JP6944906B2 - Antenna measuring device and antenna measuring method - Google Patents

Description

The present invention relates to an antenna measuring device and an antenna measuring method for measuring the characteristics of an antenna.

A near field measurement method (NFM) is known in which the near field directivity of an antenna is measured to calculate the far field directivity. Since the near-field measurement method measures the electromagnetic field near the antenna, the loss of electromagnetic waves due to spatial propagation is small, and there is an advantage that the antenna can be diagnosed not only from the directivity but also from the near-field distribution of the antenna.

FIG. 12 shows the basic configuration of the conventional antenna measuring device 100 by NFM. The signal generator 102 supplies a continuous wave (CW) of a predetermined radio frequency (RF) to the antenna 101 to be measured. In the vicinity of the antenna 101 to be measured, the probe antenna 112 receives the electromagnetic field output from the antenna 101 to be measured.

The amplitude phase detection unit 122 detects the amplitude and phase of the signal received by the probe antenna 112 with reference to the RF signal from the signal generator 102. Specifically, the amplitude phase detection unit 122 detects the amplitude ratio and the phase difference between the RF signal from the probe antenna 112 and the RF signal from the signal generator 102. A vector network analyzer in which the signal generator 102 and the amplitude phase detector 122 are integrated can also be used.

The probe scanning mechanism 113 scans the measurement plane P in the vicinity of the antenna to be measured 101 with the probe antenna 112 according to the instruction signal from the scanning control unit 121. FIG. 13 shows an example of a method of sweeping the probe antenna 112 implemented by the probe scanning mechanism 113. In the sweep method shown in FIG. 13, the sweep in the x-axis direction is repeated a predetermined number of times at an interval Δy in the y-axis direction to cover the measurement plane P. In the figure, the solid line shows the movement of the probe antenna 112 with the antenna measurement, and the broken line shows the movement (return) of the probe antenna 112 without the antenna measurement.

The far-field calculation unit 123 calculates the electric field distribution in the far-field by using the amplitude and phase information from the amplitude phase detection unit 122 and the position information of the probe antenna 112 from the scanning control unit 121. Specifically, the complex number E (x, y) = r (x, y). Represented by e ^{jθ (x, y)} , the two-dimensional complex electric field data E (x, y) on the measurement plane P is subjected to a two-dimensional complex inverse Fourier transform, and the two-dimensional coordinate axes are transformed into angles to obtain a distant field. The electric field distribution can be obtained.

The display unit 126 displays the directivity (electric field distribution) of the antenna 101 to be measured in the far field as a measurement result.

In the configuration of FIG. 12, since the amplitude phase detection unit 122 needs to detect the amplitude and phase of the RF signal received by the probe antenna 112 with reference to the RF signal from the signal generator 102, the transmitter (signal generation). There is a problem that it cannot be applied in the case of an antenna to be measured that does not have an RF signal terminal, such as an active antenna in which a device) and an antenna are integrated.

FIG. 14 shows an antenna measuring device 200 that measures an antenna to be measured that does not have an RF signal terminal by a near-field measurement method (see, for example, Patent Document 1). In this antenna measuring device 200, a plurality of probe antennas 212 are used, and the probe scanning mechanism 213 scans the measurement plane P with the probe antenna 212 while maintaining the relative positions of the plurality of probe antennas 212 according to the instruction signal from the scanning control unit 221. do. The amplitude phase difference detection unit 222 detects the amplitude and phase difference of the RF signals from the plurality of probe antennas 212. The phase calculation unit 223 converts the phase difference of the RF signals from the plurality of probe antennas 212 into the phase of the near field on the measurement plane P. The far field calculation unit 224 and the display unit 225 have the same basic configuration as described above.

This method detects the phase difference of the RF signals from the plurality of probe antennas 212, and does not use the RF signals from the signal generator 202. Therefore, the antenna 201 to be measured having no RF signal terminal is measured. Is possible. However, there is a problem that a plurality of probe antennas 212 and a plurality of channels of amplitude phase difference detection units 222 are required, which makes the device large-scale and expensive.

Therefore, as shown in FIG. 15, the amplitude and phase of the RF signal from the probe antenna 312 are used by the amplitude phase detection unit 322 without using only one probe antenna 312 and the RF signal from the signal generator 302. Consider a configuration that detects.

FIG. 16 is a configuration diagram of an amplitude phase detection unit 322 of the antenna measuring device 300 of FIG. As shown in FIG. 16, the amplitude phase detection unit 322 uses the local signal generator 331 and the mixer 332 to frequency-convert the RF signal from the probe antenna 312 into an intermediate frequency (IF) signal, and filters 333. In principle, it is possible to extract the spectrum of the desired IF signal, convert the IF signal into a digital signal with the A / D converter 334, and calculate the amplitude and phase of the digital signal with the amplitude phase calculator 335. Is.

However, in general, as shown in FIG. 17, the lower the offset frequency, the larger the phase noise exists in the RF output signal of the transmitter, the signal generator, and the local signal generator of the amplitude phase detector. For example, when the offset frequency is 1 Hz or less, the slope of −30 dB / decline increases as the offset frequency decreases. Therefore, if the amplitude phase detector 322 tries to detect the phase without using the RF signal from the signal generator 302 as a reference, an error due to the phase noise of the signal generator 302 and the local signal generator 331 occurs. The longer the measurement, the larger the phase error.

The signal generator 302 and the amplitude phase detector 322 may be synchronized with a common reference signal (for example, a 10 MHz reference signal). However, since the RF carrier frequency generally used in high-speed wireless communication systems is several GHz to several tens of GHz or more, which is orders of magnitude higher than the reference frequency such as 10 MHz, a small phase drift in the RF frequency due to a slight drift in synchronization at the reference frequency Will occur, and the phase error will increase in long-term measurement.

Since the probe scanning mechanism 313 mechanically moves (sweeps) the probe antenna 312, a large-scale mechanism is required to increase the sweep speed. Further, in order to measure a minute signal with the probe antenna 312, it is necessary to narrow the measurement bandwidth and increase the signal-to-noise ratio, and it takes a required time to measure the amplitude and phase. For these reasons, there is a limit to increasing the sweep speed of the probe antenna 312.

When sweeping the probe antenna 312 as shown in FIG. 13, one sweep in the x-axis direction can be performed in a relatively short time, whereas it takes a long time to cover the measurement plane P in the y-axis direction. Therefore, the phase detected by the amplitude phase detection unit 322 includes a large phase error when viewed in the y-axis direction, and the directional error in the y-axis direction also becomes large even in the result of conversion to the distant field. For example, if a phase drift exists in the y-axis direction in the near field, the peak of directivity in the measurement result in the far field shifts in the y-axis direction. When measuring an antenna having a sharp directivity such as a large-diameter antenna or a multi-element array antenna, a directivity error becomes a particular problem.

In order to reduce the influence of the phase error in the y-axis direction, Patent Document 2 discloses a method of sweeping the probe antenna 312 as shown in FIG. The first sweep in the figure covers the measurement plane P by repeating the sweep in the x-axis direction a predetermined number of times at an interval Δy in the y-axis direction as in FIG. In FIG. 18, the second sweep is a sweep in the y-axis direction at x = 0. Using the phase in the y-axis direction obtained in the second sweep, the phase of the signal received in the two-dimensional measurement plane P in the first sweep is corrected. Since the movement in the y-axis direction in the second sweep is completed in a shorter time than the movement in the y-axis direction in the first sweep, the phase error in the y-axis direction becomes smaller, which is compared with the sweep method of FIG. Highly accurate antenna measurement is possible.

The first sweep needs to cover the two-dimensional measurement plane P, whereas the second sweep only needs to be swept once in the y-axis direction, so that the first sweep needs to be swept. The increase in measurement time is small compared to the case of only. Further, although the case where the first sweep is performed in the x-axis direction is shown here, it is also possible to reverse the x-axis and the y-axis, and Patent Document 2 describes a method in which the first sweep is performed in the y-axis direction. It is shown.

JP-A-2017-207464 Japanese Unexamined Patent Publication No. 60-192271

In the sweep method of FIG. 18, the phase θ ₁ (x, y _i ) obtained by the first sweep and the phase θ ₂ (0, y) obtained by the second sweep are given by the following equations (1) and (2). ).

Here, i is an integer, and y _i represents the y-axis value at the time of the i-th x-axis direction sweep of the first sweep. Assuming that the sweep step in the y-axis direction is Δy, it is _{represented by y i} = y ₀ + i · Δy (y ₀ is a constant). φ (x, y) is the true phase of the electric field at the position (x, y), φ _n1 (x, y _i ) is the phase noise during the first sweep, and φ _n2 (0, y) is the second sweep. It is the phase noise of time.

The phase is corrected by the following equation (3), and the corrected phase θ (x, y _i ) is obtained.

ここで、ａ，ｂ，ｂ_２は定数である。 Here, the sweep speed in the x-axis direction of the probe antenna 312 is v _x , the sweep speed in the y-axis direction is v _{y, and the phase noise φ n} (t) = a · t + b that changes linearly with respect to the time t is set. Considering this, the phase noise at each sweep is expressed by the following equations (4) and (5).

Here, a, b, and b ₂ are constants.

となり、ｂ_１（ｙ_ｉ）の変動幅は、（ａ／ｖ_ｘ）・（ｗ_ｘ・ｗ_ｙ／Δｙ）となる。ここで、ｂ_１０は定数である。したがって、位相補正を行なわない場合、即ちφ_ｎ１（ｘ，ｙ_ｉ）の変動幅は、（ａ／ｖ_ｘ）・ｗ_ｘ＋（ａ／ｖ_ｘ）・（ｗ_ｘ・ｗ_ｙ／Δｙ）となる。 The sweep width in the x-axis direction w _x, a sweep width of the y-axis direction and w _y, sweeping steps in the y-axis direction and [Delta] y, ignoring time back after x-axis direction sweep,

Therefore, _{the fluctuation range of b 1} (y _i ) is (a / v _x ) · (w _x · w _y / Δ y). Here, b ₁₀ is a constant. Therefore, when phase correction is not performed, that is, the fluctuation range of _{φ n1} (x, y _{i ) is (a / v x} ) · w _x + (a / v _x ) · (w _x · w _y / Δ y). Become.

となる。 The corrected phase θ (x, y _i ) is obtained from the above equations (1) to (5).

Will be.

In the above equation (9), the constant phase offset b ₂ does not affect the antenna measurement. Although the influence of _b 1 _{(y i)} is canceled the phase noise of the fluctuation width _{(a / v x) · (} w x · w y / Δy) is _{reduced, (a / v x) ·} x and (a The terms of / v _y ) and y _i remain, and the fluctuation range after phase correction is
(A / v _x ) ・ w _x + (a / v _y ) ・_wy
Will be.

As described above, it is not possible to completely correct the phase noise that changes linearly with respect to the time, and the problem is that the effect of the phase correction is relatively low.

The present invention has been made to solve the above-mentioned problems, and provides an antenna measuring device and an antenna measuring method capable of measuring the directivity of an antenna with high accuracy by reducing the influence of phase noise. The purpose is.

In order to achieve the above object, the antenna measuring device according to claim 1 of the present invention has a probe antenna (12) that receives a radio signal transmitted from the measured antenna (2) in the near field, and the probe antenna. A first sweep that covers the measurement plane by sweeping in the main sweep direction a plurality of times in the measurement plane, and a second sweep that reciprocates the probe antenna in the sub-sweep direction that intersects the main sweep direction in the measurement plane. A probe scanning mechanism (13) for performing sweep, an amplitude phase detection unit (22) for detecting the amplitude and phase of a signal received by the probe antenna during the first and second sweeps, and the second sweep. Using the average value of the phase detected by the amplitude phase detection unit in the outward path and the phase detected by the amplitude phase detection unit in the return path of the second sweep, the amplitude phase detection unit in the first sweep. It is characterized in that it is provided with a phase correction unit (24) that corrects the phase detected in.

With this configuration, the antenna measuring device according to claim 1 of the present invention uses the average value of the phase detected in the outward path of the second sweep and the phase detected in the return path of the second sweep, and uses the first phase. By correcting the phase detected in the sweep, the influence of the phase noise that changes linearly with time can be reduced, so that the directivity of the antenna can be measured with high accuracy.

In the antenna measuring device according to claim 2 of the present invention, the first sweep comprises repeating a unidirectional sweep in the main sweep direction, and the phase correction unit is the first in the outward path of the second sweep. The average value of the phase detected by the amplitude phase detection unit at the intersection of the sweep and the second sweep and the phase detected by the amplitude phase detection unit at the intersection in the return path of the second sweep. It is characterized in that the phase detected by the amplitude phase detection unit in the first sweep is corrected by using the difference from the phase detected by the amplitude phase detection unit at the intersection in the first sweep.

With this configuration, the antenna measuring device according to claim 2 of the present invention can reduce the influence of phase noise that changes linearly with time as compared with the conventional sweeping method shown in FIG. Directivity can be measured with high accuracy.

In the antenna measuring device according to claim 3 of the present invention, the first sweep comprises repeating a reciprocating sweep reciprocating in the same path in the main sweep direction, and the phase correction unit is an outward path of the second sweep. The phase detected by the amplitude phase detection unit at the intersection of the first sweep and the second sweep and the phase detected by the amplitude phase detection unit at the intersection in the return path of the second sweep. The average value and the average of the phase detected by the amplitude phase detection unit at the intersection in the outward path of the first sweep and the phase detected by the amplitude phase detection unit at the intersection in the return path of the first sweep. Using the difference from the value, the phase of the average value of the phase detected by the amplitude phase detection unit in the outward path of the first sweep and the phase detected by the amplitude phase detection unit in the return path of the first sweep. Is characterized by correcting.

With this configuration, the antenna measuring device according to claim 3 of the present invention is not affected by the phase noise that changes linearly with time, so that the directivity of the antenna is higher than that of the conventional sweeping method shown in FIG. It can be measured accurately. This corrects the phase noise in the main sweep direction by averaging the phases detected in the outward and return paths of the first sweep, and also corrects the phase noise in the secondary sweep direction by averaging the phases detected in the outward and return paths of the second sweep. This is because the phase noise is corrected. Further, in the conventional sweep method shown in FIG. 18, when the sweep time in the positive direction of the main sweep direction of the first sweep is substantially equal to the return time, the measurement time is slightly shorter than that of the conventional sweep method. It only increases.

In the antenna measuring device according to claim 4 of the present invention, the first sweep comprises a bidirectional sweep in which the outward path and the return path in the main sweep direction are alternately and repeatedly arranged in the sub sweep direction, and the phase correction The unit is the phase detected by the amplitude phase detection unit at the intersection of the first sweep and the second sweep in the outward path of the second sweep and the intersection at the intersection in the return path of the second sweep. The amplitude phase detection in the first sweep is performed by using the difference between the average value with the phase detected by the amplitude phase detection unit and the phase detected by the amplitude phase detection unit at the intersection in the first sweep. It is characterized in that the phase detected by the unit is corrected.

With this configuration, the antenna measuring device according to claim 4 of the present invention can reduce the influence of phase noise that changes linearly with time as compared with the conventional sweeping method shown in FIG. Directivity can be measured with high accuracy. Further, in the first sweep, since the outward path and the return path in the main sweep direction are alternately and repeatedly arranged in the sub sweep direction, the return time of the first sweep can be effectively utilized, and the measurement time can be compared with the conventional one. Can be significantly shortened. Moreover, since the first sweep consists of a bidirectional sweep in which the outward path and the return path in the main sweep direction are alternately and repeatedly arranged in the sub sweep direction, the sign of the phase noise in the main sweep direction is inverted, so that the measurement result shows. The problem that the directivity of the antenna shifts in the main sweep direction is suppressed.

In the antenna measuring device according to claim 5 of the present invention, the first sweep is a bidirectional sweep in which the outward sweep in the main sweep direction and the sweep in the return path are alternately performed and sequentially in the sub sweep direction at regular intervals. The phase correction unit comprises the phase of the average value at the intersection of the first sweep and the second sweep, and the phase detected by the amplitude phase detection unit at the intersection during the first sweep. The difference (θ ₂₁ ) is corrected by the phase correction value interpolated in the sweep section between the intersections of the first sweep to correct the phase detected by the amplitude phase detector in the first sweep. It is characterized by that.

With this configuration, the antenna measuring device according to claim 5 of the present invention is not affected by the phase noise that changes linearly with time, as in claim 3, so that the conventional sweeping method shown in FIG. The directivity of the antenna can be measured with higher accuracy. Further, as in the case of claim 4, in the first sweep, the outward path and the return path in the main sweep direction are alternately and repeatedly arranged in the sub sweep direction, so that the return time of the first sweep is effectively utilized. This makes it possible to significantly reduce the measurement time as compared with the conventional case. Since the distance of the second sweep and the additional sweep for interpolation is short, the increase in measurement time due to it is small.

The antenna measuring method according to claim 6 of the present invention includes a moving step (S2) in which the probe antenna is moved by a predetermined distance within a predetermined measurement plane, and a radio signal is transmitted from the measured antenna (2) to transmit the probe. The movement step and the transmission / reception step include a transmission / reception step (S3) of receiving the radio signal in the near field by the antenna and a detection step (S7) of detecting the amplitude and phase of the signal received by the probe antenna. By repeating the detection step, the sweep in the main sweep direction is repeated to make a first sweep covering the measurement plane and a second sweep reciprocating in the sub sweep direction intersecting the main sweep direction in the measurement plane. In the first sweep, the probe antenna including the sweep is swept, and the average value of the phase detected in the outward path of the second sweep and the phase detected in the return path of the second sweep is used. It is characterized by further including a correction step (S12) for correcting the detected phase.

With this configuration, the antenna measuring method according to claim 6 of the present invention uses the average value of the phase detected in the outward path of the second sweep and the phase detected in the return path of the second sweep, and uses the first phase. By correcting the phase detected in the sweep, the influence of the phase noise that changes linearly with time can be reduced, so that the directivity of the antenna can be measured with high accuracy.

The antenna measuring method according to claim 7 of the present invention includes a first sweep that covers the measurement plane by repeating sweeping in the main sweep direction of the probe antenna in a predetermined measurement plane, and the probe antenna in the measurement plane. The sweep start step (S5) for starting the sweep including the second sweep reciprocating in the sub-sweep direction intersecting the main sweep direction and the antenna (2) to be measured during the sweep are transmitted. A reception step (S6) in which the radio signal is received by the probe antenna in the near field, a detection step (S7) in which the amplitude and phase of the signal received by the probe antenna are detected, and detection in the second sweep outbound route. It is characterized by including a correction step (S12) for correcting the phase detected in the first sweep by using the average value of the phase detected and the phase detected in the return path of the second sweep.

With this configuration, the antenna measuring method according to claim 7 of the present invention uses the average value of the phase detected in the outward path of the second sweep and the phase detected in the return path of the second sweep, and uses the first phase. By correcting the phase detected in the sweep, the influence of the phase noise that changes linearly with time can be reduced, so that the directivity of the antenna can be measured with high accuracy. Further, by performing the measurement while sweeping the probe antenna, it is possible to perform the measurement in a short time as compared with the method of temporarily stopping the movement of the probe antenna for the measurement.

According to the present invention, it is possible to provide an antenna measuring device and an antenna measuring method capable of measuring the directivity of an antenna with high accuracy by reducing the influence of phase noise.

It is a block diagram of the antenna measuring apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the sweeping method of the probe antenna which concerns on 1st Embodiment of this invention. It is a figure which shows the sweep order in the sweep method of FIG. It is a flowchart of the antenna measurement method which concerns on 1st Embodiment of this invention. It is another flowchart of the antenna measurement method which concerns on 1st Embodiment of this invention. It is a figure which shows the sweeping method of the probe antenna which concerns on 2nd Embodiment of this invention. It is a figure which shows the sweep order in the sweep method of FIG. It is a figure which shows the sweeping method of the probe antenna which concerns on 3rd Embodiment of this invention. It is a figure which shows the sweep order in the sweep method of FIG. It is a figure which shows the sweeping method of the probe antenna which concerns on 4th Embodiment of this invention. It is a figure which shows another sweeping method of the probe antenna which concerns on 4th Embodiment of this invention. It is a block diagram of the antenna measuring apparatus which concerns on the prior art. It is a figure which shows the sweeping method of the probe antenna in the antenna measuring apparatus of FIG. It is a block diagram of another antenna measuring apparatus which concerns on the prior art. It is a block diagram of the antenna measuring apparatus which concerns on the related technology. It is a block diagram of the amplitude phase detection part of the antenna measuring apparatus of FIG. It is a figure which shows the relationship between the offset frequency and SSB (Single Side Band) phase noise. It is a figure which shows the sweeping method of the probe antenna in the antenna measuring apparatus of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a configuration diagram of an antenna measuring device 1 according to a first embodiment of the present invention.
The antenna measuring device 1 according to the present embodiment measures the amplitude and phase of the RF signal output from the antenna 2 to be measured by the probe antenna 12 in the near field, converts it into an electric field distribution in the far field, and outputs the measurement result. To do. The antenna measuring device 1 displays a probe antenna 12, a probe scanning mechanism 13, a scanning control unit 21, an amplitude phase detection unit 22, a data storage unit 23, a phase correction unit 24, and a far field calculation unit 25. It is provided with a part 26.

The antenna 2 to be measured is supported by the antenna support portion 11, and a CW signal having a predetermined frequency or a known modulated signal is supplied from the signal generator 3.

The antenna measuring device 1 of the present embodiment has a configuration in which the RF signal output from the signal generator 3 is supplied only to the antenna 2 to be measured. Therefore, the antenna measuring device 1 can electrically control the directivity characteristics by controlling the active antenna in which the antenna 2 to be measured and the signal generator 3 are integrated, and the amplitude and phase of the signals supplied to the plurality of antennas. It can also be applied to an antenna that does not have an RF signal terminal, such as an array antenna.

The probe scanning mechanism 13 is a mechanism for scanning the probe antenna 12 on the measurement plane P in the vicinity of the antenna 2 to be measured. In FIG. 1, the scanning mechanism 13b in the y-axis direction is driven by the scanning mechanism 13a in the x-axis direction, but conversely, the scanning mechanism in the x-axis direction is driven by the scanning mechanism in the y-axis direction. May be good.

The scanning control unit 21 controls the probe scanning mechanism 13 so as to sweep (move) the probe antenna 12 at a predetermined sweep speed according to a sweeping method described later. Further, the scanning control unit 21 outputs the position information of the probe antenna 12 to the data storage unit 23 and the like.

The amplitude phase detection unit 22 measures the amplitude and phase of the RF signal received by the probe antenna 12. Specifically, for example, as in FIG. 16, the RF signal from the probe antenna 12 is frequency-converted into an IF signal using the local signal generator 331 and the mixer 332, and the spectrum of the desired IF signal is obtained by the filter 333. The IF signal is extracted, converted into a digital signal by an A / D converter 334, and the amplitude and phase of the digital signal are calculated by an amplitude phase calculator 335 composed of a CPU, a DSP, or the like. A general-purpose RF signal analyzer can also be used as the amplitude phase detector 22. The signal generator 3 and the amplitude phase detector 22 (for example, the sampling clock of the local signal generator 331 and the A / D converter 334) may be synchronized with a common reference signal (10 MHz reference signal, etc.).

The data storage unit 23 stores the amplitude and phase data detected by the amplitude phase detection unit 22 in association with the position information of the probe antenna 12.

The phase correction unit 24 corrects the phase measured by the amplitude phase detection unit 22 using the data (amplitude and phase associated with the position information) stored in the data storage unit 23, and is associated with the position information. The information on the amplitude and the corrected phase is output to the far field calculation unit 25. The phase correction unit 24 may include a data storage unit 23.

The far field calculation unit 25 uses the amplitude and corrected phase information of the RF signal received by the probe antenna 12 on the measurement plane P and the position information of the probe antenna 12 acquired from the scanning control unit 21 to be far away. Calculate the field distribution. The conversion method from the near field to the far field is the same as that of the prior art.

The display unit 26 displays the electric field distribution in the distant field of the antenna 2 to be measured as a measurement result.

The far field is defined as a position separated from the maximum diameter D (opening dimension) of the antenna 2 to be measured by a distance R or more that satisfies ^{R> 2D 2 / λ.} Here, R is the distance from the opening of the antenna 2 to be measured, and λ is the free space wavelength. The far field is a region in which the directivity does not change depending on the distance from the opening of the antenna 2 to be measured. Of the region of the electromagnetic field radiated from the opening surface of the antenna 2 to be measured, the region close to the opening of the antenna 2 to be measured is the reactive near-field region (extreme neighborhood) in which the electromagnetic field component that does not contribute to radiation is the main component. Is. The near-field is a region between the reactive near-field region and the radiated far-field region, and the directivity changes according to the distance.

The scanning control unit 21, the amplitude phase detection unit 22 (excluding the frequency conversion unit and the A / D conversion unit), the data storage unit 23, the phase correction unit 24, and the far field calculation unit 25 of the present embodiment are, for example, a CPU (Central). A computer having a processing unit, a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, an external storage device, etc. may be used, and a part or all of the functions (frequency conversion, A) may be used. (Excluding / D conversion) can be realized by executing various programs stored in ROM or the like on the CPU.

FIG. 2 is a diagram showing a method of sweeping the probe antenna 12 according to the first embodiment. In the sweep of the probe antenna 12 of the present embodiment, the probe antenna 12 is swept a plurality of times in the main sweep direction (x-axis direction) in the measurement plane P to cover the measurement plane P, and the probe antenna 12 is swept. It consists of a second sweep that reciprocates in the sub-sweep direction (y-axis direction) orthogonal to the main sweep direction in the measurement plane P. This first sweep comprises repeating a unidirectional sweep in the main sweep direction (x-axis direction).

Specifically, as shown in FIG. 2, the sweep of the probe antenna 12 of the present embodiment includes a first forward sweep, a second forward sweep, and a second reverse sweep. That is, the first sweep is a first forward sweep, and the second sweep consists of a second forward sweep and a second reverse sweep. The first forward sweep repeats the sweep in the positive direction of the x-axis a predetermined number of times with an interval Δy in the y-axis direction, and covers the inside of the measurement plane P. The second forward sweep sweeps in the positive direction of the y-axis at x = 0, and the second reverse sweep sweeps in the negative direction of the y-axis at x = 0. Although the second forward sweep and the second reverse sweep are separated for the convenience of illustration, they actually reciprocate on the same route. Here, the center of the measurement plane P corresponding to the center of the antenna 2 to be measured is set to x = 0, y = 0, but the position having the highest electric field strength may be set to x = 0, y = 0.

In the present embodiment, the second sweep (that is, the second forward sweep and the second reverse sweep) sweeps in the positive and negative directions of the y-axis at x = 0 on the measurement plane P. However, the x-coordinate at the time of the second sweep is not limited to 0, and can be set to an arbitrary value according to the radio signal transmission characteristic of the antenna 2 to be measured.

FIG. 3 is a diagram showing an example of a sweep order in the sweep method of FIG. In the figure, the path shown by the solid line shows the sweep of the probe antenna 12 with the antenna measurement in the measurement plane P, and the path shown by the broken line shows the return path of the probe antenna 12 without the antenna measurement. The sweep sequence shown in FIG. 3 starts from the lower left of the figure, repeats the sweep in the positive direction of the x-axis of the first forward sweep in sequence in the positive direction of the y-axis, and after the completion of the first forward sweep. A second reverse sweep is performed, followed by a second forward sweep. However, the sweep order is not limited to this, and the sweep order can be arbitrarily changed.

Phase θ _1f (x, y _i ) obtained by the first forward sweep, phase θ _2f (0, y) obtained by the second forward sweep, and phase θ 2f (0, y) obtained by the second forward sweep. The phase θ _2b (0, y) is represented by the following equations (10), (11), and (12), respectively.

Here, i is an integer, and y _i represents the y-axis value at the time of the i-th x-axis direction sweep of the first forward sweep. Assuming that the sweep step in the y-axis direction is Δy, it is _{represented by y i} = y ₀ + i · Δy (y ₀ is a constant). φ (x, y) is the true phase of the electric field at the position (x, y), φ _n1f (x, y _i ) is the phase noise during the first forward sweep, and φ _n2f (0, y) is the second. The phase noise during the forward sweep, φ _n2b (0, y), is the phase noise during the second reverse sweep.

In the present embodiment, the phase is corrected as shown in the following equation (13), and the corrected phase θ (x, y _i ) is obtained.

According to the above equation (13), the phase correction unit 24 sweeps the phase detected by the amplitude phase detection unit 22 at the intersection of the first sweep and the second sweep in the second forward sweep and the second reverse direction sweep. Using the difference between the average value of the phase detected by the amplitude phase detection unit 22 at the intersection and the phase detected by the amplitude phase detection unit 22 at the intersection in the first forward sweep, the first The phase detected by the amplitude phase detection unit 22 in the forward sweep is corrected.

ここで、ａ，ｂ，ｂ_２ｆ，ｂ_２ｂは定数である。 Here, the sweep rate of the x-axis direction of the probe antenna 12 and v _x, the sweep rate of the y-axis direction and v _y, linearly varying phase noise with respect to time _{t φ n (t) = a} · t + b Considering the above, the phase noise at each sweep is expressed by the following equations (14), (15), and (16).

Here, a, b, b _2f , and b _2b are constants.

となる。ｂ_１ｆ０は定数である。ｂ_１ｆ（ｙ_ｉ）の変動幅は（ａ／ｖ_ｘ）・（ｗ_ｘ・ｗ_ｙ／Δｙ）となるが、本実施形態はこれに限定されるものではないので、一般的なｙ_ｉの関数ｂ_１ｆ（ｙ_ｉ）で表している。 As shown in FIG. 3, when the sweep in the positive direction of the x-axis is sequentially repeated in the positive direction of the y-axis in the first forward sweep, the sweep width in the x-axis direction is w _x , the sweep width in the y-axis direction. the w _y, sweeping steps in the y-axis direction and [Delta] y, ignoring time back after x-axis direction sweep,

Will be. b _1f0 is a constant. fluctuation width b _{1f (y i)} is _{(a / v x) · (} w x · w y / Δy) and becomes, since the present embodiment is not limited thereto, the common _{y i} It is represented by the function b _1f (y _i).

The corrected phase θ (x, y _i ) is as follows from the above equations (10) to (16).

In the above equation (20), the constant phase offset (b _2f + b _2b ) / 2 does not affect the antenna measurement. That is, a phase θ (x, y _{i ) that is not affected by the phase noise b 1f} (y _i ) in the y-axis direction can be obtained. Although the phase noise (a / v _x ) · x in the x-axis direction remains, the fluctuation range is (a / v _x ) · w _x , which is smaller than the fluctuation range of the conventional sweep method of FIG. 18 (w _x). / _v in the case of x ₌ w _y / _v y, change the width half to 1/2). As described above, in the present embodiment, when the phase noise that changes linearly with time is present, the influence of the phase noise is reduced as compared with the conventional sweep method shown in FIG. 18, so that the directivity of the antenna is improved. It is possible to measure with higher accuracy than before.

The first forward sweep, it is necessary to sweep to cover on the two-dimensional measurement plane P, whereas the sweep distance is _{w x × (w y / Δy} ), second forward sweep and the second reverse sweep may be one round trip in the y-axis direction, since the sweep distance is w _y × 2, the measurement time as compared with the case of the first forward sweep only The increase is small.

In the present embodiment, the case where the first forward sweep is performed in the x-axis direction is shown, but the x-axis and the y-axis can be reversed, and the sweep speed and the sweep width in the x-axis and y-axis directions can be reversed. , The one with the shorter measurement time can be selected according to the sweep step.

Next, the antenna measurement method in this embodiment will be described.
FIG. 4 is a flowchart of the antenna measurement method according to the present embodiment.

First, the antenna 2 to be measured is set on the antenna support portion 11 (S1). The antenna 2 to be measured may not have an RF signal terminal and may be integrated with the signal generator 3.

Next, the scanning control unit 21 gives a command to the probe scanning mechanism 13 to drive the probe scanning mechanism 13 and move the probe antenna 12 by a predetermined distance within a predetermined measurement plane P (S2). By repeating this movement, the probe antenna 12 is swept. The sweep of the probe antenna 12 is performed by repeating the sweep in the main sweep direction (x-axis direction) a predetermined number of times to reciprocate between the first sweep covering the measurement plane P and the sub-sweep direction (y-axis direction) orthogonal to the main sweep direction. It consists of a second sweep. The measurement plane P is set in the vicinity of the antenna 2 to be measured.

A signal generator 3 supplies a CW signal or a known modulated signal having a predetermined frequency to the antenna 2 to be measured, causes the antenna 2 to transmit a radio signal, and the radio signal transmitted from the antenna 2 to be measured is a probe antenna. Received at 12 (S3). In the method of FIG. 4, the movement of the probe antenna 12 during sweeping is temporarily stopped to receive the radio signal.

Next, the amplitude phase detection unit 22 detects the amplitude and phase of the signal received by the probe antenna 12 (S7). The detected amplitude and phase data are stored in the data storage unit 23 in association with the position information of the probe antenna 12 (S8).

Then, it is determined whether or not the measurement at all the measurement points of the first sweep and the second sweep is completed (S9), and if not (in the case of No), the process returns to step S2. If it is completed (in the case of Yes), the process proceeds to the next step S12.

In step S12, as described above, in the first sweep, the phase correction unit 24 uses the average value of the phase detected in the outward path of the second sweep and the phase detected in the return path of the second sweep. The detected phase is corrected (S12).

Specifically, according to the above equation (13), the phase correction unit 24 has the phase and the phase detected by the amplitude phase detection unit 22 at the intersection of the first sweep and the second sweep in the outward path of the second sweep. Using the difference between the average value of the phase detected by the amplitude phase detection unit 22 at the intersection in the return path of the sweep of 2 and the phase detected by the amplitude phase detection unit 22 at the intersection in the first sweep, The phase detected by the amplitude phase detection unit 22 in the first sweep is corrected.

Next, in the far field calculation unit 25, the conventional method using the amplitude information detected by the amplitude phase detection unit 22, the phase information corrected by the phase correction unit 24, and the position information associated with them. Calculates the electric field strength distribution in the distant field of the antenna 2 to be measured (S13). The position information of the probe antenna 12 may be sent from the scanning control unit 21 to the phase correction unit 24 and the distant field calculation unit 25, and may be used for phase correction and calculation of the electric field strength distribution in the distant field.

Next, the display unit 26 displays the electric field strength distribution in the far field of the antenna 2 to be measured calculated by the far field calculation unit 25 as a measurement result (S14).

FIG. 5 is another flowchart of the antenna measuring method according to the present embodiment.

First, the antenna 2 to be measured is set on the antenna support portion 11 (S1). The antenna 2 to be measured may not have an RF signal terminal and may be integrated with the signal generator 3. A signal generator 3 supplies a CW signal having a predetermined frequency or a known modulated signal to the antenna 2 to be measured, and transmission of a radio signal from the antenna 2 to be measured is started (S4).

Next, the scanning control unit 21 gives a command to the probe scanning mechanism 13 to drive the probe scanning mechanism 13 and start sweeping the probe antenna 12 within the predetermined measurement plane P (S5). The sweep of the probe antenna 12 is performed by repeating the sweep in the main sweep direction (x-axis direction) a predetermined number of times to reciprocate between the first sweep covering the measurement plane P and the sub-sweep direction (y-axis direction) orthogonal to the main sweep direction. It consists of a second sweep. The measurement plane P is set in the vicinity of the antenna 2 to be measured.

During the first sweep and the second sweep (that is, while sweeping the probe antenna 12), the probe antenna 12 receives the radio signal transmitted from the antenna 2 to be measured (S6).

Next, the amplitude phase detection unit 22 detects the amplitude and phase of the signal received by the probe antenna 12 (S7). The detected amplitude and phase data are stored in the data storage unit 23 in association with the position information of the probe antenna 12 (S8).

Then, it is determined whether or not the measurement at all the measurement points of the first sweep and the second sweep is completed (S9), and if not (in the case of No), the process returns to step S6. If it is completed (in the case of Yes), the sweeping of the probe antenna 12 is completed (S10), the transmission of the radio signal from the antenna 2 to be measured is completed (S11), and the process proceeds to the next step S12.

Step S12 and subsequent steps are the same as in FIG. In the method of FIG. 5, as described above, since the measurement is performed while sweeping the probe antenna 12, the measurement can be generally performed in a shorter time than the method of FIG. 4 in which the movement of the probe antenna 12 is temporarily stopped for measurement. Is.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings.

In the second embodiment, the method of sweeping the probe antenna and the method of correcting the phase are different from those of the first embodiment. The basic configuration of the antenna measuring device is the same as the configuration of the first embodiment shown in FIG.

FIG. 6 is a diagram showing a method of sweeping the probe antenna 12 according to the second embodiment.
In the sweep method of the probe antenna 12 of the second embodiment, the first sweep consists of repeating a reciprocating sweep that reciprocates in the same path in the main sweep direction (x-axis direction), and the first sweep is in the main sweep direction. It is different from the first embodiment consisting of repeated unidirectional sweeps.

Specifically, as shown in FIG. 6, the sweep of the probe antenna 12 of the present embodiment includes a first forward sweep, a first reverse sweep, a second forward sweep, and a second reverse sweep. It consists of. That is, the first sweep consists of a first forward sweep and a first reverse sweep, and the second sweep consists of a second forward sweep and a second reverse sweep. The first forward sweep repeats the sweep in the positive direction of the x-axis a predetermined number of times with an interval Δy in the y-axis direction, and covers the inside of the measurement plane P. The first reverse sweep is a reverse sweep direction of the x-axis of the first forward sweep.

The second forward sweep sweeps in the positive direction of the y-axis at x = 0, and the second reverse sweep sweeps in the negative direction of the y-axis at x = 0. Although the first forward sweep and the first reverse sweep, and the second forward sweep and the second reverse sweep are separated for the convenience of illustration, they actually reciprocate on the same route. Further, here, the center of the measurement plane P corresponding to the center of the antenna 2 to be measured is set to x = 0, y = 0, but the position having the largest electric field strength may be set to x = 0, y = 0.

FIG. 7 is a diagram showing an example of a sweep order in the sweep method of FIG. In the figure, the path shown by the solid line shows the sweep of the probe antenna 12 with the antenna measurement in the measurement plane P, and the path shown by the broken line shows the return path of the probe antenna 12 without the antenna measurement. The sweep order shown in FIG. 7 starts from the lower left of the figure and alternates between the first forward sweep x-axis positive sweep and the first reverse sweep x-axis negative sweep. While performing (that is, performing a reciprocating sweep in the x-axis direction), the movement is sequentially repeated by Δy in the positive direction of the y-axis, and after the completion of the first forward and reverse sweeps, the second reverse sweep is performed. After that, a second forward sweep is performed. However, the sweep order is not limited to this, and the sweep order can be arbitrarily changed.

The phase θ _1f (x, y _i ) obtained by the first forward sweep, the phase θ _1b (x, y _i ) obtained by the first reverse sweep, and the phase θ 1b (x, y i) obtained by the second forward sweep. The phase θ _{2f (0, y) and the phase θ 2b} (0, y) obtained by the second reverse sweep are obtained by the following equations (21), (22), (23), and (24), respectively. expressed.

Here, i is an integer, and y _i represents the y-axis value at the time of the i-th x-axis direction sweep of the first forward sweep and the first reverse sweep. Assuming that the sweep step in the y-axis direction is Δy, it is _{represented by y i} = y ₀ + i · Δy (y ₀ is a constant). φ (x, y) is the true phase of the electric field at the position (x, y), φ _n1f (x, y _i ) is the phase noise during the first forward sweep, and φ _n1b (x, y _i ) is the first. 1 is the phase noise during the reverse sweep, φ _n2f (0, y) is the phase noise during the second forward sweep, and φ _n2b (0, y) is the phase noise during the second reverse sweep.

In the present embodiment, the phase is corrected as shown in the following equation (25), and the corrected phase θ (x, y _i ) is obtained.

According to the above equation (25), the phase correction unit 24 sweeps the phase detected by the amplitude phase detection unit 22 at the intersection of the first sweep and the second sweep in the second forward sweep and the second reverse direction sweep. The average value of the phase detected by the amplitude phase detection unit 22 at the intersection, the phase detected by the amplitude phase detection unit 22 at the intersection in the first forward sweep, and the intersection in the first reverse sweep. Using the difference between the average value and the phase detected by the amplitude phase detection unit 22 in the first forward sweep, the phase detected by the amplitude phase detection unit 22 in the first forward sweep and the amplitude phase detection in the first reverse sweep. The phase of the average value with the phase detected by the unit 22 is corrected.

となる。ここで、ａ，ｂ，ｂ_２ｆ，ｂ_２ｂは定数である。 Here, the sweep speed of the probe antenna 12 in the x-axis direction is v _x , the sweep speed in the y-axis direction is v _{y, and the phase noise φ n} (t) = a · t + b that changes linearly with respect to the time t is set. Considering that, the phase noise at each sweep is

Will be. Here, a, b, b _2f , and b _2b are constants.

となる。ここで、ｂ_１０は定数である。 As shown in FIG. 7, the positive direction of the x-axis of the first forward sweep and the negative direction of the x-axis of the first reverse sweep are alternately performed in the positive direction of the y-axis. If sequentially moved to the sweep width of the x-axis direction w _x, a sweep width of the y-axis direction and w _y, sweeping steps in the y-axis direction and [Delta] y, ignoring time [Delta] y movement in the y-axis direction,

Will be. Here, b ₁₀ is a constant.

fluctuation width b _{1f (y i)} and _b 1b _{(y i)} is the _{(a / v x) × (} 2 · w x · w y / Δy), the present embodiment is limited to this Since there is no such function, it is represented by _{the general y i} functions b _1f (y _i ) and b 1 _b (y _i).

The corrected phase θ (x, y _i ) is as follows from the above equations (21) to (29).

In the above equation (34), the constant phase offset (b _2f + b _2b ) / 2 does not affect the antenna measurement. That is, the phase θ (x, y _i ) that is not affected by the phase noise (a / v _x ) · x in the x-axis direction and the phase noise b _1f (y _i ) and b 1 _b (y _{i) in the y-axis direction} can get. As described above, in the presence of the phase noise that changes linearly with time, the present embodiment is not affected by the phase noise in the x-axis and y-axis directions, so that the conventional sweep method shown in FIG. 18 is used. Can also measure the directivity of the antenna 2 to be measured with high accuracy. This suppresses the influence of phase noise in the x-axis direction by averaging the phases obtained by the first forward and reverse sweeps, and at the same time, the phase obtained by the second forward and reverse sweeps is suppressed. This is because the influence of the phase noise in the y-axis direction is suppressed by the phase correction using the average.

In the present embodiment, since it is necessary to perform the first sweep twice in the forward direction and the reverse direction, there is sufficient time to return after the sweep in the positive direction of the x-axis of the first forward sweep in the first embodiment. Compared with the short case, it takes about twice as long as the measurement time. However, as compared with the case where the sweep time in the positive direction of the x-axis of the first forward sweep and the return time are substantially equal in the first embodiment, the forward and reverse directions are alternately swept in the order shown in FIG. As a result, the measurement can be performed in the same time as in the first embodiment.

The first forward sweep and the first reverse sweep, it is necessary to sweep to cover over the two-dimensional measurement plane P, the sweep distance is _{w x × (2 · w y} / Δy) Is. In contrast, the second forward sweep and the second reverse sweep may be one round trip in the y-axis direction, the sweep distance is w _y × 2. Therefore, the increase in the measurement time is small as compared with the case of only the first forward and reverse sweeps.

In the present embodiment, the case where the first forward and reverse sweeps are performed in the x-axis direction is shown, but the x-axis and the y-axis can be reversed, and the sweeps in the x-axis and y-axis directions are also possible. The shorter measurement time can be selected according to the speed, sweep width, and sweep step.

(Third Embodiment)
Next, a third embodiment of the present invention will be described with reference to the drawings.

In the third embodiment, the sweeping method and the phase correction method of the probe antenna 12 are different from those in the first and second embodiments. The basic configuration of the antenna measuring device is the same as the configuration of the first embodiment shown in FIG.

FIG. 8 is a diagram showing a method of sweeping the probe antenna 12 according to the third embodiment.
In the sweeping method of the probe antenna 12 of the third embodiment, the first sweep is bidirectional in which the outward path and the return path in the main sweep direction (x-axis direction) are alternately and repeatedly arranged in the sub-sweep direction (y-axis direction). In terms of sweeping, the first sweep comprises repeating unidirectional sweeps in the main sweep direction, and the first sweep comprises repeating reciprocating sweeps reciprocating in the same path in the main sweep direction. It is different from the second embodiment.

Specifically, as shown in FIG. 8, the sweep of the probe antenna 12 of the present embodiment includes a first bidirectional sweep, a second forward sweep, and a second reverse sweep. That is, the first sweep is the first bidirectional sweep, and the second sweep consists of a second forward sweep and a second reverse sweep. In the first bidirectional sweep, sweeps in the positive direction of the x-axis and sweeps in the negative direction of the x-axis are alternately arranged at an interval Δy in the y-axis direction to cover the measurement plane P. In the second embodiment, the first forward sweep and the first reverse sweep reciprocate on the same path, whereas in the third embodiment, the x-axis positive direction of the first bidirectional sweep. The difference is that the sweep and the sweep in the negative direction of the x-axis are separated from each other by Δy in the y-axis direction.

The second forward sweep sweeps in the positive direction of the y-axis at x = 0, and the second reverse sweep sweeps in the negative direction of the y-axis at x = 0. Although the second forward sweep and the second reverse sweep are separated for the convenience of illustration, they actually reciprocate on the same route. Here, the center of the measurement plane P corresponding to the center of the antenna 2 to be measured is set to x = 0, y = 0, but the position having the largest electric field strength may be set to x = 0, y = 0.

FIG. 9 is a diagram showing an example of a sweep order in the sweep method of FIG. In the figure, the path shown by the solid line shows the sweep of the probe antenna 12 with the antenna measurement in the measurement plane P, and the path shown by the broken line shows the return path of the probe antenna 12 without the antenna measurement. The sweep order shown in FIG. 9 is as follows: the first bidirectional sweep is started from the lower left of the figure, the sweep is swept in the positive direction of the x-axis, the sweep is moved in the positive direction of the y-axis by Δy, and then the negative of the x-axis. After repeating the operation of sweeping in the direction and moving in the positive direction of the y-axis by Δy a predetermined number of times to cover the inside of the measurement plane P, a second reverse sweep is performed, and then a second forward sweep is performed. It is a thing. However, the sweep order is not limited to this, and the sweep order can be arbitrarily changed.

_{Phase θ 1} (x, y _i ) obtained by the first bidirectional sweep, phase θ _2f (0, y) obtained by the second forward sweep, and phase θ 2f (0, y) obtained by the second reverse sweep. The phase θ _2b (0, y) is represented by the following equations (35), (36), and (37), respectively.

Here, i is an integer, y _i when i is an even number is the y-axis value when sweeping in the positive direction of the x-axis of the first bidirectional sweep, and y _i when i is an odd number is the first. Represents the y-axis value at the time of sweeping in the negative direction of the x-axis of bidirectional sweeping. Assuming that the sweep step in the y-axis direction is Δy, it is _{represented by y i} = y ₀ + i · Δy (y ₀ is a constant). φ (x, y) is the true phase of the electric field at the position (x, y), φ _n1 (x, y _i ) is the phase noise during the first bidirectional sweep, and φ _n2f (0, y) is the second. The phase noise during the forward sweep, φ _n2b (0, y), is the phase noise during the second reverse sweep.

In the present embodiment, the phase is corrected as shown in the following equation (38), and the corrected phase θ (x, y _i ) is obtained.

According to the above equation (38), the phase correction unit 24 sweeps the phase detected by the amplitude phase detection unit 22 at the intersection of the first sweep and the second sweep in the second forward sweep and the second reverse direction sweep. Using the difference between the average value of the phase detected by the amplitude phase detection unit 22 at the intersection and the phase detected by the amplitude phase detection unit 22 at the intersection in the first bidirectional sweep, the first method is used. The phase detected by the amplitude phase detection unit 22 in the bidirectional sweep is corrected.

となる。ここで、ａ，ｂ，ｂ_２ｆ，ｂ_２ｂは定数である。 Here, the sweep speed of the probe antenna 12 in the x-axis direction is v _x , the sweep speed in the y-axis direction is v _{y, and the phase noise φ n} (t) = a · t + b that changes linearly with respect to the time t is set. Considering that, the phase noise at each sweep is

Will be. Here, a, b, b _2f , and b _2b are constants.

となる。ここでｂ_１０は定数である。ｂ_１（ｙ_ｉ）の変動幅は（ａ／ｖ_ｘ）・（ｗ_ｘ・ｗ_ｙ／Δｙ）となるが、本実施形態はこれに限定されるものではないので、一般的なｙの関数ｂ_１（ｙ_ｉ）で表している。 As shown in FIG. 9, in the first bidirectional sweep, when the sweep in the positive direction of the x-axis and the sweep in the negative direction of the x-axis are switched for each sweep and the sweeps are sequentially performed in the y-axis direction, the sweep width in the x-axis direction. the w _x, a sweep width of the y-axis direction and w _y, ignoring time Δy moved in the y-axis direction,

Will be. Here, b ₁₀ is a constant. b ₁ variation width _{(y i)} is the _{(a / v x) · (} w x · w y / Δy), since this embodiment is not limited to this, the function of the common y It is represented by b ₁ (y _i).

The corrected phase θ (x, y _i ) is as follows from the above equations (35) to (41).

In the above equation (45), the constant phase offset (b _2f + b _2b ) / 2 does not affect the antenna measurement. That is, a phase θ (x, y _{i ) that is not affected by the phase noise b 1} (y _i ) in the y-axis direction can be obtained. Although the phase noise ± (a / v _x ) · x in the x-axis direction remains, the fluctuation range is (a / v _x ) · w _x , which is smaller than the fluctuation range of the conventional sweep method of FIG. 18 (w). in the case of _{x / v x = w y /} v y, change width is reduced to 1/2). As described above, in the present embodiment, when the phase noise that changes linearly with time is present, the influence of the phase noise is reduced as compared with the conventional sweeping method shown in FIG. Directivity can be measured with higher accuracy than before.

_{Further, in the above equation (45), the sign of the phase noise ± (a / v x} ) · x in the x-axis direction is inverted depending on whether i is an even number or an odd number, so that the directivity of the antenna in the measurement result is x. It has the feature of suppressing the problem of axial deviation.

Further, in the third embodiment, in the first bidirectional sweep, as shown in FIG. 9, the x-axis sweep returns by alternately performing the x-axis positive direction sweep and the x-axis negative direction sweep. Since the time can be effectively used, the measurement time is about halved as compared with the second embodiment, and the antenna measurement time can be significantly shortened.

First bidirectional sweep, it is necessary to sweep to cover over the two-dimensional measurement plane P, whereas the sweep distance is _{w x × (w y / Δy} ), the second order direction sweep and the second reverse sweep may be one round trip in the y-axis direction, the sweep distance is w _y × 2. Therefore, the increase in measurement time is small as compared with the case of only the first bidirectional sweep.

In this embodiment, the case where the first bidirectional sweep is performed in the x-axis direction is shown, but the x-axis and the y-axis can be reversed, and the sweep speed and the sweep width in the x-axis and y-axis directions can be reversed. , The one with the shorter measurement time can be selected according to the sweep step.

(Fourth Embodiment)
Next, a fourth embodiment of the present invention will be described with reference to the drawings.

In the fourth embodiment, the method of sweeping the probe antenna and the method of correcting the phase are different from those of the first to third embodiments. The basic configuration of the antenna measuring device is the same as the configuration of the first embodiment shown in FIG.

FIG. 10 is a diagram showing a method of sweeping the probe antenna 12 according to the fourth embodiment.
In the sweeping method of the probe antenna 12 of the fourth embodiment, the first sweep alternates between the outward sweep in the main sweep direction (x-axis direction) and the sweep in the return path, and is constant in the secondary sweep direction (y-axis direction). It differs from the first to third embodiments in that it consists of bidirectional sweeps performed sequentially at intervals and includes additional sweeps such that the start and end of the first sweep intersect with the second sweep. ..

Specifically, as shown in FIG. 10, the sweep of the probe antenna 12 of the present embodiment includes a first bidirectional sweep, a second forward sweep, and a second reverse sweep. That is, the first sweep is the first bidirectional sweep, and the second sweep consists of a second forward sweep and a second reverse sweep. In the first bidirectional sweep, sweeps in the positive direction of the x-axis and sweeps in the negative direction of the x-axis are alternately arranged at an interval Δy in the y-axis direction to cover the measurement plane P. In the third embodiment, the order of the first bidirectional sweep in the positive direction of the x-axis and the sweep in the negative direction of the x-axis does not necessarily have to be alternated. On the other hand, in the fourth embodiment, as shown in FIG. 10, it is necessary to alternately perform the sweep in the positive direction of the x-axis and the sweep in the negative direction of the x-axis of the first bidirectional sweep.

Further, in the first bidirectional sweep of the present embodiment, in addition to the sweep covering the inside of the measurement plane P, an additional sweep is required so as to start from x = 0 and end at x = 0. The additional sweep reciprocates on the same path as the sweep covering the inside of the measurement plane P as shown in FIG. 10, and outside the sweep covering the inside of the measurement plane P as shown in FIG. 11 in the y-axis direction, respectively. It may be expanded by Δy.

The second forward sweep sweeps in the positive direction of the y-axis at x = 0, and the second reverse sweep sweeps in the negative direction of the y-axis at x = 0. Although the second forward sweep and the second reverse sweep are separated for the convenience of illustration, they actually reciprocate on the same route. In the second forward sweep and the second reverse sweep, it is necessary to acquire the measurement points corresponding to the additional sweeps of the first bidirectional sweep, and in the case of FIG. 10, twice at the start point and the end point of the sweep, respectively. It is necessary to perform the measurement, and in the case of FIG. 11, it is necessary to expand the sweep range up and down by Δy in the y-axis direction to perform additional measurement.

Here, the center of the measurement plane P corresponding to the center of the antenna 2 to be measured is set to x = 0, y = 0, but the position having the largest electric field strength may be set to x = 0, y = 0. The order of the entire first bidirectional sweep, the second forward sweep and the second reverse sweep can be interchanged, eg, the second reverse sweep, the first bidirectional sweep, the second It is also possible to carry out in the order of forward sweep.

_{Phase θ 1} (x, y _i ) obtained by the first bidirectional sweep, phase θ _2f (0, y) obtained by the second forward sweep, and phase θ 2f (0, y) obtained by the second reverse sweep. The phase θ _2b (0, y) is represented by the following equations (46), (47), and (48), respectively.

Here, i is an integer, y _i when i is an even number is the y-axis value when sweeping in the positive direction of the x-axis of the first bidirectional sweep, and y _i when i is an odd number is the first. Represents the y-axis value at the time of sweeping in the negative direction of the x-axis of bidirectional sweeping. Assuming that the sweep step in the y-axis direction is Δy, it is _{represented by y i} = y ₀ + i · Δy (except for the additional sweep of the first bidirectional sweep in FIG. 10, y ₀ is a constant). φ (x, y) is the true phase of the electric field at the position (x, y), φ _n1 (x, y _i ) is the phase noise during the first bidirectional sweep, and φ _n2f (0, y) is the second. The phase noise during the forward sweep, φ _n2b (0, y), is the phase noise during the second reverse sweep.

ここで、ｗ_ｘはｘ軸方向の掃引幅である。 In the present embodiment, the phase is corrected by the following equations (49) and (50), and the corrected phase θ (x, y _i ) is obtained.

Here, w _x is the sweep width in the x-axis direction.

In the above equation (49), the phase correction value θ ₂₁ (0, y _{i ) at the discrete position (0, y i} ) is set to, for example, the position (0, y _{i-1) during the first bidirectional sweep.} ) from the position (0, an expression for the linear interpolation between the sweep of the sweep and the position of the _{y i)} from (0, _{y i)} position to _{(0, y i + 1),} Ya acceleration and deceleration times of the probe scanning mechanism 13 It is simplified by ignoring the time for Δy movement in the y-axis direction. If the acceleration / deceleration time of the probe scanning mechanism 13 and the time for moving Δy in the y-axis direction cannot be ignored, it is necessary to interpolate on the time axis in consideration of these times.

Linear interpolation phase correction value of three or more points other than θ _{21 (0,} y _i) or interpolated by second- or higher-order polynomials using a phase correction value of the predetermined number θ _{21 (0,} y _i) It is also possible to interpolate with the function sin (x) / x using. Generally, by performing interpolation using a large number of measurement points, the interpolation accuracy is improved and the effect of phase correction is increased, but it is necessary to increase the additional sweep to secure the number of measurement points required for interpolation.

According to the above equations (49) and (50) of the phase correction, the phase correction unit 24 has a phase detected by the second forward sweep at the intersection of the first sweep and the second sweep, and the second opposite direction. _{The difference (θ 21} ) between the phase of the average value with the phase detected by the sweep and the phase detected by the amplitude phase detection unit 22 at the intersection during the first bidirectional sweep is the difference (θ 21) of the first bidirectional sweep. The phase detected by the amplitude phase detection unit 22 in the first bidirectional sweep is corrected by using the phase correction value obtained by interpolating in the sweep section between the intersections.

ここで、ａ，ｂ，ｂ_１０，ｂ_２ｆ，ｂ_２ｂは定数である。 Here, the sweep speed of the probe antenna 12 in the x-axis direction is v _x , the sweep speed in the y-axis direction is v _{y, and the phase noise φ n} (t) = a · t + b that changes linearly with respect to the time t is set. Considering this, the phase noise at each sweep is expressed by the following equations (51), (52), and (53).

Here, a, b, b ₁₀ , b _2f , and b _2b are constants.

The phase correction value θ ₂₁ (0, y _i ) and the corrected phase θ (x, y _i ) are as follows from the above equations (49) to (53).

In the above equation (59), the constant phase offset (b _2f + b _2b ) / 2 does not affect the antenna measurement. That is, the phase noise ± (a / v _x ) · x in the x-axis direction and the phase noise (a / v _x ) · (w _x / Δy) · y _{i in} the y-axis direction are not affected by the phase θ (x, y _i ) is obtained. As described above, in the presence of the phase noise that changes linearly with time, the present embodiment is not affected by the phase noise in the x-axis and y-axis directions, so that the conventional sweeping method shown in FIG. 18 is used. Can also measure the directivity of the antenna with high accuracy.

Further, in the fourth embodiment, the x-axis sweep is performed in the first bidirectional sweep by alternately performing the sweep in the positive direction of the x-axis and the sweep in the negative direction of the x-axis, as in the third embodiment. Since the return time of can be effectively utilized, the antenna measurement time can be significantly shortened.

In short, this embodiment has the advantage of obtaining a phase that is not affected by the phase noise in the x-axis direction and the phase noise in the y-axis direction of the second embodiment, and the first bidirectional sweep of the third embodiment. This method has the advantage of being able to measure in a shorter measurement time.

The first bidirectional sweep, it is necessary to sweep to cover over the two-dimensional measurement plane P, the sweep distance is _{w x × (w y / Δy} ). In contrast, the second forward sweep and the second reverse sweep may be one round trip in the y-axis direction, the sweep distance is w _y × 2. Also, the additional sweep in the first bidirectional sweep in the case of linear interpolation may be one-way sweep in the x-axis direction (additional sweep distance is (w _x / 2) x 2), and only the first bidirectional sweep. Compared to the case, the increase in measurement time is small.

In the present embodiment, the case where the first bidirectional sweep is performed in the x-axis direction is shown, but the x-axis and the y-axis can be reversed, and the sweep speed and the sweep width in the x-axis and y-axis directions can be reversed. , The one with the shorter measurement time can be selected according to the sweep step.

As described above, the present invention has the effect of reducing the influence of phase noise and measuring the directivity of the antenna with high accuracy, and overall the antenna measuring device and the antenna measuring method accompanied by the phase measurement. It is useful for.

1 Antenna measuring device 2 Antenna to be measured 3 Signal generator 11 Antenna support 12 Probe antenna 13 Probe scanning mechanism 21 Scan control unit 22 Oscillation phase detection unit 23 Data storage unit 24 Phase correction unit 25 Far field calculation unit 26 Display unit P measurement Plane

Claims (7)

A probe antenna (12) that receives a radio signal transmitted from the antenna to be measured (2) in the near field, and a probe antenna (12).
A first sweep that covers the measurement plane by sweeping the probe antenna a plurality of times in the main sweep direction in a predetermined measurement plane, and a sub-sweep direction that intersects the main sweep direction with the probe antenna in the measurement plane. A probe scanning mechanism (13) that performs a second sweep that reciprocates between the antennas and
An amplitude phase detection unit (22) that detects the amplitude and phase of the signal received by the probe antenna during the first and second sweeps, and
In the first sweep, the average value of the phase detected by the amplitude phase detection unit in the outward path of the second sweep and the phase detected by the amplitude phase detection unit in the return path of the second sweep is used. A phase correction unit (24) that corrects the phase detected by the amplitude phase detection unit, and
An antenna measuring device (1). The first sweep comprises repeating a unidirectional sweep in the main sweep direction, and the phase correction unit is at the intersection of the first sweep and the second sweep in the outward path of the second sweep. The average value of the phase detected by the amplitude phase detection unit and the phase detected by the amplitude phase detection unit at the intersection in the return path of the second sweep, and the amplitude phase at the intersection in the first sweep. The antenna measuring device according to claim 1, wherein the phase detected by the amplitude phase detection unit in the first sweep is corrected by using the difference from the phase detected by the detection unit. The first sweep comprises repeating a reciprocating sweep reciprocating in the same path in the main sweep direction, and the phase correction unit includes the first sweep and the second sweep in the outward path of the second sweep. The average value of the phase detected by the amplitude phase detection unit at the intersection of the above and the phase detected by the amplitude phase detection unit at the intersection in the return path of the second sweep, and the phase detected by the amplitude phase detection unit at the intersection of the first sweep. The first sweep is used by using the difference between the average value of the phase detected by the amplitude phase detection unit at the intersection and the phase detected by the amplitude phase detection unit at the intersection in the return path of the first sweep. The antenna measuring apparatus according to claim 1, wherein the phase of the average value of the phase detected by the amplitude phase detection unit on the outward path and the phase detected by the amplitude phase detection unit on the return path of the first sweep is corrected. .. The first sweep comprises a bidirectional sweep in which the outward path and the return path in the main sweep direction are alternately and repeatedly arranged in the sub sweep direction, and the phase correction unit is the second sweep in the outward path of the second sweep. The average value of the phase detected by the amplitude phase detection unit at the intersection of the first sweep and the second sweep and the phase detected by the amplitude phase detection unit at the intersection in the return path of the second sweep. 1. The phase detected by the amplitude phase detection unit in the first sweep is corrected by using the difference from the phase detected by the amplitude phase detection unit at the intersection in the first sweep. The described antenna measuring device. The first sweep comprises a bidirectional sweep in which an outward sweep in the main sweep direction and a sweep in the return path are alternately performed and sequentially performed in the sub sweep direction at regular intervals, and the phase correction unit is the first sweep. _{The difference (θ 21} ) between the phase of the average value at the intersection of the sweep and the second sweep and the phase detected by the amplitude phase detector at the intersection at the first sweep is the first sweep. The antenna measuring device according to claim 1, wherein the phase detected by the amplitude phase detection unit in the first sweep is corrected by using the phase correction value interpolated in the sweep section between the intersections. A moving step (S2) of moving the probe antenna by a predetermined distance within a predetermined measurement plane, and
A transmission / reception step (S3) in which a radio signal is transmitted from the antenna to be measured (2) and the radio signal is received in the near field by the probe antenna.
A detection step (S7) for detecting the amplitude and phase of the signal received by the probe antenna is included.
By repeating the movement step, the transmission / reception step, and the detection step, the sweep in the main sweep direction is repeated to cover the measurement plane, and the secondary sweep that intersects the main sweep direction in the measurement plane. Sweeping the probe antenna, which consists of a second sweep that reciprocates in the sweep direction, is performed.
A correction step (S12) for correcting the phase detected in the first sweep using the average value of the phase detected in the outward path of the second sweep and the phase detected in the return path of the second sweep is performed. A method for measuring an antenna, which further comprises. A first sweep that covers the measurement plane by repeating sweeping in the main sweep direction of the probe antenna within a predetermined measurement plane, and a reciprocation of the probe antenna in the sub-sweep direction that intersects the main sweep direction in the measurement plane. A sweep start step (S5) for initiating a sweep consisting of a second sweep to be caused, and a sweep start step (S5).
A reception step (S6) in which the radio signal transmitted from the antenna to be measured (2) during the sweep is received by the probe antenna in the near field, and a reception step (S6).
A detection step (S7) for detecting the amplitude and phase of the signal received by the probe antenna, and
A correction step (S12) for correcting the phase detected in the first sweep using the average value of the phase detected in the outward path of the second sweep and the phase detected in the return path of the second sweep. ,
An antenna measurement method comprising.

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