JP4279406B2 - Reflector antenna phase distribution measuring method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for measuring the phase distribution of a reflector antenna, and more particularly to a method and apparatus for measuring the phase distribution of a reflector antenna used in a high frequency band.
[0002]
[Prior art]
An antenna used in a high frequency band such as a submillimeter wave has a problem that a sufficient dynamic range cannot be ensured because the wavelength used in the far field measurement is short for measuring antenna characteristics such as radiation characteristics. There is. In order to solve this problem, in the anechoic chamber, by measuring the amplitude and phase distribution of the electric field in the vicinity of the antenna aperture, the aperture distribution of the antenna is measured, and the radiation characteristics are calculated by using the aperture distribution. There is a near field measurement method to obtain. However, this near-field measurement method needs to measure the phase. In the case of submillimeter waves, it is difficult to accurately measure the phase distribution due to measurement error, cable temperature change, installation alignment error, etc. Therefore, the radiation characteristics of the antenna were not accurately determined.
[0003]
In order to solve this problem, there is a phase retrieval method in which amplitude distributions of two different planes are measured and the phase distribution is estimated by numerical calculation using them. Measurement of only the amplitude distribution does not require highly accurate measurement compared to the phase distribution. Conventional methods for measuring the antenna phase distribution of this type include, for example, OMBucci et al "Far-field pattern determination from the near-field amplitude on two surfaces", IEEE Transactions on Antennas and Propagation. Vol.38, No.11, Those disclosed in Nov. 1990 are known.
[0004]
FIG. 7 is a diagram schematically showing a conventional antenna phase distribution measuring apparatus disclosed in the above document. In the figure, reference numeral 1 denotes an antenna to be measured whose phase distribution is to be measured, 5 is a probe for measuring the amplitude and phase of an electric field in the vicinity of the antenna for phase distribution measurement, and 7 is an xy scanner that scans the probe 5 in the xy direction. , 8 is a transmitter / receiver that transmits / receives a signal representing the measurement result from the probe 5, 9 is an arithmetic processor for calculating the output signal from the transmitter / receiver 8 to obtain a phase distribution, and 15 is for supporting the antenna 1. The turntable rotated around the x-axis direction is shown. FIG. 8 shows a flowchart of a phase estimation algorithm by the conventional phase retrieval used in the antenna phase distribution measuring apparatus shown in FIG.
[0005]
As shown in FIG. 7, an O-xyz coordinate system is defined in which the z-axis is the direction in which radio waves are radiated on the aperture of the antenna 1 to be measured, and only the amplitude distribution of radio waves on different z = R1 and R2 surfaces. Measure. Using these amplitude distributions, the phase is estimated by the algorithm shown in FIG.
In S0, field conversion to z = R2 is performed using the amplitude distribution measured at z = R1 and an appropriate phase distribution as an initial value.
In S1, only the amplitude distribution is replaced with the amplitude distribution measured at z = R2 from the amplitude / phase distribution field-converted to z = R2, and field conversion is performed to z = R1.
In S2, from the amplitude / phase distribution field-converted to z = R1, only the amplitude distribution is replaced with the amplitude distribution measured at z = R1, and field conversion is performed again to z = R2.
In S3, the process is terminated if the difference between the field-transformed amplitude distribution at z = R2 and the actually measured amplitude distribution is sufficiently small, and the process returns to S1 otherwise.
[0006]
By performing the above repetitive calculation, the phase distributions at the time of completion are estimated as phase distributions at z = R1 and z = R2, respectively. Needless to say, if there is an amplitude / phase distribution of the electric field on a certain surface, it can be field-converted to an arbitrary position. Therefore, various characteristics such as the aperture distribution and the radiation pattern of the antenna under measurement can be calculated using the estimated phase distribution and the amplitude distribution of the measured value.
[0007]
In the near field measurement of the amplitude distribution of the antenna to be measured, when two different amplitude distributions can be measured, for example, a planar scanning near field measurement apparatus using a scanner capable of xy plane scanning, Further, the measurement can be performed using a cylindrical scanning near-field measuring device using a probe that can be scanned in a single axis and a rotating table that can rotate in one axis, or a spherical near-field measuring device that uses a rotating table that can rotate in two axes. Furthermore, field conversion is possible using any measurement value obtained using the above-described measurement apparatus.
[0008]
[Problems to be solved by the invention]
In the conventional reflector antenna phase distribution measuring method and apparatus as described above, for example, in the case of a planar scanning near-field measuring apparatus, the antenna to be measured must be moved in the z-axis direction to measure two different surfaces, There is a problem that it is necessary to consider an error in installation alignment when moving the antenna. In addition, since an antenna measuring device that can move in the z-axis direction is used, a large-scale device is required, which is costly.
[0009]
Further, in the case of a cylindrical scanning near-field measuring device and a spherical scanning near-field measuring device, it is necessary to move the probe in the radial direction from the center axis and center point of scanning, respectively. There is a problem that a larger apparatus is required.
[0010]
The present invention has been made to solve the above-described problems, and provides a method and an apparatus for measuring the phase distribution of a reflector antenna capable of measuring the phase distribution of a submillimeter wave reflector antenna with a simple configuration. The purpose is to provide.
[0011]
[Means for Solving the Invention]
According to the reflector antenna phase distribution measuring method of the present invention, in order to measure the phase distribution of the reflector antenna including the sub-reflector and the antenna to be measured, the sub-reflector is set to the on-focus position with respect to the antenna to be measured. A step of measuring an on-focus amplitude distribution at a certain time, and the sub-reflector with respect to the antenna to be measured A small amount of defocus was applied so that the amplitude distribution at the antenna aperture did not change. A step of moving to a defocus position, a step of measuring a defocus amplitude distribution when the sub-reflector is at a defocus position with respect to the antenna to be measured, and an operation by a phase retrieval method based on the both amplitude distributions Processing to obtain an aperture phase distribution of the antenna to be measured.
[0012]
The arithmetic processing can be performed according to the following procedure.
STEP 0: Prepare an amplitude distribution (A1Z) and initial phase distribution (P0) measured on-focus.
STEP 1: Field conversion is performed from the measurement surface to the antenna opening to be measured, and an amplitude distribution (A1A) converted into the aperture surface and a phase distribution (P1A) converted into the aperture surface are obtained.
STEP 2: A change amount (ΔP) of the aperture phase distribution due to defocus is added to the phase distribution (P1A) converted into the measurement antenna aperture.
STEP 3: Using the amplitude distribution (A1A) of the antenna aperture surface to be measured and the aperture phase distribution (P1A + ΔP) to which a relative change has been applied, field conversion is performed on the measurement surface, and the amplitude distribution (A2Z ′) converted to the measurement surface Obtaining a phase distribution (P2Z) on the measurement surface;
STEP 4: Of the amplitude / phase distribution converted to the measurement surface, the amplitude distribution (A2Z ′) is replaced with the amplitude distribution (A2Z) measured at the time of defocusing.
STEP 5: Using the amplitude measurement value and the phase distribution obtained in STEP 4, field conversion is again performed on the aperture surface of the antenna to be measured, and the amplitude distribution (A2A) converted into the aperture surface and the phase distribution converted into the aperture surface ( P2A)
STEP 6: A phase distribution (P2A-ΔP) is obtained by subtracting the amount of change by subtracting the relative change amount (ΔP) of the aperture phase distribution due to defocusing from the phase distribution (P2A) converted to the measured antenna aperture surface.
STEP 7: Amplitude distribution (A1Z ′) converted to the measurement surface by performing field conversion on the measurement surface using the amplitude distribution (A2A) of the measured antenna aperture surface and the aperture phase distribution (P2A−ΔP) obtained by reducing the relative change. And a phase distribution (P1Z)
STEP 8: Of the amplitude / phase distribution converted to the measurement surface, the amplitude distribution (A1Z ′) is replaced with the amplitude distribution (A1Z) measured during on-focus,
STEP 9: The difference between the amplitude distribution (A1Z ′) converted to the measurement surface and the actually measured amplitude distribution (A1Z) is compared. If the difference is sufficiently small, the phase distribution (P1Z) is taken as a solution and the procedure is performed. If not converged, return to STEP1.
[0013]
In addition, the reflector antenna phase distribution measurement method is a method for rotating the antenna under measurement around the mirror axis after the step of obtaining the aperture phase distribution of the antenna under measurement, and performing a new rotation different from the original rotation position. A step of moving the reflector antenna phase distribution measurement method according to claim 1 to the antenna under measurement at the other rotation position; and the step at the original rotation position. A step of taking an average of the phase distribution of the antenna under measurement and the phase distribution of the antenna under measurement at the new rotation position and correcting the specular error of the sub-reflecting mirror.
[0014]
The reflector antenna phase distribution measuring apparatus according to the present invention is a reflector antenna phase distribution measuring apparatus for measuring a phase distribution of a reflector antenna including a sub-reflector and an antenna to be measured. On-focus position with respect to the antenna or A small amount of defocus was applied so that the amplitude distribution at the antenna aperture did not change. A movable support device that is held at a defocus position, a probe for measuring the amplitude of the antenna under measurement, and a probe that moves relative to the antenna under measurement to move the probe relative to the mirror axis of the antenna under measurement. The on-focus amplitude distribution and the defocus amplitude distribution are obtained from the amplitude signal from the probe, and a scanning device that scans the coaxial measurement surface at a right angle with each other, and calculation processing by the phase retrieval method is performed based on both amplitude distributions. And an arithmetic processing unit for obtaining an aperture phase distribution of the antenna under measurement.
[0015]
The scanning device may include a scanner that scans the probe on a plane perpendicular to the mirror axis of the antenna to be measured.
[0016]
Further, the scanning device includes a scanner that moves the probe along a straight line passing through the mirror axis in the plane, and a rotating device that rotates the antenna under measurement around an axis parallel to the straight line. Things can be used.
[0017]
In addition, the scanning device includes a support device for fixing and supporting the probe on the mirror axis, and the antenna to be measured described above. Through mirror axis A rotating device that rotates around an axis parallel to the straight line and rotates around an axis perpendicular to the straight line may be provided.
[0018]
And a rotation device capable of rotating the antenna under measurement about a mirror axis to at least two rotation positions, wherein the arithmetic processing unit has a phase of the antenna under measurement at the at least two rotation positions. It may be provided with an average arithmetic unit that averages the distribution.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1.
1 schematically shows a reflector antenna phase distribution measuring method and apparatus according to Embodiment 1 of the present invention. In FIG. 1, the same reference numerals as those in FIG. 7 correspond to those in FIG. The operation is equivalent to that shown in FIG. In FIG. 1, 2 is a primary radiator of the antenna 1 to be measured, 4 is a sub-reflecting mirror, 4 a is a column that supports the sub-reflecting mirror 4 at a predetermined position with respect to the antenna 1 to be measured. The sub-reflecting mirror 4 is attached to the column 4a via a known appropriate position variable mechanism so that the position in the z-axis direction can be changed with respect to the antenna 1 to be measured. In the illustrated example, the position variable mechanism is a sub-reflector driving device 3 such as a screw jack driven by a motor. However, even if a simple link mechanism is used, the position is changed by selecting a combination of a screw and a screw hole. But it ’s okay. Reference numeral 6 denotes a drive device of the scanner 7 for driving the probe 5. FIG. 2 shows a flowchart of the phase estimation algorithm according to the first embodiment of the present invention. FIG. 3 shows an explanatory diagram of changes in the phase distribution due to the movement of the sub-reflecting mirror 4. 3, the same reference numerals as those in FIG. 1 are equivalent to those in FIG. 1, and the same operation as in FIG. 1 is performed.
[0020]
Next, the operation will be described. The near field amplitude distribution of the antenna 1 to be measured is measured by the reflector antenna measuring apparatus shown in FIG. The radio wave is radiated from the primary radiator 2 of the antenna 1 to be measured and radiated through the sub-reflecting mirror 4 and the antenna 1 to be measured. The sub-reflecting mirror 4 is mirrored in the mirror axis direction (z 1), the sub-reflecting mirror 4 is coaxial with the mirror axis of the antenna under measurement at a position Z1 away from the opening of the antenna under measurement 1 in the two states of A and B in FIG. A near-field amplitude distribution is measured by scanning a perpendicular measurement surface with a probe 5 by a scanner 7 which is a scanning device. The distribution measured when the sub-reflecting mirror 4 is in the on-focus state in FIG. 1A is the on-focus amplitude distribution, that is, the on-focus measurement distribution A1Z, and the sub-reflecting mirror 4 is measured in the de-focused state shown in FIG. This distribution is defined as a defocus amplitude distribution, that is, a defocus measurement distribution A2Z. The relative change in the phase distribution on the aperture of the antenna 1 to be measured during on-focusing and defocusing can be calculated by using geometric optics, and the difference is ΔP. Further, it is assumed that the amplitude distribution on the aperture of the antenna 1 to be measured at the time of on-focusing and defocusing does not change.
[0021]
Using the measured amplitude distributions of the two states, the arithmetic processor 9 obtains the phase distribution on the aperture of the antenna 1 to be measured by the algorithm shown in FIG.
STEP 0: An amplitude distribution A1Z measured with on-focus and an appropriate initial phase distribution P0 are prepared.
STEP 1: Field conversion is performed from the measurement surface Z = Z1 to the measured antenna aperture z = 0.
STEP 2: A relative change ΔP of the aperture phase distribution due to defocusing is added to the phase distribution converted to the measured antenna aperture z = 0.
STEP 3: Field conversion is performed on the measurement plane z = Z1, using the amplitude distribution on the antenna under measurement z = 0 and the aperture phase distribution with a relative change.
STEP 4: Of the amplitude / phase distribution converted to z = Z1, the amplitude distribution is replaced with the amplitude distribution A2Z measured at the time of defocusing.
STEP 5: Using the amplitude distribution A2Z and the phase distribution obtained in STEP 4, field conversion is again performed to the antenna aperture to be measured z = 0.
STEP 6: The relative change ΔP of the aperture phase distribution due to defocusing is subtracted from the phase distribution converted to the measured antenna aperture z = 0.
STEP 7: Field conversion is performed on the measurement plane z = Z1 using the amplitude distribution on the antenna under measurement z = 0 and the aperture phase distribution obtained by reducing the relative change.
STEP 8: Replace the amplitude distribution with the amplitude distribution A1Z measured at the time of on-focusing in the amplitude / phase distribution converted to z = Z1.
STEP 9: The difference between the amplitude distribution converted to z = Z1 and the actually measured amplitude distribution A1Z is compared. If the difference is sufficiently small, the phase distribution at z = Z1 is terminated as a solution. If not converged, the process returns to STEP1.
[0022]
As shown in FIG. 3, by changing the position of the sub-reflecting mirror 4 in the z-axis direction by the amount of movement δ, a phase variation corresponding to the amount of movement δ of the sub-reflecting mirror 4 can be seen at the time of defocusing. . The phase difference or phase distribution change amount ΔP can be obtained by using geometric optics as long as only the driving amount of the sub-reflecting mirror 4 is known even if the phase distribution during actual on-focus and the phase distribution during defocus are unknown. Can be used to calculate. In STEP2, this variation ΔP is added to the aperture phase distribution. Conversely, in STEP 6, this phase distribution change ΔP is subtracted to obtain the phase amount during on-focus.
[0023]
Needless to say, when amplitude / phase distributions in a certain plane are obtained, field conversion can be performed to an arbitrary position, for example, an aperture distribution, using these distributions. Needless to say, the phase distribution obtained in each step at the time of convergence is a phase distribution correctly estimated in each state.
[0024]
In summary, according to the present invention, the reflector antenna phase distribution measuring apparatus for measuring the phase distribution of the reflector antenna including the sub-reflector 4 and the antenna 1 to be measured 1 replaces the sub-reflector 4 with the antenna 1 to be measured. On the other hand, the sub-reflector driving device 3 that is a moving support device that holds the on-focus position or the defocus position, the probe 5 for measuring the amplitude of the antenna 1 to be measured, and the probe 5 with respect to the antenna 1 to be measured. An on-focus amplitude distribution and a de-focus amplitude distribution are obtained from an amplitude signal from the scanner 7 which is relatively moved and scans the measurement surface coaxial with the mirror axis of the antenna 1 to be measured, and the probe 5. An arithmetic processing unit 9 that obtains an aperture phase distribution of the antenna 1 to be measured by performing arithmetic processing by the phase retrieval method based on the amplitude distribution A.
[0025]
In the first embodiment described above, the phase distribution can be measured by driving only the sub-reflecting mirror 4 in the z-axis direction without moving the antenna 1 to be measured as in the prior art. This has the effect of not requiring a large-scale device. In addition, the alignment accuracy can be set with higher accuracy than conventional. Further, in the plane scan, the field conversion is a plane wave expansion, so that FFT can be used, and there is an effect that calculation can be performed at high speed.
[0026]
Embodiment 2.
FIG. 4 shows a reflector antenna phase distribution measuring method and apparatus according to Embodiment 2 of the present invention. In FIG. 4, the same reference numerals as those in FIG. 1 correspond to FIG. 1, and operate in the same manner as in FIG. . In FIG. 4, 10 is an x-axis direction drive scanner capable of moving the probe 5 only in the x-axis direction, 11 is a single-axis rotating table for rotating the antenna 1 to be measured about the x-axis, and 12 is a jig.
[0027]
As shown in FIG. 4, the uniaxial rotating table 11 on which the antenna 1 to be measured is installed is rotated around the x axis, and the probe 5 is scanned with respect to each angle using the uniaxial scanner 10. In addition, the amplitude distribution on the cylindrical surface of ρ = z1 can be measured. In other words, the scanning device simply moves the probe 5 along a straight line passing through the mirror axis in a plane perpendicular to the mirror axis of the antenna to be measured by the scanner 7, and the antenna 1 to be measured is a rotating device. The turntable 11 is rotated around the x axis which is an axis parallel to the straight line. Further, by driving the sub-reflecting mirror 4 in the mirror axis direction (z-axis direction) using the sub-reflecting mirror driving device 3, it is possible to obtain an amplitude distribution during on-focusing and defocusing. By using these measured amplitude distributions as the measured amplitude distribution A1Z in the flowchart shown in FIG. 2, the phase distribution can be estimated as in the first embodiment. Note that cylindrical wave expansion is used for field conversion from the measurement surface Z = Z1 to the antenna aperture to be measured z = 0 in STEP1 of FIG.
[0028]
In the second embodiment described above, the measured antenna 1 is rotated around the x axis without moving in the z axis direction as in the prior art, and only the sub-reflecting mirror 4 is driven in the z axis direction, whereby the phase of the antenna is measured. The distribution can be estimated, and there is an effect that a large-scale device is not required as compared with the conventional case. In addition, the alignment accuracy can be set with higher accuracy than conventional. In this embodiment, since the amplitude distribution is measured in a cylindrical shape, the radiation characteristic behind the antenna to be measured can be estimated.
[0029]
Embodiment 3.
FIG. 5 shows a reflector antenna phase distribution measuring method and apparatus according to Embodiment 3 of the present invention. In FIG. 5, the same reference numerals as those in FIG. 1 correspond to FIG. 1, and operate in the same manner as in FIG. . In FIG. 5, 12 is a jig, 13 is a fixing jig for supporting the probe 5 at a predetermined position, and 14 is capable of rotating the antenna 1 to be measured not only about the x axis but also about the y axis. It is a shaft turntable.
[0030]
As shown in FIG. 5, the amplitude distribution on the spherical surface with the rotation center of the biaxial rotating table as the origin is obtained by rotating the biaxial rotating table 14 on which the antenna 1 to be measured 1 is installed around the x axis and the y axis, respectively. Can be measured. By using this as the measurement surface described above and driving the sub-reflecting mirror 4 in the mirror axis direction that is the z-axis direction using the sub-reflecting mirror driving device 3, it is possible to obtain the amplitude distribution at the time of on-focusing and defocusing. it can. Using these measured amplitude distributions as the measured amplitude distributions in FIG. 2, the phase distribution can be obtained in the same manner as in the first embodiment by the procedure shown in FIG. In FIG. 2, spherical wave expansion is used for field conversion. The scanning device of this embodiment includes a support device 13 that fixes and supports the probe 5 on the mirror axis of the antenna 1 to be measured, and an axis that is parallel to the straight line (in this case, the x-axis direction) described above. And a rotating device that rotates around the axis (x axis) and rotates around the axis perpendicular to the straight line (in this case, the y axis).
[0031]
In the third embodiment, the phase distribution can be estimated by rotating the antenna 1 to be measured without moving and driving only the sub-reflecting mirror 4 as in the prior art, which is much larger than in the past. The effect is that no device is required. In addition, the alignment accuracy can be set with higher accuracy than conventional. In this embodiment, since the amplitude distribution is measured in a spherical shape, the radiation characteristic behind the antenna to be measured can also be estimated.
[0032]
Embodiment 4.
6 shows a reflector antenna phase distribution measuring method and apparatus according to Embodiment 4 of the present invention. In FIG. 6, the same reference numerals as those in FIG. The same operation is performed. In FIG. 6, reference numeral 3 a denotes a sub-reflecting mirror driving device that can move the sub-reflecting mirror 4 in the z-axis direction or rotate it about a mirror axis parallel to the z-axis.
[0033]
In the first to third embodiments shown in FIGS. 1 to 5 described above, it is assumed that the sub-reflecting mirror 4 is an ideal mirror surface with no manufacturing error. However, in reality, the sub-reflecting mirror 4 has a mirror surface error that is a phase distribution estimation error. Therefore, after obtaining the phase distribution by the method described in the first embodiment in a certain state, the sub reflecting mirror 4 is rotated around the mirror axis by the sub reflecting mirror driving device 3a, and the sub reflecting mirror 4 around the mirror axis is rotated. The rotational angle position is made different, and the phase distribution is obtained again by the same procedure at this position. By taking the average of the two phase distributions thus obtained, a phase distribution in which the mirror surface error of the sub-reflecting mirror 4 is corrected can be obtained.
[0034]
In this embodiment, there is an effect that the phase distribution in which the mirror surface error of the sub-reflecting mirror 4 is corrected can be estimated.
[0035]
In the above-described fourth embodiment, the planar scanning near-field measurement device according to the first embodiment shown in FIGS. 1 to 3 has been described. However, the cylindrical scanning near-field measurement device according to the second embodiment in FIG. 4 or the embodiment in FIG. Similar results can be obtained by using the third spherical scanning near-field measuring apparatus.
[0036]
In the above-described embodiment, the antenna to be measured 1 is configured to be a two-reflection mirror. However, the same result can be obtained by driving an arbitrary mirror surface of a plurality of reflection mirrors.
[0037]
【The invention's effect】
As described above, in the reflector antenna phase distribution measuring method of the present invention, the sub-reflector is turned on with respect to the antenna under measurement in order to measure the phase distribution of the reflector antenna including the sub-reflector and the antenna under measurement. A step of measuring an on-focus amplitude distribution at the focus position, and the sub-reflector with respect to the antenna to be measured. A small amount of defocus was applied so that the amplitude distribution at the antenna aperture did not change. A step of moving to a defocus position, a step of measuring a defocus amplitude distribution when the sub-reflector is at a defocus position with respect to the antenna to be measured, and an operation by a phase retrieval method based on the both amplitude distributions Processing to obtain an aperture phase distribution of the antenna to be measured. Therefore, the phase distribution can be measured by driving only the sub-reflecting mirror in the direction of the mirror axis without moving the antenna under measurement as in the prior art, and there is no need for a large-scale apparatus compared to the conventional case. Have In addition, the alignment accuracy can be set with higher accuracy than conventional. Further, in the plane scan, the field conversion is a plane wave expansion, so that FFT can be used, and there is an effect that calculation can be performed at high speed.
[0038]
In the above reflector antenna phase distribution measuring method, the calculation process is performed according to the following procedure.
STEP 0: Prepare an amplitude distribution (A1Z) and initial phase distribution (P0) measured on-focus.
STEP 1: Field conversion is performed from the measurement surface to the antenna opening to be measured, and an amplitude distribution (A1A) converted into the aperture surface and a phase distribution (P1A) converted into the aperture surface are obtained.
STEP 2: A change amount (ΔP) of the aperture phase distribution due to defocus is added to the phase distribution (P1A) converted to the measurement antenna aperture surface.
STEP 3: Using the amplitude distribution (A1A) of the antenna aperture surface to be measured and the aperture phase distribution (P1A + ΔP) to which a relative change has been applied, field conversion is performed on the measurement surface, and the amplitude distribution (A2Z ′) converted to the measurement surface Obtaining a phase distribution (P2Z),
STEP 4: Of the amplitude / phase distribution converted to the measurement surface, the amplitude distribution (A2Z ′) is replaced with the amplitude distribution (A2Z) measured at the time of defocusing.
STEP5: Using the amplitude measurement value and the phase distribution obtained in STEP3, field conversion is again performed on the aperture surface of the antenna to be measured, and the amplitude distribution (A2A) converted into the aperture surface and the phase distribution converted into the aperture surface ( P2A)
STEP 6: A phase distribution (P2A-ΔP) is obtained by subtracting the amount of change by subtracting the relative change amount (ΔP) of the aperture phase distribution due to defocusing from the phase distribution (P2A) converted to the measured antenna aperture surface.
STEP 7: Amplitude distribution (A1Z ′) converted to the measurement surface by performing field conversion on the measurement surface using the amplitude distribution (A2A) of the measured antenna aperture surface and the aperture phase distribution (P2A−ΔP) obtained by reducing the relative change. And a phase distribution (P1Z)
STEP 8: Of the amplitude / phase distribution converted to the measurement surface, the amplitude distribution (A1Z ′) is replaced with the amplitude distribution (A1Z) measured during on-focus,
STEP 9: The difference between the amplitude distribution (A1Z ′) converted to the measurement surface and the actually measured amplitude distribution (A1Z) is compared. If the difference is sufficiently small, the phase distribution (P1Z) is taken as a solution and the procedure is performed. If not converged, return to STEP1. Therefore, the same effect as described above can be obtained.
[0039]
In addition, after the step of obtaining the aperture phase distribution of the antenna under measurement described above, the step of rotating the antenna under measurement around the mirror axis to a new rotation position different from the original rotation position; The step of re-executing the reflector antenna phase distribution measuring method according to claim 1 for the antenna under measurement at the pivot position, the phase distribution of the antenna under measurement at the original pivot position and the new antenna The phase distribution of the sub-reflecting mirror is corrected by correcting the specular error of the sub-reflecting mirror by taking an average with the phase distribution of the antenna under measurement at a certain rotational position. be able to.
[0040]
Furthermore, the reflector antenna phase distribution measuring apparatus for measuring the phase distribution of the reflector antenna including the sub-reflector and the antenna to be measured has the on-focus position or the sub-reflector with respect to the antenna to be measured A small amount of defocus was applied so that the amplitude distribution at the antenna aperture did not change. A movable support device held at a defocus position, a probe for measuring the amplitude of the antenna under measurement, and the probe is moved relative to the antenna under measurement so that it is coaxial with the mirror axis of the antenna under measurement. The on-focus amplitude distribution and the defocus amplitude distribution are obtained from the scanning device that scans the measurement surface and the amplitude signal from the probe, and the processing of the antenna to be measured is performed by the phase retrieval method based on both amplitude distributions. And an arithmetic processing unit for obtaining an aperture phase distribution. The scanning device includes a scanner that scans the probe on a plane perpendicular to the mirror axis of the antenna to be measured. Therefore, the phase distribution can be measured by driving only the sub-reflecting mirror in the z-axis direction without moving the antenna under measurement as in the prior art, and an effect that a larger apparatus than in the prior art is not required. Have In addition, the alignment accuracy can be set with higher accuracy than conventional. Further, in the plane scan, the field conversion is a plane wave expansion, so that FFT can be used, and there is an effect that calculation can be performed at high speed.
[0041]
Further, the scanning device includes a scanner that moves the probe along a straight line passing through the mirror axis in the plane, and a rotating device that rotates the antenna under measurement around an axis parallel to the straight line. . Accordingly, since the amplitude distribution is measured in a cylindrical shape, the radiation characteristic behind the antenna to be measured can be estimated.
[0042]
Further, the scanning device rotates the support antenna for fixing and supporting the probe on the mirror axis, and the antenna to be measured about an axis parallel to the straight line. Through mirror axis And a rotating device that rotates about an axis perpendicular to the straight line. Therefore, it is possible to estimate the phase distribution by rotating the antenna 1 to be measured without moving and driving only the sub-reflecting mirror 4 as in the prior art, so that a large-scale apparatus is not required as compared with the prior art. Has an effect. Further, since the amplitude distribution is measured in a spherical shape, the radiation characteristic behind the antenna to be measured can also be estimated.
[0043]
And a rotation device capable of rotating the antenna under measurement about the mirror axis to at least two rotation positions, wherein the arithmetic processing unit has a phase distribution of the antenna under measurement at the at least two rotation positions. An average arithmetic unit that takes the average of Therefore, there is an effect that the phase distribution in which the mirror surface error of the sub-reflecting mirror is corrected can be estimated.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a reflector antenna phase distribution measuring method and apparatus according to the present invention.
FIG. 2 is a flowchart showing a calculation processing procedure used in the reflector antenna phase distribution measuring method and apparatus according to the present invention.
FIG. 3 is an explanatory diagram for explaining a change in phase distribution due to movement of a sub-reflecting mirror in the reflecting mirror antenna phase distribution measuring apparatus of the present invention.
FIG. 4 is a schematic explanatory view showing a reflector antenna phase distribution measuring method and apparatus according to another embodiment of the present invention.
FIG. 5 is a schematic explanatory view showing a reflector antenna phase distribution measuring method and apparatus according to still another embodiment of the present invention.
FIG. 6 is a schematic explanatory view showing a reflector antenna phase distribution measuring method and apparatus according to still another embodiment of the present invention.
FIG. 7 is a schematic explanatory diagram for explaining a conventional reflector antenna phase distribution measuring method and apparatus.
FIG. 8 is a flowchart showing a phase distribution estimation procedure used in a conventional reflector antenna phase distribution measuring method and apparatus.
[Explanation of symbols]
1 antenna to be measured, 3 moving support device, 4 sub-reflecting mirror, 5 probe,
6, 7, 10, 11, 12, 13, 14, scanning device, 7 scanner,
9 Arithmetic processing unit, A On-focus position, B Defocus position.

Claims (8)

In order to measure the phase distribution of the reflector antenna with the sub-reflector and the antenna to be measured,
Measuring the on-focus amplitude distribution when the sub-reflector is at the on-focus position with respect to the antenna under measurement;
Moving the sub-reflecting mirror to a defocus position where the amplitude distribution at the antenna opening does not change with respect to the antenna to be measured;
Measuring a defocus amplitude distribution when the sub-reflecting mirror is at a defocus position with respect to the antenna to be measured;
And a step of obtaining an aperture phase distribution of the antenna to be measured by performing arithmetic processing by a phase retrieval method based on both amplitude distributions. 2. The reflector antenna phase distribution measuring method according to claim 1, wherein the calculation process is performed by the following procedure.
STEP 0: Prepare an amplitude distribution (A1Z) and initial phase distribution (P0) measured on-focus.
STEP 1: Field conversion is performed from the measurement surface to the antenna opening to be measured, and an amplitude distribution (A1A) converted into the aperture surface and a phase distribution (P1A) converted into the aperture surface are obtained.
STEP 2: A change amount (ΔP) of the aperture phase distribution due to defocus is added to the phase distribution (P1A) converted to the measurement antenna aperture surface.
STEP 3: Using the amplitude distribution (A1A) of the antenna aperture surface to be measured and the aperture phase distribution (P1A + ΔP) to which a relative change has been applied, field conversion is performed on the measurement surface, and the amplitude distribution (A2Z ′) converted to the measurement surface Obtaining a phase distribution (P2Z),
STEP 4: Of the amplitude / phase distribution converted to the measurement surface, the amplitude distribution (A2Z ′) is replaced with the amplitude distribution (A2Z) measured at the time of defocusing.
STEP5: Using the amplitude measurement value and the phase distribution obtained in STEP3, field conversion is again performed on the aperture surface of the antenna to be measured, and the amplitude distribution (A2A) converted into the aperture surface and the phase distribution converted into the aperture surface ( P2A)
STEP 6: A phase distribution (P2A-ΔP) is obtained by subtracting the amount of change by subtracting the relative change amount (ΔP) of the aperture phase distribution due to defocusing from the phase distribution (P2A) converted to the measured antenna aperture surface.
STEP 7: Amplitude distribution (A1Z ′) converted to the measurement surface by performing field conversion on the measurement surface using the amplitude distribution (A2A) of the measured antenna aperture surface and the aperture phase distribution (P2A−ΔP) obtained by reducing the relative change. And a phase distribution (P1Z)
STEP 8: Of the amplitude / phase distribution converted to the measurement surface, the amplitude distribution (A1Z ′) is replaced with the amplitude distribution (A1Z) measured during on-focus,
STEP 9: The difference between the amplitude distribution (A1Z ′) converted to the measurement surface and the actually measured amplitude distribution (A1Z) is compared. If the difference is sufficiently small, the phase distribution (P1Z) is taken as a solution and the procedure is performed. If not converged, return to STEP1. After obtaining the aperture phase distribution of the antenna under measurement, rotating the antenna under measurement around a mirror axis to a new rotation position different from the original rotation position;
Re-execution of the reflector antenna phase distribution measuring method according to claim 1 with respect to the antenna under measurement at the different rotation position;
A step of taking the average of the phase distribution of the antenna under measurement at the original rotation position and the phase distribution of the antenna under measurement at the new rotation position and correcting the mirror surface error of the sub-reflecting mirror A method of measuring a reflector antenna phase distribution according to claim 1 or 2. A reflector antenna phase distribution measuring device for measuring a phase distribution of a reflector antenna including a sub-reflector and an antenna to be measured,
A movable support device that holds the sub-reflecting mirror at a defocus position that is defocused by a small amount so that the amplitude distribution at the on-focus position or the antenna opening does not change with respect to the antenna to be measured;
A probe for measuring the amplitude of the antenna under measurement;
A scanning device that moves the probe relative to the antenna to be measured and scans a coaxial measurement surface at right angles to the mirror axis of the antenna to be measured;
An arithmetic processing unit that obtains the on-focus amplitude distribution and the defocused amplitude distribution from the amplitude signal from the probe, and obtains the aperture phase distribution of the antenna under measurement by performing arithmetic processing by the phase retrieval method based on both amplitude distributions. Reflector antenna phase distribution measuring device provided.   5. The reflector antenna phase distribution measuring device according to claim 4, wherein the scanning device includes a scanner that scans the probe on a plane perpendicular to the mirror axis of the antenna to be measured.   The scanning device includes: a scanner that moves the probe along a straight line passing through the mirror axis in the plane; and a rotating device that rotates the antenna under measurement around an axis parallel to the straight line. 4. The reflector antenna phase distribution measuring device according to 4. The scanning device rotates the support antenna for fixing and supporting the probe on the mirror axis, and rotates the antenna under measurement around an axis parallel to a straight line passing through the mirror axis, and around an axis perpendicular to the straight line. 5. The reflector antenna phase distribution measuring device according to claim 4, further comprising a rotating device for rotating.   A rotation device capable of rotating the antenna under measurement about a mirror axis to at least two rotation positions, wherein the arithmetic processing unit is configured to detect a phase distribution of the antenna under measurement at the at least two rotation positions; The reflector antenna phase distribution measuring apparatus according to claim 4, further comprising an average arithmetic unit that takes an average.

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