JP7505898B2 - Phased array antenna calibration device, phased array antenna device, and phased array antenna calibration program - Google Patents

Description

This disclosure relates to techniques for calibrating phased array antennas.

Technology for calibrating phased array antennas is disclosed in Non-Patent Document 1 and elsewhere. Non-Patent Document 1 discloses the REV method (Rotating element Electric field Vector method). During transmit calibration, the transmitted waves of each element are received by an external antenna, and during receive calibration, the transmitted waves of the external antenna are received by each element. In the REV method, the transmit/receive phase and transmit/receive amplitude of an element are measured based on the change in the combined transmit/receive amplitude of all elements that accompanies a change in the transmit/receive phase of that element.

Kiyoshi Mano, Takashi Katagi, "Method of Measuring Element Amplitude and Phase of Phased Array Antenna - Element Electric Field Vector Rotation Method -", Transactions of the Institute of Electronics, Information and Communication Engineers, May 1982, Vol. B65, No. 5, pp. 555-560.

The configuration of a prior art phased array antenna device is shown in Figure 1. From a cost perspective, multiple elements share D/A and A/D converters, and each element has a transmit phase amplitude adjuster and a receive phase amplitude adjuster with adjustment values that are discrete rather than continuous.

The phased array antenna device P comprises M arrays A-1, ..., A-M and a phased array antenna calibration device C. The array A-1 comprises N elements 1-11, ..., 1-1N, N transmit phase amplitude adjusters and receive phase amplitude adjusters 2-11, ..., 2-1N, one transmit signal distributor and receive signal combiner 3-1, and one D/A converter and A/D converter 4-1. The array A-M comprises N elements 1-M1, ..., 1-MN, N transmit phase amplitude adjusters and receive phase amplitude adjusters 2-M1, ..., 2-MN, one transmit signal distributor and receive signal combiner 3-M, and one D/A converter and A/D converter 4-M. The phased array antenna calibration device C comprises a calibration value calculation unit 6 and an adjustment value calculation unit 7.

The process of phased array antenna calibration of the prior art is shown in FIG. 2. In the array A-1, the calibration value calculation unit 6 calculates the calibration values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N based on the relative values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N that shares the D/A converter and the A/D converter 4-1, using the REV method or the like. In FIG. 2, the calibration value c _phs,1,1 of the transmit/receive phase of the element 1-11 is calculated, the calibration value c _amp,1,1 of the transmit/receive amplitude of the element 1-11 is calculated, the calibration value c _phs,1,N of the transmit/receive phase of the element 1-1N is calculated, and the calibration value c _amp,1,N of the transmit/receive amplitude of the element 1-1N is calculated. The same process is performed in the arrays A-M.

The adjustment value calculation unit 7 calculates discrete adjustment values for the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N in the array A-1 based on the calibration values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N, and implements the discrete adjustment values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N. 2, a discrete adjustment value d _phs,2 (closest to c _phs,1,1 ) of the transmit/receive phase for element 1-11 is calculated, a discrete adjustment value d _amp,2 (closest to c _amp,1,1 ) of the transmit/receive amplitude for element 1-11 is calculated, a discrete adjustment value d _phs,2 (closest to c _amp,1,N ) of the transmit/receive phase for element 1-1N is calculated, and a discrete adjustment value d _amp,2 (closest to c _amp,1,N ) of the transmit/receive amplitude for element 1-1N is calculated. Similar processing is performed for arrays A-M.

Then, for the discrete adjustment value d _phs,2 of the transmit/receive phase of element 1-11, there is a residual e _{phs ,1,1} =c _phs,1,1 -d _phs,2 of the calibration value c phs,1,1 of the transmit/receive phase of element 1-11, and for the discrete adjustment value d _phs,2 of the transmit/receive phase of element 1-1N, there is a residual e _phs,1,N =c _phs,1,N -d _phs,2 of the calibration value c _phs,1,N of the transmit/receive phase of element 1-1N. Then, there exists a residual e _amp,1,1 =c _amp,1,1 -d _{amp, 2} of the calibration value c _amp, 1,1 of the transmit/receive amplitude of element 1-11 with respect to the discrete adjustment value d amp,2 of the transmit/receive amplitude of element 1-11, and there exists a residual e _amp ,1,N =c amp, _1, N -d amp _,2 of the calibration value c amp,1,N of the transmit/receive amplitude of element 1-1N with respect to the discrete adjustment value d _{amp, 2} of the transmit/receive amplitude of element 1-1N. Therefore, there is a possibility that the direction of the composite beam of all elements 1-11, ..., 1-1N tilts from the desired beam direction of all elements 1-11, ..., 1-1N.

Here, it can be assumed that the quantization errors of the transmit/receive phases of the transmit phase/amplitude adjusters and the receive phase/amplitude adjusters 2-11, ..., 2-1N are uniformly and randomly distributed from +(360°/2 ^x )/2 to -(360°/2 ^x )/2 (x is the number of bits). Therefore, if the number of elements 1-11, ..., 1-1N is infinite, the residuals e _phs ,1,1 , ..., e _phs,1,N of the transmit/receive phase calibration values c _phs,1,1 , ..., c phs _,1,N of the elements 1-11, ..., 1-1N tend to be random, so that the composite beam direction of all elements 1-11, ..., 1-1N is unlikely to tilt from the desired beam direction of all elements 1-11, ..., 1-1N. However, if the number of elements 1-11, ..., 1-1N is finite, the residuals e phs _{,1,1 , ..., e phs,1,N of the calibration values c phs,1,1} , ..., c _phs,1,N of the transmit/receive phases of elements _1-11 , ..., _1-1N may have a certain tendency (e.g., e _phs,1,1 =φ, ..., e _phs,1,n =φ+(n-1)Δφ, ..., e _phs,1,N =φ+(N-1)Δφ), and therefore there is a high possibility that all elements 1-11, ..., 1-1N will tilt from the desired beam direction.

The result of the prior art phased array antenna calibration is shown in Figure 3. The total number of elements is 8 x 4. The phase adjuster has 3 bits and has discrete adjustment values of 0°, 45°, ..., 315°. The amplitude adjuster has 3 bits and has discrete adjustment values of 0 dB, -1 dB, ..., -7 dB. For each element, random residuals of the phase and amplitude calibration values (specifically, the residuals of the phase calibration values that follow a uniform distribution within the range of ±22.5°, and the residuals of the amplitude calibration values that follow a uniform distribution within the range of ±0.5 dB) are given in each trial of 100 simulations. The composite main lobe direction of all elements is tilted within the range of ±0.5° from the desired main lobe direction of all elements.

Therefore, in order to solve the above problem, the present disclosure aims to reduce the possibility that the composite beam direction of all elements will tilt from the desired beam direction of all elements, even when multiple elements share a D/A converter or an A/D converter and each element has a transmit phase amplitude adjuster or a receive phase amplitude adjuster that has an adjustment value that is discrete rather than continuous.

If multiple elements have their own D/A converters, then digital correction can be made to the digital transmit signal input to each D/A converter to cancel out the residual error in the calibration value of the transmit phase of each element. In reality, multiple elements share a D/A converter, so digital correction can be made to the digital transmit signal input to a single D/A converter to cancel out the "average" of the residual error in the calibration value of the transmit phase of all elements.

Specifically, the present disclosure relates to a phased array antenna calibration device that includes a calibration value calculation unit that calculates a calibration value of the transmission phase of each element based on the relative value of the transmission phase of each element that shares a D/A converter in a phased array antenna, an adjustment value calculation unit that calculates a discrete adjustment value of the transmission phase of each element based on the calibration value of the transmission phase of each element and implements the discrete adjustment value of the transmission phase of each element, a residual vector calculation unit that calculates a residual vector of the calibration value of the transmission phase of each element for the discrete adjustment value of the transmission phase of each element in an IQ plane, a residual vector synthesis unit that synthesizes the residual vector of the calibration value of the transmission phase of each element and calculates a residual vector sum of the calibration values of the transmission phase of all elements that share the D/A converter, and a D/A converter correction unit that corrects the transmission signal input to the D/A converter so as to cancel the residual vector sum of the calibration values of the transmission phase of all elements.

The present disclosure also relates to a phased array antenna calibration program for causing a computer to execute, in sequence, a calibration value calculation step for calculating a calibration value of the transmission phase of each element based on the relative value of the transmission phase of each element that shares a D/A converter in a phased array antenna; an adjustment value calculation step for calculating a discrete adjustment value of the transmission phase of each element based on the calibration value of the transmission phase of each element and implementing the discrete adjustment value of the transmission phase of each element; a residual vector calculation step for calculating a residual vector of the calibration value of the transmission phase of each element for the discrete adjustment value of the transmission phase of each element in an IQ plane; a residual vector synthesis step for synthesizing the residual vector of the calibration value of the transmission phase of each element and calculating a residual vector sum of the calibration values of the transmission phase of all elements that share the D/A converter; and a D/A converter correction step for correcting the transmission signal input to the D/A converter so as to cancel the residual vector sum of the calibration values of the transmission phase of all elements.

With these configurations, even when multiple elements share a D/A converter and each has a transmit phase adjuster with an adjustment value that is discrete rather than continuous, the possibility of the composite beam direction of all elements tilting from the desired beam direction of all elements can be reduced.

The present disclosure also relates to a method for implementing a method for implementing a transmission phase and transmission amplitude of each element, the calibration value calculation unit calculating a calibration value of the transmission phase and transmission amplitude of each element based on the relative values of the transmission phase and transmission amplitude of each element, the adjustment value calculation unit calculating a discrete adjustment value of the transmission phase and transmission amplitude of each element based on the calibration value of the transmission phase and transmission amplitude of each element, and implementing the discrete adjustment value of the transmission phase and transmission amplitude of each element, and the residual vector calculation unit calculating a residual vector of each element for the discrete adjustment value of the transmission phase and transmission amplitude of each element. The phased array antenna calibration device is characterized in that the residual vector synthesis unit synthesizes the residual vectors of the calibration values of the transmission phase and transmission amplitude of each element, calculates the residual vector sum of the calibration values of the transmission phase and transmission amplitude of all elements, and the D/A converter correction unit corrects the transmission signal input to the D/A converter so as to cancel the residual vector sum of the calibration values of the transmission phase and transmission amplitude of all elements.

This configuration reduces the possibility that the composite beam direction of all elements will tilt from the desired beam direction of all elements, even when multiple elements share a D/A converter and each has a transmit phase amplitude adjuster with an adjustment value that is discrete rather than continuous.

The present disclosure also relates to a phased array antenna device comprising the above-mentioned phased array antenna calibration device, each of the elements, the D/A converter, a transmission phase adjuster that each of the elements has individually, and a transmission signal distributor that each of the elements shares.

This configuration makes it possible to provide a phased array antenna device that performs the above-mentioned phased array antenna calibration process during transmission calibration.

If multiple elements have their own A/D converters, then digital correction can be applied to the digital received signal output by each A/D converter to cancel out the residual error in the calibration value of the receive phase of each element. In reality, multiple elements share an A/D converter, so digital correction can be applied to the digital received signal output by a single A/D converter to cancel out the "average" of the residual error in the calibration value of the receive phase of all elements.

Specifically, the present disclosure relates to a phased array antenna calibration device that includes a calibration value calculation unit that calculates a calibration value of the reception phase of each element based on the relative value of the reception phase of each element that shares an A/D converter, an adjustment value calculation unit that calculates a discrete adjustment value of the reception phase of each element based on the calibration value of the reception phase of each element and implements the discrete adjustment value of the reception phase of each element, a residual vector calculation unit that calculates a residual vector of the calibration value of the reception phase of each element for the discrete adjustment value of the reception phase of each element in the IQ plane, a residual vector synthesis unit that synthesizes the residual vector of the calibration value of the reception phase of each element and calculates a residual vector sum of the calibration values of the reception phase of all elements that share the A/D converter, and an A/D converter correction unit that corrects the reception signal output by the A/D converter so as to cancel the residual vector sum of the calibration values of the reception phase of all elements.

The present disclosure also relates to a phased array antenna calibration program for causing a computer to execute, in sequence, a calibration value calculation step for calculating a calibration value of the reception phase of each element based on the relative value of the reception phase of each element that shares an A/D converter in a phased array antenna; an adjustment value calculation step for calculating a discrete adjustment value of the reception phase of each element based on the calibration value of the reception phase of each element and implementing the discrete adjustment value of the reception phase of each element; a residual vector calculation step for calculating a residual vector of the calibration value of the reception phase of each element for the discrete adjustment value of the reception phase of each element in an IQ plane; a residual vector synthesis step for synthesizing the residual vector of the calibration value of the reception phase of each element and calculating a residual vector sum of the calibration values of the reception phase of all elements that share the A/D converter; and an A/D converter correction step for correcting the reception signal output by the A/D converter so as to cancel the residual vector sum of the calibration values of the reception phase of all elements.

With these configurations, even when multiple elements share an A/D converter and each has a receive phase adjuster with an adjustment value that is discrete rather than continuous, the possibility of the composite beam direction of all elements tilting from the desired beam direction of all elements can be reduced.

The present disclosure also relates to a method for calculating a calibration value for each of the elements based on the relative values of the reception phase and reception amplitude of each of the elements, the adjustment value calculation unit calculates a discrete adjustment value for the reception phase and reception amplitude of each of the elements based on the calibration values of the reception phase and reception amplitude of each of the elements, and implements the discrete adjustment values of the reception phase and reception amplitude of each of the elements, and the residual vector calculation unit calculates a residual vector for each of the elements based on the discrete adjustment values of the reception phase and reception amplitude of each of the elements. The phased array antenna calibration device is characterized in that the residual vector of the calibration values of the reception phase and reception amplitude of each element is calculated, the residual vector synthesis unit synthesizes the residual vectors of the calibration values of the reception phase and reception amplitude of each element and calculates the residual vector sum of the calibration values of the reception phase and reception amplitude of all elements, and the A/D converter correction unit corrects the reception signal output by the A/D converter so as to cancel the residual vector sum of the calibration values of the reception phase and reception amplitude of all elements.

With this configuration, even when multiple elements share an A/D converter and each has a receive phase amplitude adjuster with an adjustment value that is discrete rather than continuous, the possibility of the composite beam direction of all elements tilting from the desired beam direction of all elements can be reduced.

The present disclosure also relates to a phased array antenna device comprising the above-mentioned phased array antenna calibration device, each of the elements, the A/D converter, a receiving phase adjuster that each of the elements has individually, and a receiving signal combiner that each of the elements shares.

This configuration makes it possible to provide a phased array antenna device that performs the above-mentioned phased array antenna calibration process during reception calibration.

In this manner, the present disclosure can reduce the likelihood that the composite beam direction of all elements will tilt from the desired beam direction of all elements, even when multiple elements share a D/A converter or an A/D converter and each have a transmit phase amplitude adjuster or a receive phase amplitude adjuster with an adjustment value that is discrete rather than continuous.

FIG. 1 is a diagram showing a configuration of a phased array antenna device according to a conventional technique. FIG. 1 illustrates a prior art process for phased array antenna calibration. FIG. 1 illustrates the results of prior art phased array antenna calibration. FIG. 1 is a diagram showing a configuration of a phased array antenna apparatus according to the present disclosure. FIG. 1 illustrates a procedure for phased array antenna calibration according to the present disclosure. FIG. 1 illustrates a process for phased array antenna calibration of the present disclosure. FIG. 1 illustrates a process for phased array antenna calibration of the present disclosure. FIG. 1 illustrates the results of the phased array antenna calibration of the present disclosure. FIG. 1 illustrates the results of phased array antenna calibration according to the prior art and the present disclosure.

Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementations of the present disclosure, and the present disclosure is not limited to the following embodiments.

The configuration of the phased array antenna device of the present disclosure is shown in FIG. 4. From the viewpoint of cost, multiple elements share D/A converters and A/D converters, and each element has a transmit phase amplitude adjuster and a receive phase amplitude adjuster with adjustment values that are discrete rather than continuous.

The phased array antenna device P comprises M arrays A-1, ..., A-M and a phased array antenna calibration device C. The array A-1 comprises N elements 1-11, ..., 1-1N, N transmit phase amplitude adjusters and receive phase amplitude adjusters 2-11, ..., 2-1N, one transmit signal distributor and receive signal combiner 3-1, one D/A converter and A/D converter 4-1, and one digital multiplier 5-1. The array A-M comprises N elements 1-M1, ..., 1-MN, N transmit phase amplitude adjusters and receive phase amplitude adjusters 2-M1, ..., 2-MN, one transmit signal distributor and receive signal combiner 3-M, one D/A converter and A/D converter 4-M, and one digital multiplier 5-M. The phased array antenna calibration device C includes a calibration value calculation unit 6, an adjustment value calculation unit 7, a residual vector calculation unit 8, a residual vector synthesis unit 9, a D/A converter correction unit, and an A/D converter correction unit 10, and can be realized by installing the phased array antenna calibration program in FIG. 5 in a computer.

The procedure of the phased array antenna calibration of the present disclosure is shown in FIG. 5. The process of the phased array antenna calibration of the present disclosure is shown in FIG. 6 and FIG. 7. The calibration value calculation unit 6 calculates the calibration values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N based on the relative values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N sharing the D/A converter and the A/D converter 4-1 in the array A-1 using the REV method or the like (step S1). In FIG. 6, the calibration value c _phs,1,1 of the transmit/receive phase of the element 1-11 is calculated, the calibration value c _amp,1,1 of the transmit/receive amplitude of the element 1-11 is calculated, the calibration value c _phs,1,N of the transmit/receive phase of the element 1-1N is calculated, and the calibration value c _amp,1,N of the transmit/receive amplitude of the element 1-1N is calculated. A similar process is performed for arrays A-M and other arrays, i.e., for each m (m=an integer from 1 to M) and for all n (n=an integer from 1 to N), calibration values c _phs,m,n , c _amp,m,n of the transmit/receive phase and transmit/receive amplitude of each element are calculated.

The adjustment value calculation unit 7 calculates discrete adjustment values for the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N in the array A-1 based on the calibration values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N, and implements the discrete adjustment values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N (step S2). 6, a discrete adjustment value d _phs,2 (closest to c _phs,1,1 ) of the transmit/receive phase of element 1-11 is calculated, a discrete adjustment value d _amp,2 (closest to c _amp,1,1 ) of the transmit/receive amplitude of element 1-11 is calculated, a discrete adjustment value d _phs,2 (closest to c _amp,1,N ) of the transmit/receive phase of element 1-1N is calculated, and a discrete adjustment value d _amp,2 (closest to c _amp,1,N ) of the transmit/receive amplitude of element 1-1N is calculated. Similar processing is performed for arrays A-M and other arrays. That is, for each m (m=an integer from 1 to M) and for all n (n=an integer from 1 to N), discrete adjustment values d _phs , d _amp of the transmit/receive phase and transmit/receive amplitude of each element are calculated.

The residual vector calculation unit 8 calculates the residual of the calibrated values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N in the array A-1 relative to the discrete adjustment values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N (step S3). In FIG. 6 , a residual e _phs, 1,1 =c _phs,1,1 -d phs _,2 of the calibration value c _phs, 1,1 of the transmit/receive phase of elements 1-11 relative to a discrete adjustment value d phs, _{2 of the transmit/receive phase of elements 1-11 is calculated, and a residual e phs,1,N =c phs,1,N -d phs ,2} of the calibration value c _{phs,1,N of} the transmit/receive phase of elements 1-1N relative to a discrete adjustment value d _{phs ,2} of the transmit/receive phase of elements 1-1N is calculated. Then, a residual e _amp,1,1 =c _amp,1,1 -d _{amp, 2} of the calibration value c _amp,1,1 of the transmit/receive amplitude of elements 1-11 with respect to the discrete adjustment value d amp, _{2 of the transmit/receive amplitude of elements 1-11 is calculated, and a residual e amp,1,N =c amp,1,N -d amp,2} of the calibration value c _{amp, 1,N} of the transmit/receive amplitude of elements 1-1N with respect to the discrete adjustment value d _{amp, 2} of the transmit/receive amplitude of elements 1-1N is calculated. Similar processing is performed for arrays A-M and other arrays. That is, for each m (m=an integer from 1 to M) and for all n (n=an integer from 1 to N), residuals e _phs,m,n , e _amp,m,n of the calibration values of the transmit/receive phase and transmit/receive amplitude of each element are calculated.

If the elements 1-11, ..., 1-1N have their own D/A converters and A/D converters, then digital correction can be made to the digital transmit/receive signals input/output by each D/A converter and A/D converter to cancel out the residuals of the calibration values of the transmit/receive phases and transmit/receive amplitudes of each element 1-11, ..., 1-1N. In reality, since the elements 1-11, ..., 1-1N share the D/A converter and A/D converter 4-1, digital correction can be made to the digital transmit/receive signals input/output by a single D/A converter and A/D converter 4-1 to cancel out the "average" of the residuals of the calibration values of the transmit/receive phases and transmit/receive amplitudes of all elements 1-11, ..., 1-1N.

The residual vector calculation unit 8 calculates a residual vector of the calibrated values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N for the discrete adjustment values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N in the IQ plane of the array A-1 (step S4). In Fig. 6, the residual vector A _1,1 = (1 + e _{amp, 1,1} ) exp (je _{phs, 1,1} ) of the calibration values c _{phs, 1,1} , c _amp, 1,1 of the transmit/receive phase and transmit/receive amplitude of the elements 1-11 is calculated, and the residual vector A _1,N = (1 + e amp, 1,N ) exp (je _{phs, 1,N} ) of the calibration values c _{phs, 1,N} , c _{amp, 1,N} of the transmit/receive phase and transmit/receive amplitude of the elements 1-1N is calculated. A similar process is performed for the arrays A-M and other arrays. That is, the residual vector A m,n of the calibration values of the transmit/receive phase and transmit/receive amplitude of each element is calculated for each m (m = an integer from 1 to M) and for all n ( _n = an integer from 1 to N).

If the elements 1-11, ..., 1-1N have "individual" D/A converters and A/D converters, the calibration values of the transmit/receive phases and transmit/receive amplitudes of the elements 1-11, ..., 1-1N can be accurately realized by multiplying the digital transmit/receive signals input/output by "each" D/A converter and A/D converter by the residual vector A _1,n .

The residual vector synthesis unit 9 synthesizes the residual vectors of the calibration values of the transmit/receive phase and transmit/receive amplitude of each element 1-11, ..., 1-1N in the array A-1, and calculates the residual vector sum of the calibration values of the transmit/receive phase and transmit/receive amplitude of all elements 1-11, ..., 1-1N that share the D/A converter and A/D converter 4-1 (steps S5, S6).

In Fig. 6, the residual vector sum A ₁ =Σ(1+e amp,1,n ) exp(je _phs,1,n ) of the calibration values c _phs,1,n , c _amp,1,n of the transmit/receive phases and transmit/receive amplitudes of elements 1-11, ..., 1-1N before normalization is calculated. In Fig. 7, the residual vector sum A _M =Σ(1+e _amp, M,n ) exp(je _phs,M,n ) of the calibration values c _phs,M,n , c _{amp ,M,n} of the transmit/receive phases and transmit/receive amplitudes of elements 1-M1, ..., 1-MN before normalization is calculated. Similar processing is performed for other arrays. That is, for each m (m = an integer from 1 to M), a residual vector sum A _m before normalization of the calibration values of the transmit/receive phases and transmit/receive amplitudes of all elements is calculated. Here, "before normalization" refers to a stage before the "average" is calculated for the residuals of the calibration values of the transmit/receive phases and transmit/receive amplitudes of "all" elements 1-11, ..., 1-1N.

7, a residual vector sum C ₁ =A ₁ /A max (where |A max |=max(|A 1 |, ..., |A _M |) _{, max} is the maximum value) after normalization of the calibration values c _{phs,1,n ,} c _amp,1,n of the transmit/receive phases and transmit/receive amplitudes of elements 1-11, ..., 1-1N is calculated. Then, a residual vector sum C M =A _M /A _max (where |A _max |=max(|A 1 |, ..., |A M |), max is the maximum value) after normalization of the calibration values c _{phs,M,n , c amp,M, n} of the transmit/receive phases and transmit/receive amplitudes of elements _1-M1 , ..., 1-MN is calculated. Similar processing is performed for other arrays. That is, for each m (m = an integer from 1 to M), a residual vector sum _Cm is calculated after normalization of the calibration values of the transmit/receive phases and transmit/receive amplitudes of all elements. Here, "after normalization" refers to the stage after the "average" is calculated for the residuals of the calibration values of the transmit/receive phases and transmit/receive amplitudes of "all" elements 1-11, ..., 1-1N.

The D/A converter correction unit and A/D converter correction unit 10 corrects the transmit/receive signals input/output by the D/A converter and A/D converter 4-1 so as to cancel the residual vector sum of the calibration values of the transmit/receive phase and transmit/receive amplitude of all elements 1-11, ..., 1-1N in the array A-1 (step S7). In FIG. 7, the residual vector sum C 1 after standardization of the calibration values c _phs,1,n , c _amp,1,n of the transmit/receive phase and transmit/receive amplitude of elements 1-11, ..., _1-1N is input to the digital multiplier 5-1 as the transmit/receive signal correction value. Then, the residual vector sum C _M after standardization of the calibration values c _phs,M,n , c _amp,M,n of the transmit/receive phase and transmit/receive amplitude of elements 1-M1, ..., 1-MN is input to the digital multiplier 5-M as the transmit/receive signal correction value. Similar processing is performed for other arrays. That is, for each m (m=an integer from 1 to M), the residual vector sum C _m after normalization of the calibration values of the transmit/receive phases and transmit/receive amplitudes of all elements is applied as the transmit/receive signal correction value.

In reality, since the elements 1-11, ..., 1-1N "share" the D/A converter and A/D converter 4-1, by multiplying the digital transmit/receive signal input/output by the "single" D/A converter and A/D converter _4-1 by the normalized residual vector sum C1, it is possible to approximately realize the calibrated values of the transmit/receive phase and transmit/receive amplitude of the elements 1-11, ..., 1-1N.

The result of the phased array antenna calibration of the present disclosure is shown in FIG. 8. The total number of elements is 8×4. The phase adjuster has 3 bits and has discrete adjustment values of 0°, 45°, ..., 315°. The amplitude adjuster has 3 bits and has discrete adjustment values of 0 dB, -1 dB, ..., -7 dB. For each element, random residuals of the phase and amplitude calibration values (specifically, the residuals of the phase calibration values that follow a uniform distribution within the range of ±22.5°, and the residuals of the amplitude calibration values that follow a uniform distribution within the range of ±0.5 dB) are given in each trial of 100 simulations. The composite main lobe direction of all elements is tilted only within the range of ±0.05° from the desired main lobe direction of all elements.

The results of the phased array antenna calibration of the conventional technology and the present disclosure are shown in FIG. 9. The right column of FIG. 9 is an enlarged view of the vicinity of the desired main lobe elevation angle direction of all elements = 0° in the left column of FIG. 9. Among the results of the phased array antenna calibration of the conventional technology in FIG. 3, the result in which the composite main lobe elevation angle direction of all elements is tilted by +0.5° from the desired main lobe elevation angle direction of all elements = 0° is shown by the solid line graph in FIG. 9. Among the results of the phased array antenna calibration of the present disclosure in FIG. 8, the result in which the composite main lobe elevation angle direction of all elements is not tilted from the desired main lobe elevation angle direction of all elements = 0° is shown by the dashed line graph in FIG. 9.

As described above, even when multiple elements share D/A converters and A/D converters and each has a transmit phase amplitude adjuster and a receive phase amplitude adjuster with adjustment values that are discrete rather than continuous, the possibility that the composite beam direction of all elements will tilt from the desired beam direction of all elements can be reduced. Furthermore, by reducing the number of D/A converters and A/D converters and reducing the number of bits of the transmit phase amplitude adjuster and the receive phase amplitude adjuster, it is possible to reduce the cost of the phased array antenna device, since it is only necessary to install a phased array antenna calibration program on a computer.

In this embodiment, the transmit/receive phase and transmit/receive amplitude of each element are calibrated. As a variant, only the transmit/receive phase of each element may be calibrated, only the transmit phase and transmit amplitude of each element may be calibrated, or only the receive phase and receive amplitude of each element may be calibrated.

In this embodiment, the residual vector sum after normalization of the calibration values of the transmit/receive phases and transmit/receive amplitudes of all elements of each array is calculated as _Cm = _Am / _Amax ( _Amax is close to the number of elements N). As a modified example, the residual vector sum after normalization of the calibration values of the transmit/receive phases and transmit/receive amplitudes of all elements of each array may be calculated as _Cm = _Am /N (N is the number of elements).

In this way, the phased array antenna calibration device, phased array antenna apparatus, and phased array antenna calibration program disclosed herein can reduce the possibility that the composite beam direction of all elements will tilt from the desired beam direction of all elements in weather radars that detect precipitation, etc., over long distances of up to hundreds of kilometers.

P: Phased array antenna device A-1, A-M: Array C: Phased array antenna calibration device 1-11, 1-1N, 1-M1, 1-MN: Elements 2-11, 2-1N, 2-M1, 2-MN: Transmission phase and amplitude adjuster, reception phase and amplitude adjuster 3-1, 3-M: Transmission signal distributor, reception signal combiner 4-1, 4-M: D/A converter, A/D converter 5-1, 5-M: Digital multiplier 6: Calibration value calculation unit 7: Adjustment value calculation unit 8: Residual vector calculation unit 9: Residual vector combination unit 10: D/A converter correction unit, A/D converter correction unit

Claims (8)

a calibration value calculation unit for, in a phased array antenna , receiving a transmission wave from each element sharing a D/A converter by an external antenna, measuring a transmission phase of a certain element based on a change in a transmission composite amplitude of all elements accompanying a change in the transmission phase of the certain element, and calculating a calibration value of the transmission phase of each element based on a relative value of the transmission phase of each element;
an adjustment value calculation unit that calculates a discrete adjustment value of the transmission phase of each of the elements based on a calibration value of the transmission phase of each of the elements, and implements the discrete adjustment value of the transmission phase of each of the elements;
a residual vector calculation unit that calculates a residual of a calibrated value of the transmission phase of each of the elements with respect to a discrete adjustment value of the transmission phase of each of the elements, and calculates a residual vector of the calibrated value of the transmission phase of each of the elements in an IQ plane based on the residual of the calibrated value of the transmission phase of each of the elements;
a residual vector synthesis unit that synthesizes a residual vector of the calibration values of the transmission phases of the elements and calculates a residual vector sum of the calibration values of the transmission phases of all the elements that share the D/A converter;
a D/A converter correction unit that corrects a transmission signal input to the D/A converter so as to cancel a residual vector sum of the calibration values of the transmission phases of all the elements;
A phased array antenna calibration device comprising: the calibration value calculation unit receives the transmission waves of the elements by the external antenna, measures the transmission phase and transmission amplitude of the certain element based on a change in the transmission composite amplitude of all the elements accompanying a change in the transmission phase of the certain element, and calculates calibration values of the transmission phase and transmission amplitude of each of the elements based on the relative values of the transmission phase and transmission amplitude of each of the elements;
The adjustment value calculation unit calculates discrete adjustment values of the transmission phase and transmission amplitude of each of the elements based on the calibration values of the transmission phase and transmission amplitude of each of the elements, and implements the discrete adjustment values of the transmission phase and transmission amplitude of each of the elements;
the residual vector calculation unit calculates a residual of a calibrated value of the transmission phase and transmission amplitude of each element with respect to a discrete adjustment value of the transmission phase and transmission amplitude of each element, and calculates a residual vector of the calibrated value of the transmission phase and transmission amplitude of each element in an IQ plane based on the residual of the calibrated value of the transmission phase and transmission amplitude of each element;
the residual vector synthesis unit synthesizes residual vectors of the calibration values of the transmission phase and transmission amplitude of each of the elements, and calculates a residual vector sum of the calibration values of the transmission phase and transmission amplitude of all of the elements;
2. The phased array antenna calibration device according to claim 1, wherein the D/A converter correction unit corrects the transmission signal input to the D/A converter so as to cancel a residual vector sum of calibration values of transmission phases and transmission amplitudes of all elements. A phased array antenna device comprising the phased array antenna calibration device according to claim 1 or 2, each of the elements, the D/A converter, a transmission phase adjuster that each of the elements has individually, and a transmission signal distributor that each of the elements shares. a calibration value calculation step of, in the phased array antenna, receiving a transmission wave from each element sharing a D/A converter by an external antenna, measuring a transmission phase of a certain element based on a change in a combined transmission amplitude of all elements accompanying a change in the transmission phase of the certain element, and calculating a calibration value of the transmission phase of each element based on a relative value of the transmission phase of each element;
an adjustment value calculation step of calculating a discrete adjustment value of the transmission phase of each of the elements based on the calibration value of the transmission phase of each of the elements, and implementing the discrete adjustment value of the transmission phase of each of the elements;
a residual vector calculation step of calculating a residual of a calibrated value of the transmission phase of each of the elements for a discrete adjustment value of the transmission phase of each of the elements, and calculating a residual vector of the calibrated value of the transmission phase of each of the elements in an IQ plane based on the residual of the calibrated value of the transmission phase of each of the elements;
a residual vector synthesis step of synthesizing a residual vector of the calibration values of the transmission phases of the elements and calculating a residual vector sum of the calibration values of the transmission phases of all the elements that share the D/A converter;
a D/A converter correction step of correcting a transmission signal input to the D/A converter so as to cancel a residual vector sum of the calibration values of the transmission phases of all the elements;
A phased array antenna calibration program for causing a computer to execute the above steps in sequence. a calibration value calculation unit for calculating a calibration value of the reception phase of each element based on a relative value of the reception phase of each element, after a transmission wave of an external antenna is received by each element sharing an A /D converter, and measuring the reception phase of a certain element based on a change in a combined reception amplitude of all elements that accompanies a change in the reception phase of the certain element;
An adjustment value calculation unit that calculates a discrete adjustment value of the reception phase of each element based on a calibration value of the reception phase of each element and implements the discrete adjustment value of the reception phase of each element;
a residual vector calculation unit that calculates a residual of a calibrated value of the reception phase of each of the elements with respect to a discrete adjustment value of the reception phase of each of the elements, and calculates a residual vector of the calibrated value of the reception phase of each of the elements in an IQ plane based on the residual of the calibrated value of the reception phase of each of the elements;
a residual vector synthesis unit that synthesizes a residual vector of the calibration values of the reception phases of the elements and calculates a residual vector sum of the calibration values of the reception phases of all the elements that share the A/D converter;
an A/D converter correction unit that corrects the received signal output by the A/D converter so as to cancel a residual vector sum of the calibration values of the reception phases of all the elements;
A phased array antenna calibration device comprising: the calibration value calculation unit receives a transmission wave from the external antenna at each of the elements, measures a reception phase and a reception amplitude of the certain element based on a change in a reception composite amplitude of all the elements that accompanies a change in the reception phase of the certain element, and calculates a calibration value of the reception phase and the reception amplitude of each of the elements based on a relative value of the reception phase and the reception amplitude of each of the elements;
The adjustment value calculation unit calculates a discrete adjustment value of the reception phase and reception amplitude of each of the elements based on the calibration value of the reception phase and reception amplitude of each of the elements, and implements the discrete adjustment value of the reception phase and reception amplitude of each of the elements;
the residual vector calculation unit calculates a residual of a calibrated value of the reception phase and reception amplitude of each element with respect to a discrete adjustment value of the reception phase and reception amplitude of each element, and calculates a residual vector of the calibrated value of the reception phase and reception amplitude of each element in an IQ plane based on the residual of the calibrated value of the reception phase and reception amplitude of each element;
the residual vector synthesis unit synthesizes residual vectors of the calibration values of the reception phase and reception amplitude of each of the elements, and calculates a residual vector sum of the calibration values of the reception phase and reception amplitude of all of the elements;
6. The phased array antenna calibration device according to claim 5, wherein the A/D converter correction unit corrects the received signal output by the A/D converter so as to cancel a residual vector sum of calibration values of the received phases and received amplitudes of all the elements. A phased array antenna device comprising the phased array antenna calibration device according to claim 5 or 6, each of the elements, the A/D converter, a receiving phase adjuster that each of the elements has individually, and a receiving signal combiner that each of the elements shares. a calibration value calculation step of, in the phased array antenna, receiving a transmission wave from an external antenna by each element sharing an A/D converter, measuring the reception phase of a certain element based on a change in a combined reception amplitude of all elements that accompanies a change in the reception phase of the certain element, and calculating a calibration value of the reception phase of each element based on a relative value of the reception phase of each element;
An adjustment value calculation step of calculating a discrete adjustment value of the reception phase of each element based on the calibration value of the reception phase of each element, and implementing the discrete adjustment value of the reception phase of each element;
a residual vector calculation step of calculating a residual of the calibration value of the reception phase of each element for the discrete adjustment value of the reception phase of each element, and calculating a residual vector of the calibration value of the reception phase of each element in an IQ plane based on the residual of the calibration value of the reception phase of each element;
a residual vector synthesis step of synthesizing a residual vector of the calibration values of the reception phases of the elements and calculating a residual vector sum of the calibration values of the reception phases of all the elements that share the A/D converter;
an A/D converter correction step of correcting the received signal output by the A/D converter so as to cancel a residual vector sum of the calibration values of the receive phases of all the elements;
A phased array antenna calibration program for causing a computer to execute the above steps in sequence.

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