JP2005114391A - Antenna measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna measuring apparatus capable of finding concurrently element electric field amplitudes and phases of at least two element antennas. <P>SOLUTION: A phased array antenna 100 has a transmitter 5, an electric power distribution circuit 3, the plurality of element antennas 1 for emitting a high frequency signal, digital phase shifters 2 for imparting a passing phase to the high frequency signal, and a phase shifter control circuit 4 for the plurality of elements for rotating the passing phases of the at least two digital phase shifters 2 at the same time. This antenna measuring instrument includes a pick-up antenna 6a, a detection circuit 7 for measuring reception power of the high frequency signal received thereby, a Fourier series expansion computing circuit 8 for expanding a change of the measured reception power to find Fourier coefficients, and an electric field computing circuit 9 for the plurality of elements for computing a reception power change when rotating an excitation phase of one of the element antennas on the basis of the Fourier coefficients, and for measuring the element electric field amplitude and the phase of the element antenna on the basis of a result computed therein. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antenna measurement apparatus, and more particularly to an antenna measurement apparatus for measuring an element electric field of an element antenna constituting a phased array antenna such as communication / radar.

  In the conventional antenna measurement apparatus, the high frequency signal transmitted from the transmitter is radiated from the pickup antenna to the space. The radiated high frequency signal is received by a plurality of element antennas. In this received state, the variable phase shifter is controlled, and the set phase shift of each element antenna is sequentially changed by the control circuit. The measurement arithmetic circuit measures the ratio between the maximum value and the minimum value of the total array combined output and the phase shift change amount that gives the maximum value, and calculates the amplitude and phase of each element antenna (see, for example, Patent Document 1). .)

  In the conventional antenna measuring apparatus configured as described above, in order to obtain the element electric field of the element antenna, it is necessary to change the phase value of only the phase shifter connected to the element antenna. That is, in order to obtain the element electric fields of all the element antennas, it was necessary to repeat the measurement for the number of elements. For this reason, in the case of a multi-element array antenna, there is a problem that the measurement time becomes enormous.

  A technique for avoiding this has also been proposed. This method measures changes in the amplitude and phase of the array combined electric field when the phases of at least two phase shifters are simultaneously rotated, and performs Fourier transform to measure the element electric field amplitude and phase of each element antenna. It is what you want. Therefore, this method can simultaneously determine the element electric field amplitude and phase of a plurality of element antennas (see, for example, Non-Patent Document 1).

Japanese Examined Patent Publication No. 1-37782 (particularly FIG. 4) G.A.Hampson and A.B.Smolder, "A Fast And Accurate Scheme for Calibration of Active Phased-Array Antennas," 1999 IEEE AP-S Int. Symp. Digest, pp. 1040-1043, 1999.

  As described above, in the conventional example of Patent Document 1, in order to obtain the element electric fields of all the element antennas, the measurement must be repeated for the number of elements. There was a problem that became huge.

  In the conventional example of Non-Patent Document 1, the problem of Patent Document 1 is solved. However, since not only the amplitude of the array combined electric field but also the phase must be measured, it is difficult to accurately measure the phase. At very high frequencies such as the millimeter wave band and the submillimeter wave band, there is a problem that it is difficult to obtain the element electric field amplitude and phase of the element antenna as a result.

  The present invention has been made to solve such a problem, and an antenna measurement apparatus capable of simultaneously obtaining the element electric field amplitude and phase of at least two element antennas only by measuring the amplitude of the array combined power is obtained. It is an object.

  The present invention includes a transmitter that transmits a high-frequency signal, a power distribution circuit that distributes the high-frequency signal, at least two element antennas that radiate the distributed high-frequency signal, and the high-frequency waves that are radiated by the element antennas. A phased array antenna having a digital phase shifter that gives a passing phase to a signal, and a multi-element phase shifter control circuit that simultaneously rotates the passing phase of at least two of the digital phase shifters; A pick-up antenna for receiving the high-frequency signal, a detector circuit for measuring the received power of the high-frequency signal received by the pick-up antenna, and the digital phase shifter by the multi-element phase shifter control circuit of the phased array antenna. Measured by the above detection circuit when the passage phase of the detector is rotated The received power when the excitation phase of one element antenna is rotated from the Fourier series expansion arithmetic circuit for obtaining the Fourier coefficient by expanding the Fourier series of the received power change, and the Fourier coefficient obtained by the Fourier series expansion arithmetic circuit. It is an antenna measurement device provided with a multiple element electric field calculation circuit that calculates a change and measures the element electric field amplitude and phase of the element antenna from the calculation result.

  The present invention is configured as described above, and measures a change in array combined power when the phases of at least two element antennas are simultaneously rotated, and uses the result of Fourier series expansion of the change in the power to measure the element antenna. Since the element electric field amplitude and phase are measured, the element electric field amplitude and phase of at least two element antennas can be obtained simultaneously only by measuring the amplitude of the array combined power, and the measurement time can be shortened.

Embodiment 1 FIG.
1 is a block diagram showing a configuration of an antenna measurement apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, a plurality of element antennas 1-n (n = 1, 2,..., N) are arranged on the same opening, and each element antenna 1-n has an M-bit digital signal. One phase shifter 2-n (n = 1, 2,..., N) is connected to each one. Each digital phase shifter 2-n is connected to the power distribution circuit 3. Each digital phase shifter 2-n is also connected to a multi-element phase shifter control circuit 4. The multi-element phase shifter control circuit 4 simultaneously rotates the passing phases of at least two of the digital phase shifters 2-n. A transmitter 5 is connected to the power distribution circuit 3. The phased array antenna 100 is configured by the above components.

  Further, as shown in FIG. 1, the pickup antenna 6a is provided facing the element antenna 1-n and spaced apart. A detector circuit 7 for measuring the received power of the pickup antenna 6a is connected to the pickup antenna 6a. A Fourier series expansion calculation circuit 8 is connected to the detection circuit 7. The Fourier series expansion operation circuit 8 is measured by the detection circuit 7 when the passing phase of the digital phase shifter 2-n of at least two element antennas 1-n is rotated by the multi-element phase shifter control circuit 4. A change in received power is expanded by Fourier series to obtain a Fourier coefficient. In addition, a multi-element electric field calculation circuit 9 is connected to the Fourier series expansion calculation circuit 8. The multi-element electric field calculation circuit 9 obtains the element electric field amplitude and phase of the element antenna 1-n from the Fourier coefficient obtained by the Fourier series expansion calculation circuit 8.

  The operation will be briefly described. The high-frequency signal transmitted from the transmitter 5 is distributed by the power distribution circuit 3 and given an appropriate passing phase by the digital phase shifter 2-n, and then radiated from the plurality of element antennas 1-n to the space. Note that the passing phase of the digital phase shifter 2-n at this time is simultaneously rotated by the multi-element phase shifter control circuit 4. The high frequency signal radiated from the element antenna 1-n in this way is received by the pickup antenna 6a. The detection power 7 at this time is measured by the detection circuit 7, and the change of the reception power is Fourier series expanded by the Fourier series expansion calculation circuit 8 to obtain the Fourier coefficient. Next, the multi-element electric field calculation circuit 9 obtains the element electric field amplitude and phase of the element antenna 1 -n from the Fourier coefficient obtained by the Fourier series expansion calculation circuit 8.

Next, the calculation principle of the multi-element electric field calculation circuit 9 in the present invention is shown below. The amplitude of the element electric field of the element antenna 1-n in the initial state is E _n , the phase is φ _n , the amplitude of the array combined electric field at this time is E ₀ , and the phase is φ ₀ . Array combined electric field when the antenna elements 1-n phase was simultaneously rotated by [Phi _n of the initial state N 'pieces (2 ≦ N' ≦ N) can be determined by the following equation (1).

  Considering the relative value with the array combined electric field in the initial state, the following equation (2) is obtained.

Here, k _m is a relative value of the array combined electric field amplitude in the initial state, the X _m is a relative value of the array combined electric field phase of the initial state. When the array combined power is obtained from the equation (2), the following equation (3) is obtained.

  In equation (3), considering that the terms obtained by exchanging n and n ′ are equal, equation (3) can be expressed as the following equation (4).

_{Here, A, XC n'n, XS n'n} , C n, S n is a coefficient with a predetermined element as is apparent from the initial state from the form N 'pieces of the formula (4) antennas 1- A change in the array combined power when the phase of n is simultaneously rotated is observed, and this is the Fourier series itself obtained by the Fourier series expansion arithmetic circuit 8. That is, among the Fourier coefficients obtained by the Fourier series expansion arithmetic circuit 8, A is a constant term, XC _n′n is a Fourier coefficient related to cos (Φ _{n ′} −Φ _n ), and XS _n′n is sin (Φ _{n ′} - [Phi] _n) related Fourier coefficients, it is _{C n} Fourier coefficients for cos _n, is _{S n} is the Fourier coefficient for the sin .PHI _n. Except for the term n = P in equation (4), if Φ _n = 0, the following equation (5) is obtained.

  Equation (5) means that the change in the array combined power becomes a cosine curve when the excitation phase of the element antenna 1-n where n = P is rotated 360 degrees. Therefore, the ratio r between the maximum value and the minimum value of the change in array combined power when the excitation phase of the element antenna 1-n where n = P is rotated 360 degrees can be obtained by the following equation (6).

  However, in Formula (6), the variables α, c, and s are defined as follows.

Further, the phase value −Φ _{0 at} which the array combined power becomes the maximum value when the excitation phase of the element antenna 1-n where n = P is rotated 360 degrees can be obtained by the following equation (10).

  Therefore, the ratio between the maximum value and the minimum value of the array combined power when the excitation phase of the element antenna 1-n where n = P is rotated 360 degrees, and the phase change amount that gives the maximum value are expressed by the following equations (6). ) And Equation (10), the element electric field amplitude and phase of the element antenna can be obtained from these values. As a calculation method for obtaining the element electric field amplitude and phase of the element antenna from the ratio between the maximum value and the minimum value of the array combined power and the phase change amount that gives the maximum value, for example, the calculation shown in Patent Document 1 above What is necessary is just to calculate using a formula. The above is the principle for obtaining the element electric field amplitude and phase by the multi-element electric field calculation circuit 9.

  As described above, according to the present embodiment, a change in array combined power when the phases of N ′ element antennas are simultaneously rotated is measured, and the change in the combined power is Fourier-transformed by the Fourier series arithmetic circuit 8. The element electric field amplitude and phase can be obtained by the multiple element electric field calculation circuit 9 using the result of series expansion. Therefore, since the element electric field amplitude and phase of the N ′ element antennas can be obtained from the change in the combined power, the measurement time can be greatly shortened as compared with the conventional measuring apparatus. In addition, since it is only necessary to measure the amplitude of the array combined power, even when accurate phase measurement is difficult such as in the millimeter wave band or submillimeter wave band, the element electric field amplitude and phase can be obtained with high accuracy. effective.

Embodiment 2. FIG.
In the present embodiment, in the same configuration as in the first embodiment, the passing phase of the digital phase shifter 2-n is rotated by a certain phase interval, and the phase interval is equal to any of the following phase values. Choose to be different.

(1) Phase interval of another digital phase shifter that simultaneously rotates the phase.
(2) The difference in phase interval for any two digital phase shifters that are simultaneously phase rotated.

Accordingly, since all of the triangular functions constituting the above equation (4) are orthogonal to each other, coefficients _{A, XC n'n, XS n'n,} C n, can be determined accurately _{S n.}

Accordingly, in this embodiment, with the same effects as in the first embodiment, in addition, the coefficient _{A, XC n'n, XS n'n,} C n, can be determined accurately to _{S n} Therefore, there is an effect that the element electric field amplitude and phase can be obtained with high accuracy. Note that this embodiment can be applied not only to the first embodiment but also to other embodiments described later.

Embodiment 3 FIG.
In the present embodiment, when the phase interval for rotating the passing phase of the digital phase shifter 2-n is q times the lowest bit passing phase in the first or second embodiment, the digital phase shifter 2-n The integer q is selected so that the total number of phase shift states of q and the q are relatively prime. With this selection, when measuring the change in array combined power when the phases of the N ′ element antennas 1-n are simultaneously rotated, the array combination corresponding to all the bit states of the digital phase shifter 2-n. The power measurement result can be obtained.

  Therefore, in this embodiment, the same effect as in the first or second embodiment is obtained, and in addition, measurement results of the array combined power corresponding to all the bit states of the digital phase shifter 2-n are obtained. Therefore, when the pass characteristic of the digital phase shifter 2-n has a random error for each bit, the effect of this error can be reduced. Note that this embodiment can be applied not only to the first and second embodiments, but also to other embodiments described later.

Embodiment 4 FIG.
FIG. 2 is a block diagram showing a configuration of an antenna measurement apparatus according to Embodiment 4 of the present invention. The components corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted here. As shown in FIG. 2, in the present embodiment, a plurality of pickup antennas 6a to 6c are provided. In FIG. 2, an example in which three pickup antennas are provided is described. However, the present invention is not limited to this, and an arbitrary number of two or more may be used. A power combining circuit 10 is connected to the pickup antennas 6a to 6c. The power combining circuit 10 is a circuit for combining high-frequency signals received by the pickup antennas 6a to 6c.

  As described above, the present embodiment has the same effects as those of the first embodiment, and in addition, the high-frequency signals received by the plurality of pickup antennas 6a to 6c are combined by the power combining circuit 10. Since detection is performed at a later high received power, there is an effect that accurate measurement is possible.

Embodiment 5. FIG.
FIG. 3 is a block diagram showing a configuration of an antenna measurement apparatus according to Embodiment 5 of the present invention. The configuration in FIG. 3 is basically the same as the configuration in FIG. 2 described above, and thus the same configuration is denoted by the same reference numeral and description thereof is omitted here. 2 is different from the configuration of FIG. 2 in the present embodiment in that the plurality of pickup antennas 6a to 6d are all made up of element antennas 1-n (n = 1, 2,...). , N) on the same opening. Although FIG. 3 shows an example in which four pickup antennas are provided, the present invention is not limited to this, and an arbitrary number of two or more may be provided. Further, the present embodiment may be applied to the configuration of FIG.

  Therefore, the present embodiment has the same effect as the second embodiment, and in addition, the pickup antennas 6a to 6d are connected to the element antenna 1-n (n = 1, 2,..., N). By providing the same on the same opening, the element electric field can be measured even when the pickup antenna and the phased array antenna cannot be opposed to each other, for example, when the phased array antenna is in operation. There is an effect.

Embodiment 6 FIG.
In the present embodiment, in the first embodiment, the digital phase shifter 2-n is a 5-bit phase shifter, and the number of digital phase shifters 2-n that simultaneously rotate the phase is three. At this time, the phase interval for rotating the passing phase of the digital phase shifter 2-n is set to be 1, 3 and 7 times the lowest bit passing phase, respectively.

  Therefore, the present embodiment satisfies the conditions of the second embodiment and has the same effect as the second embodiment. In addition, since the condition of the third embodiment is satisfied, there is an effect that the element electric field amplitude and phase can be obtained with high accuracy. This embodiment is applicable not only to the first embodiment but also to other fourth and fifth embodiments.

Embodiment 7 FIG.
In the present embodiment, in the first embodiment, the digital phase shifter 2-n is a 5-bit phase shifter, and the number of digital phase shifters 2-n that simultaneously rotate the phase is three. In addition, the phase interval for rotating the passing phase of the digital phase shifter 2-n is set to be 1, 5, and 7 times the lowest bit passing phase, respectively.

  Therefore, the present embodiment satisfies the conditions of the second embodiment and has the same effect as the second embodiment. In addition, since the condition of the third embodiment is satisfied, there is an effect that the element electric field amplitude and phase can be obtained with high accuracy. This embodiment is applicable not only to the first embodiment but also to other fourth and fifth embodiments.

Embodiment 8 FIG.
In the present embodiment, in the first embodiment, the digital phase shifter 2-n is a 4-bit phase shifter, and the number of digital phase shifters 2-n that simultaneously rotate the phase is two. In addition, the phase interval for rotating the passing phase of the digital phase shifter 2-n is set to be 1 or 3 times the lowest bit passing phase, respectively.

  Therefore, the present embodiment satisfies the conditions of the second embodiment and has the same effect as the second embodiment. In addition, since the condition of the third embodiment is satisfied, there is an effect that the element electric field amplitude and phase can be obtained with high accuracy. This embodiment is applicable not only to the first embodiment but also to other fourth and fifth embodiments.

Embodiment 9 FIG.
In the present embodiment, in the first embodiment, the digital phase shifter is a 4-bit phase shifter, and the number of digital phase shifters that simultaneously rotate the phase is two. In addition, the phase interval for rotating the passing phase of the digital phase shifter is set to be 1 and 5 times the lowest bit passing phase, respectively.

  Therefore, the present embodiment satisfies the conditions of the second embodiment and has the same effect as the second embodiment. In addition, since the condition of the third embodiment is satisfied, there is an effect that the element electric field amplitude and phase can be obtained with high accuracy. This embodiment is applicable not only to the first embodiment but also to other fourth and fifth embodiments.

Embodiment 10 FIG.
In the first to ninth embodiments, the same effect can be obtained even if transmission and reception are interchanged. That is, for example, referring to the example of FIG. 1, instead of the transmitter 5 of FIG. 1, a detection circuit 7, a Fourier series expansion calculation circuit 8, and a multi-element electric field calculation circuit 9 are connected, and the detection circuit 7 of FIG. Instead of the Fourier series expansion calculation circuit 8 and the multi-element electric field calculation circuit 9, the transmitter 5 may be connected. In this case, instead of the power distribution circuit 3 in FIG. 1, a power combining circuit (not shown, see reference numeral 10 in FIG. 2) is provided. Other configurations are the same as those in FIG.

  Alternatively, as shown in FIG. 4, switches 11 and 12 are provided, and both the transmitter 5, the detection circuit 7, the Fourier series expansion calculation circuit 8, and the multiple element electric field calculation circuit 9 are connected to the phased array antenna 100 </ b> A side. You may make it connect with any of the pick-up antenna 6a side. In such a configuration, transmission and reception may be switched as appropriate by switching with the switches 11 and 12. In the case of switching appropriately, a power distribution / combination circuit 3 </ b> A capable of both distribution and combination is provided instead of the power distribution circuit 3. Regarding other configurations, components corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted here.

  The operation when the pickup antenna 6a is on the transmission side and the phased array antenna 100A is on the reception side will be briefly described. The high frequency signal transmitted from the transmitter 5 is radiated into the space from the pickup antenna 6a. The radiated high-frequency signal is received by a plurality of element antennas 1-n and given an appropriate passing phase by a digital phase shifter 2-n, and then a power combining circuit (not shown) or a power distribution combining circuit 3A. Is synthesized. Note that the passing phase of the digital phase shifter 2-n at this time is simultaneously rotated by the multi-element phase shifter control circuit 4. In this way, the detection circuit 7 measures the received power combined by the power distribution / combination circuit 3, and the Fourier series expansion calculation circuit 8 expands the received power in a Fourier series to obtain a Fourier coefficient. Next, the multi-element electric field calculation circuit 9 obtains the element electric field amplitude and phase of the element antenna 1 -n from the Fourier coefficient obtained by the Fourier series expansion calculation circuit 8.

  In the above description, the example in which the present embodiment is applied to the configuration of the first embodiment has been described. However, it goes without saying that the present invention can be similarly applied to any of the second to ninth embodiments. Description is omitted.

  As described above, in the above first to ninth embodiments, transmission and reception may be switched, or may be switched as appropriate by the switches 11 and 12, and in that case as well, the same as in the first to ninth embodiments. The effect of can be obtained.

It is the block diagram which showed the structure of the antenna measuring device which concerns on Embodiment 1 of this invention. It is the block diagram which showed the structure of the antenna measuring device which concerns on Embodiment 4 of this invention. It is the block diagram which showed the structure of the antenna measuring device which concerns on Embodiment 5 of this invention. It is the block diagram which showed the structure of the antenna measuring device which concerns on Embodiment 10 of this invention.

Explanation of symbols

  1-1, 1-2, 1-n, 1-N element antenna, 2-1, 2-2, 2-n, 2-N digital phase shifter, 3 power distribution circuit, 3A power distribution synthesis circuit, 4 Multi-element phase shifter control circuit, 5 transmitter, 6a, 6b, 6c, 6d pickup antenna, 7 detector circuit, 8 Fourier series expansion arithmetic circuit, 9 multi-element electric field arithmetic circuit, 10 power combiner circuit, 11, 12 switch, 100, 100A phased array antenna.

Claims (7)

A transmitter for transmitting a high-frequency signal; a power distribution circuit for distributing the high-frequency signal; at least two element antennas for radiating the distributed high-frequency signal; and a passing phase for the high-frequency signal radiated by each element antenna. A phased array antenna having a digital phase shifter that provides a multi-element phase shifter control circuit that simultaneously rotates the passing phase of at least two of the digital phase shifters;
A pickup antenna that receives the high-frequency signal radiated from each of the element antennas;
A detector circuit for measuring the received power of the high-frequency signal received by the pickup antenna;
Fourier transform that obtains a Fourier coefficient by Fourier series expansion of a change in received power measured by the detection circuit when the phase of the digital phase shifter is rotated by the multi-element phase shifter control circuit of the phased array antenna A series expansion arithmetic circuit;
A plurality of elements for calculating the received electric power change when the excitation phase of one element antenna is rotated from the Fourier coefficient obtained by the Fourier series expansion calculation circuit, and measuring the element electric field amplitude and phase of the element antenna from the calculation result An antenna measurement apparatus comprising: an element electric field calculation circuit. A first switch connected to the detector circuit;
A second transmitter that is connected to the first switch, is switched to the detection circuit by the first switch, and outputs a high-frequency signal to be radiated by the pickup antenna;
Each element antenna of the phased array antenna receives a high frequency signal radiated from the pickup antenna, and a digital phase shifter of the phased array antenna gives a passing phase to the high frequency signal received by each element antenna. There,
The above phased array antenna
A power combining circuit that combines the high-frequency signals received by the element antennas;
A second switch connected to the transmitter;
A second detection circuit connected to the second switch and switched to the transmitter by the second switch;
The antenna measurement apparatus according to claim 1, wherein the Fourier series expansion arithmetic circuit expands a change in received power measured by either one of the detection circuit or the second detection circuit. A transmitter for transmitting a high-frequency signal;
A pickup antenna connected to the transmitter and radiating the high-frequency signal;
A phased array antenna that receives the radiated high-frequency signal, and
The above phased array antenna
At least two element antennas;
A digital phase shifter that gives a passing phase to the high-frequency signal received by each element antenna;
A multi-element phase shifter control circuit for simultaneously rotating the passing phases of at least two of the digital phase shifters;
A power combining circuit for combining the high-frequency signal to which the passing phase is given by the digital phase shifter;
A detection circuit for measuring the received power of the high-frequency signal synthesized by the power synthesis circuit;
A Fourier series expansion arithmetic circuit that obtains a Fourier coefficient by performing Fourier series expansion on a change in received power measured by the detection circuit when the passing phase of the digital phase shifter is rotated by the multi-element phase shifter control circuit; ,
A plurality of elements for calculating the received electric power change when the excitation phase of one element antenna is rotated from the Fourier coefficient obtained by the Fourier series expansion calculation circuit, and measuring the element electric field amplitude and phase of the element antenna from the calculation result An antenna measurement apparatus comprising: an element electric field calculation circuit. The multi-element phase shifter control circuit rotates the passing phase of the digital phase shifter by a certain phase interval, and the phase interval is
(1) Phase interval of another digital phase shifter that simultaneously rotates the phase,
And (2) the difference in phase spacing for any two digital phase shifters that rotate in phase simultaneously,
The antenna measurement device according to claim 1, wherein the antenna measurement device is different from any of the phase values.   When the phase interval for rotating the pass phase of the digital phase shifter by the multi-element phase shifter control circuit is n times the lowest bit pass phase, the total number of phase shift states of the digital phase shifter and the n The antenna measurement apparatus according to claim 1, wherein the antenna measurement apparatus is disjoint.   6. The antenna measurement apparatus according to claim 1, wherein two or more pickup antennas are provided, and the pickup antennas are connected by a power combining circuit.   7. The antenna measuring apparatus according to claim 1, wherein the pickup antenna is provided on an opening of the phased array antenna.

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