Evaluation device, evaluation method for evaluating radiation disturbance wave and anechoic box

Abstract

To provide an evaluation device and an evaluation method for radiation disturbance waves, and an anechoic box capable of obtaining measurement results in which the influence of dips occurring in measurement values is suppressed, in a simplified measurement method different from the measurement method compliant with CISPR 25.SOLUTION: An evaluation device 1 comprises: a test table 2 on which a wire harness 100 is placed; an antenna 3 which is disposed at a predetermined distance D1 from the wire harness 100 to receive electromagnetic waves; moving means 4 which moves the antenna 3 horizontally at the predetermined distance D1; measuring means 5 which measures transmission characteristics between the wire harness 100 and the antenna 3; dip reduction means 6 which calculates a composite value being a value in which dips in the frequency spectrum of the measurement values are reduced on the basis of measurement values of the transmission characteristics measured by the measuring means 5; and calculating means 7 which calculates an evaluation value of radiation disturbance waves emitted from the wire harness 100 on the basis of the composite value calculated by the dip reduction means 6.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an evaluation device, an evaluation method, and an anechoic box for evaluating radiated interference waves emitted from a measurement object. [Background technology]

[0002] In recent years, technological advances in the electrification and autonomous driving of automobiles have been remarkable. For example, the so-called EV (electric vehicle) shift, which aims to convert conventional automobiles to electric vehicles powered by motors, and the development of automobiles equipped with autonomous driving technology are progressing. To realize these advances, automobiles must be controlled by electronic devices installed in automobiles (hereinafter referred to as "on-board equipment"). For example, automobile collision prevention is controlled by various on-board devices that make up positioning systems using millimeter-wave radar and LiDAR (light detection and ranging). Because such on-board equipment is involved in automobile control, malfunctions of such devices could lead to accidents. Therefore, to ensure automobile safety, on-board equipment must have a certain level of electromagnetic compatibility (EMC; hereinafter, "EMC" refers to "EMC").

[0003] EMC testing is essential to ensure that in-vehicle equipment complies with EMC standards. EMC testing includes EMI (Electromagnetic Interference) testing, which measures unwanted electromagnetic waves emitted as radiated disturbances, and EMS (Electromagnetic Susceptibility) testing, which measures resistance to external electromagnetic waves. Regarding emissions related to in-vehicle equipment, the international standard CISPR25 (Limits and Measurement Methods for Disturbances for the Protection of In-Vehicle Receivers) was created by the International Special Committee on Radio Interference (CISPR) and defines the measurement methods and allowable values for radiated disturbances. The CISPR25 emissions standard consists of conducted and radiated emission measurements, and the measurement frequency range is 150 kHz to 5925 MHz. In-vehicle equipment is designed and measured in accordance with these standards.

[0004] As an example of a device for measuring emissions from electronic devices such as in-vehicle devices, Patent Document 1 proposes a test device for EMC testing of electronic devices. The test device in Patent Document 1 is capable of measuring radiated noise by using a probe specially positioned in relation to a virtual antenna to function as a loop antenna. Patent Document 2 also proposes a noise measurement device capable of calculating the conducted noise of multiple wire harnesses. The noise measurement device in Patent Document 2 detects magnetic fields by moving a sensor capable of detecting magnetic fields so that it passes through all of the wire harnesses, and can measure conducted noise based on these magnetic fields. Furthermore, Non-Patent Document 1 describes a simple evaluation method in which a monopole antenna is placed in a test facility compliant with CISPR25. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6052355 [Patent Document 2] Patent No. 5430145 [Non-patent literature]

[0006] [Non-Patent Document 1] Heinz Rebholz, Stefan Tenbohlen, “A fast radiated emission model for arbitrary cable harness configurations based on measurements and simulations”, IEEE International Symposium on Electromagnetic Compatibility, 2008 Summary of the Invention [Problem to be solved by the invention]

[0007] If radiated emissions exceeding the permissible limits are detected during radiated emission measurements conforming to CISPR 25, measures must be taken, such as the addition of EMC components or redesigning the electronic circuit board. Furthermore, because in-vehicle devices are connected to wire harnesses, which communicate with other devices and supply power through these harnesses, emission control measures are required not only for the in-vehicle devices but also for the radiated emissions from the wire harnesses. In particular, in the 30 MHz to 1000 MHz frequency band, radiated emissions from the wire harnesses and those from the ECU (Electronic Control Unit) coexist, making it difficult to distinguish which one requires countermeasures. Therefore, specialized evaluation equipment and methods are needed to measure radiated emissions from wire harnesses. Furthermore, in bundles of multiple wire harnesses, radiated emissions from the wire harnesses themselves can cause malfunctions, a phenomenon known as self-poisoning, so measurement of radiated emissions from each individual wire harness is essential. Therefore, there is a demand for evaluation devices and methods specialized for measuring radiated interference waves from wire harnesses.

[0008] However, the test device described in Patent Document 1 has a unique probe arrangement that makes measurement difficult. Furthermore, it evaluates only vertically polarized waves of radiated interference from wire harnesses; data on horizontal polarization is not provided, and measurement of both horizontally and vertically polarized waves of electromagnetic fields is not considered. Furthermore, the noise measurement device described in Patent Document 2 uses a loop antenna to measure and evaluate conducted noise (conducted interference) in a non-contact manner for conducted emissions measurement. Therefore, it is not suitable as a device for measuring radiated noise (radiated interference) that is emitted as radio waves into the air at a relatively high frequency. Furthermore, the simplified evaluation method described in Non-Patent Document 1 does not consider how to deal with noise caused by a dip in the frequency characteristics of radiated interference waves in the correction coefficient used to convert measurements using a rod antenna to CISPR 25 standards.

[0009] Furthermore, measuring radiated emissions for in-vehicle equipment in accordance with CISPR25 requires the use of an anechoic chamber and expensive equipment, which increases measurement costs and takes time, making it difficult to implement. Therefore, if radiated emissions could be measured using a simple method, it would be possible to measure them on-site during the development of in-vehicle equipment, contributing to the improvement of product development. Furthermore, if a measurement method for radiated emissions could be realized that does not require an anechoic chamber and uses a simple antenna, it would contribute to reducing measurement costs and accelerating product development.

[0010] Therefore, an object of the present invention is to provide an evaluation device, an evaluation method, and an anechoic chamber for radiated interference that can obtain measurement results in which the influence of dips occurring in measurements is suppressed using a simple measurement method that differs from the measurement method compliant with CISPR 25. Another object of the present invention is to provide an evaluation device, an evaluation method, and an anechoic chamber for radiated interference that can suppress the influence of dips occurring in measurements and obtain measurement results that are highly similar to the measurement method for radiated interference that complies with CISPR 25. [Means for solving the problem]

[0011] The evaluation device according to the present disclosure is for evaluating radiated interference waves emitted from a measurement object, and comprises: a test stand on which the measurement object is placed; an antenna that is positioned at a predetermined distance from the measurement object and receives electromagnetic waves; a moving means for moving the antenna horizontally over the predetermined distance; a measurement means for measuring an evaluated transmission characteristic, which is the transmission characteristic between the measurement object and the antenna; a dip reduction means for calculating a composite value, which is a value obtained by reducing a dip in the frequency spectrum of the evaluated transmission characteristic value, based on an evaluated transmission characteristic value, which is the measurement value of the evaluated transmission characteristic measured by the measurement means; and a calculation means for calculating an evaluation value of the radiated interference waves based on the composite value, wherein the measurement means measures the evaluated transmission characteristic at two or more different positions to which the antenna is moved by the moving means, and the dip reduction means calculates the composite value by combining the maximum or average value for each frequency of the evaluated transmission characteristic values measured by the measurement means.

[0012] The evaluation device according to the present disclosure includes a storage means for storing, as a first transmission characteristic value, a measurement value of a first transmission characteristic, which is the transmission characteristic between the calibration object and the EMI measurement antenna when the electromagnetic waves radiated from the calibration object are received by the EMI measurement antenna conforming to CISPR25; the measurement means measures a second transmission characteristic, which is the transmission characteristic between the calibration object and the antenna when the electromagnetic waves radiated from the calibration object placed on the test stand instead of the object are received by the antenna; the dip reduction means calculates a correction combined value, which is a value obtained by reducing a dip in the frequency spectrum of the second transmission characteristic value, based on the second transmission characteristic value, which is the measurement value of the second transmission characteristic measured by the measurement means; and the calculation means calculates a correction coefficient by subtracting the correction combined value from the first transmission characteristic value and adding this correction coefficient to the combined value to calculate the evaluation value.

[0013] The evaluation device according to the present disclosure is characterized in that the frequency band that the antenna can receive is from 150 kHz to 6000 MHz.

[0014] The evaluation device according to the present disclosure is characterized in that the object to be measured is a wire harness, the wire harness is placed parallel to one side of the rectangular test stand at a position 100 mm from the one side, the predetermined distance is one selected from between 200 mm and 500 mm in the direction opposite to the one side, and the moving means moves the antenna parallel to the longitudinal direction of the wire harness.

[0015] The evaluation device according to the present disclosure is characterized in that the moving means moves the antenna from a position corresponding to the center of the longitudinal direction of the wire harness toward either end of the wire harness to a position corresponding to one-quarter of the total length of the wire harness and / or one-half of the total length of the wire harness, and the measuring means measures the evaluated transmission characteristics at at least two positions out of the position corresponding to the center, the position corresponding to the one-quarter length, and the position corresponding to the one-half length.

[0016] The anechoic box according to the present disclosure is an anechoic box for evaluating radiated interference waves emitted from a measurement object, and comprises: a mounting base on which the measurement object is placed; an antenna positioned at a predetermined distance from the measurement object and receiving electromagnetic waves; a moving means for horizontally moving the antenna over the predetermined distance; a measuring means for measuring an evaluated transmission characteristic which is the transmission characteristic between the measurement object and the antenna; a dip reduction means for calculating a composite value which is a value obtained by reducing a dip in the frequency spectrum based on an evaluated transmission characteristic value which is a measurement value of the evaluated transmission characteristic measured by the measuring means; a calculating means for calculating an evaluated value of the radiated interference waves based on the composite value; a housing having the mounting base and capable of accommodating at least the measurement object and the antenna; and a radio wave absorber provided on the inner surface of the housing, wherein the measuring means measures the evaluated transmission characteristic at two or more different positions to which the antenna is moved by the moving means, and the dip reduction means calculates the composite value by combining the maximum or average value for each frequency of the evaluated transmission characteristic values measured by the measuring means.

[0017] The evaluation method according to the present disclosure includes a first transmission characteristic value acquisition step of measuring first transmission characteristics, which are transmission characteristics between the calibration object placed on a test stand and the EMI measurement antenna when electromagnetic waves radiated from the calibration object placed on a test stand are received by the EMI measurement antenna conforming to CISPR25, and acquiring a first transmission characteristic value, which is a measurement value of the first transmission characteristic; and a correction combined value calculation step of horizontally moving the antenna at a predetermined distance from the calibration object placed on the test stand, measuring second transmission characteristics, which are transmission characteristics between the calibration object and the antenna, at two or more different positions at the predetermined distance, and calculating a correction combined value, which is a value that reduces a dip in the frequency spectrum of the second transmission measurement value, by taking and combining the maximum or average value for each frequency of the second transmission characteristic values, which are measurement values of the second transmission characteristics. and a composite value calculation step of horizontally moving the antenna at the predetermined distance from an object to be measured placed on the test stand, measuring an evaluated transmission characteristic, which is a transmission characteristic between the object to be measured and the antenna, at two or more different positions at the predetermined distance, and calculating a composite value, which is a value in which a dip in the frequency spectrum of the evaluated transmission characteristic value is reduced, by taking and combining the maximum or average values for each frequency of the evaluated transmission characteristic values, which are the measurement values of the evaluated transmission characteristic, and wherein after the first transmission characteristic value acquisition step, the correction composite value calculation step, and the correction composite value calculation step are performed in any order, a correction coefficient is calculated by subtracting the correction composite value from the first transmission characteristic value, and the correction coefficient is added to the composite value to calculate an evaluated value of radiated interference waves emitted from the object to be measured. [Effects of the Invention]

[0018] According to the evaluation device of the present disclosure, the measurement means measures the evaluation transmission characteristic, which is the transmission characteristic between the object to be measured and the antenna, at two or more different positions to which the antenna is moved by the movement means, and the dip reduction means calculates a composite value by combining the maximum or average value of the evaluation transmission characteristic values for each frequency based on the evaluation transmission characteristic values, which are the measurement values of the evaluation transmission characteristic measured by the measurement means. Therefore, the evaluation transmission characteristic value, which is the measurement value of the evaluation transmission characteristic, can be a composite value that adopts the maximum or average value for each frequency, and therefore it is possible to suppress the influence of dips that occur in the measurement value. Furthermore, since the calculation means calculates an evaluation value of the radiated interference wave based on the composite value calculated by the dip reduction means, it is possible to calculate an evaluation value that suppresses the effects of dips simply by moving the antenna position and measuring the transmission characteristics at two or more different positions. Therefore, by using the evaluation device of the present disclosure, it is possible to obtain measurement results in which the influence of dips occurring in the measurement values is suppressed using a simple measurement method that differs from the measurement method compliant with CISPR25.

[0019] Furthermore, according to the evaluation device of the present disclosure, a storage means stores a measurement value of a first transmission characteristic, which is the transmission characteristic between the calibration object and the EMI measurement antenna, as a first transmission characteristic value, a measurement means measures a second transmission characteristic, which is the transmission characteristic between the calibration object and the antenna when the antenna receives electromagnetic waves radiated from the calibration object placed on a test stand instead of the object to be measured, and a dip reduction means calculates a correction combined value, which is a value obtained by reducing a dip in the frequency spectrum of the second transmission characteristic value, based on the second transmission characteristic value, which is the measurement value of the second transmission characteristic measured by the measurement means. Therefore, the effect of the dip is also reduced in the correction combined value calculated based on the second transmission characteristic value, and accordingly, the effect of the dip is also reduced in the correction coefficient calculated by subtracting the correction combined value from the first transmission characteristic value. As a result, the influence of dips is suppressed in the evaluation value calculated by adding the correction coefficient to the composite value, and the simple evaluation method using the evaluation device of the present disclosure can suppress the influence of dips and obtain measurement results that are highly similar to the radiated disturbance measurement method in accordance with CISPR 25. Therefore, there is no need to use an anechoic chamber or expensive equipment, and radiated disturbance can be easily measured and evaluated.

[0020] Furthermore, the evaluation device of the present disclosure can measure radiated interference signals over a frequency range from 150 kHz to 6000 MHz, which is within the measurement frequency range required by the CISPR25-compliant measurement method.

[0021] Furthermore, according to the evaluation device of the present disclosure, the object to be measured is a wire harness, and the wire harness is placed 100 mm from one side of a rectangular test stand and parallel to that side. An antenna is then placed a predetermined distance from the wire harness, in other words, at a distance selected from the range of 200 mm to 500 mm from the wire harness in the direction opposite the side. Therefore, the evaluation device of the present disclosure can evaluate radiated emissions as an evaluation device specialized for measuring radiated emissions from wire harnesses, and because the measurement area is smaller than that of the measurement method compliant with CISPR25, it can be applied to anechoic boxes, etc.

[0022] Furthermore, according to the evaluation device of the present disclosure, the moving means moves the antenna from a position corresponding to the center of the wire harness in the longitudinal direction toward either end of the wire harness to a position corresponding to one-quarter and / or one-half of the total length of the wire harness, and the measuring means measures the transmission characteristics at at least two positions out of the position corresponding to the center of the wire harness in the longitudinal direction, the position corresponding to one-quarter of the total length of the wire harness, and the position corresponding to one-half of the total length of the wire harness. This makes it possible to clearly define the criteria for moving the antenna, and to easily measure the transmission characteristics at two or more different positions.

[0023] The anechoic box and evaluation method of the present disclosure can achieve the same effects as the evaluation device described above. In particular, the anechoic box of the present disclosure enables simple measurements, for example, at product development sites, without using a CISPR25-compliant anechoic chamber or EMI measurement antenna. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a block diagram showing the configuration of an evaluation device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an explanatory diagram illustrating an overview of an evaluation device according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is an explanatory diagram showing an example of a state in which an antenna is moved in the evaluation device according to the embodiment of the present disclosure. [Figure 4] FIG. 4 is an explanatory diagram showing an example of a state in which the antenna is moved in the evaluation device according to the embodiment of the present disclosure. [Figure 5] FIG. 5 is an explanatory diagram for explaining a measurement method for measuring transmission characteristics between a calibration measurement object and an EMI measurement antenna in order to calculate correction coefficients used in an evaluation device according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a graph showing an example of the measurement results of the transmission characteristics between the calibration wire and the EMI measurement antenna for calculating the correction coefficient used in the evaluation device according to the embodiment of the present disclosure. [Figure 7] FIG. 7 is a graph showing an example of the measurement results of the transmission characteristics between the calibration wire and the antenna for calculating the correction coefficient used in the evaluation device according to the embodiment of the present disclosure. [Figure 8] FIG. 8 is a graph showing an example of a correction composite value for calculating a correction coefficient used in the evaluation device according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a graph showing an example of a composite value for correction used to calculate a correction coefficient used in the evaluation device according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a graph showing an example of a calculation result of a correction coefficient used in the evaluation device according to an embodiment of the present disclosure. [Figure 11] FIG. 11 is a graph showing an example of a calculation result of a correction coefficient used in the evaluation device according to an embodiment of the present disclosure. [Figure 12] FIG. 12 is a graph showing an example of a calculation result of a correction coefficient used in the evaluation device according to an embodiment of the present disclosure. [Figure 13] FIG. 13 is a graph showing an example of a measurement result of the transmission characteristics between the wire harness and the antenna by the evaluation device according to the embodiment of the present disclosure. [Figure 14]FIG. 14 is a graph showing an example of a measurement result of the transmission characteristics between the wire harness and the antenna by the evaluation device according to the embodiment of the present disclosure. [Figure 15] FIG. 15 is a graph showing an example of measurement results of transmission characteristics between a wire harness and an antenna by an evaluation device according to an embodiment of the present disclosure. [Figure 16] FIG. 16 is a graph for explaining the dip suppression effect in the evaluation device according to the embodiment of the present disclosure. [Figure 17] FIG. 17 is a graph for explaining the dip suppression effect in the evaluation device according to the embodiment of the present disclosure. [Figure 18] FIG. 18 is a graph for explaining the dip suppression effect in the evaluation device according to the embodiment of the present disclosure. [Figure 19] FIG. 19 is a graph showing an example of an evaluation value calculated using the evaluation device according to an embodiment of the present disclosure. [Figure 20] FIG. 20 is a graph showing an example of an evaluation value calculated using the evaluation device according to an embodiment of the present disclosure. [Figure 21] FIG. 21 is a graph showing the measurement results of the transmission characteristics between the wire harness and the EMI measurement antenna, measured in accordance with CISPR25. [Figure 22] FIG. 22 is a graph showing a comparison between an evaluation value obtained by adding a correction coefficient to an evaluation transmission characteristic value measured only at a reference position using an evaluation device according to an embodiment of the present disclosure and a measurement result obtained using a measurement method compliant with CISPR25, where (a) is a comparison for horizontal polarization and (b) is a comparison for vertical polarization. [Figure 23] FIG. 23 is a graph showing a comparison between an evaluation value calculated by adding a correction coefficient to a composite value calculated based on an evaluated transmission characteristic value at a reference position and an evaluated transmission characteristic value at a position corresponding to one-fourth of the total length of the wire harness 100 using an evaluation device according to an embodiment of the present disclosure, and a measurement result obtained by a measurement method compliant with CISPR25, where (a) is a comparison for horizontal polarization and (b) is a comparison for vertical polarization. [Figure 24]FIG. 24 is a schematic development view for explaining the appearance of the anechoic box according to the embodiment of the present disclosure. [Figure 25] FIG. 25 is a schematic development view illustrating the inside of an anechoic box according to an embodiment of the present disclosure. [Figure 26] FIG. 26 is a perspective view showing an outline of an anechoic box according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of an evaluation device, an evaluation method, and an anechoic box according to the present disclosure will be described with reference to the accompanying drawings. In this embodiment, an example will be described in which a wire harness is used as the measurement object and a calibration wire is used as the calibration measurement object, but the measurement object and the calibration measurement object are not limited to a wire harness and a calibration wire, respectively, and may be other electronic devices or electronic components.

[0026] <Configuration of evaluation device> An evaluation device 1 shown in FIG. 1 calculates an evaluation value for evaluating radiated interference waves radiated from a wire harness 100 (FIG. 2), which is an object to be measured. The evaluation device 1 includes a test stand 2 on which the wire harness 100 is placed, an antenna 3 that is disposed at a predetermined distance D1 from the wire harness 100 and receives electromagnetic waves, a moving means 4 that horizontally moves the antenna 3 at the predetermined distance D1 from the wire harness 100, a measuring means 5 that measures an evaluated transmission characteristic that is a transmission characteristic between the wire harness 100 and the antenna 3, a dip reduction means 6 that calculates, based on an evaluated transmission characteristic value that is a measurement value of the evaluated transmission characteristic measured by the measuring means 5, a composite value that is a value obtained by reducing a dip in the frequency spectrum of the evaluated transmission characteristic value, and a calculation means 7 that calculates an evaluation value of radiated interference waves radiated from the wire harness 100, based on the composite value calculated by the dip reduction means 6. The evaluation device 1 also includes a storage means 8 that stores a first transmission characteristic value that is a measurement value of a first transmission characteristic that is a transmission characteristic between a calibration wire 200, which is an object to be measured for calibration, and an EMI measurement antenna 20 (FIG. 5). In the following description, the longitudinal direction of the test stand 2 is defined as the left-right direction X, and the lateral direction of the test stand 2 is defined as the front-rear direction Y, with the test stand 2 shown in FIG.

[0027] The test stand 2 complies with CISPR25 (Limits and Measurement Methods for Disturbances for the Protection of Vehicle Receivers), an international standard created by the International Special Committee on Radio Interference (CISPR). The top surface of the test stand 2 is formed as a rectangular reference ground plane 2A with its longitudinal direction in the left-right direction X (Figure 2). This reference ground plane 2A is formed by placing a copper, brass, or zinc-plated steel plate with a thickness of 0.5 mm or more on a non-conductive base, and functions as a so-called ground plane. In addition, ground straps 2B are attached to the rear end of the reference ground plane 2A at intervals of 300 mm or less.

[0028] A foam support 2C for placing the wire harness 100 is provided on the reference ground plane 2A. The foam support 2C is made of a material such as expanded polystyrene and has a height of 50 mm. The foam support 2C is formed as a long, narrow support corresponding to the length of the wire harness 100 so that a long wire harness 100 can be placed thereon. For example, in the evaluation device 1, the foam support 2C can accommodate a wire harness 100 with a total length of 1500 mm. The foam support 2C is arranged so that its longitudinal direction is parallel to the front end of one of the long sides of the reference ground plane 2A. The foam support 2C is also arranged near the front end of the reference ground plane 2A so that, when the wire harness 100 is placed thereon, the wire harness 100 can be placed 100 mm from the front end of the reference ground plane 2A (one side of the test stand 2). Furthermore, metal sheet angle brackets 2D are provided at both ends of the foam support 2C in the left-right direction X, and a 50 Ω terminator 9 is provided on the left-end metal sheet angle 2D. One end of the wire harness 100 placed on the foam support 2C is connected to a 50Ω terminator 9, and the other end is connected to the measuring means 5 via a metal sheet angle 2D and an attenuator. Here, in the evaluation device 1, the entire wire harness 100 is placed so as to be parallel to the front end of the reference ground plane 2A (one side of the test stand 2). Therefore, for example, if the total length of the wire harness 100 is 1500 mm, the portion of the wire harness 100 placed on the foam support 2 that is parallel to the front end of the reference ground plane 2A is also 1500 mm, and the total length and the length of the portion parallel to the front end of the reference ground plane 2A are the same. On the other hand, for example, when the wire harness 100 is placed by bending both end portions of the wire harness 100 in the left-right direction X toward the rear end of the reference ground plane 2A, it is assumed that the total length of the wire harness 100 and the length of the portion parallel to the front end of the reference ground plane 2A may differ. In this case, the bent both end portions are not included in the total length of the wire harness 100, and only the portion of the wire harness 100 that is placed parallel to the front end of the reference ground plane 2A is counted as the total length of the wire harness 100.

[0029] Various antennas capable of receiving electromagnetic waves in the frequency band from 150 kHz to 6000 MHz can be used for the antenna 3. Specific examples include a self-complementary, constant-impedance antenna, a tuned dipole antenna, and a dipole antenna with detachable elements of different lengths for different frequencies. Using these antennas makes it possible to measure radiated interference in the frequency band from 150 kHz to 5925 MHz, which is the measurement frequency range in the measurement method compliant with CISPR25. The evaluation device 1 uses a wideband antenna for the antenna 3, capable of receiving electromagnetic waves in the frequency band from 30 MHz to 1000 MHz. Examples of wideband antennas include biconical antennas, log periodic antennas, tuned dipole antennas, and bowtie antennas. A dipole antenna and a monopole antenna can also be used in combination. Using such a wideband antenna enables measurement of radiated interference with a single antenna, and enables measurement of both horizontally and vertically polarized radiated interference. Furthermore, measurement of radiated interference can be achieved using a simple antenna such as a wideband antenna, without the need for an expensive EMI measurement antenna compliant with CISPR25. For these reasons, it is preferable to use a wideband antenna for the antenna 3. As shown in FIG. 2 , the antenna 3 is disposed on the reference ground plane 2A at a predetermined distance D1 from the wire harness 100 placed on the foam support base 2C. The predetermined distance D1 is selected from the wire harness 100 placed on the foam support base 2C toward the rear end of the test stand 2 in the depth direction, i.e., toward the rear end (rear end direction) opposite the front end of the reference ground plane 2A, taking into consideration the size of the reference ground plane 2A and application to the anechoic chamber 10 (described later). The predetermined distance D1 is preferably 300 mm from the wire harness 100 toward the rear end of the reference ground plane 2A. The evaluation device 1 also sets the predetermined distance D1 to 300 mm from the wire harness 100 toward the rear end of the reference ground plane 2A. Therefore, the antenna 3 is disposed at the predetermined distance D1 from the wire harness 100, with its phase center located at a height of 200 mm above the reference ground plane 2A. The predetermined distance D1 can be any distance between 200 mm and 500 mm from the wire harness 100 toward the rear end of the reference ground plane 2A, but it is not appropriate to combine two or more different distances; any one distance (for example, 300 mm from the wire harness 100 toward the rear end of the reference ground plane 2A) must be set. Furthermore, the antenna 3 is connected to the measuring means 5 via a coaxial cable. The antenna 3 is supported by a support rod 18 provided in the moving means 4, which will be described later, and is configured to be rotatable around the axis of the support rod 18. Therefore, the evaluation device 1 can measure both horizontally polarized waves and vertically polarized waves by rotating the antenna 3.

[0030] The moving means 4 is a mechanism that includes a support rod 18, supports the antenna 3 with the support rod 18, and horizontally moves the antenna 3 a predetermined distance D1 via the support rod 18. The moving means 4 may, for example, manually move the antenna 3 via the support rod 18, or may automatically move the antenna 3 by driving the support rod 18 using a rail, a crank, or the like. The moving means 4 moves the antenna 3 parallel to the longitudinal direction of the wire harness 100, in other words, in the left-right direction X along the longitudinal direction of the wire harness 100. The moving means 4 moves the antenna 3 from a reference position corresponding to the center of the longitudinal direction of the wire harness 100 shown in FIG. 2 , specifically, 300 mm from the center of the longitudinal direction of the wire harness 100 placed on the foam support 2 toward the rear side in the depth direction of the test stand 2 (toward the rear end of the reference ground plane 2A) and 200 mm above the reference ground plane 2A, toward either one of the left and right directions X, to a predetermined position. In the evaluation device 1, the antenna 3 is moved to a predetermined position, for example, in the direction of arrow A (rightward) shown in FIGS. 3 and 4 . The predetermined position is, for example, one or both of a position corresponding to one-quarter of the total length of the wire harness 100 shown in FIG. 3 and a position corresponding to one-half of the total length of the wire harness 100 shown in FIG. 4 . More specifically, for example, if the total length of the wire harness 100 is 1500 mm and the entire wire harness 100 is placed so as to be parallel to the front end of the reference ground plane 2A, the predetermined position will be either or both of a position slid a distance of 375 mm (FIG. 3), which is one-fourth of the total length of the wire harness 100, from the reference position, and a position slid a distance of 750 mm (FIG. 4), which is one-half of the total length of the wire harness 100. Note that the predetermined position is not limited to the above example, and two or more different positions slid a given distance may be used.

[0031] The measuring means 5 is configured with a measuring instrument such as a vector network analyzer (VNA) capable of measuring the transmission characteristics of electromagnetic waves. With the wire harness 100 connected to port 1 and the antenna 3 connected to port 2, the measuring means 5 measures the transmission characteristics between the wire harness 100 and the antenna 3 for electromagnetic waves radiated from the wire harness 100 and received by the antenna 3. Specifically, of the transmission characteristics, the forward transmission characteristics represented by the S parameter S21 are measured. Note that this transmission characteristic is an evaluated transmission characteristic, and the measurement value of this evaluated transmission characteristic is an evaluated transmission characteristic value. At this time, the measuring means 5 moves the antenna 3 to at least two of the positions shown in Figures 2 to 4 using the moving means 4, and measures the transmission characteristics at at least two different positions from the reference position (Figure 2), the position corresponding to one-quarter of the total length of the wire harness 100 (Figure 3), and the position corresponding to one-half of the total length of the wire harness 100 (Figure 4). The measuring means 5 is also configured to be able to measure the second transmission characteristic used when calculating a correction coefficient (k) described later, by the same method as the above-mentioned measuring method. In the evaluation device 1 of this embodiment, an example is described in which the transmission characteristics of electromagnetic waves are measured at two different positions, but the positions measured by the measurement means 5 are not limited to two, and may be three or more different positions.

[0032] The dip reduction means 6 calculates a composite value that is a value in which dips in the frequency spectrum of the evaluated transmission characteristic values are reduced, based on the evaluated transmission characteristic values that are measurement values of the evaluated transmission characteristic measured at two different positions by the measurement means 5. Specifically, the dip reduction means 6 employs the maximum values for each frequency of the evaluated transmission characteristic values measured by the measurement means 5, or the average values for each frequency of the evaluated transmission characteristic values measured by the measurement means 5, and calculates either a composite value in which the maximum values are combined or a composite value in which the average values are combined. As will be described later, the composite value calculated in this way has reduced dips in the frequency spectrum. The dip reducing means 6 is also configured to be able to calculate a correction composite value used when calculating a correction coefficient (k) described later, using a method similar to the method for calculating the composite value described above.

[0033] The calculation means 7 calculates an evaluation value of the radiated interference wave radiated from the wire harness 100 by adding a predetermined correction coefficient (k) to the composite value calculated by the dip reduction means 6. At this time, the correction coefficient (k) to be added to the composite value is calculated as follows. First, as shown in FIG. 5, a calibration wire 200, which is a calibration object to be measured, is placed on a foam support base 2C of a test stand 2, and electromagnetic waves radiated from the calibration wire 200 are received by an EMI measurement antenna 20. Then, the transmission characteristic (S21) between the calibration wire 200 and the EMI measurement antenna 20 at this time is measured. This transmission characteristic is the first transmission characteristic, and the measured value of this first transmission characteristic is the first transmission characteristic value. The procedure for acquiring this first transmission characteristic value is the first transmission characteristic value acquisition procedure. The first transmission characteristic value is measured in advance and stored in a storage means 8, which will be described later. 2 to 4, a calibration wire 200 is placed on the foam support base 2C of the test stand 2 in place of the wire harness 100, and the transmission characteristic (S21) between the calibration wire 200 and the antenna 3 is measured using the antenna 3, the moving means 4, and the measuring means 5 when the antenna 3 receives electromagnetic waves radiated from the calibration wire 200. This transmission characteristic is the second transmission characteristic, and the measured value of this second transmission characteristic is the second transmission characteristic value. At this time, the measuring means 5 measures the second transmission characteristic between the calibration wire 200 and the antenna 3 at two different positions to which the antenna 3 is moved by the moving means 4, as shown in FIGS. 2 to 4. Next, the dip reducing means 6 calculates a correction combined value, which is a value obtained by reducing the dip, based on the second transmission characteristic value, which is a measurement value of the second transmission characteristic measured by the measuring means 5. The method for calculating this correction combined value is the same as the method for calculating the combined value described above, and the procedure for obtaining this correction combined value is the correction combined value calculation procedure. Then, the calculation means 7 subtracts the correction combined value from the first transmission characteristic value to calculate the correction coefficient (k). In this manner, the correction coefficient (k) is calculated. As a result, the calculation means 7 can calculate the evaluation value of the radiated interference wave by adding the correction coefficient (k) to the combined value calculated by the dip reduction means 6.

[0034] The storage means 8 is configured by a recording device such as a hard disk drive (HDD) or a solid state drive (SSD), and stores the first transmission characteristic values calculated in advance. As described above, the first transmission characteristic values stored in the storage means 8 are used when the calculation means 7 calculates the correction coefficient (k).

[0035] The evaluation device 1 is configured as described above. Next, the theoretical concept of the above-mentioned correction coefficient (k) will be explained.

[0036] <Theoretical concept of correction factor (k)> First, let us consider a case where a noise current flows through the wire harness 100. In this case, the wire harness 100 behaves as follows based on the behavior of the antenna 3:

number

number

number

[0037] In equation (1), J(r) is a current vector, and in equations (2) and (3), J(r) is a current flowing in the wire harness 100, and M(r) is a magnetic current. In the wire harness 100, current flows through the conductors, and the current vector is dominant, so only equation (2) is considered.

[0038]

number

[0039] When considering an electromagnetic wave that is a combination of a direct wave from the wire harness 100 and a wave reflected from the reference ground plane 2A of the CISPR25 test stand 2, the sum of the vector potentials is expressed by the following equation (5).

number

[0040]

number

number

number

number

[0041] The theoretical concept of the correction coefficient (k) has been explained above. Next, a method for calculating the evaluation value of radiated interference using the correction coefficient (k) and a method for reducing dips will be described.

[0042] First, a correction coefficient (k) is calculated based on the first transmission characteristic value and the second transmission characteristic value using the following equation (10).

number

[0043] Next, an evaluation transmission characteristic, which is the transmission characteristic (S21) between the antenna 3 and the desired wire harness 100, is measured, and an evaluation value is calculated using the following equation (11).

number

[0044] As described above, in the method for calculating the evaluation value of radiated disturbances using the correction coefficient (k) shown on the right side of equation (11), a dip occurs when measuring the transmission characteristics (second transmission characteristics and evaluated transmission characteristics) using the antenna 3, causing a sudden change in the evaluation value. The dip occurs, for example, because the direct wave generated from the calibration wire 200 and the reflected wave from the test stand 2 are combined and received by the antenna 3, or because the direct wave generated from the wire harness 100 and the reflected wave from the test stand 2 are combined and received by the antenna 3. In particular, when the direct wave generated from the calibration wire 200 and the reflected wave from the test stand 2 are combined and received by the antenna 3, the dip portion has a positive sign in the correction coefficient (k) due to the subtraction in equation (10), and a large error occurs when the results are added together.

[0045] Therefore, in order to reduce errors caused by dips, the evaluation device 1 uses, for example, the moving means 4 to horizontally move the antenna 3 to the right, parallel to the longitudinal direction of the calibration wire 200, at a predetermined distance D1 from the calibration wire 200, and the measurement means 5 measures the second transmission characteristic at at least two different positions at the predetermined distance D1 from the calibration wire 200. Then, based on the second transmission characteristic value, which is the measurement value of the second transmission characteristic measured by the measurement means 5, the dip reduction means 6 calculates a correction combined value as a combined value, and this correction combined value is used as the measurement result of the second transmission characteristic. In other words, the evaluation device 1 uses the correction combined value calculated based on the second transmission characteristic value as Saa-caw in equation (10). This makes it possible to suppress the effects caused by dips in the second transmission characteristic value. At this time, the dip reducing means 6 calculates the correction combined value by combining the maximum value for each frequency or the average value for each frequency of the second transmission characteristic values. The above-described procedure is the correction combined value calculation procedure.

[0046] Similarly, for example, the moving means 4 moves the antenna 3 horizontally to the right at a predetermined distance D1 from the wire harness 100 in parallel to the longitudinal direction of the wire harness 100, and the measuring means 5 measures the evaluated transmission characteristic at at least two different positions at the predetermined distance D1 from the wire harness 100. Then, based on the evaluated transmission characteristic values, which are the measured values of the evaluated transmission characteristic measured by the measuring means 5, the dip reduction means 6 calculates a composite value as a composite value, and sets this composite value as the measurement result of the evaluated transmission characteristic. In other words, the evaluation device 1 uses the composite value calculated based on the evaluated transmission characteristic values for Saa-wh in equation (11). This makes it possible to suppress the influence caused by dips in the evaluated transmission characteristic values. At this time, the dip reducing means 6 calculates a composite value by combining the maximum or average values of the evaluated transmission characteristic values for each frequency. The above-described procedure is the composite value calculation procedure.

[0047] The method for calculating the evaluation value of radiated interference using the correction coefficient (k) and the method for reducing dips have been described above. Next, the measurement results of the measurement experiment will be explained. In the following Figures 6 to 15, the solid lines show the measurement results for vertically polarized waves, and the dashed lines show the measurement results for horizontally polarized waves.

[0048] <Measurement of the first transmission characteristic> Using the EMI measurement antenna 20 conforming to CISPR25, the first transmission characteristic, which is the transmission characteristic (S21) between the calibration wire 200 and the EMI measurement antenna 20, is measured, and the measured value is defined as the first transmission characteristic value. Specifically, as shown in FIG. 5, a calibration wire 200 was placed on a foam support 2C of a test stand 2 in an anechoic chamber AC. The calibration wire 200 was a single-stranded, automotive constant-voltage cable (Yazaki Corporation, AWG14) with a length of 1500 mm and a conductor cross-sectional area of 2.08 mm. The calibration wire 200 was placed 100 mm from the front end of the reference ground plane 2A of the test stand 2, with its entire length parallel to the front end of the reference ground plane 2A. Connectors were connected to both ends of the calibration wire 200, one end was connected to a 50 Ω terminator 9, and the other end was connected to a measuring instrument (measurement means 5) via an attenuator. A vector network analyzer (Keysight, E5071C) was used as the measuring instrument. In accordance with CISPR25, an EMI measurement antenna 20 was positioned at a distance D2 from the calibration wire 200. Distance D2 is a position 1000 mm forward from calibration wire 200. In addition, for EMI measurement antenna 20, in order to measure electromagnetic waves in the frequency band from 30 MHz to 1000 MHz, a biconical antenna (Schwarzbeck, BBA9106 / VHA9103B) was used for frequencies from 30 MHz to 200 MHz, and a log periodic antenna (Schwarzbeck, UHALP9108-A) was used for frequencies from 200 MHz to 1000 MHz. The other end of the calibration wire 200 is connected to port 1 of the vector network analyzer, and the EMI measurement antenna 20 is connected to port 2 of the vector network analyzer via a coaxial cable. In this state, a current was supplied to the calibration wire 200, and a first transmission characteristic, which is the transmission characteristic (S21) between the calibration wire 200 and the EMI measurement antenna 20, was measured for the electromagnetic waves radiated from the calibration wire 200. This measured value was then taken as the first transmission characteristic value. The procedure for acquiring this first transmission characteristic value is the first transmission characteristic value acquisition procedure.

[0049] 6 shows an example of a first transmission characteristic value, which is the measurement result of the first transmission characteristic between the EMI measurement antenna 20 and the calibration wire 200, measured as described above. This first transmission characteristic value is used in equation (10) for calculating the correction coefficient (k).

[0050] <Measurement of the second transmission characteristic and calculation of the combined value for correction> Next, the antenna 3 is used to measure the second transmission characteristic, which is the transmission characteristic (S21) between the calibration wire 200 and the antenna 3, and the measured value is set as the second transmission characteristic value. For example, as shown in FIG. 2, in an anechoic chamber AC, a calibration wire 200 was placed on a foam support 2C of a test stand 2. The calibration wire 200 was placed 100 mm from the front end of the reference ground plane 2A of the test stand 2, with its entire length parallel to the front end of the reference ground plane 2A. Connectors were connected to both ends of the calibration wire 200, one end was connected to a 50 Ω terminator 9, and the other end was connected via an attenuator to a vector network analyzer (Keysight, E5071C) serving as measurement means 5. A biconical antenna (Schwarzbeck UBAA 9115 / BBUK9139) was used as the antenna 3, and its phase center was positioned 300 mm from the longitudinal center of the calibration wire 200 placed on the foam support 2 toward the rear end of the reference ground plane 2A and at a height of 200 mm above the reference ground plane 2A. The other end of the calibration wire 200 is connected to port 1 of the vector network analyzer, and an antenna 3 is connected to port 2 of the vector network analyzer via a coaxial cable. In this state, a current was supplied to the calibration wire 200, and a second transmission characteristic, which was the transmission characteristic (S21) between the calibration wire 200 and the antenna 3, was measured for the electromagnetic waves radiated from the calibration wire 200. This measured value was then taken as the second transmission characteristic value.

[0051] Fig. 7 shows an example of the second transmission characteristic value, which is the measurement result of the second transmission characteristic between the antenna 3 and the calibration wire 200, measured as described above. Note that Fig. 7 shows the second transmission characteristic value at the reference position (Fig. 2), which is the position corresponding to the center of the wire harness 100 in the longitudinal direction.

[0052] Furthermore, the antenna 3 is moved to a position (FIG. 3) corresponding to a quarter length (375 mm) of the total length (1500 mm) of the calibration wire 200, and an example of the calculation result of the correction combined value combined by the dip reduction means 6 based on the second transmission characteristic value between the antenna 3 and the calibration wire 200 measured at this position and the second transmission characteristic value between the antenna 3 and the calibration wire 200 at the reference position (FIG. 2) is shown in FIG. 8.

[0053] 7 and 8, it can be seen that the dips in the frequency spectrum are reduced in the correction combined value combined by the dip reduction means 6. The effect of dip reduction is particularly noticeable in horizontally polarized waves. Comparing Figures 7 and 8, vertical polarization has large fluctuations in the vertical axis direction because various antennas are less susceptible to the influence of ground surfaces such as floors, and horizontal polarization has the characteristic of having a lower amplitude in the frequency spectrum than vertical polarization because it tends to be more susceptible to the influence of ground surfaces.

[0054] Furthermore, the antenna 3 is moved to a position (FIG. 4) corresponding to half the length (750 mm) of the total length of the calibration wire 200, and an example of the calculation result of another correction combined value combined by the dip reduction means 6 based on the second transmission characteristic value between the antenna 3 and the calibration wire 200 measured at this position and the second transmission characteristic value between the antenna 3 and the calibration wire 200 measured at a position (FIG. 3) corresponding to a quarter of the total length (375 mm) of the calibration wire 200 is shown in FIG. 9.

[0055] A comparison of FIG. 7 and FIG. 9 also reveals that the dips in the frequency spectrum are reduced in the corrective composite value.

[0056] <Calculation of correction coefficient (k)> Next, the frequency spectrum of the correction coefficient (k) calculated based on Equation (10) is shown in FIG. 10. FIG. 10 is calculated based only on the second transmission characteristic value at the reference position (FIG. 2), and shows the vertically polarized and horizontally polarized waves of the correction coefficient (k). Next, FIG. 11 shows the correction coefficient (k) when using a composite correction value calculated based on the second transmission characteristic value at the reference position (FIG. 2) and the second transmission characteristic value at a position (FIG. 3) corresponding to one-fourth the total length (375 mm) of the calibration wire 200. Comparing FIG. 10 with FIG. 11, it can be seen that the abrupt change in the frequency spectrum of the horizontally polarized wave is reduced. Next, Fig. 12 shows the correction coefficient (k) when using a correction composite value calculated based on the second transmission characteristic value at the reference position (Fig. 2) and the second transmission characteristic value at a position (Fig. 4) corresponding to half the total length (750 mm) of the calibration wire 200. Comparing Fig. 10 with Fig. 12 also reveals that the abrupt change in the frequency spectrum of the horizontally polarized wave is reduced.

[0057] <Measurement of evaluation transmission characteristics> Next, similar to the measurement of the second transmission characteristic between the calibration wire 200 and the antenna 3, the antenna 3 is used to measure the evaluation transmission characteristic, which is the transmission characteristic (S21) between the desired wire harness 100 and the antenna 3, and the measurement result is set as the evaluation transmission characteristic value. The measurement results shown in Fig. 13 are the evaluated transmission characteristic values at the reference position (Fig. 2), which is the position corresponding to the center of the wire harness 100 in the longitudinal direction. Note that two wires of an automotive wiring cord (Dai Jidosha Kogyo, AWG16) were used for the wire harness 100. This automotive wiring cord (Dai Jidosha Kogyo, AWG16) has a total length of 1500 mm and a conductor cross-sectional area of 1.31 mm2. This simulates a 12 / 24V DC electric wire in an EMI test conforming to CISPR25.

[0058] Furthermore, the antenna 3 is moved to a position (FIG. 3) corresponding to a quarter length (375 mm) of the total length (1500 mm) of the wire harness 100, and an example of the calculation result of the composite value synthesized by the dip reduction means 6 based on the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 measured at this position and the evaluated transmission characteristic value at the reference position (FIG. 2) is shown in FIG. 14.

[0059] In addition, the antenna 3 is moved to a position (Figure 4) corresponding to half the length (750 mm) of the total length of the wire harness 100, and an example of the calculation result of the composite value calculated by the dip reduction means 6 based on the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 measured at this position and the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 measured at a position (Figure 3) corresponding to a quarter of the length (375 mm) of the total length of the wire harness 100 is shown in Figure 15.

[0060] A comparison between FIG. 13 and FIG. 14 and a comparison between FIG. 13 and FIG. 15 also reveals that the dips in the frequency spectrum are reduced in the synthesized value.

[0061] Here, the reduction of the dip will be explained more specifically. In Figure 16 below, the solid line indicates the evaluated transmission characteristic value at a position corresponding to half the length (750 mm) of the total length of the wire harness 100 (Figure 4), and the dashed line indicates the evaluated transmission characteristic value at a position corresponding to a quarter of the length (375 mm) of the total length of the wire harness 100 (Figure 3). Figure 16 shows the evaluated transmission characteristic values between the antenna 3 and the wire harness 100 at a position corresponding to one-quarter of the total length of the wire harness 100 (Figure 3) in a vertically polarized state, and the evaluated transmission characteristic values between the antenna 3 and the wire harness 100 at a position corresponding to one-half of the total length of the wire harness 100 (Figure 4).It can be seen that a dip occurs around 800 MHz in the evaluated transmission characteristic values at a position corresponding to one-quarter of the total length of the wire harness 100 (Figure 3), and a dip occurs around 1000 MHz in the evaluated transmission characteristic values at a position corresponding to one-half of the total length of the wire harness 100 (Figure 4).

[0062] In contrast to Fig. 16, when the dip reduction means 6 performs a process of reducing dips, in other words, calculates a combined value obtained by using the maximum value of the evaluation transmission characteristic values for each frequency or an average value of the evaluation transmission characteristic values for each frequency based on the evaluation transmission characteristic values measured by the measurement means 5, the respective calculation results are shown in Fig. 17 and Fig. 18. Fig. 17 shows the combined value obtained by using the maximum value, and Fig. 18 shows the combined value obtained by using the average value.

[0063] A comparison between FIG. 16 and FIG. 17, and a comparison between FIG. 16 and FIG. 18 also reveals that the dips in the frequency spectrum are reduced.

[0064] <Calculation of the evaluation value of radiated interference> Next, the calculation results of the evaluation value of radiated interference waves will be explained. Figures 19 and 20 show examples of the results of calculating the evaluation value of radiated interference by adding a correction coefficient (k) to the combined value with the dip reduced as shown in Figure 17 or 18. In Figures 19 and 20, the solid line indicates the measurement result of vertical polarization, and the dashed line indicates the measurement result of horizontal polarization. Figure 19 shows an evaluation value calculated by adding a correction coefficient (k) to a composite value synthesized by the dip reduction means 6 based on the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 at the reference position (Figure 2) and the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 at a position (Figure 3) corresponding to a quarter of the total length (375 mm) of the wire harness 100. On the other hand, Figure 20 shows an evaluation value calculated by adding a correction coefficient (k) to a composite value synthesized by the dip reduction means 6 based on the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 at a position (Figure 3) corresponding to a quarter of the total length of the wire harness 100 (375 mm) and the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 at a position (Figure 4) corresponding to a half of the total length of the wire harness 100 (750 mm).

[0065] <Validity of the evaluation value of radiated interference> 21 shows the measurement results (Sant-wh) obtained by measuring the radiated interference waves of the wire harness 100 using the EMI measurement antenna 20 in accordance with a measurement method compliant with CISPR 25. The solid line shows the measurement results for vertically polarized waves, and the dashed line shows the measurement results for horizontally polarized waves. Here, by comparing Figures 19 and 21 and by comparing Figures 20 and 21, it can be seen that by adding a correction coefficient (k) to the composite value calculated based on the measurement results of the evaluated transmission characteristic value between the antenna 3 and the wire harness 100, as expressed in equation (11), it is possible to obtain measurement results equivalent to those obtained by a measurement method compliant with CISPR25 using the EMI measurement antenna 20.

[0066] <Dip reduction results> FIG. 22 shows a comparison between the evaluation value (Saa-wh+k) calculated by adding the correction coefficient (k) to the evaluation transmission characteristic value (Saa-wh) between the antenna 3 and the wire harness 100 at only the reference position (FIG. 2), and the measurement result (Sant-wh) obtained using a measurement method compliant with CISPR25. FIG. 22(a) shows the comparison for horizontal polarization, and FIG. 22(b) shows the comparison for vertical polarization. The solid line shows the evaluation value (Saa-wh+k), and the dashed line shows the measurement result (Sant-wh). FIG. 22 shows that the antenna 3 is affected by the dip when it is not moved. FIG. 23 shows a comparison between an evaluation value (Saa-wh+k) calculated by adding a correction coefficient (k) to a composite value calculated based on the evaluated transmission characteristic value (Saa-wh) between the antenna 3 and the wire harness 100 and the measurement result (Sant-wh) obtained using a measurement method compliant with CISPR25. FIG. 23(a) shows the comparison for horizontal polarization, and FIG. 23(b) shows the comparison for vertical polarization. The solid line shows the evaluation value (Saa-wh+k), and the dashed line shows the measurement result (Sant-wh). The evaluation value in FIG. 23 uses a composite value calculated based on the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 at the reference position (FIG. 2) and the evaluated transmission characteristic value between the antenna 3 and the wire harness 100 at a position (FIG. 4) corresponding to one-fourth the total length (375 mm) of the wire harness 100. 22 and 23, it can be seen that the error due to the dip is reduced in Fig. 23. For horizontally polarized waves, the frequency spectrum shows good agreement with an error of 13.1 dB on the positive side. Similarly, for vertically polarized waves, the frequency spectrum shows good agreement with an error of 11.8 dB on the positive side. This proves the effectiveness of using antenna 3 and moving antenna 3 horizontally parallel to the longitudinal direction of wire harness 100. In Figure 23(b), there are some areas (especially in the frequency band below 300 MHz) where the dashed line showing the measurement result (Sant-wh) is difficult to see. This is because the measurement result (Sant-wh) and the evaluation value (Saa-wh+k) are almost identical, and the dashed line and the solid line overlap.

[0067] <Anechoic box> Next, the anechoic box 10 shown in FIGS. 24 to 26 will be described. Since the anechoic box 10 has components in common with the evaluation device 1, the same components as those in the evaluation device 1 will be assigned the same reference numerals and their description will be omitted, and the following description will focus mainly on the components that differ from the evaluation device 1. In addition, in the following description, with the anechoic box 10 shown in Fig. 26 as the reference, the width direction of the anechoic box 10 will be the left-right direction X, the depth direction of the anechoic box 10 will be the front-back direction Y, and the height direction of the anechoic box 10 will be the up-down direction Z.

[0068] The anechoic box 10 includes a mounting table 2' on which the wire harness 100, which is the object to be measured, and the calibration wire 200, which is the object to be calibrated, can be placed in place of the test table 2 provided in the evaluation device 1 described above; an antenna 3' which is either a biconical antenna, a bowtie antenna, or a tuning dipole antenna; a moving means 4' which has a support rod 18' that supports the antenna 3'; a measuring means 5; a dip reduction means 6; a calculation means 7; and a memory means 8.

[0069] The anechoic box 10 includes a box-shaped housing 11 made of a conductive material such as metal, and is large enough to accommodate at least the wire harness 100 or the calibration wire 200 and the antenna 3'. As shown in FIG. 24, the housing 11 includes a left side panel 11A, a right side panel 11B, an upper panel 11C, a lower panel 11D, a front door 11E, and a rear panel 11F. As shown in FIG. 25, radio wave absorbers 12 are provided on the inner surfaces of the left side panel 11A, the right side panel 11B, the upper panel 11C, the front door 11E, and the rear panel 11F, excluding the lower panel 11D. A connector panel 13 is provided on the left side panel 11A, allowing connection to circuits, a measuring unit 5, and the like. The front door 11E has a handle 17 on its outer side, which can be pulled toward the front of the anechoic box 10 to open and close it, as shown in FIG. 26.

[0070] The mounting base 2' is formed by a lower plate 11D, and the inner surface of this lower plate 11D, i.e., the upper surface of the lower plate 11D, is a reference ground surface 2A' on which the wire harness 100 or the calibration wire 200 is placed, and functions as a so-called ground plane. A connection fixture 15 is provided on the right side near the front end of the reference ground surface 2A' to fix the right end of the wire harness 100 or the calibration wire 200 and connect it to the 50 Ω terminator 9, and a signal application connector 16 is provided on the left end near the front end of the reference ground surface 2A' to fix the left end of the wire harness 100 or the calibration wire 200 and to supply current, etc. The rear panel 11F is formed with a groove 14 through which a support rod 18' of the moving means 4' is passed in order to move the antenna 3' horizontally. The support rod 18' supports the antenna 3' inside the housing 11 and is configured so that the antenna 3' can be moved by operating it from outside the housing 11. Note that the groove 14 is not a complete hole, but is covered with a member such as a radio wave absorbing material (not shown) to prevent electromagnetic waves from leaking. Furthermore, like the evaluation device 1, the antenna 3' is configured to be rotatable around the axis of the support rod 18'.

[0071] The anechoic box 10 configured as described above has the same functions as the evaluation device 1, and enables simple measurements without using equipment such as an anechoic chamber or an EMI measurement antenna 20. Furthermore, compared to the measurement method compliant with CISPR25, which uses an anechoic chamber, it allows measurements in a very small measurement area, making it possible to measure radiated interference even in development sites.

[0072] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made to the present invention without departing from the scope of the claims.

[0073] For example, in the evaluation device 1, evaluation method, and anechoic chamber 10, which are embodiments of the present disclosure, an example has been shown in which the composite value and the correction composite value are calculated from measurement values of transmission characteristics measured at two different positions, but the composite value and the correction composite value may also be calculated based on measurement values measured at two or more different positions, i.e., three different positions or four different positions, and the maximum or average value of those measurement values may be used as the composite value or the correction composite value.

[0074] Furthermore, for example, in the evaluation device 1, the evaluation method, and the anechoic chamber 10 according to the embodiments of the present disclosure, an example has been shown in which the predetermined distance D1 is 300 mm from the wire harness 100 toward the rear end of the reference ground planes 2A and 2A', but the predetermined distance D1 may be any distance that allows the antenna 3 to properly receive electromagnetic waves. However, in order to reduce the measurement area, it is preferable to set the predetermined distance D1 to a distance selected from between 200 mm and 500 mm from the wire harness 100 toward the rear end of the reference ground planes 2A and 2A' so that the antenna 3 is disposed at least on the reference ground planes 2A and 2A'.

[0075] Furthermore, for example, the evaluation device 1, evaluation method, and anechoic chamber 10 according to the embodiments of the present disclosure include a storage means 8 that stores a first transmission characteristic value, a measurement means 5 that measures the second transmission characteristic, a dip reduction means 6 that calculates a correction composite value that reduces a dip in the frequency spectrum of the second transmission characteristic value, which is a measurement value of the second transmission characteristic, and a calculation means 7 that subtracts the correction composite value from the first transmission characteristic value to calculate a correction coefficient and adds this correction coefficient to the composite value to calculate an evaluation value. However, for example, the storage means 8 may store correction coefficients calculated from the first transmission characteristic value and the second transmission characteristic value that have been measured in advance, and the calculation means 7 may add the composite value to the correction coefficient stored in the storage means 8 to calculate an evaluation value.

[0076] In the evaluation device 1, the evaluation method, and the anechoic chamber 10 according to the embodiments of the present disclosure, the moving unit 4 moves the antenna 3 from a reference position to two positions: a position corresponding to one-fourth (375 mm) of the total length of the wire harness 100; and a position corresponding to one-half (750 mm) of the total length of the wire harness 100. The measuring unit 5 measures the transmission characteristics at the reference position, a position 375 mm from the reference position, and a position 750 mm from the reference position. However, the distance over which the moving unit 4 moves the antenna 3 is not limited to the above-described lengths and may be any. However, to obtain the same effects as those of the evaluation device 1, the evaluation method, and the anechoic chamber 10 according to the embodiments of the present disclosure, it is preferable that the predetermined positions are the reference position, a position corresponding to one-fourth (1 / 4) of the total length of the wire harness 100, and a position corresponding to one-half (1 / 2) of the total length of the wire harness 100. Furthermore, the direction in which the moving unit 4 moves the antenna 3 is not limited to the rightward direction and may be the leftward direction.

[0077] Furthermore, for example, the evaluation device 1 and the anechoic chamber 10 of the embodiment of the present disclosure are provided with the storage means 8, but may not be provided with the storage means 8. Furthermore, for example, the evaluation method of the embodiment of the present disclosure is provided with an example in which the first transmission characteristic value acquisition procedure, the correction combined value calculation procedure, and the combined value calculation procedure are performed in this order, but the first transmission characteristic value acquisition procedure, the correction combined value calculation procedure, and the combined value calculation procedure may be performed in any order. [Explanation of symbols]

[0078] 1 Evaluation device 2 Test bench 2´ Mounting table 2A Reference Ground Plane 2A´ Reference Ground Plane 2B Ground Strap 2C Foam support base 2D Metal Sheet Angle 3 Antennas 3´ Antenna 4. Transportation 4´ Transportation 5 Measurement means 6. Dip reduction measures 7 Calculation method 8 Memory means 9 50Ω terminator 10 Anechoic box 11. Housing 11A Left side plate 11B Right side plate 11C Upper Plate 11D lower plate 11E Front door 11F back plate 12 Radio wave absorber 13 Connector Panel 14 groove 15 Connection fixture 16 Signal applying connector 17 Handle 18 Support rod 18´ support rod 20 EMI measurement antenna 100 Wire Harness 200 Calibration Wire A arrow AC anechoic chamber D1 Distance D2 distance X Left / right direction Y Front-to-rear direction Z vertical direction

Claims

1. An evaluation device for evaluating radiated interference waves emitted from a measurement object, a test stand on which the object to be measured is placed; an antenna disposed at a predetermined distance from the object to be measured and receiving electromagnetic waves; a moving means for horizontally moving the antenna over the predetermined distance; a measuring means for measuring an evaluation transmission characteristic which is a transmission characteristic between the object to be measured and the antenna; a dip reduction means for calculating a composite value, which is a value obtained by reducing a dip in the frequency spectrum of the evaluation transmission characteristic value, based on the evaluation transmission characteristic value, which is a measurement value of the evaluation transmission characteristic measured by the measurement means; a calculation means for calculating an evaluation value of the radiated interference wave based on the combined value, the measuring means measures the evaluated transmission characteristics at two or more different positions to which the antenna is moved by the moving means; the dip reduction means calculates the composite value by combining maximum or average values of the evaluated transmission characteristic values measured by the measurement means for each frequency. An evaluation device characterized by:

2. a storage means for storing, as a first transmission characteristic value, a measurement value of a first transmission characteristic, which is a transmission characteristic between the calibration object and the EMI measurement antenna when an electromagnetic wave radiated from the calibration object is received by the EMI measurement antenna conforming to CISPR25; the measuring means measures a second transmission characteristic which is a transmission characteristic between the calibration object and the antenna when the antenna receives an electromagnetic wave radiated from the calibration object placed on the test stand instead of the object to be measured, the dip reduction means calculates a correction synthesis value, which is a value obtained by reducing a dip in the frequency spectrum of the second transmission characteristic value, based on a second transmission characteristic value that is a measurement value of the second transmission characteristic measured by the measurement means; the calculation means calculates a correction coefficient by subtracting the correction combined value from the first transmission characteristic value, and calculates the evaluation value by adding the correction coefficient to the combined value.

2. The evaluation device according to claim 1.

3. The antenna has a receivable frequency band from 150 kHz to 6000 MHz.

3. The evaluation device according to claim 1 or 2.

4. the object to be measured is a wire harness, The wire harness is placed at a position 100 mm from one side of the rectangular test stand and parallel to the one side, The predetermined distance is one selected from the range of 200 mm to 500 mm in the direction opposite to the one side, The moving means moves the antenna parallel to the longitudinal direction of the wire harness.

3. The evaluation device according to claim 1 or 2.

5. the moving means moves the antenna from a position corresponding to the center of the longitudinal direction of the wire harness toward either end of the wire harness to a position corresponding to a quarter of the total length of the wire harness and / or a half of the total length of the wire harness, the measuring means measures the evaluated transmission characteristics at at least two positions out of a position corresponding to the center, a position corresponding to the quarter length, and a position corresponding to the half length.

5. The evaluation device according to claim 4.

6. An anechoic box for evaluating radiated interference waves emitted from a measurement object, a mounting table on which the measurement object is placed; an antenna disposed at a predetermined distance from the object to be measured and receiving electromagnetic waves; a moving means for horizontally moving the antenna over the predetermined distance; a measuring means for measuring an evaluation transmission characteristic which is a transmission characteristic between the object to be measured and the antenna; dip reduction means for calculating a composite value that is a value obtained by reducing a dip in the frequency spectrum based on an evaluation transmission characteristic value that is a measurement value of the evaluation transmission characteristic measured by the measurement means; a calculation means for calculating an evaluation value of the radiated interference wave based on the composite value; a housing having the mounting base and capable of accommodating at least the object to be measured and the antenna therein; a radio wave absorber provided on the inner surface of the housing, the measuring means measures the evaluated transmission characteristics at two or more different positions to which the antenna is moved by the moving means; the dip reduction means calculates the composite value by combining maximum or average values of the evaluated transmission characteristic values measured by the measurement means for each frequency. The electromagnetic anechoic box is characterized by the above.

7. a first transmission characteristic value acquisition step of measuring a first transmission characteristic, which is a transmission characteristic between the calibration object to be measured and the EMI measurement antenna when an electromagnetic wave radiated from the calibration object to be measured placed on a test stand is received by the EMI measurement antenna conforming to CISPR25, and acquiring a first transmission characteristic value, which is a measurement value of the first transmission characteristic; a correction combined value calculation step of horizontally moving an antenna at a predetermined distance from the calibration object placed on the test stand, measuring second transmission characteristics that are transmission characteristics between the calibration object and the antenna at two or more different positions at the predetermined distance, and calculating a correction combined value that is a value that reduces a dip in the frequency spectrum of the second transmission measurement value by taking and combining maximum or average values for each frequency of second transmission characteristic values that are measurement values of the second transmission characteristics; a composite value calculation step of horizontally moving the antenna at the predetermined distance from the object to be measured placed on the test stand, measuring an evaluation transmission characteristic that is a transmission characteristic between the object to be measured and the antenna at two or more different positions at the predetermined distance, and calculating a composite value that is a value in which dips in the frequency spectrum of the evaluation transmission characteristic value have been reduced by taking and combining maximum or average values for each frequency of the evaluation transmission characteristic values that are the measurement values of the evaluation transmission characteristic, after performing the first transmission characteristic value acquisition procedure, the correction combined value calculation procedure, and the combined value calculation procedure in any order, subtracting the correction combined value from the first transmission characteristic value to calculate a correction coefficient, and adding the correction coefficient to the combined value to calculate an evaluation value of the radiated interference wave emitted from the object to be measured; An evaluation method characterized by:

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