Dielectric constant measuring device and dielectric constant measuring method

Abstract

To allow a user to measure a relative dielectric constant of a dielectric material with a simpler method.SOLUTION: In a dielectric constant measuring device 1, a dielectric material 30 is arranged between a transmission / reception unit 10 that transmits an electromagnetic wave R1 for measuring a relative dielectric constant and receives a reflection wave R2 of the electromagnetic wave R1 and a target 20 reflecting the electromagnetic wave R1. The dielectric constant measuring device measures receiving power of the electromagnetic wave R1 while changing a distance L between the transmission / reception unit 10 and the dielectric material 30, determines maximum power of the electromagnetic wave R1 and the minimum power of the electromagnetic wave, and measures the relative dielectric constant on the basis of a ratio of the minimum power of the electromagnetic wave R1 to the maximum power of the electromagnetic wave R1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dielectric constant measuring device and a dielectric constant measuring method for measuring the relative dielectric constant of a dielectric material. [Background technology]

[0002] In the development and manufacturing of radar systems, it is necessary to measure the relative permittivity of dielectric materials used in radar systems, such as radomes, which protect the radar system's antenna and reduce reflections to the antenna.

[0003] Conventionally, when measuring the relative permittivity of a dielectric material, a method has been used in which the permittivity is measured by measuring S parameters with high precision using a high-frequency probe. For example, a technique has been proposed in which a cylindrical test piece made of a dielectric material is inserted into a measuring device that measures the permittivity using a network analyzer, and the measuring device is equipped with a cylindrical circular waveguide (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-105541 Summary of the Invention [Problem to be solved by the invention]

[0005] In this method, the dielectric material to be measured must be processed to fit the measurement device, and the measurement equipment must be controlled with high precision, which results in the high cost of the measurement device.

[0006] An object of the present invention is to provide a dielectric constant measuring device and a dielectric constant measuring method that are capable of measuring the relative dielectric constant of a dielectric material using a simpler technique. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the dielectric constant measuring device of the present invention is a dielectric constant measuring device for measuring the relative dielectric constant of a dielectric material, wherein the dielectric material is arranged between a transmitter / receiver that transmits electromagnetic waves for measuring the relative dielectric constant and receives reflected waves of the electromagnetic waves, and a reflector that reflects the electromagnetic waves, and the device measures the received power of the electromagnetic waves by changing the distance between the transmitter / receiver and the dielectric material, determines the maximum power of the electromagnetic waves and the minimum power of the electromagnetic waves, and measures the relative dielectric constant based on the ratio between the maximum power of the electromagnetic waves and the minimum power of the electromagnetic waves.

[0008] The dielectric constant measuring device of the present invention may be configured such that, when the transmitter / receiver and the dielectric material are positioned, the transmitter / receiver or the dielectric material is placed on a movable sliding device, and the distance between the transmitter / receiver and the dielectric material is changed by moving the sliding device.

[0009] The dielectric constant measuring device of the present invention may be configured such that the sliding device moves the position of the transmitter / receiver or the dielectric material in distance units sufficiently shorter than half the wavelength of the electromagnetic wave (for example, 1 / 16 of the wavelength).

[0010] In the dielectric constant measuring device according to the present invention, the transmitting / receiving unit may include a planar antenna that receives a reflected wave of the electromagnetic wave.

[0011] The dielectric constant measurement method according to the present invention is a dielectric constant measurement method for measuring the relative dielectric constant of a dielectric material, characterized in that the dielectric material is placed between a transmitter / receiver that transmits electromagnetic waves for measuring the relative dielectric constant and receives reflected waves of the electromagnetic waves, and a reflector that reflects the electromagnetic waves, and includes the steps of measuring the received power of the electromagnetic waves by changing the distance between the transmitter / receiver and the dielectric material, determining the maximum power and the minimum power of the electromagnetic waves from the measurement results of the received power of the electromagnetic waves, and measuring the relative dielectric constant based on the ratio between the maximum power and the minimum power of the electromagnetic waves. [Effects of the Invention]

[0012] According to the dielectric constant measuring device and dielectric constant measuring method of the present invention, a dielectric material is placed between a transmitter / receiver that transmits electromagnetic waves for measuring the relative dielectric constant and receives reflected waves, and a reflector of the electromagnetic waves. The distance between the transmitter / receiver and the dielectric material is changed to measure the received power of the electromagnetic waves, and the maximum and minimum powers of the electromagnetic waves are determined. The relative dielectric constant is measured based on the ratio of the maximum and minimum powers of the electromagnetic waves. Therefore, there is no need to process the dielectric material to be measured, and the relative dielectric constant can be measured simply by measuring the received power of the electromagnetic waves. This makes it possible to measure the relative dielectric constant of a dielectric material using a method simpler than conventional techniques.

[0013] According to the dielectric constant measuring device of the present invention, the transmitter / receiver or the dielectric material is placed on a sliding device, and the distance between the transmitter / receiver and the dielectric material is changed by moving the sliding device, which makes it possible to control the distance by a simple method.

[0014] In the dielectric constant measuring device according to the present invention, the sliding device moves the position of the transmitter / receiver or the dielectric material in distance units that are sufficiently shorter than half the wavelength of the electromagnetic wave (for example, 1 / 16 of the wavelength), making it possible to control the distance with high precision.

[0015] According to the dielectric constant measuring device of the present invention, the transmitting / receiving unit includes a planar antenna that receives reflected electromagnetic waves. Therefore, it is possible to receive reflected waves over a wide range, thereby enabling highly accurate measurement of the relative dielectric constant of a dielectric material. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram showing the overall configuration of a dielectric constant measuring device 1 according to a first embodiment. [Figure 2] 2 is a graph showing an example of the measurement results of a reflected wave R2 by the transmitting / receiving unit 10 of FIG. [Figure 3]2 is a graph showing an example of the measurement results of a reflected wave R2 by the transmitting / receiving unit 10 of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described below based on the illustrated embodiments. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0018] (Embodiment) <1 Overall Configuration of Dielectric Constant Measuring Device 1> FIG. 1 is a schematic diagram showing the overall configuration of a dielectric constant measuring device 1 according to an embodiment. The dielectric constant measuring device 1 is a device for measuring the relative dielectric constant of a dielectric material. The dielectric constant measuring device 1 is used, for example, to measure in advance the relative dielectric constant of a dielectric material used in a radome of a radar device. As shown in FIG. 1, the dielectric constant measuring device 1 has a transmitting / receiving unit 10, a target (reflector) 20, a dielectric (dielectric material) 30, a base 40, and a processing unit 50. .

[0019] The transmitter / receiver 10 is a device for emitting electromagnetic waves R1 used to measure the relative permittivity of a dielectric material, and also a device for receiving reflected waves R2 that are generated when the emitted electromagnetic waves R1 collide with a target 20, a dielectric 30, or the like, which will be described later. The transmitter / receiver 10 may be any device capable of emitting electromagnetic waves R1 in a desired frequency band, and may be, for example, a signal generator or may be a network analyzer together with a processing unit 50, which will be described later. The electromagnetic waves R1 emitted by the transmitter / receiver 10 are, for example, radar waves in a high-frequency band exceeding 10 GHz, known as quasi-millimeter waves. However, as long as good distance resolution and sensitivity can be achieved, the electromagnetic waves R1 may be pulse waves, frequency-modulated waves, or coded pulse waves.

[0020] Since the electromagnetic wave R1 is a superposition of the reflected wave R2 and the electromagnetic wave reflected again, it may be stronger than the intensity initially sent out by the transmitting / receiving unit 10 depending on the phase relationship between them.

[0021] The transmitting / receiving unit 10 may be configured as a planar antenna in order to receive the reflected waves over a wide range.

[0022] The transmitting / receiving unit 10 is connected to a processing unit 50, which will be described later, and is controlled by the processing unit 50 to transmit an electromagnetic wave R1 and receive a reflected wave R2.

[0023] The target 20 is an object that reflects the electromagnetic wave R1 transmitted by the transmitter / receiver 10 and transmits a reflected wave R2. The target 20 may be any object that can reflect the electromagnetic wave R1 with a certain degree of reproducibility, and may be formed, for example, by a metal corner reflector.

[0024] The target 20 is placed in front of the transmitting / receiving unit 10 in the direction in which the electromagnetic wave R1 is emitted, and is placed at a predetermined distance, for example, several meters, from the transmitting / receiving unit 10.

[0025] The dielectric 30 is a dielectric material whose relative permittivity is to be measured by the dielectric constant measuring device 1. The dielectric 30 is an object whose dielectric property is superior to its electrical conductivity, and is, for example, a plastic material such as polycarbonate, ceramics, or an object coated with oil or grease. The dielectric 30 needs to be larger than the distance resolution of the electromagnetic wave R1, and is therefore formed in the shape of a flat plate with a thickness that is not significantly smaller than the distance resolution of the electromagnetic wave R1, for example, about several centimeters.

[0026] The dielectric body 30 is disposed in front of the transmitting / receiving unit 10 in the direction in which the electromagnetic wave R1 is transmitted, with the plane of the plate facing in a direction perpendicular to the transmitting direction of the electromagnetic wave R1.

[0027] The base 40 is a base for fixing the dielectric 30. The base 40 is disposed between the transmitter / receiver 10 and the target 20 with the dielectric 30 fixed thereto.

[0028] The base 40 is provided with a sliding mechanism that can move the base 40 by controlling the distance L between the transmitter / receiver 10 and the dielectric 30. This sliding mechanism is, for example, provided along the direction in which the transmitter / receiver 10 transmits the electromagnetic wave R1, and is configured by a device that can precisely control the distance L without tilting the electromagnetic wave R1 transmission surface of the transmitter / receiver 10 and the flat surface of the dielectric 30. The sliding mechanism moves its placement position in units of distances shorter than half the wavelength of the electromagnetic wave R1, because it is necessary to determine the maximum and minimum values ​​of power that change depending on the phase of the electromagnetic wave R1, as will be described later. The sliding mechanism may be configured to be controlled by the processing unit 50, for example.

[0029] It is preferable that this slide mechanism be configured to move the base 40 as described above, but it may also be configured to move the transmitter / receiver 10.

[0030] The processing unit 50 is a device that measures the electromagnetic waves R1 and the reflected waves R2, and may be configured as a computer (desktop, laptop, tablet, etc.), or may be configured as a network analyzer as described above. The processing unit 50 is connected to the transmitting / receiving unit 10 via a cable 51 as shown in FIG. 1, and acquires and analyzes measurement data of the electromagnetic waves R1 and the reflected waves R2. The processing unit 50 may also be connected to the transmitting / receiving unit 10 via wireless communication using various communication protocols.

[0031] Furthermore, the processing unit 50 may be configured to be connected to a slide mechanism capable of controlling the distance L, and to control the operation of the slide mechanism.

[0032] <2. Dielectric constant measurement> Fig. 2 is a graph showing an example of received power, which is a measurement result of the reflected wave R2 by the transmitting / receiving unit 10 of Fig. 1, with the horizontal axis representing distance and the vertical axis representing received power. Fig. 3 is a graph showing an example of received power, which is a measurement result of the reflected wave R2 by the transmitting / receiving unit 10, with the horizontal axis representing distance and the vertical axis representing signal amplitude. The principle of measurement of the relative dielectric constant of a dielectric 30 by the dielectric constant measuring apparatus 1 will be described with reference to Figs. 2 and 3.

[0033] As shown in FIG. 2, the received power of the reflected wave R2 by the transceiver 10 is represented by a waveform with peaks corresponding to the distance from the transceiver 10. Since the measurement results by the transceiver 10 also detect received power other than that of the reflected wave from the target 20, the graph shown in FIG. 2 also shows peaks other than those of the reflected wave from the target 20. Here, the distance between the transceiver 10 and the target 20 is known, and it is known that peak P1 shown in the graph of FIG. 2 is the reflected wave from the target 20. Therefore, the amplitude of the reflected wave (echo) is evaluated. The amplitude is evaluated by examining the change in amplitude while slightly changing the distance between the transceiver 10 and the dielectric 30.

[0034] The signal amplitude of the power of the reflected wave R2 from the target 20 received by the transmitter / receiver 10, as shown in Figure 3, changes with slight changes in the distance between the transmitter / receiver 10 and the dielectric 30, and this amplitude is evaluated. The signal amplitude shown in Figure 3 has a waveform that repeatedly rises and falls in a half-wavelength cycle, and in this case, the half-wavelength is 2.5 mm when the signal frequency is 60 GHz, for example. From this characteristic, the maximum value Amax and minimum value Amin of the amplitude A, which will be described later, are extracted to determine the dielectric constant.

[0035] Next, measurement of the relative dielectric constant of the dielectric (dielectric material) 30 by the dielectric constant measuring device 1 will be described.

[0036] When electromagnetic waves (radar) pass through the surface of a dielectric (dielectric 30), part of the electromagnetic wave energy is transmitted and the remaining part is reflected. The reflected electromagnetic wave energy is reflected again by the surface of the antenna (the planar antenna of the transceiver 10). The electromagnetic waves reflected by the antenna surface are combined with the electromagnetic waves radiated from the antenna at that time and propagate again toward the dielectric surface. At this time, the electromagnetic waves resulting from the multiple reflections and the electromagnetic waves radiated from the antenna are combined, and the amplitude of this combined wave differs depending on the phase difference between these signals.

[0037] The amplitude reflection of an electromagnetic wave on the surface of a dielectric material determines the reflection intensity according to the amplitude reflection coefficient r, which is expressed by the following equation: Here, n is an optical parameter called the refractive index.

number

[0038] In a typical dielectric, the refractive index n and relative dielectric constant ε r for,

number

number

number

[0039] In other words, the amplitude of the electromagnetic wave is multiplied by the above factor each time it is reflected.Since the electromagnetic wave that passes through a dielectric is a superposition of electromagnetic waves that are repeatedly reflected, the amplitude of the passing electromagnetic wave becomes a value shown in the following formula.

number

[0040] The phase rotation θ depends on the distance between the antenna and the dielectric. When θ=2nπ, the amplitude A is at its maximum value, and when θ=(2n+1)π, the amplitude A is at its minimum value. In other words, the maximum value A max and minimum value A min is expressed as the following formula:

number

[0041] Since power is proportional to the square of the amplitude, the maximum transmission power P max and the minimized transmission power P min are expressed as the following formulas, respectively:

number

[0042] Here, P0 is the radar transmission power. Calculating the ratio between the maximized and minimized transmission power from these results in the following equation, which coincides with the relative dielectric constant:

number

[0043] That is, by placing a dielectric in front of the radar antenna and measuring the fluctuations in the received power while changing the distance between the dielectric and the radar antenna, the relative dielectric constant of the dielectric can be measured. Therefore, the processing unit 50 measures the power of the electromagnetic wave R1 and the reflected wave R2, finds the maximum power and the minimum power of the electromagnetic wave R1, and measures the relative dielectric constant based on the ratio between the maximum power and the minimum power of the electromagnetic wave R1.

[0044] <3. Effects> According to the dielectric constant measuring device 1 and dielectric constant measuring method of the first embodiment, the dielectric (dielectric material) 30 to be measured is placed between the transmitter / receiver 10 and the target (reflector) 20 while being fixed to the base 40. The distance L between the transmitter / receiver 10 and the dielectric 30 is changed to measure the received power of the electromagnetic wave R1, and the maximum power P of the electromagnetic wave R1 is calculated. max and minimum power P min and calculate the maximum power P of the electromagnetic wave R1. max and minimum power P min The relative permittivity is measured based on the ratio of . Therefore, the dielectric material to be measured does not need to be processed since it is simply fixed to the base 40, and the relative permittivity can be measured simply by measuring the received power of the electromagnetic waves. This makes it possible to measure the relative permittivity of a dielectric material using a method simpler than conventional techniques.

[0045] Furthermore, the dielectric constant measuring device 1 measures the received power of the electromagnetic wave R1 by changing the distance L between the transmitting / receiving unit 10 and the dielectric 30 using a sliding mechanism. At this time, the sliding mechanism moves the placement position in distance units (e.g., 1 / 16 of the wavelength) that are sufficiently shorter than half the wavelength of the electromagnetic wave R1. Therefore, it is possible to control the distance L between the transmitting / receiving unit 10 and the dielectric 30 with high accuracy using a simple method.

[0046] Furthermore, the dielectric constant measuring device 1 has a planar antenna as the transmitting / receiving unit 10. This allows the reflected wave to be received over a wide range, enabling highly accurate measurement of the relative dielectric constant of a dielectric material.

[0047] The above describes an embodiment of the present invention, but the specific configuration is not limited to the above embodiment, and even if there are design changes within the scope of the present invention that do not deviate from the gist of the present invention, they are included in the present invention. [Explanation of symbols]

[0048] 1: Dielectric constant measuring device 10: Transmitter / receiver 20: Target 30: Dielectric 40: Pedestal 50: Processing section 51: Cable

Claims

1. A dielectric constant measuring apparatus for measuring the relative dielectric constant of a dielectric material, the dielectric material is disposed between a transceiver that transmits electromagnetic waves for measuring the relative dielectric constant and receives reflected waves of the electromagnetic waves, and a reflector that reflects the electromagnetic waves; measuring the received power of the electromagnetic waves while changing the distance between the transmitter / receiver and the dielectric material, determining the maximum power of the electromagnetic waves and the minimum power of the electromagnetic waves, and measuring the relative dielectric constant based on the ratio between the maximum power of the electromagnetic waves and the minimum power of the electromagnetic waves; A dielectric constant measuring device characterized by:

2. When arranging the transmitter / receiver and the dielectric material, the transmitter / receiver or the dielectric material is placed on a slide device that can move the arrangement position of the transmitter / receiver or the dielectric material, and the distance between the transmitter / receiver and the dielectric material is changed by moving the slide device.

2. The dielectric constant measuring device according to claim 1 .

3. the sliding device moves the arrangement position of the transmitting / receiving unit or the dielectric material in units of a distance shorter than half the wavelength of the electromagnetic wave.

3. The dielectric constant measuring device according to claim 2.

4. The transmitting / receiving unit includes a planar antenna that receives the reflected electromagnetic wave.

4. The dielectric constant measuring device according to claim 1, wherein the dielectric constant measuring device is a dielectric constant measuring device.

5. A dielectric constant measurement method for measuring the relative dielectric constant of a dielectric material, comprising: the dielectric material is disposed between a transceiver that transmits electromagnetic waves for measuring the relative dielectric constant and receives reflected waves of the electromagnetic waves, and a reflector that reflects the electromagnetic waves; measuring the received power of the electromagnetic wave by changing the distance between the transmitter / receiver and the dielectric material; determining a maximum power of the electromagnetic waves and a minimum power of the electromagnetic waves from the measurement results of the received power of the electromagnetic waves; measuring the relative permittivity based on a ratio between a maximum power of the electromagnetic wave and a minimum power of the electromagnetic wave; A dielectric constant measuring method comprising:

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