CN112162251B - Dual-calibration antenna radio frequency channel calibration method for millimeter wave security imaging - Google Patents
Dual-calibration antenna radio frequency channel calibration method for millimeter wave security imaging Download PDFInfo
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Abstract
The invention relates to the technical field of radio frequency channel calibration, and discloses a double-calibration antenna radio frequency channel calibration method for millimeter wave security imaging. The calibration method of the double-calibration antenna radio frequency channel for millimeter wave security inspection imaging does not need to directly measure the position coordinates of the calibration antenna, but accurately obtains the position of the calibration antenna through data statistics analysis, so that the positioning accuracy is high, and the calibration result of the corresponding system radio frequency receiving/transmitting channel can meet the imaging quality requirement.
Description
Technical Field
The invention relates to the technical field of radio frequency channel calibration, in particular to a dual-calibration antenna radio frequency channel calibration method for millimeter wave security imaging.
Background
An active millimeter wave security inspection imager generally adopts a multichannel MIMO working mode, as shown in fig. 1, so as to reduce the hardware cost of the system and improve the imaging speed of the system. In order to improve the imaging performance of the system, the amplitude-frequency characteristic, the phase-frequency characteristic and the electrical length of each radio frequency receiving/transmitting channel need to be calibrated before imaging. In addition, according to the related requirements of an imaging algorithm, any receiving and transmitting antenna pair in the antenna array is used for detecting signals aiming at a target to be detected, and the phase center of the corresponding antenna is used as a zero-phase reference point. As shown in fig. 2, the calibration horn antenna is placed in the far field region of the rf receiving/transmitting antenna array, or a sufficient distance is ensured so that the calibration horn antenna is located in the irradiation range of the main lobe beams of all the rf receiving/transmitting antennas, and the calibration data of all the channels can be rapidly obtained through one calibration measurement, so that the calibration efficiency is improved, and the mass production of products is facilitated.
However, the method needs to accurately measure the position coordinates of the calibration horn antenna relative to the radio frequency receiving/transmitting antenna array, and for millimeter wave bands, millimeter-level positioning errors can have a great influence on the system calibration accuracy, so that the imaging effect is influenced.
Therefore, it is needed to provide a new technical solution to solve the above problems.
Disclosure of Invention
The invention aims to solve the problem of poor radio frequency channel calibration imaging effect in the prior art, and provides a double-calibration antenna radio frequency channel calibration method for millimeter wave security imaging.
In order to achieve the above purpose, the invention provides a dual-calibration antenna radio frequency channel calibration method for millimeter wave security imaging, which specifically comprises the following steps: s1, providing two external calibration antennas, namely a first calibration antenna and a second calibration antenna, respectively obtaining corresponding calibration test values, namely receiving calibration signals of all receiving antennas relative to the first calibration antenna and the second calibration antenna; s2, performing mutual calibration and correlation analysis processing on the two groups of calibration test values to obtain true values of the coordinates of the two external calibration antennas; and S3, calibrating the radio frequency channel by utilizing the true values of the coordinates of the two external calibration antennas.
Preferably, in S1, the test values of the receiving scaling of the first scaling antenna and the second scaling antenna are respectively:
Wherein, L1 rl is the length of the first calibration antenna calibration transmitting path, L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L1 Rx(nr),cal is the true value of the spatial distance from the first calibration antenna to each receiving antenna, and S1 Rx(nr,f) is the phase relative value of the "first calibration antenna+nr-th receiving antenna path" relative to the reference path; l2 rl is the length of the second calibration antenna calibration transmitting path, L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L2 Rx(nr),cal is the true value of the spatial distance from the second calibration antenna to each receiving antenna, and S2 Rx(nr,f) is the phase relative value of the second calibration antenna plus the nr receiving antenna path relative to the reference path; λ is the wavelength corresponding to the operating frequency point, and j is the complex imaginary part indicator.
Preferably, the step S2 specifically includes the following steps: s21, acquiring coordinate ranges of a first calibration antenna and a second calibration antenna, respectively taking a point in the coordinate ranges of the first calibration antenna and the second calibration antenna, and calculating the distance from the point to each receiving antenna;
s22, pre-calibrating the received calibration signals in the formulas (1) and (2) by combining the points taken by the first calibration antenna and the second calibration antenna to obtain received pre-calibration signals; and
S23, carrying out mathematical operation on the received pre-calibration signals corresponding to the points taken by the first calibration antenna and the second calibration antenna, and obtaining true values of the coordinates of the first calibration antenna and the second calibration antenna.
Preferably, in S21, the coordinate ranges of the first calibration antenna and the second calibration antenna are obtained by visual inspection or ruler amount, and the coordinates of the two external calibration antennas and the distances from the point selected in the coordinate ranges to each receiving antenna are specifically:
first calibration antenna ：X1cal∈(X11,X1Nx1)Y1cal∈(Y11,Y1Ny1)Z1cal∈(Z11,Z1Nz1)
The second calibration antenna ：X2cal∈(X21,X2Nx2)Y2cal∈(Y21,Y2Ny2)Z2cal∈(Z21,Z2Nz2) is the true value of the coordinates of the first calibration antenna, (X1 cal,Y1cal,Z1cal), and (X2 cal,Y2cal,Z2cal); the selected point on the first calibration antenna is marked with (X1 nx1,Y1ny1,Z1nz1) and the selected point on the second calibration antenna is marked with (X2 nx2,Y2ny2,Z2nz2), then the distance from the selected point on the first calibration antenna to each receiving antenna is L1 Rx(nr),(X1nx1,Y1ny1,Z1nz1), and the distance from the selected point on the second calibration antenna to each receiving antenna is L2 Rx(nr),(X2nx2,Y2ny2,Z2nz2).
Preferably, the point taken by the first calibration antenna and the second calibration antenna in S22 is pre-calibrated by using the distance L1 Rx(nr),(X1nx1,Y1ny1,Z1nz1) from the selected point on the first calibration antenna to each receiving antenna, and the distance L2 Rx(nr),(X2nx2,Y2ny2,Z2nz2), from the selected point on the second calibration antenna to each receiving antenna, so as to obtain the pre-calibration signals in the formulas (1) and (2), where the pre-calibration signals are respectively:
Preferably, in the step S23, the phase difference value of the received pre-calibration signal obtained by using the points respectively taken on the first calibration antenna and the second calibration antenna through mathematical operation is specifically:
wherein, The phase value of (2) is Representation and rendering ofSumming absolute values of all the receiving antennas and all the testing frequency points;
Traversing the first scaled antenna location (X1 nx1,Y1ny1,Z1nz1) and the second scaled antenna location (X2 nx2,Y2ny2,Z2nz2) to cause The minimum values (X1 nx1,Y1ny1,Z1nz1) and (X2 nx2,Y2ny2,Z2nz2) were obtained, i.e., the true values of (X1 cal,Y1cal,Z1cal) and (X2 cal,Y2cal,Z2cal).
Preferably, the step S3 specifically includes the following steps: s31, obtaining phase relative values of the link relative reference paths from the transmitting antennas to the scaling receiving antennas and phase relative values of the link relative reference paths from the transmitting antennas to the scaling receiving antennas; s32, measuring scattering measurement values of all the receiving and transmitting antenna pairs relative to a target point, and finishing pre-calibration of a phase value of a link and a phase value during measurement in actual application; s33, obtaining the phase residual quantity in S32 by utilizing background calibration; s34, the phase residual quantity is supplemented to achieve final calibration of the radio frequency channel.
Preferably, the phase relative value of the link relative reference path from the transmitting antenna to the receiving antenna and the phase relative value of the link relative reference path from the transmitting antenna to the receiving antenna in S31 are specifically:
Wherein, L rl is the length of the calibration transmitting path (comprising an external calibration cable and calibration antennas), L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L Rx(nr),cal is the spatial distance from the calibration antennas to each receiving antenna, and S Rx(nr,f) is the relative phase value of the link relative to the reference path of the calibration transmitting to each receiving antenna; l tl is the length of the scaled receiving path (including the external scaled cable and the scaled antenna), L Tx(nt) is the length of each transmitting channel, L Tx(nt),cal is the spatial distance from the scaled antenna to each transmitting antenna, and S Tx(nt,f) is the phase relative value of each transmitting antenna to the scaled receiving link relative to the reference path.
Preferably, the scatter measurements for all transceiver antenna pairs with respect to the target point are:
wherein, (Xn, yn, zn) is the coordinates of the target point.
Preferably, the signal of formula (8) is pre-calibrated using the determined amounts L Rx(nr),cal and L Tx(nt),cal obtained by formulas (6), (7) and S21/S22/S23 to obtain a pre-calibrated signal:
wherein, Is effective phase value S Tx(nt),Rx(nr),f,(XnYnZn) (afterCal) in practical applicationIs the residual phase after pre-calibration.
Preferably, in the step S33, the phase residual in the step S32 is calculated by obtaining a mutual coupling test signal of a certain transceiver antenna pair and processing the value thereof by using background calibration
Preferably, the pre-calibration value S Tx(nt),Rx(nr),f,(XnYnZn) (pre-calibration) obtained in S32 and the phase residual obtained in S33The phase data needed in practical application can be obtained by multiplication:
Through the technical scheme, the invention provides a dual-calibration antenna radio frequency channel calibration method for millimeter wave security inspection imaging, which utilizes two external calibration antennas only needing rough estimation of positions to respectively acquire calibration test data, and precisely calculates the position coordinates of the two calibration antennas through mutual calibration and correlation analysis processing between the two groups of calibration test data, thereby completing the calibration of a radio frequency receiving/transmitting channel. The calibration method of the double-calibration antenna radio frequency channel for millimeter wave security inspection imaging does not need to directly measure the position coordinates of the calibration antenna, but accurately obtains the position of the calibration antenna through data statistics analysis, so that the positioning accuracy is high, and the calibration result of the corresponding system radio frequency receiving/transmitting channel can meet the imaging quality requirement.
Drawings
FIG. 1 is a schematic diagram of the calibration system of a millimeter wave human body security inspection imager;
FIG. 2 is a schematic diagram of a single-scale RF channel antenna calibration method;
FIG. 3 is a schematic structural diagram of an implementation process of a dual-calibration antenna radio frequency channel calibration method for millimeter wave security imaging according to the present invention;
FIG. 4 is a schematic flow chart of steps of a dual-calibration antenna radio frequency channel calibration method for millimeter wave security imaging according to the present invention;
FIG. 5 is a schematic illustration of a point target test;
FIG. 6 is a background calibration schematic diagram of a dual-calibration antenna radio frequency channel calibration method for millimeter wave security imaging according to the present invention;
Fig. 7 is a diagram of actual imaging effect of the system.
Description of the reference numerals
1. A receiving antenna; 2. a transmitting antenna; 3. a reference path; 4. calibrating a receiving/transmitting path; 5. calibrating an antenna; 51. a first calibration antenna; 52. and a second scaled antenna.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
In the description of the present application, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating relative importance or implicitly indicating the number of technical features indicated. Thus, unless otherwise indicated, features defining "first", "second" may include one or more such features either explicitly or implicitly; the meaning of "plurality" is two or more. The terms "comprises," "comprising," and any variations thereof, are intended to cover a non-exclusive inclusion, such that one or more other features, integers, steps, operations, elements, components, and/or groups thereof may be present or added.
In addition, terms of the azimuth or positional relationship indicated by "center", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., are described based on the azimuth or relative positional relationship shown in the drawings, are merely for convenience of description of the present application, and do not indicate that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present application.
Furthermore, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; either directly or indirectly through intermediaries, or in communication with each other. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
Referring to fig. 3-4, the present invention provides a dual-calibration antenna radio frequency channel calibration method S10 for millimeter wave security imaging, where the dual-calibration antenna radio frequency channel calibration method S10 for millimeter wave security imaging is suitable for a millimeter wave security imager, and specifically includes the following steps:
S1, providing two external calibration antennas, namely a first calibration antenna and a second calibration antenna, respectively obtaining corresponding calibration test values, namely receiving calibration signals of all receiving antennas relative to the first calibration antenna and the second calibration antenna;
S2, performing mutual calibration and correlation analysis processing on the two groups of calibration test values to obtain true values of the coordinates of the two external calibration antennas;
and S3, calibrating the radio frequency channel by utilizing the true values of the coordinates of the two external calibration antennas.
The calibration method of the double-calibration antenna radio frequency channel for millimeter wave security inspection imaging does not need to directly measure the position coordinates of the calibration antenna, but obtains the true value of the position of the calibration antenna through data statistics analysis, thereby accurately realizing the calibration of the radio frequency receiving and transmitting channel and ensuring better imaging effect of the millimeter wave security inspection imager.
Specifically, the test values of the receiving scaling of the first scaling antenna and the second scaling antenna in S1 are respectively:
Wherein, L1 rl is the length of the first calibration antenna calibration transmitting path, L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L1 Rx(nr),cal is the true value of the spatial distance from the first calibration antenna to each receiving antenna, and S1 Rx(nr,f) is the phase relative value of the "first calibration antenna+nr-th receiving antenna path" relative to the reference path; l2 rl is the length of the second calibration antenna calibration transmitting path, L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L2 Rx(nr),cal is the true value of the spatial distance from the second calibration antenna to each receiving antenna, and S2 Rx(nr,f) is the phase relative value of the second calibration antenna plus the nr receiving antenna path relative to the reference path; λ is the wavelength corresponding to the operating frequency point, and j is the complex imaginary part indicator.
It should be noted that S1 Rx(nr,f)、S2Rx(nr,f) is a measured value that can be automatically obtained by the two calibration antenna receiving calibrations, and L1 Rx(nr),cal、L2Rx(nr),cal is an objectively existing measured value, but only if (X1 cal, Y1cal, Z1 cal), (X2 cal, Y2cal, Z2 cal) is precisely located, L1 Rx(nr),cal、L2Rx(nr),cal can participate in the related calibration operation as a precisely known quantity.
According to the dual-calibration antenna radio frequency channel calibration method for millimeter wave security check imaging, under the condition that the positions (X1 cal, Y1cal, Z1 cal) and (X2 cal, Y2cal, Z2 cal) of two calibration antennas are unknown, true values of (X1 cal, Y1cal, Z1 cal) and (X2 cal, Y2cal, Z2 cal) are obtained through corresponding tests and algorithm analysis, and further calibration accuracy is improved, so that the consistency calibration of radio frequency channels can be guaranteed.
Further, the step S2 specifically includes the following steps:
s21, acquiring coordinate ranges of a first calibration antenna and a second calibration antenna, respectively taking a point in the coordinate ranges of the first calibration antenna and the second calibration antenna, and calculating the distance from the point to each receiving antenna;
s22, pre-calibrating the received calibration signals in the formulas (1) and (2) by combining the points taken by the first calibration antenna and the second calibration antenna to obtain received pre-calibration signals; and
S23, carrying out mathematical operation on the received pre-calibration signals corresponding to the points taken by the first calibration antenna and the second calibration antenna, and obtaining true values of the coordinates of the first calibration antenna and the second calibration antenna.
Furthermore, the coordinate ranges of the first calibration antenna and the second calibration antenna in S21 are obtained by visual inspection or measurement, and only the decimeter level is required to be accurate. The coordinates of the two external calibration antennas and the distances from the point selected in the coordinate range to each receiving antenna are specifically as follows:
first calibration antenna ：X1cal∈(X11,X1Nx1)Y1cal∈(Y11,Y1Ny1)Z1cal∈(Z11,Z1Nz1)
Second calibration antenna ：X2cal∈(X21,X2Nx2)Y2cal∈(Y21,Y2Ny2)Z2cal∈(Z21,Z2Nz2)
And respectively taking a point in the coordinate ranges of the first calibration antenna and the second calibration antenna, namely (X1 nx1,Y1ny1,Z1nz1) and (X2 nx2,Y2ny2,Z2nz2), wherein the distance from the selected point on the first calibration antenna to each receiving antenna is L1 Rx(nr),(X1nx1,Y1ny1,Z1nz1), and the distance from the selected point on the second calibration antenna to each receiving antenna is L2 Rx(nr),(X2nx2,Y2ny2,Z2nz2).
It should be noted that (X1 cal,Y1cal,Z1cal) is the true value of the coordinates of the first calibration antenna, and (X2 cal,Y2cal,Z2cal) is the true value of the coordinates of the second calibration antenna.
The point taken by the first calibration antenna and the second calibration antenna in S22 is pre-calibrated by using the distance L1 Rx(nr),(X1nx1,Y1ny1,Z1nz1) from the selected point on the first calibration antenna to each receiving antenna, and the distance L2 Rx(nr),(X2nx2,Y2ny2,Z2nz2), from the selected point on the second calibration antenna to each receiving antenna, so as to obtain the pre-calibration signals in the formulas (1) and (2):
In the process of two calibration tests of the first calibration antenna and the second calibration antenna, the same connecting cable is used, and then: l1 rl＝L2rl. Of course, the use of the same connecting cable is not necessary, but for simplifying the process, a different connecting cable may be used.
The conjugate of the formula (3) is multiplied by the formula (4), and the unknown reference path length L ref, the radio frequency receiving channel length L Rx(nr), and the scaling path lengths L1 rl and L2 rl are eliminated, so that the phase difference value of the received pre-calibration signal obtained by the mathematical operation in the step S23 by using the points respectively taken on the first scaling antenna and the second scaling antenna is specifically:
wherein, The phase value of (2) is Representation and rendering ofSumming absolute values of all the receiving antennas and all the testing frequency points;
Traversing the first scaled antenna location (X1 nx1,Y1ny1,Z1nz1) and the second scaled antenna location (X2 nx2,Y2ny2,Z2nz2) to cause The minimum values (X1 nx1,Y1ny1,Z1nz1) and (X2 nx2,Y2ny2,Z2nz2) were obtained, i.e., the true values of (X1 cal,Y1cal,Z1cal) and (X2 cal,Y2cal,Z2cal).
Through the dual-antenna calibration test and the data analysis, the obtained calibration antenna positions (X1 cal,Y1cal,Z1cal) and (X2 cal,Y2cal,Z2cal) have high enough precision (true value), so that a foundation can be laid for realizing the accurate calibration of the radio frequency receiving/transmitting channel of the millimeter wave security inspection imager, and the imaging requirement of a system is met.
In the present invention, the step S3 specifically includes the following steps:
S31, obtaining phase relative values of the link relative reference paths from the transmitting antennas to the scaling receiving antennas and phase relative values of the link relative reference paths from the transmitting antennas to the scaling receiving antennas;
S32, measuring scattering measurement values of all the receiving and transmitting antenna pairs relative to a target point, and finishing pre-calibration of a phase value of a link and a phase value during measurement in actual application;
S33, obtaining the phase residual quantity in S32 by utilizing background calibration;
S34, the phase residual quantity is supplemented to achieve final calibration of the radio frequency channel.
For the precisely obtained calibration antenna position coordinates (Xcal, ycal, zcal), the radio frequency calibration process of the millimeter wave security imaging instrument is specifically divided into three steps, namely receiving calibration, transmitting calibration and background calibration, wherein the calibration refers to the consistency correction of each transmitting/receiving antenna channel in a phased array antenna system, and is a calibration process.
Further, the phase relative value of the link relative reference path of the scaled transmit to each receiving antenna in S31 is:
Where L rl is the length of the scaled transmit path (including the external scaled cable and the scaled antenna), L ref is the length of the reference path, L Rx(nr) is the length of each receive channel (the amount to be calibrated), L Rx(nr),cal is the spatial distance from the scaled antenna to each receive antenna, and S Rx(nr,f) is the relative phase value of the link to the reference path for the scaled transmit to each receive antenna, which is a measured known quantity. Equation (6) is a process of receiving calibration, and is obtained by conjugate multiplication of a link acquisition signal transmitted to each receiving antenna and a reference path acquisition signal through calibration.
The phase relative value of the link from each transmitting antenna to the scaling receiving reference path in S31 is specifically:
Where L tl is the length of the scaled receive path (including the external scaled cable and the scaled antenna), L Tx(nt) is the length of each transmit channel (the amount to be calibrated), L Tx(nt),cal is the spatial distance from the scaled antenna to each transmit antenna, and S Tx(nt,f) is the relative phase value of each transmit antenna to the scaled receive link relative to the reference path, which is a measured known amount. Equation (7) is a process of transmitting calibration, and the link acquisition signal from the transmitting antenna to the calibration receiving is obtained by conjugate multiplication of the reference channel acquisition signal.
In S32, the scattering measurement values of all the transceiver antenna pairs with respect to the target point are obtained, specifically:
Wherein, (Xn, yn, zn) is the target point coordinates, as shown in fig. 5.
Then, the equation (8) is pre-calibrated by using the determined amounts L Rx(nr),cal and L Tx(nt),cal obtained by the equation (6), the equation (7) and the S21\s22\s23, to obtain a pre-calibration signal:
wherein, S Tx(nt),Rx(nr),f,(XnYnZn) (afterCal),/>, which is an effective phase value in practical applicationIs the residual phase after pre-calibration.
Further, in the step S33, the phase residual in the step S32 is calculated by obtaining a mutual coupling test signal of a certain transceiver antenna pair and processing the value thereof by using background calibration
Specifically, as shown in fig. 6, the background scaling is obtained by obtaining a mutual coupling test signal of the transmitting antenna 4 and the receiving antenna 1 (the antenna pair with the strongest mutual coupling signal), and performing conjugate multiplication on the mutual coupling test signal and the reference path acquisition signal, where the scaling test value is:
Wherein L 4-1 is the spatial distance from the horn mouth of the transmitting antenna 4 to the horn mouth of the receiving antenna 1, L ref is the length of the reference path, and S 4-1,f is the phase relative value of the antenna pair formed by the transmitting antenna 4 and the receiving antenna 1 to the reference path.
Using formula (6), formula (7), and formula (8.1), nr=1 for formula (6), and nt=4 for formula (7), it is possible to obtain:
Namely:
The right-hand end of formula (8.2) is the amount obtained or known by three sets of calibration tests, then the amount to the left of formula (8.2) The phase residual amount required in S32 can be obtained simply.
The pre-calibration value S Tx(nt),Rx(nr),f,(XnYnZn) (pre-calibration) obtained in S32 and the phase residual obtained in S33The phase data needed in practical application can be obtained by multiplication:
In S32, the formula (8) is calibrated according to the formulas (6), (7) and (8.2), so as to obtain the link phase value required in practical application:
The specific calibration process of the formula (9) is as follows:
Wherein S Tx(nt),Rx(nr),f,(XnYnZn)、SRx(nr,f)、STx(nt,f) is the measured data, And (3) for the obtained quantity, finishing the available formula (9), wherein the formula (9) is calibrated test data of each receiving and transmitting channel required by a related imaging algorithm, and the data simultaneously calibrate the zero-phase reference point of the receiving and transmitting channel of the antenna to the phase center of the antenna.
The final formula (9) is effective test data required by the millimeter wave security inspection imager in practical application, the practical imaging effect is shown in fig. 7, and of course, the calibration process in practical application is automatically completed through program control.
Through the technical scheme, the invention provides a dual-calibration antenna radio frequency channel calibration method for millimeter wave security inspection imaging, which utilizes two external calibration antennas only needing rough estimation of positions to respectively acquire calibration test data, and precisely calculates the position coordinates of the two calibration antennas through mutual calibration and correlation analysis processing between the two groups of calibration test data, thereby completing the calibration of a radio frequency receiving/transmitting channel. The calibration method of the double-calibration antenna radio frequency channel for millimeter wave security inspection imaging does not need to directly measure the position coordinates of the calibration antenna, but accurately obtains the position of the calibration antenna through data statistics analysis, so that the positioning accuracy is high, and the calibration result of the corresponding system radio frequency receiving/transmitting channel can meet the imaging quality requirement.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (8)
1. The method for calibrating the double-calibration antenna radio frequency channel for millimeter wave security imaging is characterized by comprising the following steps of:
s1, providing two external calibration antennas, namely a first calibration antenna and a second calibration antenna, and respectively obtaining corresponding calibration test values;
S2, performing mutual calibration and correlation analysis processing on the two groups of calibration test values to obtain true values of the coordinates of the two external calibration antennas;
S3, calibrating the radio frequency channel by utilizing true values of the coordinates of the two external calibration antennas;
The calibration test values of the first calibration antenna and the second calibration antenna in the S1 are respectively as follows:
（1）
（2）
Wherein, L1 rl is the length of the first calibration antenna calibration transmitting path, L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L1 Rx(nr),cal is the true value of the spatial distance from the first calibration antenna to each receiving antenna, and S1 Rx(nr,f) is the phase relative value of the "first calibration antenna+nr-th receiving antenna path" relative to the reference path; l2 rl is the length of the second calibration antenna calibration transmitting path, L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L2 Rx(nr),cal is the true value of the spatial distance from the second calibration antenna to each receiving antenna, and S2 Rx(nr,f) is the phase relative value of the second calibration antenna plus the nr receiving antenna path relative to the reference path; j is a complex imaginary part indicator for the wavelength corresponding to the working frequency point;
The step S2 specifically comprises the following steps:
s21, acquiring coordinate ranges of a first calibration antenna and a second calibration antenna, respectively taking a point in the coordinate ranges of the first calibration antenna and the second calibration antenna, and calculating the distance from the point to each receiving antenna;
s22, pre-calibrating the received calibration signals in the formulas (1) and (2) by combining points taken in the coordinate ranges of the first calibration antenna and the second calibration antenna to obtain received pre-calibration signals; and
S23, carrying out mathematical operation on the received pre-calibration signals corresponding to the points obtained in the coordinate ranges of the first calibration antenna and the second calibration antenna, and obtaining true values of the coordinates of the first calibration antenna and the second calibration antenna;
The step S3 specifically comprises the following steps:
S31, obtaining phase relative values of the link relative reference paths from the transmitting antennas to the scaling receiving antennas and phase relative values of the link relative reference paths from the transmitting antennas to the scaling receiving antennas;
S32, measuring scattering measurement values of all the receiving and transmitting antenna pairs relative to a target point, and finishing pre-calibration of a phase value of a link and a phase value during measurement in actual application;
S33, obtaining the phase residual quantity in S32 by utilizing background calibration;
S34, the phase residual quantity is supplemented to achieve final calibration of the radio frequency channel.
2. The method for calibrating a dual-calibration antenna radio frequency channel for millimeter wave security imaging according to claim 1, wherein the coordinate ranges of the first calibration antenna and the second calibration antenna in S21 are obtained by visual inspection or measurement, and the coordinates of the two external calibration antennas and the distances from the point selected in the coordinate ranges to each receiving antenna are specifically:
First calibration antenna:
A second scaled antenna:
Wherein, the method comprises the following steps of ,/>,/>) I.e. the true value of the coordinates of the first definite mark antenna, (/ >),/>,) The true value of the coordinates of the second calibration antenna; the point selected in the coordinate range of the first definite mark antenna is marked as (/ >),/>,/>) The point selected in the coordinate range of the second scaled antenna is marked as (/ >,,/>) The distance from the point selected in the coordinate range of the first calibration antenna to each receiving antenna is L1 Rx(nr),(X1nx1,Y1ny1,Z1nz1), and the distance from the point selected in the coordinate range of the second calibration antenna to each receiving antenna is L2 Rx(nr),(X2nx2,Y2ny2,Z2nz2).
3. The method for calibrating a dual-calibration antenna rf channel for millimeter wave security imaging according to claim 2, wherein the point in the coordinate range of the first calibration antenna and the second calibration antenna in S22 is pre-calibrated with respect to the received calibration signal in equation (1) and equation (2) by using the distance L1 Rx(nr),(X1nx1,Y1ny1,Z1nz1) from the point selected in the coordinate range of the first calibration antenna to each receiving antenna and the distance L2 Rx(nr),(X2nx2,Y2ny2,Z2nz2), from the point selected in the coordinate range of the second calibration antenna to each receiving antenna, so as to obtain the received pre-calibration signal respectively:
（3）
（4）。
4. The method for calibrating a dual-calibration antenna radio frequency channel for millimeter wave security imaging according to claim 3, wherein the phase difference value of the received pre-calibration signal obtained by using points respectively taken in the coordinate ranges of the first calibration antenna and the second calibration antenna through mathematical operation in S23 is specifically:
wherein, The phase value of (2) is，
Representation and rendering ofSumming absolute values of all the receiving antennas and all the testing frequency points;
traversing the first definite mark antenna position [ ] ,/>,/>) And a second scaled antenna position (/ >,/>,) Make/>Obtain the minimum (/ >),/>,/>) And (/ >),/>,/>) Namely (/ >),/>,/>) And%,/>,/>) Is a true value of (c).
5. The method for calibrating a dual-calibration antenna rf channel for millimeter wave security imaging according to claim 4, wherein the phase relative values of the link relative reference paths from the calibration transmitting to each receiving antenna and the phase relative values of the link relative reference paths from each transmitting antenna to the calibration receiving antenna in S31 are specifically:
（6）
（7）
Wherein, L rl is the length of the calibration transmitting path and comprises an external calibration cable and a calibration antenna, L ref is the length of the reference path, L Rx(nr) is the length of each receiving channel, L Rx(nr),cal is the spatial distance from the calibration antenna to each receiving antenna, and S Rx(nr,f) is the relative phase value of the link relative to the reference path of the calibration transmitting to each receiving antenna; l tl is the length of the calibration receiving path and comprises an external calibration cable and calibration antennas, L Tx(nt) is the length of each transmitting channel, L Tx(nt),cal is the spatial distance from each calibration antenna to each transmitting antenna, and S Tx（nt,f） is the phase relative value of each transmitting antenna to the calibration receiving link relative to the reference path.
6. The method for calibrating a dual-scaled antenna radio frequency channel for millimeter wave security imaging of claim 5, wherein the scattering measurements of all transceiver antenna pairs relative to the target point are:
（8）
Wherein, (Xn, yn, zn) is the coordinates of the target point, For the distance of each transmit antenna to the target point,For the distance of each receive antenna to the target point.
7. The method for calibrating a dual-calibration antenna radio frequency channel for millimeter wave security imaging according to claim 6, wherein the signal of formula (8) is determined by using formula (6), formula (7) and the determination amount obtained by S21\S22\S23AndPre-calibrating to obtain a pre-calibrated signal:
wherein, For effective phase value in practical application,/>The phase residual quantity after pre-calibration;
the pre-calibration value obtained in S32 And the phase residual obtained in S33The phase data needed in practical application can be obtained by multiplication:
（9）。
8. The method for calibrating a dual-calibration antenna radio frequency channel for millimeter wave security imaging according to claim 7, wherein the step S33 is performed by obtaining a mutual coupling test signal of a certain transceiver antenna pair by background calibration, processing the value, and calculating the phase residual in step S32 。
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2267603A (en) * | 1992-05-27 | 1993-12-08 | Marconi Gec Ltd | Electronically scannable array of antenna elements. |
| CN102135610A (en) * | 2010-12-28 | 2011-07-27 | 中国航天科工集团第二研究院二○三所 | Near-field real-time calibration method for human body millimeter wave imaging safety inspection system |
| CN109495189A (en) * | 2017-09-11 | 2019-03-19 | 大唐移动通信设备有限公司 | A kind of array antenna calibration method and device |
| CN109541510A (en) * | 2018-11-12 | 2019-03-29 | 北京航空航天大学 | One kind being suitable for array radiation meter channel calibration of amplitude and phase method and device |
| CN111342911A (en) * | 2018-12-18 | 2020-06-26 | 华为技术有限公司 | Method and apparatus for calibrating radio frequency link |
-
2020
- 2020-09-15 CN CN202010968491.4A patent/CN112162251B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2267603A (en) * | 1992-05-27 | 1993-12-08 | Marconi Gec Ltd | Electronically scannable array of antenna elements. |
| CN102135610A (en) * | 2010-12-28 | 2011-07-27 | 中国航天科工集团第二研究院二○三所 | Near-field real-time calibration method for human body millimeter wave imaging safety inspection system |
| CN109495189A (en) * | 2017-09-11 | 2019-03-19 | 大唐移动通信设备有限公司 | A kind of array antenna calibration method and device |
| CN109541510A (en) * | 2018-11-12 | 2019-03-29 | 北京航空航天大学 | One kind being suitable for array radiation meter channel calibration of amplitude and phase method and device |
| CN111342911A (en) * | 2018-12-18 | 2020-06-26 | 华为技术有限公司 | Method and apparatus for calibrating radio frequency link |
Non-Patent Citations (3)
| Title |
|---|
| Phased array antenna calibration problems, including in-service and multi-element PAA calibration;Y. V. Korotetskiy;2013 IX Internatioal Conference on Antenna Theory and Techniques;全文 * |
| 宽带数字阵列接收通道均衡技术研究;李园诚;中国硕士学位论文全文数据库 信息科技辑;全文 * |
| 阵列天线微波成像多通道相位误差校正方法;韩阔业;王彦平;谭维贤;洪文;;中国科学院研究生院学报(05);全文 * |
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