Radio wave reflection characteristic estimation device and program

Abstract

To nondestructively estimate a physical property parameter of an object for estimating reflection characteristics of a radio wave.SOLUTION: A radio wave reflection characteristic estimation device 1 comprises a calculation part 2 for calculating physical property parameters related to radio wave reflection characteristics of a target object T formed in a multilayer structure by a plurality of media. The calculation part is configured to: acquire a measurement value resulting from measurement of radio wave reflection characteristics of a reflected wave of a radio wave incident on the target object; calculate the radio wave reflection characteristics by using a multiple reflection model for estimating radio wave reflection characteristics based on multiple reflections occurring to the target object; adjust the physical property parameters set for the plurality of media included in the multiple reflection model so as to reduce a difference between a calculation value of the radio wave reflection characteristics and the measurement value; execute calculation processing for calculating the calculation value by using the multiple reflection model using the adjusted physical property parameters; repeatedly execute the calculation processing until the difference between the calculation value and the measurement value is minimized; and calculate the number of layers of the plurality of media and also calculate a physical property parameter for each layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a radio wave reflection characteristic estimation device and a program capable of estimating physical property parameters of an object.

Background Art

[0002] When predicting the quality of a communication area of a wireless network, a ray tracing method for calculating the radio wave propagation characteristics of the communication area by simulation is widely used. The ray tracing method is a simulation method that creates a three-dimensional environmental model of a communication area using a computer and calculates the radio wave propagation characteristics in the area by calculating the reflection, diffraction, and transmission of radio waves (rays). In order to perform accurate calculations using the ray tracing method, it is important to apply parameters such as the shape of an object, electrical characteristics, and thickness information of a material to create an accurate environmental model.

[0003] Conventionally, as methods for estimating the dielectric characteristics and thickness information of an object, a reflection power method and an ellipsometry method that utilize the reflection characteristics of a test radio wave irradiated from the outside are known. Non-Patent Document 1 proposes a measurement method using an ellipsometry method for measuring the complex dielectric constant of an object in the millimeter wave band. Non-Patent Document 2 proposes a method for measuring the anisotropy of the dielectric constant of an object having a multilayer structure.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

[0005] The geometric shape of an object existing in an environment can be measured using laser measurement or the like. In order to estimate the radio wave reflection characteristics of an object, it is necessary to measure the electrical characteristics of the object, the thickness information of the material, and the like. However, it is unrealistic to shave the actual object for measurement and investigate the sample of the object. Therefore, a technique for predicting the radio wave reflection characteristics of an object using a non-destructive method is required.

[0006] An object of the present invention is to provide a radio wave reflection characteristic estimation device and a program capable of non-destructively estimating physical property parameters including the dielectric characteristics and thickness information of an object for estimating the radio wave reflection characteristics. Means for Solving the Problems

[0007] One aspect of the present invention includes an arithmetic unit that calculates physical property parameters related to the radio wave reflection characteristics of an object formed in a multilayer structure by a plurality of media. The arithmetic unit acquires a measurement value obtained by measuring the radio wave reflection characteristics of the reflected wave of the radio wave incident on the object, calculates the radio wave reflection characteristics using a multiple reflection model for estimating the radio wave reflection characteristics based on multiple reflections occurring in the object, adjusts the physical property parameters set for the plurality of media included in the multiple reflection model so as to reduce the difference between the calculated value of the radio wave reflection characteristics and the measurement value, executes a calculation process for calculating the calculated value using the multiple reflection model with the adjusted physical property parameters, repeatedly executes the calculation process until the difference between the calculated value and the measurement value is minimized, calculates the number of layers of the plurality of media, and calculates the physical property parameters for each layer, which is a radio wave reflection characteristic estimation device.

Advantages of the Invention

[0008] According to the present invention, it is possible to non-destructively estimate physical property parameters such as the dielectric characteristics and thickness information of an object.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0010] As shown in FIG. 1, the radio wave reflection characteristic estimation device 1 is configured to acquire the measurement value of the object T measured by the measurement device 10. The measurement device 10, for example, radiates radio waves from the radiation unit 11 to the object T, and the receiving unit 12 receives the reflected wave reflected from the object T. The measurement device 10 is, for example, a vector network analyzer (VNA). The radiation unit 11 is constituted by, for example, a dielectric lens antenna that radiates radio waves.

[0011] The dielectric lens antenna of the radiation unit 11 is configured to synchronize the phases of the radio waves radiated from the primary radiator in front of the lens and radiate the radio waves with directivity. The receiving unit 12 is constituted by a dielectric lens antenna similar to the radiation unit 11, and is configured to receive the reflected wave having directivity generated in the object T, contrary to the radiation unit 11. The measurement device 10 measures the radio wave intensity of the radio wave received by the receiving unit 12 and outputs the measurement value to the radio wave reflection characteristic estimation device 1.

[0012] The radio wave reflection characteristic estimation device 1 executes an arithmetic process for estimating the radio wave reflection characteristic based on the acquired measurement value data. The radio wave reflection characteristic estimation device 1 is realized by, for example, an information processing device such as a personal computer. The radio wave reflection characteristic estimation device 1 includes an arithmetic unit 2 that executes an arithmetic process. The radio wave reflection characteristic estimation device 1 includes a storage unit 3 in which data and programs necessary for the arithmetic operation are stored. The arithmetic unit is configured to execute the program stored in the storage unit 3 by a hardware processor such as a CPU (Central Processing Unit), for example.

[0013] The calculation unit 2 may be implemented by hardware (including circuitry) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), GPU (Graphics Processing Unit), or may be implemented by the cooperation of software and hardware. The program may be stored in a storage device such as an HDD (Hard Disk Drive) or a flash memory that the storage unit 3 has in advance, or may be stored in a removable storage medium such as a DVD or a CD-ROM, and may be installed by mounting the storage medium on a drive device.

[0014] The radio wave reflection characteristic estimation device 1 includes an input unit 5 for inputting information necessary for calculation. The input unit 5 is constituted by, for example, a device for inputting information such as a keyboard device or a touch panel. The radio wave reflection characteristic estimation device 1 includes a display unit 4 for outputting the calculation result calculated by the calculation unit 2. The display unit 4 is constituted by, for example, a display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display. The display unit 4 may be constituted by a touch panel, and in that case, it may be configured as the input unit 5 by displaying a display image for receiving an input operation. With the above configuration, the radio wave reflection characteristic estimation device 1 calculates the radio wave reflection characteristic of the object T based on the acquired measurement value data, and displays the calculation result on the display unit 4.

[0015] FIG. 2 shows a method for measuring the object T. Using the measuring device 10, the reflected waves of radio waves incident on the object T at various incident angles θ are measured by the free space method. The measuring device 10 measures the measured values of the propagation channel of the reflected waves. The object T is, for example, a building material such as a building or a material such as furniture, and is formed in a multilayer structure by a plurality of media. Each layer of the object T is formed of media having different dielectric constants and magnetic permeabilities. When radio waves are incident on the object T from the radiation unit 11 at a predetermined incident angle (θi), the radio waves are transmitted and incident on each layer, and the radio waves are reflected by the reflection surfaces of each layer, and a plurality of reflected waves are received by the receiving unit 12.

[0016] The radiation unit 11 radiates radio waves under different polarization conditions of TE (Transverse Electric) waves and TM (Transverse Magnetic) waves. The receiving unit 12 receives the reflected waves in each polarization mode. The measuring device 10 measures the measured values related to the propagation channel such as the radio wave intensity of a plurality of reflected waves reflected from the object T via a plurality of propagation paths and the reflection angle θi at the time of reception. The measured values are output to the radio wave reflection characteristic estimation device 1.

[0017] FIG. 3 shows the radio wave reflection characteristics based on the relationship between the reflection angle (incident angle = reflection angle: θi) and the reflectivity R of the reflected waves of the object T. In the radio wave reflection characteristic estimation device 1, the calculation unit 2 calculates so as to search for the dielectric constant and magnetic permeability that fit the measurement points based on the measured values, and estimates the physical property parameters that match the radio wave reflection characteristics of the object T. Hereinafter, a method for estimating the physical property parameters of the object T will be described.

[0018] FIG. 4 shows an object T formed of a single medium M1. The object T is formed of, for example, a single medium M1 having a dielectric constant ε0. An incident wave H1 is incident on the first reflection surface #1 of the object T at a predetermined incident angle θ i Thereby being incident. The incident wave H1 is incident on the object T from the space M2 having a dielectric constant ε1. The incident wave H1 is incident in the mode of a TM wave, and a reflected wave H2 is measured in the TM wave mode. The incident wave H1 is also incident in the mode of a TE wave, and a reflected wave H2 is measured in the TE wave mode.

[0019] The incident wave H1 is reflected at the first reflection surface #1 of the object T at the reflection angle θ i to generate a reflected wave H2. A part of the incident wave H1 penetrates from the first reflection surface #1 into the medium M1 and refracts and enters. As a result, the radio wave intensity of the reflected wave H2 decreases compared to the incident wave H1.

[0020] The calculation unit 2 calculates the reflectance R of a single reflection of a radio wave (incident wave) in the TE mode input to the object T based on the Fresnel reflection model represented by the following formula (1).

Equation

[0021] The calculation unit 2 calculates the reflectance R of a single reflection of a radio wave (incident wave) in the TM mode input to the object T based on the Fresnel reflection model represented by the following formula (2).

Equation

[0022] Figure 5 shows an object T formed by two layers of media M1 and M2. The object T is formed, for example, by adding a medium M2 with a permittivity ε1 on the upper layer of a medium M1 with a permittivity ε0. The incident wave H1 is incident on the second reflection surface #2 of the added medium M2 at a predetermined incident angle θ i . The incident wave H1 is incident on the object T from the space M3 with a permittivity ε2. The incident wave H1 is incident in the mode of a TM wave, and the reflected wave H2 is measured in the TM wave mode. The incident wave H1 is also incident in the mode of a TE wave, and the reflected wave H2 is measured in the TE wave mode. The incident wave H1 is reflected at the second reflection surface #2 of the object T at the reflection angle θ i to generate a reflected wave H2.

[0023] A part of the incident wave H1 transmits from the second reflecting surface #2 into the medium M2 and refracts and enters. The radio wave incident in the medium M2 reflects at the first reflecting surface #1 of the medium M1, refracts again at the second reflecting surface #2, and is radiated into the space M3 at the reflection angle θ i and a reflected wave H3 is generated. The incident wave H1 incident on the object T formed by the two-layer media M1 and M2 generates multiple reflections by the two reflecting surfaces and reflects the two reflected waves H2 and H3. The calculation unit 2 calculates the reflectance R of the multiple reflection (two-layer) of the TM-mode radio wave (incident wave) input to the object T by the following formula (3) showing the multiple reflection model.

[0024]

Equation

Equation

[0025] Similarly, the calculation unit 2 calculates the reflectance R of the multiple reflection of the TE-mode radio wave (incident wave) input to the object T formed by m (m: natural number) layers of media by the following formula (4) showing the multiple reflection model.

Equation

Equation

Equation

[0026] The calculation unit 2 acquires, from the measurement device 10, a measurement value obtained by measuring the radio wave reflection characteristics of the reflected wave of the radio wave incident on the object T. The calculation unit 2 calculates a calculated value of the radio wave reflection characteristics using the above-described multiple reflection model based on the multiple reflections occurring in the object. The calculation unit 2 adjusts the physical property parameters set for a plurality of media included in the multiple reflection model so as to reduce the difference between the calculated value and the measurement value according to the following formula (5).

Number

Number

Number

[0027] The calculation unit 2 executes a calculation process of calculating a calculated value using the multiple reflection model with the adjusted physical property parameters. The calculation unit 2 repeatedly executes the calculation process so that the difference between the calculated value and the measurement value decreases. The calculation unit 2 calculates the number of layers of the object T by the calculation process, and calculates the physical property parameters including the complex dielectric constant and the layer thickness of the plurality of media for each layer.

[0028] The calculation unit 2 estimates the physical property parameters of the object T by the following calculation process. For example, assuming that the object T has a first reflection surface #1 (see FIG. 4), the calculation unit 2 outputs a first calculated value of the radio wave reflection characteristics (reflectivity) of the object T based on the multiple reflection model to which the initial values of the physical property parameters (ε0, ε1) are applied. The calculation unit 2 adjusts the physical property parameters (ε0, ε1) including the complex dielectric constant indicating the radio wave reflection characteristics of the object T based on single reflection and the thickness of the object T so as to minimize the difference between the measured value of the reflectivity of the object T and the first calculated value of the reflectivity calculated using the multiple reflection model based on formula (7).

[0029] The calculation unit 2 calculates a first calculated value of the radio wave reflection characteristics of the object T based on the multiple reflection model to which the adjusted physical property parameters are applied. The calculation unit 2 compares the difference between the first calculated value and the measured value with a preset threshold value. The calculation unit 2 determines whether the difference between the first calculated value and the measured value is equal to or greater than the threshold value. When the difference between the first calculated value and the measured value is equal to or greater than the threshold value, the calculation unit 2 adds a second reflecting surface #2 above the first reflecting surface #1 of the object T (see FIG. 5).

[0030] The calculation unit 2 substitutes the first calculated value of the radio wave reflection characteristics obtained by applying the physical property parameters of the previous first reflecting surface #1 into the radio wave reflection characteristics of the second reflecting surface #2, and calculates a new second calculated value of the radio wave reflection characteristics of the first reflecting surface #1. Based on Equation (7), the calculation unit 2 adjusts the physical property parameters including the complex dielectric constant indicating the radio wave reflection characteristics of the object T based on multiple reflections and the thickness of the object T so that the difference between the measured value of the reflectivity of the object T and the second calculated value of the reflectivity calculated using the multiple reflection model is minimized. The calculation unit 2 executes a calculation process of calculating a second calculated value of the radio wave reflection characteristics of the first reflecting surface of the object T based on the multiple reflection model with the adjusted new physical property parameters as the initial values.

[0031] The calculation unit 2 repeatedly executes the calculation process by adding the m-th reflecting surface up to the m-th layer where the difference between the calculated value and the measured value becomes less than the threshold value, calculates the number of layers of the plurality of media, and calculates the physical property parameters for each layer.

[0032] FIG. 6 shows the flow of the process of the radio wave reflection characteristic estimation method executed in the radio wave reflection characteristic estimation apparatus 1. The above-described radio wave reflection characteristic estimation method is executed by a program installed in a computer constituting the radio wave reflection characteristic estimation apparatus 1. The calculation unit 2 acquires a measured value of the radio wave reflection characteristics of the reflected wave of the radio wave incident on the object T (step S100). The calculation unit 2 calculates the radio wave reflection characteristics using a multiple reflection model for estimating the radio wave reflection characteristics based on the multiple reflections occurring in the object T (step S102). The calculation unit 2 adjusts the physical property parameters set for the plurality of media included in the multiple reflection model so as to reduce the difference between the calculated value of the radio wave reflection characteristics and the measured value (step S104).

[0033] The calculation unit 2 executes a calculation process of calculating the radio wave propagation characteristics using a multiple reflection model with the adjusted physical property parameters (step S106). The calculation unit 2 determines whether the difference between the calculated value and the measured value is less than the threshold value (step S108). When the difference between the calculated value and the measured value is less than the threshold value, the calculation unit 2 applies the parameters at that time, calculates the number of layers of the plurality of media, and calculates the physical property parameters for each layer (step S110).

[0034] As described above, according to the radio wave reflection characteristic estimation device 1, when creating an environmental model of a communication area used in a radio wave propagation simulation such as the ray tracing method, the physical property parameters of the object T existing in the area can be calculated. According to the radio wave reflection characteristic estimation device 1, it is possible to calculate the thickness of each layer of the object T having a multilayer structure, the physical property parameters including the complex dielectric constant, and the number of layers of each layer. According to the radio wave reflection characteristic estimation device 1, the physical property parameters of the object T can be estimated based on a non-destructive method. According to the radio wave reflection characteristic estimation device 1, it is possible to estimate the physical property parameters for performing a highly accurate radio wave propagation simulation. According to the radio wave reflection characteristic estimation device 1, it can be expected to be used for communication area design, communication simulation with a radio wave emulator, etc.

[0035] Each embodiment according to the present invention is an example and does not limit the scope of the invention. These embodiments can be implemented in various other forms. These embodiments can be variously omitted, replaced, and changed without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0036] 1 Radio wave reflection characteristic estimation device 2 Calculation unit 3 Storage unit 4 Display unit 5 Input unit 10 Measuring device 11 Radiation unit 12 Receiver T Object

Claims

1. An arithmetic unit that calculates physical property parameters related to the radio wave reflection characteristics of an object formed in a multilayer structure by a plurality of media, wherein the arithmetic unit obtains a measurement value obtained by measuring the radio wave reflection characteristics of the reflected wave of the radio wave incident on the object, calculates the radio wave reflection characteristics using a multiple reflection model for estimating the radio wave reflection characteristics based on multiple reflections occurring in the object, adjusts the physical property parameters set for the plurality of media included in the multiple reflection model so as to reduce the difference between the calculated value of the radio wave reflection characteristics and the measurement value, performs a calculation process of calculating the calculated value using the multiple reflection model using the adjusted physical property parameters, repeatedly performs the calculation process until the difference between the calculated value and the measurement value is minimized, calculates the number of layers of the plurality of media and calculates the physical property parameters for each layer, A radio wave reflection characteristic estimation device.

2. In the calculation process, the arithmetic unit calculates the physical property parameters on the first reflection surface of the object using the multiple reflection model, calculates the radio wave reflection characteristics of the first reflection surface to which the physical property parameters are applied, when the difference between the calculated value of the radio wave reflection characteristics and the measurement value is equal to or greater than a threshold value, a second reflection surface is added above the first reflection surface, applies the physical property parameters of the first reflection surface to the second reflection surface, calculates new physical property parameters of the first reflection surface, using the new physical property parameters as an initial value, performs the calculation process of calculating the calculated value of the radio wave reflection characteristics of the first reflection surface based on the multiple reflection model, adds an m-th reflection surface up to the m-th layer where the difference between the calculated value and the measurement value is less than the threshold value, repeatedly performs the calculation process, and calculates the physical property parameters, The radio wave reflection characteristic estimation device according to claim 1.

3. The arithmetic unit calculates the physical property parameters including the complex dielectric constant and the layer thickness of the medium, The radio wave reflection characteristic estimation device according to claim 1.

4. A program installed in a computer that executes a radio wave reflection characteristic estimation method for calculating physical property parameters related to the radio wave reflection characteristics of an object formed in a multilayer structure by a plurality of media, obtains a measurement value obtained by measuring the radio wave reflection characteristics of the reflected wave of the radio wave incident on the object, calculates a calculated value of the radio wave reflection characteristics using a multiple reflection model for estimating the radio wave reflection characteristics based on multiple reflections occurring in the object, Adjust the physical property parameters set for a plurality of media included in the multiple reflection model so as to reduce the difference between the calculated value and the measured value, Execute a calculation process for calculating the calculated value using the multiple reflection model with the adjusted physical property parameters, Repeatedly execute the calculation process until the difference between the calculated value and the measured value is minimized, Cause the computer to execute a process of calculating the number of layers of the plurality of media and calculating the physical property parameters for each layer, Program.

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