JP2010054302A - Method of estimating anechoic characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of estimating an anechoic characteristic, which facilitates estimating the anechoic characteristic in an anechoic domain in a short time. <P>SOLUTION: A transmission antenna 4 and receiving antennas 6 are arranged in a radio wave anechoic chamber 1. Each receiving antenna 6 is arranged on three points, a center position O, an upper end P1 and a lower end P2 of the anechoic domain QZ, and each propagation loss L0, L1, L2 between the antennas 4, 6 on each position is measured. Then, the maximum value Lmax and the minimum value Lmin in propagation losses L1e, L2e determined by performing distance correction of each propagation loss L1, L2 and the propagation loss L0 are determined, and a fluctuation width of an electric field is estimated from a difference (propagation loss difference ΔL) between the maximum value Lmax and the minimum value Lmin. Finally, the anechoic characteristic R is operated based on a fluctuation width estimation value A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an anechoic characteristic estimation method for estimating an anechoic characteristic of an anechoic region (Quiet Zone) using a transmitting antenna and a receiving antenna provided in an anechoic chamber.

  In general, an anechoic chamber is configured such that a radio wave absorber is provided on front, rear, left, and right wall surfaces, floor surfaces, and ceiling surfaces. For example, when measuring the EMI characteristics or the like of an object to be measured such as a mobile phone, the object to be measured and the measurement antenna are disposed in the anechoic chamber, and electromagnetic waves from the object to be measured are received using the measurement antenna. .

  In addition, the wall surface of the anechoic chamber suppresses the generation of reflected waves by the radio wave absorber. However, since the reflected wave cannot be completely eliminated, there are a portion where the influence of the reflected wave is large and a portion where the reflected wave is small in the anechoic chamber. For this reason, it is preferable to search for an anechoic region where the influence of the reflected wave is small before the measurement, and to measure various characteristics by placing an object to be measured in the anechoic region.

  A free space standing wave ratio method is known as a method for measuring an anechoic characteristic (also referred to as an antireflective characteristic) corresponding to the return loss in such an anechoic region (see, for example, Non-Patent Document 1). In this free space standing wave ratio method, a transmission signal from a transmission antenna is received while moving the reception antenna in an anechoic region with the transmission antenna fixed at the position where the measurement antenna is placed. As a result, standing waves in the anechoic region are directly detected, and strong reflected waves and weak reflected waves are detected based on the difference (standing wave ratio) between the maximum and minimum amplitudes of the standing waves. The anechoic characteristic, which is the ratio of

Limited company TSS JAPAN, "Evaluation method of antenna anechoic chamber free space standing wave ratio method", [online], October 30, 2001, limited company TSS JAPAN, [April 30, 2008 search], Internet <URL: http: //tssj.co.jp/pdf/antenahyoka.pdf>

  By the way, in the free space standing wave ratio method, since a transmission signal is continuously received while moving a receiving antenna, a long time is required for measuring a standing wave. In order to move the receiving antenna, for example, it is necessary to attach the receiving antenna to a cart or the like and to make the cart run by itself using a motor, or to pull a string or belt using a motor. At this time, a reflected wave is generated from the motor or the carriage, which may affect the measurement result. Furthermore, there is a problem that a dedicated jig is necessary to continuously move the receiving antenna in the height direction.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an anechoic characteristic estimation method that can easily estimate an anechoic characteristic in an anechoic region in a short time. There is.

  In order to solve the above-mentioned problem, the invention of claim 1 is characterized in that a transmitting antenna and a receiving antenna are placed in a radio anechoic chamber having a space extending in three axial directions of X axis, Y axis and Z axis orthogonal to each other. Estimate the anechoic characteristics according to the standing wave of the transmission signal generated in the anechoic region by arranging the transmission signals from the transmission antenna at multiple locations using the reception antenna. A method for estimating reverberation characteristics, comprising: a center position measuring step of measuring a propagation loss between the transmitting antenna and the receiving antenna by disposing the receiving antenna at a center position of the anechoic region; and One side end measurement step of measuring the propagation loss between the transmitting antenna and the receiving antenna by being arranged at one side end in any one of the three axial directions in the anechoic region; and Before the anechoic region The other side end measurement step of measuring the propagation loss between the transmitting antenna and the receiving antenna by being arranged at the other side end portion in the uniaxial direction, the propagation loss measured in the one side end measurement step, and the other side Propagation loss correction step for correcting the propagation loss measured in the edge measurement step according to the distance between the transmission antenna and the reception antenna, and the propagation loss measured in the center position measurement step and the propagation loss correction step A propagation loss difference calculation step of calculating a difference between the maximum value and the minimum value by determining a maximum value and a minimum value among the two corrected propagation losses, and a propagation loss difference by the propagation loss difference calculation step The fluctuation range estimation step of estimating the fluctuation range of the electric field estimated from the regression equation and the anechoic characteristic calculation step of calculating the anechoic characteristic based on the fluctuation range estimation value by the fluctuation range estimation step .

  In the invention of claim 2, the receiving antenna is configured to use an omnidirectional antenna.

  According to a third aspect of the present invention, when the wavelength of the transmission signal radiated from the transmission antenna is λ, the anechoic region has a major axis dimension d1 parallel to the X-axis direction that is less than or equal to the wavelength λ, and the Y-axis direction. An ellipse is formed by rotating an ellipse whose parallel minor axis dimension d2 is equal to or less than half of the wavelength λ around the Y axis passing through the center position.

  According to the first aspect of the present invention, the amplitude fluctuation range (standing wave ratio) is estimated using the three propagation losses measured in the center position measuring step, the one side end measuring step, and the other side end measuring step. Then, the anechoic characteristics are calculated based on the estimated fluctuation range. For this reason, it is only necessary to measure the propagation loss between the transmitting antenna and the receiving antenna at three points in one axial direction in the anechoic region, and the measurement time can be shortened. In addition, since the receiving antennas only need to be arranged at three locations with respect to one axial direction, there is no need to continuously move the receiving antennas with a carriage or the like, and the influence of reflected waves from the motor or carriage can be eliminated. it can. In addition, since it is not necessary to continuously move the receiving antenna in the height direction (Z-axis direction), there is no need to use a special jig or the like, and the anechoic characteristic measuring device can be simplified. it can.

  According to the invention of claim 2, since the receiving antenna is configured using an omnidirectional antenna, for example, even when evaluating an omnidirectional object to be measured such as a mobile phone in an anechoic region. The anechoic characteristics in the anechoic region applicable to such evaluation can be obtained.

  According to the invention of claim 3, the anechoic region has a circular shape having a diameter of not more than the wavelength λ with the center position as the center in the XZ plane. Here, for example, when the diameter is set to a value greater than or equal to twice the wavelength λ, there are a plurality of maximum and minimum values of the standing wave, so in the measurement at only three locations, for example, only a value close to the maximum or minimum value is obtained. There is a possibility of measurement, and the reliability of the estimated fluctuation range of the electric field is lowered. On the other hand, in the present invention, since the diameter of the anechoic region on the XZ plane is equal to or less than the wavelength λ, the maximum value and the minimum value of the standing wave are 1 in the anechoic region with respect to the X-axis direction. In addition, there are only one standing wave maximum value and one minimum value in the anechoic region in the Z-axis direction. For this reason, even if only three propagation losses are measured, values corresponding to the maximum value and the minimum value can be measured, respectively, and the fluctuation range estimated value and fluctuation of the electric field with respect to the X-axis direction and the Z-axis direction can be measured. The reliability of anechoic characteristics calculated from the estimated width is improved.

  The anechoic region has an elliptical shape centered on the center position on the XY plane, and the ellipse has a short axis parallel to the Y-axis direction and a long axis parallel to the X-axis direction. At this time, the minor axis dimension parallel to the Y-axis direction is half or less of the wavelength λ, and the major axis dimension d1 parallel to the X-axis direction is less than or equal to the wavelength λ.

  Here, since the transmission antenna and the reception antenna are separated from each other in the Y-axis direction, the reflected wave reciprocates between the transmission antenna and the reception antenna and the wall surface and enters the reception antenna. At this time, since the path length of the reflected wave changes twice as much as the displacement when the receiving antenna is displaced in the Y-axis direction, a half wavelength (λ / 2) is constant in the Y-axis direction. It almost coincides with one wave period.

  On the other hand, in the present invention, since the short axis dimension d2 of the anechoic region is less than half of the wavelength λ, the maximum value and the minimum value of the standing wave are within the anechoic region with respect to the Y-axis direction. There is only one each. As a result, the reliability of the estimated fluctuation range and the anechoic characteristics can be improved also in the Y-axis direction.

  Hereinafter, an anechoic characteristic estimation method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  1 to 3 show an anechoic characteristic measuring apparatus. Here, the radio wave anechoic chamber 1 is formed by providing a radio wave absorber 3 inside a room 2 made of, for example, a hexahedron. The room 2 has a front wall surface 2A, a rear wall surface 2B, a left wall surface 2C, a right wall surface 2D, a floor surface 2E, and a ceiling surface 2F. These wall surfaces 2A to 2D, the floor surface 2E, and the ceiling surface 2F are conductive. It is made of a metal material. The radio wave anechoic chamber 1 blocks external electromagnetic waves and prevents reflection of internal electromagnetic waves.

  In the anechoic chamber 1, for example, a length of about several meters to several tens of meters with respect to the width direction (X-axis direction), the depth direction (Y-axis direction), and the height direction (Z-axis direction). A space having a vertical dimension is formed. At this time, the front wall surface 2A and the rear wall surface 2B are disposed to face each other in the depth direction, and the left wall surface 2C and the right wall surface 2D are disposed to face each other in the width direction. Further, the floor surface 2E and the ceiling surface 2F are disposed opposite to each other on both sides in the height direction.

  The radio wave absorber 3 covers the wall surfaces 2A to 2D, the floor surface 2E, and the ceiling surface 2F over substantially the entire surface. The radio wave absorber 3 is formed in a pyramid shape or a taper shape having a projecting dimension of about 10 to 15 cm using a radio wave absorbing material such as a urethane material containing carbon, and projects toward the inside of the room 2. ing. The radio wave absorber 3 does not necessarily have a shape with a protruding tip, and may be formed in a flat plate shape (sheet shape), for example.

  The transmitting antenna 4 is disposed inside the anechoic chamber 1 at, for example, an intermediate position between the left and right wall surfaces 2C and 2D with respect to the X-axis direction, and at a position close to the front wall surface 2A with respect to the Y-axis direction. Has been placed. Here, the transmission antenna 4 is attached to an antenna positioner 5 and is fixed inside the anechoic chamber 1. Further, the transmission antenna 4 is arranged at a position spaced apart from a reception antenna 6 described later in the Y-axis direction (depth direction). The transmission antenna 4 is connected to a network analyzer 8 to be described later, and outputs a transmission signal composed of, for example, a horizontally polarized wave or a vertically polarized wave having a predetermined frequency f. The polarization plane of the transmission antenna 4 may be switched automatically using the antenna positioner 5 or may be switched manually by the measurer.

  The receiving antenna 6 is separated from the transmitting antenna 4 by a distance D0 with respect to the Y-axis direction, and is disposed at a position close to the rear wall surface 2B in the anechoic chamber 1. Here, the receiving antenna 6 is positioned inside the anechoic region QZ and attached to the antenna installation jig 7. The receiving antenna 6 is configured using, for example, an omnidirectional antenna. And the receiving antenna 6 is arrange | positioned in the end part of the center position O, the X-axis direction, the Y-axis direction, and the Z-axis direction inside the anechoic region QZ, and receives the transmission signal from the transmitting antenna 4 at each position. To do.

  At this time, the anechoic region QZ has an ellipsoidal shape centered on a center position O that is the same height position and width direction position as the transmitting antenna 4 and is separated by a distance D0 in the Y-axis direction. Further, for example, when the wavelength of the transmission signal is λ, the ellipsoid has a major axis dimension d1 parallel to the X-axis direction that is less than or equal to the wavelength λ (d1 ≦ λ) and a minor axis dimension d2 parallel to the Y-axis direction. Is a spheroid shape obtained by rotating an ellipse whose wavelength is less than half of the wavelength λ (d2 ≦ λ / 2) around the Y axis (axis Y0-Y0) passing through the center position O. Thereby, in the anechoic region QZ, a standing wave is generated for only one period in any of the X-axis direction, the Y-axis direction, and the Z-axis direction.

  Further, the antenna installation jig 7 transmits the height dimension H0 from the floor surface 2E when the reception antenna 6 is arranged at the center position O, the end in the X-axis direction, and the Y-axis direction within the anechoic region QZ. The height position of the receiving antenna 6 is adjusted so as to be the same value as the antenna 4. On the other hand, when the receiving antenna 6 is arranged at the upper end P1 that is the end in the Z direction of the anechoic region QZ, the height position of the receiving antenna 6 is set so that the height dimension Hmax is larger than the height dimension H0. adjust. Similarly, when the receiving antenna 6 is disposed at the lower end portion P2 that is the end portion in the Z direction of the anechoic region QZ, the height position of the receiving antenna 6 is set so that the height dimension Hmin is smaller than the height dimension H0. Adjust.

  When estimating the anechoic characteristic R in the Z-axis direction, it is only necessary that the receiving antenna 6 can be arranged at three locations with respect to the Z-axis direction. For this reason, it is good also as a structure which prepares the three antenna installation jigs 7 from which a height dimension differs, and replaces the antenna installation jig 7 according to the height position of the receiving antenna 6. FIG.

  The network analyzer 8 constitutes a propagation loss measuring device that measures a propagation loss L, which is a spatial attenuation amount between the transmission antenna 4 and the reception antenna 6, and is connected to the transmission antenna 4 through the high-frequency cable 8A. It is connected to the receiving antenna 6 through 8B. The network analyzer 8 receives the electromagnetic wave (transmission signal) transmitted from the transmission antenna 4 using the reception antenna 6. Thereby, the network analyzer 8 calculates the ratio between the power supplied to the transmission antenna 4 and the power received from the reception antenna 6, and measures the parameter S21 (propagation loss) of the S matrix corresponding to the space loss.

  The anechoic characteristic measurement apparatus according to the present embodiment is configured as described above. Next, an anechoic characteristic estimation method using this measurement apparatus will be described with reference to FIG.

  First, before starting the measurement, the network analyzer 8 directly connects the high-frequency cable 8A connected to the transmission antenna 4 and the high-frequency cable 8B connected to the reception antenna 6, and corrects the scale by the loss caused by the high-frequency cables 8A and 8B. (Calibration) is performed. The transmission antenna 4 outputs a horizontally polarized transmission signal, for example.

  Next, in the center position measuring step, the receiving antenna 6 is arranged at the center position O of the anechoic region QZ. In this state, the transmission signal from the transmission antenna 4 is received using the reception antenna 6, and the propagation loss L0 (dBm) at the center position O is measured.

  Next, in the one-side end measurement step, for example, the receiving antenna 6 is arranged at the upper end P1 in the Z-axis direction in the anechoic region QZ. In this state, the transmission signal from the transmission antenna 4 is received using the reception antenna 6, and the propagation loss L1 (dBm) at the upper end P1 is measured.

  Next, in the other end measurement step, for example, the receiving antenna 6 is arranged at the lower end P2 in the Z-axis direction in the anechoic region QZ. In this state, the transmission signal from the transmission antenna 4 is received using the reception antenna 6, and the propagation loss L2 (dBm) at the lower end P2 is measured.

  Next, in the propagation loss correction step, the distance attenuation of the propagation losses L1 and L2 is corrected according to the distance between the antennas 4 and 6. More specifically, the distances D1 and D2 between the antennas 4 and 6 when the propagation losses L1 and L2 are measured are longer than the distance D between the antennas 4 and 6 when the propagation loss L0 is measured. Yes. For this reason, the propagation losses L1 and L2 are larger than the propagation loss L0 by the increase of the distance dimension. At this time, the relationship between the arbitrary distance d between the antennas 4 and 6 and the propagation loss L (dB) is expressed as the following formula 2 based on the Friis transfer formula shown in the following formula 1. Can do.

  In Equations 1 and 2, Pt represents transmission power transmitted from the transmission antenna 4, and Pr represents reception power received by the reception antenna 6. Gt represents the gain of the transmission antenna 4, and Gr represents the gain of the reception antenna 6. Further, λ represents the wavelength of the transmission signal.

  For this reason, correction values CF1 and CF2 (dB) corresponding to the distances D1 and D2 can be obtained using the following equation (3) based on the equations (1) and (2).

  In the equation (3), it is assumed that the transmission antenna 4 and the reception antenna 6 are both non-directional antennas, and the transmission antenna gain Gt and the reception antenna gain Gr are constant values regardless of directions. However, the present invention is not limited to this. For example, when the antennas 4 and 6 have directivity, the gains Gt and Gr may be corrected together with the distance correction.

  Further, the distances D1 and D2 in Equation 3 are based on, for example, the angles θ1 and θ2 between the transmission antenna 4 and the reception antenna 6 and the distance D0 between the transmission antenna 4 and the center position O as shown in the following Equation 4 It is calculated using the following formula.

  Based on the following equation (5), corrected propagation losses L1e and L2e are obtained by adding correction values CF1 and CF2 to the propagation losses L1 and L2, respectively.

  Next, in the propagation loss difference calculation step, the maximum value Lmax and the minimum value Lmin are determined among the propagation loss L0 and the corrected propagation losses L1e and L2e, and the propagation loss is the difference between the maximum value Lmax and the minimum value Lmin. The difference ΔL (dB) is calculated.

  Next, in the fluctuation range estimation step, a fluctuation range estimation value A estimated from the regression equation is obtained by multiplying the propagation loss difference ΔL by a coefficient K as shown in the following equation (6). At this time, the coefficient K corresponds to a correlation coefficient between the actual standing wave ratio and the propagation loss difference ΔL by three-point measurement, and is a value obtained experimentally using a regression equation. The value is about 15 (K≈1.15).

  Finally, in the anechoic characteristic calculation step, the anechoic characteristic R (dB) is calculated using the fluctuation range estimated value A as shown in the following equation (7).

  By the above estimation work, the anechoic characteristic R with respect to the Z-axis direction of the anechoic region QZ can be estimated. Similarly, the above operation is similarly performed in the X-axis direction and the Y-axis direction. In addition, the polarization plane of the transmission antenna 4 is switched to perform the transmission signal of vertical polarization. Thereby, the anechoic characteristic R of the whole anechoic region QZ can be estimated.

  In this embodiment, the anechoic characteristic estimation method as described above is used, and then the anechoic characteristic R of the anechoic chamber 1 is estimated using the above-described anechoic characteristic estimation method. The case where the standing wave waveform was actually measured and the anechoic characteristic R0 was calculated (standing wave ratio method) was compared.

  The height dimension H0 of the center position O of the anechoic region QZ was 2.15 m. The frequency f of the transmission signal was 210 MHz. At this time, since the wavelength λ of the transmission signal is about 1.43 m, the long axis dimension d1 of the anechoic region QZ is set to 1.3 m. That is, the upper end portion P1 of the anechoic region QZ is set to a position 0.65 m higher than the center position O, and the lower end portion P2 of the anechoic region QZ is set to a position 0.65 m lower than the center position O.

  First, as a comparative example, the propagation loss L was continuously measured by moving the receiving antenna 6 in the Z-axis direction, as in the prior art. After that, the value measured at other than the center position O among the propagation losses L was corrected according to the distance d, and the corrected propagation loss LE was obtained. The result is shown by a solid line in FIG.

  As the measurement result of FIG. 4 shows, the corrected propagation loss LE increases or decreases according to the height position of the receiving antenna 6 and changes in a sine wave shape. This is because the reception antenna 6 receives not only the direct wave directly incident on the reception antenna 6 from the transmission antenna 4 but also the reflected wave reflected by the wall surfaces 2A to 2D, the floor surface 2E, and the ceiling surface 2F. This is because the direct wave and the reflected wave interfere with each other, and the reception power Pr by the reception antenna 6 changes according to the position of the reception antenna 6.

  Therefore, when the maximum value LEmax and the minimum value LEmin are obtained from the corrected propagation loss LE, the maximum value LEmax is −8.28 dB and the minimum value LEmin is −10.47 dB. As a result, the fluctuation range A0, which is the amplitude of the standing wave waveform, is 2.19 dB based on the difference between the maximum value LEmax and the minimum value LEmin, so that the anechoic characteristic R0 is -18. It became 0 dB.

  On the other hand, in the present embodiment, propagation losses L0, L1, and L2 are measured at three locations, the center position O, the upper end portion P1, and the lower end portion P2. Thereafter, the propagation losses L1 and L2 at the upper end P1 and the lower end P2 are corrected according to the distances D1 and D2, and the corrected propagation losses L1e and L2e are obtained. The result is shown by white circles in FIG.

  Then, when the maximum value Lmax and the minimum value Lmin are obtained among the propagation loss L0 and the corrected propagation losses L1e and L2e, the maximum value Lmax becomes −8.69 dB based on the propagation loss L0 at the center position O, and the minimum value Lmin was -10.39 dB based on the corrected propagation loss L2 at the lower end P2. At this time, the propagation loss difference ΔL is 1.70 dB based on the difference between the maximum value Lmax and the minimum value Lmin, and therefore, by multiplying the propagation loss difference ΔL by the correlation coefficient K, the fluctuation range estimation value A is 1. 955 dB. As a result, the anechoic characteristic R was -19.0 dB based on the fluctuation range estimated value A, and it was confirmed that it substantially coincided with the anechoic characteristic R0 (R0 = -18.0 dB) obtained by the standing wave ratio method.

  Thus, in the present embodiment, the amplitude fluctuation range is estimated using the three propagation losses L0 to L2 measured in the center position measuring step, the one side end measuring step, and the other side end measuring step, and this fluctuation is determined. Based on the estimated width A, the anechoic characteristic R is calculated. For this reason, it is only necessary to measure the propagation losses L0 to L2 between the transmitting antenna 4 and the receiving antenna 6 at three points in one axial direction in the anechoic region QZ, so that the measurement time can be shortened. Thus, an anechoic region QZ having a good anechoic characteristic R can be easily found.

  Further, since the receiving antenna 6 only needs to be arranged at three positions with respect to one axial direction, it is not necessary to continuously move the receiving antenna 6 with a carriage or the like, and the influence of reflected waves from the motor and the carriage is eliminated. be able to. Further, since it is not necessary to continuously move the receiving antenna 6 in the height direction (Z-axis direction), there is no need to use a special jig or the like, and the anechoic characteristic R measuring device is simplified. be able to.

  Further, since the receiving antenna 6 is configured using an omnidirectional antenna, for example, even when evaluating an omnidirectional object to be measured such as a cellular phone in an anechoic region QZ, such an evaluation is performed. The anechoic characteristic R of the anechoic region QZ applicable to the above can be obtained.

  Further, the anechoic region QZ has a circular shape with the diameter of the wavelength λ or less centered on the center position O on the XZ plane. Here, when this diameter is set to a value more than twice the wavelength λ, for example, there are a plurality of maximum and minimum values of the standing wave in the anechoic region QZ. Only the value close to the minimum value may be measured, and the reliability of the estimated fluctuation range A of the electric field decreases. On the other hand, in the present invention, since the diameter of the anechoic region QZ on the XZ plane is equal to or less than the wavelength λ, the maximum value and the minimum value of the standing wave are within the anechoic region QZ with respect to the X-axis direction. There is only one each, and there is only one maximum value and one minimum value of the standing wave in the anechoic region QZ in the Z-axis direction. For this reason, even if only three propagation losses L are measured, values corresponding to the maximum value and the minimum value of the standing wave can be measured respectively, and the electric field fluctuations in the X-axis direction and the Z-axis direction. The reliability of the anechoic characteristic R calculated from the estimated width A and the estimated variation A is improved.

  On the other hand, the anechoic region QZ has an elliptical shape centered on the center position O on the XY plane, and the ellipse has a short axis parallel to the Y-axis direction and a long axis parallel to the X-axis direction. . At this time, the minor axis dimension d2 parallel to the Y-axis direction was set to half or less of the wavelength λ, and the major axis dimension d1 parallel to the X-axis direction was set to the wavelength λ or less.

  Here, since the transmission antenna 4 and the reception antenna 6 are separated from each other in the Y-axis direction, the reflected wave reciprocates between the transmission antenna 4 and the front wall surface 2A, for example, or passes through the reception antenna 6 to the rear wall surface. Reciprocates between 2B and enters the receiving antenna 6. At this time, since the path length of the reflected wave changes twice as much as the displacement when the receiving antenna 6 is displaced in the Y-axis direction, a half wavelength (λ / 2) is fixed in the Y-axis direction. It almost coincides with one period of the standing wave.

  On the other hand, in the present embodiment, since the short axis dimension d2 of the anechoic region QZ is less than half of the wavelength λ, the maximum value of the standing wave in the anechoic region QZ with respect to the Y-axis direction. And there is only one minimum. Thereby, the reliability of the fluctuation range estimated value A and the anechoic characteristic R can be improved also in the Y-axis direction.

  In the above embodiment, the receiving antenna 6 is configured using an omnidirectional antenna, but may be configured using a directional antenna. The transmission antenna 4 may also be configured using an omnidirectional antenna, or may be configured using a directional antenna.

It is sectional drawing which shows the measuring apparatus of the anechoic characteristic by embodiment of this invention. It is sectional drawing which looked at the measuring apparatus of the anechoic characteristic from the arrow II-II direction in FIG. FIG. 3 is a cross-sectional view of a receiving antenna and the like when viewed from the direction of arrows III-III in FIG. It is a characteristic diagram which shows the relationship between the height of a receiving antenna, propagation loss, and correction | amendment propagation loss.

Explanation of symbols

1 Anechoic chamber 4 Transmitting antenna 6 Receiving antenna 8 Network analyzer QZ Anechoic region

Claims (3)

A transmitting antenna and a receiving antenna are arranged apart from each other in the Y-axis direction in a radio anechoic chamber having a space extending in three axial directions of X axis, Y axis and Z axis orthogonal to each other, and a transmission signal from the transmitting antenna is transmitted. An anechoic characteristic estimation method for estimating an anechoic characteristic according to a standing wave of a transmission signal generated in an anechoic region by receiving at a plurality of locations using a receiving antenna,
A center position measuring step of measuring the propagation loss between the transmitting antenna and the receiving antenna by arranging the receiving antenna at the center position of the anechoic region;
One side edge measurement step of measuring the propagation loss between the transmission antenna and the reception antenna by arranging the reception antenna at one side edge in any one of the three axial directions of the anechoic region;
The other side edge measurement step of measuring the propagation loss between the transmission antenna and the reception antenna by arranging the reception antenna at the other side edge in the uniaxial direction in the anechoic region,
A propagation loss correction step of correcting the propagation loss measured in the one side edge measurement step and the propagation loss measured in the other side edge measurement step according to the distance between the transmission antenna and the reception antenna;
A maximum value and a minimum value are determined between the propagation loss measured in the center position measurement step and the two corrected propagation losses corrected in the propagation loss correction step, and a difference between the maximum value and the minimum value is calculated. Propagation loss difference calculation process;
A fluctuation range estimating step of estimating a fluctuation range of the electric field estimated from the regression equation based on the propagation loss difference by the propagation loss difference calculating step;
An anechoic characteristic estimation method comprising: an anechoic characteristic calculation step of calculating an anechoic characteristic based on a fluctuation range estimation value obtained by the fluctuation range estimation step.   The anechoic characteristic estimation method according to claim 1, wherein the reception antenna is configured using an omnidirectional antenna.   In the anechoic region, when the wavelength of the transmission signal radiated from the transmitting antenna is λ, the major axis dimension d1 parallel to the X-axis direction is less than or equal to the wavelength λ, and the minor axis dimension d2 parallel to the Y-axis direction is The method of estimating anechoic characteristics according to claim 1 or 2, wherein an ellipsoid having a spheroid shape obtained by rotating an ellipse having a wavelength less than or equal to half of the wavelength λ about the Y axis passing through the center position.

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