contact with the sample to be measured, the dielectric constant measuring unit 2 outputs a control signal to the switch 12 via the control terminal 15. As a result, the dielectric constant measuring unit 2 switches the switch 12 so that the antenna unit 110 is connected to the port of the dielectric constant measuring unit 2 via the RF terminal 14. The dielectric constant measuring unit 2 outputs an RF signal to apply an electric field to the sample from the antenna unit 110, and calculates the reflection coefficient of the sample based on the voltage amplitude and phase of the reflected wave reflected by the sample and the voltage of the incident wave measured by the dielectric constant measuring unit 2. The complex dielectric constant can be calculated from the measured reflection coefficient as follows:

[0047]

[0048] where ε ＊ is the dielectric constant of the sample, ε Ａ ＊ is the known permittivity of air, ε Ｂ ＊ is the known dielectric constant of the metal constituting the conductor layer 27, ε Ｃ ＊ is the known dielectric constant of the dielectric 1137. ＊ is the complex reflection coefficient, and the reflection coefficient obtained by measurement is Γ ｉ , the phase is φ ｉ Then, it is expressed by the following equation (2).

[0049]

[0050] ρ Ａ ＊ is the measurement result for the open portion 111, and ρＢ ＊ is the measurement result for the short circuit part 112, and ρ Ｃ ＊ is the measurement result for the dielectric portion 113, and ρ ＊ correspond to the measurement results of the sample. In this way, the dielectric constant measuring unit 2 can calculate the complex dielectric constant of the sample from the measurement results of the reflection coefficients of the open portion 111, the short portion 112, and the dielectric portion 113 measured in advance, the measurement result of the reflection coefficient of the antenna portion 110, and the known complex dielectric constants of the open portion 111 (air), the short portion 112 (metal constituting the conductor layer 27), and the dielectric portion 113 (dielectric 1137).

[0051] Moreover, the complex dielectric constant of the dielectric 1137 changes depending on the temperature. Therefore, the temperature characteristic of the complex dielectric constant of the dielectric 1137 is measured in advance. The dielectric constant measuring unit 2 corrects the complex dielectric constant of the dielectric 1137 based on the temperature characteristic of the complex dielectric constant of the dielectric 1137 and the ambient temperature measured by the temperature sensor 13. In this way, the dielectric constant measuring unit 2 can calculate the complex dielectric constant of the sample by using the corrected complex dielectric constant of the dielectric 1137.

[0052] As described above, in this embodiment, the antenna portion 110, the short portion 112, the open portion 111, and the dielectric portion 113 are integrated on the same substrate, thereby reducing drift errors caused by the coaxial probe. Since they are on the same substrate, the temperature difference between the antenna portion 110, the short portion 112, the open portion 111, and the dielectric portion 113 is reduced, thereby improving calibration accuracy. Furthermore, this embodiment facilitates the calibration of the dielectric constant measurement portion 2 (measurement of the reflection coefficients of the short portion 112, the open portion 111, and the dielectric portion 113) at any time. Calibration may be performed, for example, after each sample measurement, at regular intervals, or according to user instructions. As a result, this embodiment enables wideband data acquisition while reducing drift errors caused by environmental fluctuations and changes in the state of the sample over time.

[0053] Furthermore, in this embodiment, the complex dielectric constant of the sample can be corrected based on the temperature measured by the temperature sensor 13. As a result, in this embodiment, it is possible to reduce measurement errors in the dielectric constant due to temperature changes.

[0054] The microstrip lines 120 to 125 on the dielectric substrate 10 are made of a metal material, for example, with a conductor width of 100 to 300 μm and spacing of 50 μm, such as Au, Cu, or Al.

[0055] The multilayer wiring substrate 21 is, for example, several centimeters by several centimeters square and has a thickness of 10 to 500 μm. Materials for the insulator layers 22 to 25 (dielectrics) include FR4 (Flame Retardant Type 4), Megtron 6 (registered trademark), Teflon (registered trademark), LCP (Liquid Crystal Polymer), polyimide, LTCC (Low Temperature Co-fired Ceramics), etc.

[0056] In this embodiment, one antenna portion 110 is formed on the coaxial probe 11, but multiple antenna portions 110 may be formed, each having a different shape, which allows the antenna portion 110 to be selected depending on the target sample.

[0057] Similarly, multiple dielectric sections may be formed in the coaxial probe 11, with each dielectric section being made of a material with a different dielectric constant. A cross-sectional view of the coaxial probe 11 having multiple dielectric sections is shown in FIG. 8. In the dielectric section 114, a land 1140 made of a conductor is formed on the upper surface of the topmost insulator layer 22 of the multilayer wiring substrate 21, and a land 1141 made of a conductor is formed on the lower surface of the bottommost insulator layer 25. The lands 1140 and 1141 are connected by a high-frequency signal via 1142, which is a conductor that vertically penetrates the insulator layers 22 to 25 along the stacking direction of the conductor layers 26 to 30.

[0058] The land 1140 and the conductor layer 26 are separated by a conductor removal area 1143 that is circular in plan view and has no conductor. The land 1141 and the conductor layer 30 are separated by a conductor removal area 1144 that is circular in plan view and has no conductor. In the dielectric section 114, the layer on which the conductor layers 27 to 29 are formed has a conductor removal area 1145 that is circular in plan view and is a region that is filled with a dielectric and has no conductor. The high-frequency signal via 1142 passes through the centers of the conductor removal areas 1143 to 1145. In the dielectric section 114, the conductor layers 26 to 30 are connected by a through via (through hole) 1146.

[0059] The insulator layers 22 to 25, the lands 1140 and 1141, the high-frequency signal via 1142 that vertically passes through the insulator layers 22 to 25, the conductor layers 26 to 30 around the high-frequency signal via 1142, and the through via 1146 that connects the conductor layers 26 to 30 form a pseudo-coaxial line. A dielectric 1147 is formed on the land 1140 and the conductor layer 26.

[0060] A pad 66 made of a conductor and a conductor layer 46 serving as a ground conductor are formed on the upper surface of the dielectric substrate 10. The pad 66 and the conductor layer 46 are separated by a conductor removal area 67 that is circular in plan view and has no conductor. A pad 68 made of a conductor and a conductor layer 55 serving as a ground conductor are formed on the lower surface of the dielectric substrate 10. The pad 68 and the conductor layer 55 are separated by a conductor removal area 69 that is circular in plan view and has no conductor.

[0061] The pads 66 and 68 are connected by a high-frequency signal via 70, which is a conductor that penetrates vertically through the dielectric substrate 10. The dielectric substrate 10, the pads 66 and 68, the high-frequency signal via 70, the conductor layers 46 and 55 around the high-frequency signal via 70, and the through via 64 that connects the conductor layers 46 and 55 form a pseudo-coaxial line. The land 1141 and the pad 66 are connected by solder 65.

[0062] Second Embodiment Figure 9 is a cross-sectional view of a dielectric section according to a second embodiment of the present invention. In this embodiment, in dielectric section 113, conductor layers 26 and 27 and insulator layers 22 and 23 of multilayer wiring substrate 21 are removed to form cavity 1138, which is a rectangular recess in plan view for accommodating dielectric 1137. Land 1150 made of a conductor is formed on the upper surface of insulator layer 24 exposed at the bottom of cavity 1138, and land 1131 made of a conductor is formed on the lower surface of bottom-most insulator layer 25. Lands 1150 and 1131 are connected by high-frequency signal via 1132, which is a conductor that vertically penetrates insulator layers 24 and 25 along the stacking direction of conductor layers 26 to 30.

[0063] The land 1150 and the conductor layer 28 are separated by a conductor removal area 1151 that is circular in plan view and has no conductor. The land 1131 and the conductor layer 30 are separated by a conductor removal area 1134 that is circular in plan view and has no conductor. In the dielectric section 113, the layer on which the conductor layer 29 is formed has a conductor removal area 1135 that is circular in plan view and is a region that has no conductor and is filled with a dielectric. The high-frequency signal via 1132 passes through the centers of the conductor removal areas 1134, 1135, and 1151. In the dielectric section 113, the conductor layers 28 to 30 are connected by a through via (through hole) 1136.

[0064] The insulator layers 24 and 25, the lands 1131 and 1150, the high-frequency signal via 1132 that vertically penetrates the insulator layers 24 and 25, the conductor layers 28 to 30 around the high-frequency signal via 1132, and the through via 1136 that connects the conductor layers 28 to 30 form a pseudo-coaxial line. A dielectric 1137 is formed on the conductor layer 28 and the land 1150 that are exposed at the bottom surface of the cavity 1138. The cavity 1138 is sealed by a sealing window 1139 made of, for example, glass. The sealing window 1139 can be fixed, for example, by bonding the sealing window 1139 to the conductor layer 26.

[0065] Fig. 10 is a plan view of the dielectric portion 113 of this embodiment. Although Fig. 9 and Fig. 10 only show the configuration of the dielectric portion 113, the configuration of the dielectric spectroscopy measurement device other than the dielectric portion 113 is the same as that of the first embodiment.

[0066] 3 and 8, the dielectrics 1137 and 1147 are formed on the surface of the coaxial probe 11, and therefore the dielectrics 1137 and 1147 may interfere with contact between the antenna portion 110 and the sample. On the other hand, in this embodiment, the dielectric 1137 is formed inside the cavity 1138, which eliminates irregularities on the surface of the coaxial probe 11, thereby facilitating contact between the antenna portion 110 and the sample.

[0067] 9 and 10, there is a gap in cavity 1138, but as shown in Fig. 11, cavity 1138 may be filled with dielectric 1137. The dielectrics 1137 and 1147 used in the first and second embodiments are, for example, resin compositions made by mixing binder resin and alumina filler.

[0068] In the first and second embodiments, the microstrip lines 120 to 123 connecting the coaxial probe 11 and the switch 12 are formed on the bottom surface of the dielectric substrate 10, but they may also be formed on the top surface of the dielectric substrate 10. Cross-sectional views of this case are shown in Figures 12 and 13. The pad 40 of the antenna section 110 and the first selection terminal of the switch 12, the pad 41 of the open section 111 and the second selection terminal of the switch 12, the pad 42 of the short section 112 and the third selection terminal of the switch 12, and the pad 43 of the dielectric section 113 and the fourth selection terminal of the switch 12 are each connected by a microstrip line formed on the top surface of the dielectric substrate 10. The pads 51 to 54 and the high-frequency signal vias 60 to 63 are no longer necessary.

[0069] In addition, in the first and second embodiments, the temperature sensor 13 is housed in the recess 133 on the side surface of the multilayer wiring board 21, but it is also possible to form a through hole that penetrates the conductor layers 26 to 30 and the insulator layers 22 to 25, and house the temperature sensor 13 in the through hole.

[0070] The dielectric constant measuring unit 2 described in the first and second embodiments can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in FIG.

[0071] The computer includes a CPU 300, a storage device 301, a communication device 303, a transmitter 302, a receiver 304, a directional coupler 305, a power supply 306, a transformer 307, and a regulator 308. The transmitter 302 and the receiver 304 are connected to the sensor unit 1 via the directional coupler 305. Electromagnetic waves in the microwave band generated by the transmitter 302 are irradiated onto the measurement sample. A signal reflected from the measurement sample is input from the sensor unit 1 via the directional coupler 305 to the receiver 304, converted into a digital signal, and then read by the CPU 300. The CPU 300 outputs a control signal to the sensor unit 1 and controls the switch 12 to sequentially read the reflected signals from the antenna unit 110, the short portion 112, the open portion 111, and the dielectric portion 113.

[0072] In such a computer, a program for implementing the dielectric spectroscopy measurement method of the present invention is stored in a storage device 301. A CPU 300 executes the control and arithmetic processing described in the first and second embodiments in accordance with the program stored in the storage device 301. The reflection coefficient and dielectric constant obtained by the processing are transmitted to an external computer by a communication device 303 connected to the CPU 300. For example, a frequency synthesizer using a phase-locked loop is used as the transmitter 302. For example, a double-balanced mixer is used as the receiver 304. A circulator may be used instead of the directional coupler 305.

[0073] While the example in Figure 14 shows an example of a direct conversion transmission / reception configuration, a low IF (Intermediate Frequency) transmission / reception configuration may also be adopted by adding a transmitter with a slightly different transmission frequency. The power supply 306 supplies power to each device. For example, a DC-DC converter is used as the transformer 307. The regulator 308 converts the input voltage from the transformer 307 to the desired voltage. A linear regulator that can operate even with a low input / output potential difference is used as the regulator 308. A lithium-ion battery or the like is used as the power supply 306.

[0074] Some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0075] a switch configured to selectively connect any one of the antenna unit, the open unit, the short unit, and the dielectric unit to a port of the dielectric measurement unit; and the dielectric measurement unit controls the switch to sequentially connect the short unit, the open unit, the dielectric unit, and the antenna unit to a port of the dielectric measurement unit to measure a reflection coefficient for each unit, and calculates the dielectric constant of the sample based on the known dielectric constants of the short unit, the open unit, and the dielectric unit, as well as the measurement results of the reflection coefficient.

[0076] (Supplementary Note 2) In the dielectric spectroscopy measurement device according to Supplementary Note 1, the dielectric is formed on a surface of the substrate.

[0077] (Supplementary Note 3) In the dielectric spectroscopy measurement device according to Supplementary Note 1, the dielectric is accommodated in a recess formed in the surface of the substrate.

[0078] (Supplementary Note 4) The dielectric spectroscopy measuring apparatus according to Supplementary Note 1 further includes a temperature measuring unit arranged inside or around the substrate, and the dielectric constant measuring unit calculates the complex dielectric constant of the sample after correcting the dielectric constant of the dielectric based on the known temperature characteristics of the dielectric constant of the dielectric and the ambient temperature measured by the temperature measuring unit.

[0079] (Appendix 5) In the dielectric spectroscopy measurement device described in Appendix 1, each of the antenna portion, the open portion, the short portion, and the dielectric portion has a coaxial line structure in which a ground conductor is arranged around a center conductor which is a signal line.

[0080] 1...sensor part, 2...dielectric constant measuring part, 10...dielectric substrate, 11...coaxial probe, 12...switch, 13...temperature sensor, 14...RF terminal, 15...control terminal, 16...temperature measurement terminal, 21...multilayer wiring board, 110...antenna part, 111...open part, 112...short part, 113, 114...dielectric part, 1137, 1147...dielectric, 1138...cavity, 1139...sealing window.

Claims

a switch configured to selectively connect any one of the antenna unit, the open unit, the short unit, and the dielectric unit to a port of the dielectric measurement unit; and the dielectric measurement unit controls the switch to sequentially connect the short unit, the open unit, the dielectric unit, and the antenna unit to a port of the dielectric measurement unit to measure the reflection coefficient of each unit, and calculate the dielectric constant of the sample based on the known dielectric constants of the short unit, the open unit, and the dielectric unit and the measurement result of the reflection coefficient.

2. A dielectric spectroscopy measuring device according to claim 1, wherein the dielectric is formed on the surface of the substrate.

3. A dielectric spectroscopy measuring device according to claim 1, characterized in that the dielectric is accommodated in a recess formed in the surface of the substrate.

4. A dielectric spectroscopy measuring apparatus according to claim 1, further comprising a temperature measuring unit arranged inside or around the substrate, wherein the dielectric constant measuring unit calculates the complex dielectric constant of the sample after correcting the dielectric constant of the dielectric based on the known temperature characteristics of the dielectric constant of the dielectric and the ambient temperature measured by the temperature measuring unit.

5. A dielectric spectroscopy measuring device according to claim 1, characterized in that the antenna section, the open section, the short section and the dielectric section each have a coaxial line structure in which a ground conductor is arranged around a central conductor which is a signal line.

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