CN104614715B - Measurement calibration and polarimetric calibration device for target bistatic radar cross section and measurement calibration method thereof - Google Patents

Abstract

The invention discloses a measurement calibration and polarimetric calibration device (BPARC) for a target bistatic radar cross section (RCS) and a measurement calibration method thereof. The device is a double-antenna active polarization radar calibration (PARC) device with a biaxial rotation control mechanism, can simultaneously solve the problems of target bistatic RCS calibration and target bistatic polarization scattering matrix measurement calibration under the bistatic scattering measurement condition. As the bistatic RCS measurement calibration device, the BPARC can overcome the defects of the existing technology and device and ensures the stability of an RCS calibration value under different bistatic angles. As the polarimetric calibration device for bistatic polarization scattering matrix measurement, the BPARC retains all advantages of the existing single-station polarimetric calibration PARC device and also can be used for bistatic polarimetric calibration. The functions of bistatic RCS calibration and bistatic polarimetric calibration of the traditional PARC are increased.

Description

One kind can be used for the measurement calibration of target Bistatic RCS and Polarimetric Calibration device And its measurement calibration steps

Technical field

The present invention relates to RCS (rcs) measurement of target and the technical field processing, more particularly to a kind of Can be used for target Bistatic RCS (rcs) measurement calibration and Polarimetric Calibration device (referred to as bparc) and its measurement school Quasi- method.

Background technology

Bistatic RCS (rcs) measure geometry relation schematic diagram is as shown in Figure 1.Bistatic radar equation can represent For:

$p_r=\frac{p_t{g}_t{g}_r{\mathrm{\λ}}^2}{{\left(4\mathrm{\π}\right)}^3{r}_t^2{r}_r^2{l}_t{l}_r}{\mathrm{\σ}}_t^b---\left(1\right)$

In formula, p_rFor receiver inlet power (w)；p_tFor transmitter power (w)；g_r,g_tIt is respectively reception antenna and send out Penetrate the gain (zero dimension) of antenna；l_tFor the total loss of transmission channel (zero dimension)；l_rFor the total loss of receiving channel (no because Secondary)；r_t,r_rIt is respectively target to the distance (m) of transmitting antenna, reception antenna；For target EM scattering section (m²)；λ is Radar operation wavelength (m).

According to relative calibration principle (referring to document [1] Huang Peikang chief editor, " Radar Target Features ", the 6th chapter, aerospace Publishing house, 1993.), can derive that dual station rcs measurement calibration equation is by bistatic radar equation:

${\mathrm{\σ}}_t^b=k_b\·\frac{p_{\mathrm{rt}}}{p_{\mathrm{rc}}}\·{\mathrm{\σ}}_c^b=k_b\·{\left|\frac{s_t}{s_c}\right|}^2\·{\mathrm{\σ}}_c^b---\left(2\right)$

In formulaFor target dual station rcs,Dual station rcs for calibration body；p_rcAnd p_rtIt is respectively and measure standard type and survey mesh The echo power that timestamp radar receives；s_tAnd s_cIt is respectively in single rcs measurement sampling, when measurement target and measurement calibration body The multiple echo-signal of radar；k_bIt is the corresponding scaling constant of same bistatic measurement geometrical relationship, have:

$k_b={\left(\frac{r_{\mathrm{tt}}{r}_{\mathrm{rt}}}{r_{\mathrm{tc}}{r}_{\mathrm{rc}}}\right)}^2\·\frac{l_{\mathrm{tt}}{l}_{\mathrm{rt}}}{l_{\mathrm{tc}}{l}_{\mathrm{rc}}}---\left(3\right)$

R in formula_ttAnd r_tcRepresent target range and the calibration body distance of transmission channel respectively；r_rtAnd r_rcRepresent respectively and receive The target range of passage and calibration body distance；l_ttAnd l_tcRepresent the total losses of transmission channel when surveying target and measuring standard type respectively； l_rtAnd l_rcRepresent the total losses of receiving channel when surveying target and measuring standard type respectively.As long as target range and calibration body in test Distance is to determine, dual station geometrical relationship keeps constant, then k_bThe constant that value is also to determine.

When selecting dual station rcs to measure calibration body it is desirable to the scattering properties of calibration body is with the change energy measuring dual station angle Enough stablize in a relatively small level range, to ensure sufficiently high dual station calibration precision.

However, some traditional list station rcs measurement calibration body such as metal ball, metal cylinder, dihedral angle and trihedral angles are anti- Emitter, metal plate etc., with the increase at dual station angle, its scattering properties all assumes oscillating characteristic, when dual station angle is larger, uncomfortable Preferably it is used as standard calibration body.For example, by mie accurate solution, the EM scattering of metal ball calibration body is calculated, when ka value As shown in Figure 2 with the variation characteristic at dual station angle for normalization rcs when 20.It is obvious that for little dual station angular measurement, metal ball is used Remain suitable in the calibration of dual station rcs, but with dual station angle more than 90 ° after, its oscillating characteristic is increasingly severe, and this will be Largely affect calibration precision.

It can be seen that, how to find or design suitable EM scattering calibration body, be that the technology of dual station rcs measurement calibration is difficult Topic.

Prior art related to the present invention is analyzed as follows:

Prior art -1: there is the calibration body of simple shape using tradition

This is the technology being most frequently with current dual station rcs measurement calibration.Bradley et al. is (referring to document [2] C.j.bradley, p.j.collins, et.al, " an investigation of bistatic calibration Objects, " ieee trans.on geoscience and remote sensing, vol.43, no.10, oct.2005: 2177-2184. and document [3] c.j.bradley, p.j.collins, et.al, " an investigation of Bistatic calibration techniques, " ieee trans.on geoscience and remote sensing, Vol.43, no.10, oct.2005:2185-2190.) under European remote sensing features signal laboratory (emsl) measuring condition Dual station Scaling Problem is studied, metal cylinder, dihedral angle and trihedral corner reflector during selective analysis given dual station angle, The calibration characteristic of the calibration body such as rosette and woven wire.

The defect of prior art -1: bradley et al. simply have studied some traditional calibration body calibration characteristic and its Applicability in bistatic measurement calibration, does not solve to increase with dual station angle, the EM scattering of calibration body presents with dual station angle Oscillation and fluctuation, cause this key issue of big calibration error.

Prior art -2: the dual station calibration body of design specialized

Monzon proposes a kind of dual station calibration body and designs (referring to document [4] c.monzon, " a cross-polarized Bistatic calibration device for rcs measurements, " ieee trans.on antennas and Propagation, vol.51, no.4, april 2003:833-839.), metal conductive wire is pressed on dielectric circular cylinder certain Angle of inclination beta helically coiling forms.Numerical computations show that this calibration body has preferable EM scattering characteristic and cross polarization scattering Characteristic.

The defect of prior art -2: lead to this calibration body design so far and to have no the main skill being really put to Practical Art defect includes three aspects: (1) metal conductive wire is wound on dielectric circular cylinder in strict accordance with certain inclination angle due to needs, Physical treatment manufactures relatively difficult；(2) there is certain difficulty in the accurate calculating of the theoretical scattering value of this robot scaling equipment；(3) add How work error affects calibration precision is difficult to analytical analysis.

Prior art -3: launched and receiver using two, derive the calibration letter of bistatic measurement by single station measurement twice Number

Alexander and currie et al. (referring to document [5] n.t.alexander, n.c.currie, m.t.tuley, " Calibration of bistatic rcs measurements, " proc.of antenna measurement Techniques association 1995 symposium, columbus, oh, nov.1995:166-171. and [6] N.c.currie, n.t.alexander, m.t.tuley, " unique calibration issues for bistatic Radar reflectivity measurements, " proc.ieee 1996 national radar conference, an Arbor, michigan, may 1996:142-147.) solving USAF state-run scattering checkout area (ratscat) dual station phase During the dual station rcs Scaling Problem of ginseng measuring system (bicoms), propose to adopt two transmittings and receiver in bistatic measurement (such as Shown in Fig. 4), by the single twice station measurement derivation dual station scaling function to calibration body, and analyze its calibration uncertainty.

The major advantage of prior art -3: can using traditional standard type of singly standing firm, for example metal ball, metal cylinder, Corner reflector, flat board etc., only need to be through single stations and twice bistatic measurement twice, you can complete dual station rcs used as dual station calibration body Measurement and calibration, its calibration body uncertainty readily satisfies engineer applied requirement, and calibration under big dual station corner condition will not be subject to double Stand and scatter the big harmful effect that rises and falls, because calibration body rcs theoretical value only need to be using single station rcs theoretical value.

The major defect of prior art -3: the measurement of (1) common dual station rcs only needs an emitter and a receiver, puts Put in the position (as shown in Figure 1) needing, and adopt this calibration technology then must survey using two basically identical rcs of performance Amount radar (inclusion transmitter and receiver), leads to system cost to significantly improve；(2) due to needing by calibration body twice The measurement of single station and twice bistatic measurement data could derive scaling function, increased the factor of impact calibration error, with using single The calibrating method of individual transmitter and receiver is compared, and increases rcs calibration uncertainty.

Prior art -4: using active polarimetric radar robot scaling equipment (parc)

Active Polarimetric Calibration device (polarimetric active radar calibrators, parc) is used for polarizing POLARIZATION CHANNEL calibration in scatterometry and rcs calibration.

Assume that receiving channel transmission matrix r, the transmission channel transmission matrix t and background clutter i of radar can lead to target Measurement polarization scattering matrix s^mThere is deviation with target true polarization scattering matrix s.Measured value s^mFull with target psm actual value s (referring to document [7] Xiao Zhihe, nest increases bright, Jiang Xin, Wang Chen to sufficient relationship below, and radar target Polarization scattering lifts e measurement technology [j]. system engineering and electronic technology, 1996, (3): 13-32.)

s^m=r s t+i (4)

The purpose of Polarimetric Calibration is to restore the true psm of target, solution side from measured data as far as possible without distortion Cheng Wei

S=r^-1·(s^m-i)·t^-1(5)

It can be seen that it is necessary to try to achieve transceiver channel transmission matrix r, t and the background clutter i of system simultaneously, just enabling to any The calibration of target.

The usual way of Polarimetric Calibration is: control test environment background clutter sufficiently low thus negligible its to measurement Impact, approx has i=0, or directly records background clutter matrix i and carry out background vector and subtract each other process, on this basis By the use of target known to theoretical psm as Polarimetric Calibration body, in conjunction with the psm data that it is surveyed, theorized by formula (4) Quantitative relationship between psm and the measured value after background is offset, has:

M=s^m- i=r s t (6)

To solve calibration parameter r, t of radar measurement system, thus there being following simplification formula

S=r^-1·m·t^-1(7)

Most basic parc is the active transponder with fiber delay line, and its simple structural representation is as shown in Figure 5 (referring to document [8] k.sarabandi, f.t.ulaby, " performance characterization of Polarimetric active radar calibrators and a new single antenna design, " ieee Transactions on antennas and propagation, 1992,40 (10): 1147-1154.).The course of work is: Reception antenna receives radar signal from space, after this signal amplified device enhanced processing, filters radar work by bandpass filter Clutter beyond frequency range；By adjust delay line time delay size Lai equivalent change measurement distance, as such, it is possible to remove fixation away from Make approx to have i=0 from upper background clutter；Finally forward through forwarding antenna again, thus being received and processed by radar.

Compared with passive calibration body, the RCS of parc is not limited by physical size, and its size can be passed through Changing, its calculated value is regulated attenuator:

$\mathrm{\σ}=g_{\mathrm{loop}}\·\frac{g_t\·g_r\·{\mathrm{\λ}}^2}{4\mathrm{\π}}---\left(8\right)$

In formula, g_tAnd g_rIt is respectively the gain of parc forwarding antenna and reception antenna, g_loopFor in Fig. 5 in addition to antenna, entirely The overall gain in loop.Typically also its rcs size can be recorded by the method for relative calibration.

The dual-mode antenna of parc typically adopts electromagnetic horn, and antenna has single linear polarization mode.As shown in fig. 6, I The linear polarization state of antenna and horizontal x-axis (level is to the right) angle be called antenna polarizing angle.If parc reception antenna Polarizing angle is θ_r, the polarizing angle of forwarding antenna is θ_t, then the theoretical psm of parc be:

$s_p=\frac{1}{4}\sqrt{\frac{\mathrm{\σ}}{\mathrm{\π}}}\·h_t\·{h_r}^t=\frac{1}{4}\sqrt{\frac{\mathrm{\σ}}{\mathrm{\π}}}\·\left[\begin{array}{cc}\cos {\mathrm{\θ}}_t\·\cos {\mathrm{\θ}}_r& \cos {\mathrm{\θ}}_t\·\sin {\mathrm{\θ}}_r\\ \sin {\mathrm{\θ}}_t\·\cos {\mathrm{\θ}}_r& \sin {\mathrm{\θ}}_t\·\sin {\mathrm{\θ}}_r\end{array}\right]---\left(9\right)$

In formula, h_t=[cos θ_tsinθ_t]^tAnd h_r=[cos θ_rsinθ_r]^tIt is respectively parc forwarding antenna and reception antenna Jones vector, the transposition computing of subscript t representing matrix or vector.

From formula (9), according to double antenna parc design, by changing the polarizing angle θ of reception antenna_rAnd forwarding antenna Polarizing angle θ_t, it is possible to obtain the theoretical polarization scattering matrix s of parc various polarizing angle combination_p1, s_p2..., s_pn, in conjunction with correspondence Polarization scattering matrix measured value m_p1, m_p2..., m_pn, can be arranged according to formula (7) and write out some equation group, and then transmitting-receiving can be solved Channel transfer matrix r and t, thus complete the acquisition of Polarimetric Calibration parameter.The basic point of departure of this exactly this invention.

In practical application, obtained its precision of Polarimetric Calibration parameter depends greatly in Polarimetric Calibration measurement Whether the theoretical psm of selected calibration body is accurate, and whether Polarimetric Calibration parametric solution equation has robustness.

Single antenna parc:

A kind of structure of single antenna parc is proposed, its theory diagram is shown in Figure 5 in document [8].In Antenna aperture There is the feed of a pair mutually orthogonal placement inside, is respectively used to receipt signal and forward signal, so, receives and forward signal Polarization mode is mutually orthogonal, as shown in Figure 7 all the time.By antenna is rotated to different Angle Position, sky around radar line of sight The transmitting-receiving polarized state of line also changes therewith, thus obtaining different polarization scattering matrix.

Basic step using this parc Polarimetric Calibration is [8]:

(1) calculate theoretical value s of the polarization scattering matrix of single antenna parc under two kinds of attitudes_p1、s_p2；

(2) measure the measured value μ of the single antenna parc under two kinds of attitudes_p1、μ_p2, in the measurements, processing through delay line makes Echo must be received and be delayed by the distance that is located away from parc, thus the impact of background clutter i can be eliminated；

(3) by above-mentioned μ_p1、μ_p2、s_p1And s_p2Equation group is set up by formula (7), solves the monostatic radar of transmitting-receiving shared antenna Transceiver channel transmission matrix r and t of system.

Although the single antenna parc structure that document [8] proposes is simple and can preferably complete Polarimetric Calibration work, but still Have the disadvantage in that

(1) the reception polarization mode of parc antenna and transmitting polarization mode are mutually orthogonal all the time, and dual-mode antenna polarizes Can not be combined, this considerably reduce the form of its theoretical polarization scattering matrix, the polarization scattering matrix of a lot of special shapes Cannot be obtained by this single antenna parc, such as unit matrix, thus limiting its range of application；

(2) because the program is that parc to certain several antenna corner measures and obtains measured data, when in measurement When there is micro-corner error, impact can be produced on the precision of calibration；

(3) adopt the robustness of the Polarimetric Calibration parameter extraction algorithm of this parc poor: once some time in calibration process When the system measurement carved has exceptional value or larger error, the precision of extracted calibration parameter will be substantially reduced；

(4) because a pair of orthogonal polarization feed is worked it is impossible to be improved the polarization of antenna using polarization filtering device simultaneously Isolation, have impact on Polarimetric Calibration precision to a great extent.

Double antenna parc:

Document [9] (m.he, y.z.li, s.p.xiao, et al., " scheme of dynamic polarimetric Calibration, " electronics letters, 2012,48 (4): 237-238.) one kind is proposed based on digital RF storage The parc system of device, its master-plan block diagram is as shown in Figure 5.The signal that this system docking receives carries out discrete sampling, will be from Scattered signal is stored in digital radiofrequency memory, and all relevant treatment to signal are all that the discrete signal in memory is entered Row operation, converts the signal into analog signal by d/a converter again after process and is forwarded.Reception by turning table control parc Antenna is rotated with different angular speed from forwarding antenna, and during radar surveying, parc dual-mode antenna is turning all the time, based on this Parc structure proposes the active Polarimetric Calibration method based on frequency domain.

Basic step using this its Polarimetric Calibration of parc is:

(1) parc dual-mode antenna is respectively with angular velocity omega_rAnd ω_tRotation, measures its measured value μ_p；

(2) by parc theory polarization scattering matrix s_pAnd measured value μ_pIt is rewritten as the vector of 4x1 With ${\tilde{m}}_p={[m_p^{\mathrm{hh}},m_p^{\mathrm{vh}},m_p^{\mathrm{hv}},m_p^{\mathrm{vv}}]}^t,$ And the error model described by formula (3) is rewritten as ${\tilde{m}}_p=e_r\·{\tilde{s}}_p,$ Wherein $e_r=t^t\&circletimes;r$ (Amass for kroneker), it comprehensively describes radar system calibration parameter；

(3) willBoth sides take Fourier transformation simultaneously, can be in the hope ofAnd this solution is only Have and set up when the angular velocity of rotation of parc reception antenna and forwarding antenna is unequal；

The frequency dynamic Polarimetric Calibration method that document [9] is proposed based on double antenna digital parc structure, in theory may be used To realize the calibration to radar system, but its shortcoming existing is as follows:

(1) Technology design is extremely complex.This digital parc requires very high, numeral to the sampling rate of a/d and d/a The sequential logic of RF memory circuit is complicated, and the write of signal is required for clock to enter with the operation such as reading and delay disposal Row controls, and in the circuit running up, competition, risk easily, so that whole system can not be stablized normally working；

(2) calibration parameter solution procedure and algorithm are complicated；

(3) high cost, reliability and stability are still to be tested, have no its actual products and practical application report at present.

The defect of prior art -4: two kinds of parc devices using above-mentioned single antenna or double antenna design belong to singly stand pole Change calibration parc device it is impossible to calibrate and bistatic measurement Polarimetric Calibration for bistatic measurement rcs, therefore do not solve bistatic measurement Rcs calibration and Polarimetric Calibration problem.

Content of the invention

The technical problem to be solved is: the present invention propose a kind of using the double skies with dual-axis rotation controlling organization Line parc device and its measurement calibration steps, can solve the calibration of target dual station rcs and target under EM scattering measuring condition simultaneously Dual station polarization scattering matrix measures Polarimetric Calibration problem.Measure robot scaling equipment as dual station rcs, aforementioned existing skill can be overcome Whole shortcomings of art -1～4 it is ensured that under different dual station angle rcs scaled values stability；As the measurement of dual station polarization scattering matrix Polarimetric Calibration device, both remained all advantages of existing single Polarimetric Calibration parc device of standing, can be used for dual station pole simultaneously again Change calibration, increased the calibration of dual station rcs and the dual station Polarimetric Calibration function of traditional parc device.

The technical solution used in the present invention is: a kind of radar target EM scattering measurement rcs calibration and Polarimetric Calibration device, This device includes reception antenna, transmitting antenna, two orientation-sight line dual-axis rotation units, orientation rotation drive with controller, bow Face upward rotation driving and controller, radio frequency combining and power source combination, wherein:

Described reception antenna, for receiving the radiation signal of bistatic measurement transmitting radar antenna, is fed by radio-frequency cable Radio frequency combining；

Described radio frequency combining: it includes amplifier, wave filter, delay line and the attenuator being sequentially connected, and it completes right The amplification of bistatic measurement radar emission signal that described reception antenna is received, filtering, obtain output signal after delay process, And through attenuator to output signal level regulation after, fed transmitting antenna by radio-frequency cable；

Described transmitting antenna, for completing radiofrequency signal to the radiation of bistatic measurement radar receiving antenna；

Two described orientation-sight line dual-axis rotation unit: one of them is used for placing described reception antenna, another For placing described transmitting antenna,

Described orientation rotation drives and controller: for controlling described orientation-sight line dual-axis rotation unit around orientation To rotation；

Described sight line rotation driving and controller: for controlling described orientation-sight line dual-axis rotation unit around sight line The rotation of axle；

Described power source combination: for the power supply supply of this device.

Further, described reception antenna and described transmitting antenna are respectively made up of an electromagnetic horn, meanwhile, in order to Reduce antenna cross-polarization coupling error as far as possible, improve polarization isolation ratio, install micro-strip polarization filter at each Antenna aperture additional Ripple device device, each electromagnetic horn is installed on an orientation-sight line dual-axis rotation unit carrying angular coding, by orientation Rotation driving and controller and sight line rotation driving and controller control each antenna can independently about radar line of sight rotation and around Orientation rotates, and the orientation with angular coding-sight line dual-axis rotation unit can provide the sight line corner of antenna simultaneously and orientation turns The precise position information at angle.

Further, described orientation-sight line dual-axis rotation unit: mainly by sight line rotaty step motor, sight angle Encoder, azimuth rotating platform, orientation angles encoder and between antenna Matching installation interface composition；Wherein " sight line " means Line between bistatic measurement radar transmitter and reception antenna or between bistatic measurement radar receiver and transmitting antenna；" side When position " means that instrumentation radar is set up in xoy plane, the corner in xoy plane, rotated by sight line and drive control device, Each antenna can be accurately controlled in real time around the rotary speed of radar antenna sight line and angle position, by orientation rotation and drive Movement controller, can accurately control each antenna in real time around the rotary speed of azimuthal plane radar antenna sight line and corner position Put, in working order under, EM scattering measures rcs calibration and the reception of Polarimetric Calibration device and transmitting antenna in orientation respectively Turn to the transmitter and receiver antenna of be aligned bistatic measurement radar.

Further, described orientation rotation drives and controller, by control azimuth turntable, complete to reception antenna and Transmitting antenna is in the rotation of orientation, and provides the position of orientation information of each antenna by azimuth angular encoders, orientation rotation Driving can be by RCI by EM scattering measuring system controller remotely control with controller.

Further, described sight line rotation driving and controller: by controlling sight line electric rotating machine, complete to reception sky Line and transmitting antenna are around the rotation of sight line axle, and provide the sight line angle position information of each antenna by sight line angular encoder, Sight line rotation driving can be by RCI by EM scattering measuring system controller remotely control with controller.

Survey with the above-mentioned target Bistatic RCS measurement calibration dual station corresponding with Polarimetric Calibration device that can be used for Amount and the method for calibration process, it specifically comprises the following steps that

Step -1:bparc device adjustment, comprising:

Adjust the sight line rotating mechanism of bparc reception antenna and forwarding antenna so that the initial polarization angle of two antennas is adjusted For consistent, and control the rotating speed of two rotating mechanisms, make dual-mode antenna keep the same rotating speed w_rAt the uniform velocity rotate, wherein w_r=w_t, single Position rad/s, being polarized with the dual-mode antenna ensureing bparc in whole measurement process is on all four all the time, for this reason, whirler Structure can be using stepper motor it is ensured that antenna stops when often going to an angle, one group of data of radar surveying, then controls antenna to turn To next Angle Position, such Repetitive controller and measurement, you can the polarization of guarantee dual-mode antenna is synchronous change；

Angular encoder accurately records the angle γ that antenna turns over, then the number of turns that bparc turns over can by n=γ/ 360 ° calculate.In measurement, bparc double antenna can be controlled to carry out the measurement of whole circle, this ensure that initial polarization angle Choosing does not affect on whole calibration process；

The installation of step -2:bparc device, comprising:

Bparc Polarimetric Calibration device proposed by the invention is installed on calibration support, according to instrumentation radar system Require to adjust its delay parameter；

For the dual station angle of the bistatic measurement currently giving, control azimuth turntable, make bparc reception antenna to locating tab assembly thunder The transmitting antenna reaching, bparc forwarding antenna is directed at the reception antenna of instrumentation radar, when changing measurement dual station angle every time, is both needed to weight This bparc installation steps multiple；

Step -3: Polarimetric Calibration measurement data admission

Maintain and maintain static according to the azimuth rotating platform position that given measurement dual station angle regulates, control the sight line of bparc Rotating mechanism, makes two antennas of bparc at the uniform velocity rotate at a slow speed it is assumed that corotation crosses n circle, instrumentation radar transmission signal simultaneously receives The echo-signal of bparc forwarding antenna radiation is complete under admission bparc antenna diverse location in instrumentation radar sight line rotary course The echo-signal of portion's POLARIZATION CHANNEL, the whole measurement data obtaining；

When changing measurement dual station angle every time, it is both needed to repeat this bparc measurement data recording step；

Step -4: Polarimetric Calibration parameter extraction

Solve the whole Polarimetric Calibration parameters obtaining instrumentation radar system by the measurement data in step -3；

When changing measurement dual station angle every time, it is both needed to solve instrumentation radar using to the bparc measurement data under this dual station angle The calibration parameter of system；

Step -5: target dual station polarization measurement

Target to be measured is installed, and is enrolled the target echo of all POLARIZATION CHANNEL by bistatic measurement radar；

Under same dual station angle, bistatic measurement can be carried out to multiple identical or different targets using identical instrumentation radar；

Step -6: Polarimetric Calibration is processed

According to the target measurement value recording in the Polarimetric Calibration parameter having obtained in step -4 and step -5, applying equation (6- 1) Polarimetric Calibration of surveyed target can be completed, obtain the true polarization scattering matrix value of target；

$s_t=\frac{1}{(1-{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_r^v)}\·\frac{1}{(1-{\mathrm{\ϵ}}_t^h\·{\mathrm{\ϵ}}_t^v)}\·\left[\begin{array}{cc}1& -{\mathrm{\ϵ}}_r^h\\ -{\mathrm{\ϵ}}_r^v& 1\end{array}\right]\·\left[\begin{array}{cc}\frac{m_t^{\mathrm{hh}}}{r_{\mathrm{hh}}\·t_{\mathrm{hh}}}& \frac{m_t^{\mathrm{hv}}}{r_{\mathrm{hh}}\·t_{\mathrm{vv}}}\\ \frac{m_t^{\mathrm{vh}}}{r_{\mathrm{vv}}\·t_{\mathrm{hh}}}& \frac{m_t^{\mathrm{vv}}}{r_{\mathrm{vv}}\·t_{\mathrm{vv}}}\end{array}\right]\·\left[\begin{array}{cc}1& -{\mathrm{\ϵ}}_t^h\\ -{\mathrm{\ϵ}}_t^v& 1\end{array}\right]---(6-1)$

In formula $m_t=\left[\begin{array}{cc}{m}_t^{\mathrm{hh}}& m_t^{\mathrm{hv}}\\ m_t^{\mathrm{vh}}& m_t^{\mathrm{vv}}\end{array}\right]$ For the measured value under 4 polarization combination of target to be calibrated；s_tFor target to be calibrated True polarization scattering matrix；r_hhAnd r_vvIt is respectively the gain factor of the polarization of measuring system hh and vv polarization reception passage, t_hhAnd t_vv It is respectively the gain factor of the polarization of measuring system hh and vv polar transmitter passage,Friendship for measuring system Fork polarization factor, this 8 parameters are to need by -5 pairs of bparc measurements of step -1～step and measurement data is processed to The measuring system Polarimetric Calibration parameter solving；

Under same dual station angle, when bistatic measurement is carried out to multiple identical or different targets using identical instrumentation radar, can To carry out Polarimetric Calibration process with same group of calibration parameter；

If only doing the measurement of dual station rcs and calibrating, above-mentioned 6 steps can simplify further it is not necessary to extract polarization school Quasi- parameter, only need to measure according to the dual station calibration equation given by formula (6-2) and calibrate calculating with rcs,

${\mathrm{\σ}}_t^b=k_b\·\frac{p_{\mathrm{rt}}}{p_{\mathrm{rc}}}\·{\mathrm{\σ}}_c^b=k_b\·{\left|\frac{s_t}{s_c}\right|}^2\·{\mathrm{\σ}}_c^b---(6-2)$

In formulaFor target dual station rcs,Theoretical dual station rcs for bparc；p_rcAnd p_rtIt is respectively and measure standard type and survey The echo power that during target, radar receives；s_tAnd s_cIt is respectively in single rcs measurement sampling, measure target and measurement calibration body When the multiple echo-signal of radar；k_bIt is the corresponding scaling constant of same bistatic measurement geometrical relationship；

The theoretical dual station rcs value of bparcComputing formula is；

${\mathrm{\σ}}_c^b=g_{\mathrm{loop}}\·\frac{g_t\·g_r\·{\mathrm{\λ}}^2}{4\mathrm{\π}}---(6-3)$

In formula, g_tAnd g_rIt is respectively the gain of bparc forwarding antenna and reception antenna, g_loopFor in bparc in addition to antenna, The overall gain in whole loop；The theoretical rcs value of bparc also can be by being passed through relatively using another calibration body known to rcs value Calibrate the method measuring to record；

With the corresponding scaling constant k of bistatic measurement geometrical relationship_bCalculating then according to bistatic measurement geometrical relationship by formula (6-4) complete:

$k_b={\left(\frac{r_{\mathrm{tt}}{r}_{\mathrm{rt}}}{r_{\mathrm{tc}}{r}_{\mathrm{rc}}}\right)}^2\·\frac{l_{\mathrm{tt}}{l}_{\mathrm{rt}}}{l_{\mathrm{tc}}{l}_{\mathrm{rc}}}---(6-4)$

R in formula_ttAnd r_tcRepresent target range and the calibration body distance of transmission channel respectively；r_rtAnd r_rcRepresent respectively and receive The target range of passage and calibration body distance；l_ttAnd l_tcRepresent the total losses of transmission channel when surveying target and measuring standard type respectively； l_rtAnd l_rcRepresent the total losses of receiving channel when surveying target and measuring standard type respectively；As long as target range and calibration body in test Distance is to determine, dual station geometrical relationship keeps constant, then k_bThe constant that value is to determine.

What technical solution of the present invention was brought has the beneficial effect that

1) the rotatable double antenna active calibrating installation bparc proposed in the present invention remains the complete of existing parc device Portion's advantage, solves the problems, such as the measurement calibration of dual station rcs and Polarimetric Calibration simultaneously again, has traditional calibration body and parc device is not had A series of important advantage having.

2) compare with traditional simple calibration body in document [2,3,4] (prior art -1 with): due to the transmitting-receiving sky of bparc Line sensing is controlled, accurately can be aligned with the transmitting of bistatic measurement radar and reception antenna, therefore does not receive measurement dual station angle size Affect, the rcs solving the simple calibration body of tradition increases the big fluctuating of appearance, is difficult to complete big dual station angle rcs survey with dual station angle Amount precise calibration problem.

3) compare with technology (prior art -3) in document [5,6]: using bparc as bistatic measurement calibration and calibration cartridge When putting, bistatic measurement radar is no longer necessary to two sets of transmittings and receiver, only needs an emitter and a receiver, you can complete Bistatic measurement, calibration and Polarimetric Calibration.

4) compared with the single antenna parc (prior art -4) in document [8]: the advantage of (1) this invention bparc includes Can be used for completing bistatic measurement rcs calibration and Polarimetric Calibration: (2) polarisation filter can be installed additional so that parc antenna polarization every Greatly improve from degree, be conducive to provide measurement calibration accuracy；(3) transmitting-receiving polarization combination is various informative, it is possible to provide more diversified Polarization scattering characteristic signal so that Polarimetric Calibration measurement and processing scheme selection can variation it is ensured that in different engineer applied In be respectively provided with realizability.

5) compared with parc (prior art -4) digital in document [9]: (1) this invention bparc can be used for completing double The measurement rcs that stands calibrates and Polarimetric Calibration；(2) radiofrequency signal need not be made with a/d and d/a and process the signal it is ensured that receiving and forwarding Undistorted；(3) structure is simple, stable performance, and R＆D costs are relatively low, and engineering is easily realized；(4) transmitting-receiving polarization combination form is many Sample, it is possible to provide more diversified Polarization scattering characteristic signal so that Polarimetric Calibration measurement and processing scheme selection can variation, Guarantee to be respectively provided with realizability in different engineer applied.

Brief description

Fig. 1 is dual station rcs measure geometry relation schematic diagram；

Fig. 2 is the variation characteristic with dual station angle for the normalization rcs of metal ball；

Fig. 3 is the design dual station robot scaling equipment of monzon；

Fig. 4 is the dual station rcs measurement calibration schematic diagram using two transmitter and receivers；

Fig. 5 is parc structured flowchart；

Fig. 6 is double antenna parc antenna front view；

Fig. 7 is single antenna parc antenna front view；

Fig. 8 is double antenna digital parc structured flowchart；

Fig. 9 measures the general structure schematic diagram of rcs calibration and Polarimetric Calibration device for EM scattering；

Figure 10 for EM scattering measurement rcs calibration and Polarimetric Calibration device in concrete measurement with bistatic measurement radar between Geometrical relationship schematic diagram.

Specific embodiment

Below in conjunction with the accompanying drawings and specific embodiment further illustrates the present invention.

A kind of target Bistatic RCS that can be used for proposed by the invention measures calibration and Polarimetric Calibration device General structure schematic diagram is as shown in Figure 9.

In Fig. 9, EM scattering measurement rcs calibration and Polarimetric Calibration device by reception antenna, transmitting antenna, two orientation- Sight line dual-axis rotation unit, orientation rotation drive with controller, pitching rotation driving and controller, radio frequency combining, power source combination, The functional module such as relevant matches mounting interface and RCI forms.Wherein:

Receive and transmitting antenna: reception antenna is used for receiving the radiation signal of bistatic measurement transmitting radar antenna, by radio frequency Cable is fed radio frequency combining, after amplified, filtering, time delay and attenuator are to output signal level regulation, is fed by radio-frequency cable Transmitting antenna completes radiofrequency signal to the radiation of bistatic measurement radar receiving antenna, as shown in Figure 10.Receive and transmitting antenna is each It is made up of an electromagnetic horn, meanwhile, in order to reduce antenna cross-polarization coupling error as far as possible, improve polarization isolation ratio, Install additional at each Antenna aperture micro-strip polarisation filter device (referring to document [10] m.kuloglu, c-c chen, “ultrawideband electromagnetic polarization filter(uwb-empf)applications to conventional horn antennas for substantial cross-polarization level Reduction, " ieee antennas and propagation magazine, 2013,55 (2): 280-288.).Each loudspeaker Antenna is installed on an orientation-sight line bi-axial swivel mechanism carrying angular coding, controls each antenna by controller Can rotate independently about radar line of sight rotation with around orientation, the sight line corner of antenna and the accurate position of orientation corner can be given simultaneously Confidence ceases.

Orientation-sight line dual-axis rotation unit: main by sight line rotaty step motor, sight angle encoder, azimuth rotating platform, Orientation angles encoder and with Matching installation interface between antenna etc. composition.Wherein " sight line " means bistatic measurement in Figure 10 Between radar transmitter and apparatus of the present invention reception antenna or bistatic measurement radar receiver and apparatus of the present invention transmitting antenna it Between line；When " orientation " means that in Figure 10, instrumentation radar is set up in xoy plane, in corner in xoy plane, such as Figure 10 Shown θ angle.Rotated by sight line and drive control device, each antenna can be accurately controlled in real time around radar antenna sight line Rotary speed and angle position.By orientation rotation and drive control device, each antenna can be accurately controlled in real time around orientation The rotary speed of angle plane radar antenna sight line and angle position.Under in working order, EM scattering measurement rcs calibrates and polarization The reception of calibrating installation and transmitting antenna turn to the transmitter and receiver sky of be aligned bistatic measurement radar respectively in orientation Line, and the exemplary polarization combination front view when sight line axle goes to diverse location can be found in shown in Fig. 6.

Orientation rotation drives and controller: by control azimuth turntable, completes the reception to apparatus of the present invention and transmitting sky Line is in the rotation of orientation, and provides the position of orientation information of each antenna by azimuth angular encoders.Orientation rotation drive with Controller can be by RCI by EM scattering measuring system controller remotely control.

Sight line rotation driving and controller: by controlling sight line electric rotating machine, complete the reception to apparatus of the present invention and send out Penetrate the rotation around sight line axle for the antenna, and provide the sight line angle position information of each antenna by sight line angular encoder.Sight line is revolved Turn to drive and can pass through RCI by EM scattering measuring system controller remotely control with controller.

Radio frequency combining: the amplification of bistatic measurement radar emission signal that completes reception antenna is received, filtering, time delay, And after output signal level being adjusted through attenuator, transmitting antenna of feeding is to complete the letter to bistatic measurement radar receiver antenna Number radiation.The operation principle of the amplifier in Figure 10, wave filter, attenuator, delay line, power supply etc. is as good as with traditional parc, Here is not covered.

Power source combination: the power supply supply of the whole unit of complete cost apparatus and assembly.

Device designed by our present invention is called dual station active Polarimetric Calibration device (bistatic below Polarimetric active radar calibrators), referred to as bparc device, to be different from traditional being simply possible to use in Single station measurement rcs calibration and the parc device of Polarimetric Calibration.

Due to using the device bparc designed by the present invention, when measuring the change of dual station angle, Synchronization Control can be passed through The azimuth rotating platform of bparc rotates so that the reception antenna of bparc keeps the transmitting antenna sight line phase one with instrumentation radar forever Cause, and the forwarding antenna of bparc is consistent with the transmitting antenna sight line of instrumentation radar forever.Therefore, no matter measure dual station angle Much, the theoretical rcs value of bparc and polarization characteristic all do not change with dual station angle, thus ensure that bparc device can be used for Complete single station, the measurement of dual station rcs and the various application scenario of Polarimetric Calibration.

The dual-mode antenna of bparc device can be operated in various polarization combination, by the multiple conventional nothing of bparc simulated implementation The polarization scattering matrix of source calibration body, thus the range of application of bparc can be greatly expanded.Additionally, by sending and receiving Antenna aperture Install polarisation filter additional, be greatly improved cross polarization isolation, solve the cross polarization existing for single antenna parc and be coupled to The negative influence that Polarimetric Calibration is brought.

Compared with existing parc device, another important advantage of the present invention is, due to employing rotatable double antenna Design, the different attitude integrations of sending and receiving antenna may make up different polarization combination, thus can design different Polarimetric Calibrations and survey Amount scheme and calibration algorithm, are discussed below.

Dual station polarization measurement calibrating principle is described below with scheme:

Require to complete 4 POLARIZATION CHANNEL are calibrated it is ensured that final because quantitative polarization measurement and calibration process are general The target polarization scattering matrix measurement obtaining is accurate, this also means that and completes target rcs under 4 polarization combination simultaneously Measurement calibration.Therefore, we individually do not discuss dual station rcs measurement Scaling Problem below, but discuss polarization measurement calibration Principle and scheme.

The Polarimetric Calibration model of formula (3) is rewritten into matrix form to be had:

$\left[\begin{array}{cc}{m}_{\mathrm{hh}}& m_{\mathrm{hv}}\\ m_{\mathrm{vh}}& m_{\mathrm{vv}}\end{array}\right]=\left[\begin{array}{cc}{r}_{\mathrm{hh}}& r_{\mathrm{hv}}\\ r_{\mathrm{vh}}& r_{\mathrm{vv}}\end{array}\right]\·\left[\begin{array}{cc}{s}_{\mathrm{hh}}& s_{\mathrm{hv}}\\ s_{\mathrm{vh}}& s_{\mathrm{vv}}\end{array}\right]\·\left[\begin{array}{cc}{t}_{\mathrm{hh}}& t_{\mathrm{hv}}\\ t_{\mathrm{vh}}& t_{\mathrm{vv}}\end{array}\right]---\left(8\right)$

Formula (8) can be decomposed as follows:

$\left[\begin{array}{cc}{m}_{\mathrm{hh}}& m_{\mathrm{hv}}\\ m_{\mathrm{vh}}& m_{\mathrm{vv}}\end{array}\right]=\left[\begin{array}{cc}{r}_{\mathrm{hh}}& 0\\ 0& r_{\mathrm{vv}}\end{array}\right]\·\left[\begin{array}{cc}1& {\mathrm{\ϵ}}_r^h\\ {\mathrm{\ϵ}}_r^v& 1\end{array}\right]\·\left[\begin{array}{cc}{s}_{\mathrm{hh}}& s_{\mathrm{hv}}\\ s_{\mathrm{vh}}& s_{\mathrm{vv}}\end{array}\right]\·\left[\begin{array}{cc}1& {\mathrm{\ϵ}}_t^v\\ {\mathrm{\ϵ}}_t^h& 1\end{array}\right]\·\left[\begin{array}{cc}{t}_{\mathrm{hh}}& 0\\ 0& t_{\mathrm{vv}}\end{array}\right]---\left(9\right)$

In formula, ${\mathrm{\ϵ}}_r^h=\frac{r_{\mathrm{hv}}}{r_{\mathrm{hh}}},{\mathrm{\ϵ}}_r^v=\frac{r_{\mathrm{vh}}}{r_{\mathrm{vv}}},{\mathrm{\ϵ}}_t^h=\frac{t_{\mathrm{vh}}}{t_{\mathrm{hh}}},{\mathrm{\ϵ}}_t^v=\frac{t_{\mathrm{hv}}}{t_{\mathrm{vv}}}$ The cross polarization factor for measuring system.

According to formula (9), in Polarimetric Calibration, as long as parameter is tried to achieve by a series of measurement and resolvingr_hh、r_vv、t_hhAnd t_vv, you can complete Polarimetric Calibration, and pass through bparc proposed by the invention and obtain The method of above-mentioned Polarimetric Calibration parameter can be varied.Wherein 3 kind typical scenarios are described below, the begging for of each of which scheme By being both for given measurement dual station angle and carry out, when changing measurement dual station angle, because by controlling two of bparc Azimuth rotating platform can make its reception antenna and forwarding antenna be respectively aligned to transmitting antenna and the reception antenna of bistatic measurement radar, because This, the polarization measurement under different dual station angles and calibrating principle and process are duplicate.

Scheme -1:

In bparc sending and receiving antenna, one of antenna is kept to fix (namely being operated in fixing polarized state), another Individual antenna can make 0～360 ° of rotation (namely polarized state can change in the range of 0～360 °).It is illustrated below:

First, forwarding antenna keeps 45 ° of linear polarizations constant, i.e. θ_t=45 °, reception antenna rotates in the range of 0～360 °. From formula (6), now the psm of parc is:

$s_{c1}^p=\mathrm{\β}\·\left[\begin{array}{cc}\cos {\mathrm{\θ}}_r& \sin {\mathrm{\θ}}_r\\ \cos {\mathrm{\θ}}_r& \sin {\mathrm{\θ}}_r\end{array}\right]---\left(10\right)$

Wherein,This coefficient can be carried out calibrating to parc according to other calibration body before Polarimetric Calibration Arrive, also can be calculated by formula (5), herein be accordingly to be regarded as known quantity.It can be seen that, in that case, the polarization of parc dissipates Penetrate the polarizing angle θ that each component of matrix is with reception antenna_rChange in sine and cosine rule.

Take θ_r=90 ° and θ_r=0 °, then from formula (8), the theoretical psm under corresponding attitude is respectively as follows:

$s_{c\mathrm{1,1}}^p=\mathrm{\β}\·\left[\begin{array}{cc}0& 1\\ 0& 1\end{array}\right]---\left(11a\right)$

$s_{c1,2}^p=\mathrm{\β}\·\left[\begin{array}{cc}1& 0\\ 1& 0\end{array}\right]---\left(11b\right)$

Formula (11a) and formula (11b) are substituted into formula (8) respectively launch, have:

$m_{c\mathrm{1,1}}^p=r\·s_{c\mathrm{1,1}}^p\·t=\mathrm{\β}\·\left[\begin{array}{cc}{t}_{\mathrm{vh}}\·(r_{\mathrm{hh}}+r_{\mathrm{hv}})& t_{\mathrm{vv}}\·(r_{\mathrm{hh}}+r_{\mathrm{hv}})\\ t_{\mathrm{vh}}\·(r_{\mathrm{vh}}+r_{\mathrm{vv}})& t_{\mathrm{vv}}\·(r_{\mathrm{vh}}+r_{\mathrm{vv}})\end{array}\right]---\left(12a\right)$

$m_{c1,2}^p=r\·s_{c1,2}^p\·t=\mathrm{\β}\·\left[\begin{array}{cc}{t}_{\mathrm{hh}}\·(r_{\mathrm{hh}}+r_{\mathrm{hv}})& t_{\mathrm{hv}}\·(r_{\mathrm{hh}}+r_{\mathrm{hv}})\\ t_{\mathrm{hh}}\·(r_{\mathrm{vh}}+r_{\mathrm{vv}})& t_{\mathrm{hv}}\·(r_{\mathrm{vh}}+r_{\mathrm{vv}})\end{array}\right]---\left(12b\right)$

Have

${\mathrm{\ϵ}}_t^h=\frac{t_{\mathrm{vh}}}{t_{\mathrm{hh}}}=\frac{m_{c\mathrm{1,1}}^{p,\mathrm{hh}}}{m_{c\mathrm{1,2}}^{p,\mathrm{hh}}}---\left(13a\right)$

${\mathrm{\ϵ}}_t^v=\frac{t_{\mathrm{hv}}}{t_{\mathrm{vv}}}=\frac{m_{c1,2}^{p,\mathrm{vv}}}{m_{c1,1}^{p,\mathrm{vv}}}---\left(13b\right)$

Secondly, reception antenna keeps 45 ° of linear polarizations constant, i.e. θ_r=45 °, forwarding antenna rotates in the range of 0～360 °.

Take θ_t=90 ° and θ_t=0 °, then the theoretical psm corresponding under attitude is respectively as follows:

$s_{c1,3}^p=\mathrm{\β}\·\left[\begin{array}{cc}0& 0\\ 1& 1\end{array}\right]---\left(14a\right)$

$s_{c1,4}^p=\mathrm{\β}\·\left[\begin{array}{cc}1& 1\\ 0& 0\end{array}\right]---\left(14b\right)$

Formula (14a) and formula (14b) are substituted into formula (8) respectively launch, have:

$m_{c1,3}^p=r\·s_{c1,3}^p\·t=\mathrm{\β}\·\left[\begin{array}{cc}{r}_{\mathrm{hv}}\·(t_{\mathrm{hh}}+t_{\mathrm{vh}})& r_{\mathrm{hv}}\·(t_{\mathrm{hv}}+t_{\mathrm{vv}})\\ r_{\mathrm{vv}}\·(t_{\mathrm{hh}}+t_{\mathrm{vh}})& r_{\mathrm{vv}}\·(t_{\mathrm{hv}}+t_{\mathrm{vv}})\end{array}\right]---\left(15a\right)$

$m_{c1,4}^p=r\·s_{c1,4}^p\·t=\mathrm{\β}\·\left[\begin{array}{cc}{r}_{\mathrm{hh}}\·(t_{\mathrm{hh}}+t_{\mathrm{vh}})& r_{\mathrm{hh}}\·(t_{\mathrm{hv}}+t_{\mathrm{vv}})\\ r_{\mathrm{vh}}\·(t_{\mathrm{hh}}+t_{\mathrm{vh}})& r_{\mathrm{vh}}\·(t_{\mathrm{hv}}+t_{\mathrm{vv}})\end{array}\right]---\left(15b\right)$

Have

${\mathrm{\ϵ}}_r^h=\frac{r_{\mathrm{hv}}}{r_{\mathrm{hh}}}=\frac{m_{c1,3}^{p,\mathrm{hh}}}{m_{c1,4}^{p,\mathrm{hh}}}---\left(16a\right)$

${\mathrm{\ϵ}}_r^v=\frac{r_{\mathrm{vh}}}{r_{\mathrm{vv}}}=\frac{m_{c1,4}^{p,\mathrm{vv}}}{m_{c1,3}^{p,\mathrm{vv}}}---\left(16b\right)$

WillWithSubstitution formula (9), expansion can be tried to achieve:

$r_{\mathrm{hh}}{t}_{\mathrm{hh}}=\frac{1}{\mathrm{\β}}\·\frac{m_{c\mathrm{1,2}}^{p,\mathrm{hh}}}{1-{\mathrm{\ϵ}}_r^h}---\left(17a\right)$

$r_{\mathrm{hh}}{t}_{\mathrm{vv}}=\frac{1}{\mathrm{\β}}\·\frac{m_{c\mathrm{1,2}}^{p,\mathrm{hv}}}{{\mathrm{\ϵ}}_t^h(1-{\mathrm{\ϵ}}_r^h)}---\left(17b\right)$

$r_{\mathrm{hh}}{t}_{\mathrm{hh}}=\frac{1}{\mathrm{\β}}\·\frac{m_{c\mathrm{1,2}}^{p,\mathrm{vh}}}{{\mathrm{\ϵ}}_r^v-1}---\left(17c\right)$

$r_{\mathrm{hh}}{t}_{\mathrm{hh}}=\frac{1}{\mathrm{\β}}\·\frac{m_{c\mathrm{1,2}}^{p,\mathrm{vv}}}{{\mathrm{\ϵ}}_t^h({\mathrm{\ϵ}}_r^v-1)}---\left(17d\right)$

So far, all calibration parameters of system are all obtained, can complete the calibration operation to target arbitrarily to be calibrated.False If target measurement value to be calibrated is m_t, the true polarization scattering matrix s of target to be calibrated_t, from formula (10) and formula (11), have with Lower Polarimetric Calibration equation:

$s_t=\frac{1}{(1-{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_r^v)}\·\frac{1}{(1-{\mathrm{\ϵ}}_t^h\·{\mathrm{\ϵ}}_t^v)}\·\left[\begin{array}{cc}1& -{\mathrm{\ϵ}}_r^h\\ -{\mathrm{\ϵ}}_r^v& 1\end{array}\right]\·\left[\begin{array}{cc}\frac{m_t^{\mathrm{hh}}}{r_{\mathrm{hh}}\·t_{\mathrm{hh}}}& \frac{m_t^{\mathrm{hv}}}{r_{\mathrm{hh}}\·t_{\mathrm{vv}}}\\ \frac{m_t^{\mathrm{vh}}}{r_{\mathrm{vv}}\·t_{\mathrm{hh}}}& \frac{m_t^{\mathrm{vv}}}{r_{\mathrm{vv}}\·t_{\mathrm{vv}}}\end{array}\right]\·\left[\begin{array}{cc}1& -{\mathrm{\ϵ}}_t^h\\ -{\mathrm{\ϵ}}_t^v& 1\end{array}\right]---\left(18\right)$

Scheme -2:

Keep forwarding antenna identical with receiving polarization mode, and two antennas synchronous rotary in the range of 0～360 °.This When, the polarization scattering matrix of parc is:

$s_{c2}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}\cos 2{\mathrm{\θ}}_r& \sin 2{\mathrm{\θ}}_r\\ \sin 2{\mathrm{\θ}}_r& -\cos 2{\mathrm{\θ}}_r\end{array}\right]+\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]---\left(19\right)$

It can be seen that, now parc can be considered that an existing puppet Dihedral Corner Reflectors scattering properties has metal ball scattering properties concurrently again Comprehensive calibration body, the passive Polarimetric Calibration method traditionally adopting Dihedral Corner Reflectors and metal ball therefore can be copied to realize Active Polarimetric Calibration.Detailed process is as follows.

According to matrix multiplication, formula (9) can be written as:

$m_{\mathrm{hh}}=r_{\mathrm{hh}}{t}_{\mathrm{hh}}(s_{\mathrm{hh}}+{\mathrm{\ϵ}}_t^h{s}_{\mathrm{hv}}+{\mathrm{\ϵ}}_r^h{s}_{\mathrm{vh}}+{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^h{s}_{\mathrm{vv}})---\left(20a\right)$

$m_{\mathrm{hv}}=r_{\mathrm{hh}}{t}_{\mathrm{vv}}({{\mathrm{\ϵ}}_t^{v}s}_{\mathrm{hh}}+s_{\mathrm{hv}}+{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^v{s}_{\mathrm{vh}}+{\mathrm{\ϵ}}_r^h{s}_{\mathrm{vv}})---\left(20b\right)$

$m_{\mathrm{vh}}=r_{\mathrm{vv}}{t}_{\mathrm{hh}}({{\mathrm{\ϵ}}_r^{v}s}_{\mathrm{hh}}+{{\mathrm{\ϵ}}_r^v\mathrm{\ϵ}}_t^h{s}_{\mathrm{hv}}+s_{\mathrm{vh}}+{\mathrm{\ϵ}}_t^h{s}_{\mathrm{vv}})---\left(20c\right)$

$m_{\mathrm{vv}}=r_{\mathrm{vv}}{t}_{\mathrm{vv}}({{\mathrm{\ϵ}}_r^v{\mathrm{\ϵ}}_t^{v}s}_{\mathrm{hh}}+{\mathrm{\ϵ}}_r^v{s}_{\mathrm{hv}}+{\mathrm{\ϵ}}_t^v{s}_{\mathrm{vh}}+s_{\mathrm{vv}})---\left(20d\right)$

The parc polarization scattering matrix of formula (19) is brought into formula (20a) respectively to formula (20d), that is, under different rotary angle Parc measure, the measured value obtaining is:

$m_{c2}^{p,\mathrm{hh}}=r_{\mathrm{hh}}\·t_{\mathrm{hh}}\·\mathrm{\β}/\sqrt{2}\·[(1-{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^h)\cos 2{\mathrm{\θ}}_r+({\mathrm{\ϵ}}_r^h+{\mathrm{\ϵ}}_t^h)\sin 2{\mathrm{\θ}}_r+(1+{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^h)]---\left(21a\right)$

$m_{c2}^{p,\mathrm{hv}}=r_{\mathrm{hh}}\·t_{\mathrm{vv}}\·\mathrm{\β}/\sqrt{2}\·[({\mathrm{\ϵ}}_t^v-{\mathrm{\ϵ}}_r^h)\cos 2{\mathrm{\θ}}_r+\left({1+\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^v\right)\sin 2{\mathrm{\θ}}_r+({\mathrm{\ϵ}}_t^v+{\mathrm{\ϵ}}_r^h)]---\left(21b\right)$

$m_{c2}^{p,\mathrm{vh}}=r_{\mathrm{vv}}\·t_{\mathrm{hh}}\·\mathrm{\β}/\sqrt{2}\·[({\mathrm{\ϵ}}_r^v-{\mathrm{\ϵ}}_t^h)\cos 2{\mathrm{\θ}}_r+\left({1+\mathrm{\ϵ}}_r^v{\mathrm{\ϵ}}_t^h\right)\sin 2{\mathrm{\θ}}_r+({\mathrm{\ϵ}}_r^v-{\mathrm{\ϵ}}_t^h)]---\left(21c\right)$

$m_{c2}^{p,\mathrm{vv}}=r_{\mathrm{vv}}\·t_{\mathrm{vv}}\·\mathrm{\β}/\sqrt{2}\·[({\mathrm{\ϵ}}_r^v{\mathrm{\ϵ}}_t^v-1)\cos 2{\mathrm{\θ}}_r+({\mathrm{\ϵ}}_r^v+{\mathrm{\ϵ}}_t^v)\sin 2{\mathrm{\θ}}_r+({\mathrm{\ϵ}}_r^v{\mathrm{\ϵ}}_t^v+1)]---\left(21d\right)$

Taking hh POLARIZATION CHANNEL as a example, the measured value that the parc according to measuring rotation obtainsCarry out Fourier space exhibition Open, have:

$m_{c2}^{p,\mathrm{hh}}=c_{0,\mathrm{hh}}+\underset{n=1}{\overset{+\∞}{\mathrm{\σ}}}(a_{n,\mathrm{hh}}\cos n{\mathrm{\θ}}_r+b_{n,\mathrm{hh}}\sin n{\mathrm{\θ}}_r)---\left(22\right)$

Formula (22) is extracted constant term and 2 rank Fourier coefficients, and is compared with formula (21a), be easy to get:

$a_2=r_{\mathrm{hh}}\·t_{\mathrm{hh}}\·\mathrm{\β}/\sqrt{2}\·(1-{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^h)---\left(23a\right)$

$b_2=r_{\mathrm{hh}}\·t_{\mathrm{hh}}\·\mathrm{\β}/\sqrt{2}\·({\mathrm{\ϵ}}_r^h+{\mathrm{\ϵ}}_t^h)---\left(23b\right)$

$c_0=r_{\mathrm{hh}}\·t_{\mathrm{hh}}\·\mathrm{\β}/\sqrt{2}\·(1+{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^h)---\left(23c\right)$

By unknown quantity a_hh=r_hh·t_hhIt is considered as a unknown quantity, 3 equations of formula (23a), (23b) and (23c) can be constituted Equation group solved, solve 3 unknown quantity a therein_hh,Similarly, to hv, vh, vv POLARIZATION CHANNEL is carried out Fourier expansion and solving equations, can solve remaining unknown quantity a_hv=r_hh·t_vv, a_vh=r_vv·t_hh, a_vv=r_vv· t_vv,

So far, all systematic parameters in polarization measurement error model all solve and obtain, and can carry out pole to target to be calibrated Change calibration.

Assume that target measurement value to be calibrated is $m_t=\left[\begin{array}{cc}{m}_t^{\mathrm{hh}}& m_t^{\mathrm{hv}}\\ m_t^{\mathrm{vh}}& m_t^{\mathrm{vv}}\end{array}\right],$ Understand itself and the true Polarization scattering of target to be calibrated Matrix $s_t=\left[\begin{array}{cc}{s}_t^{\mathrm{hh}}& s_t^{\mathrm{hv}}\\ s_t^{\mathrm{vh}}& s_t^{\mathrm{vv}}\end{array}\right]$ Meet

$\left[\begin{array}{cc}{m}_t^{\mathrm{hh}}& m_t^{\mathrm{hv}}\\ m_t^{\mathrm{vh}}& m_t^{\mathrm{vv}}\end{array}\right]=\left[\begin{array}{cc}{r}_{\mathrm{hh}}& r_{\mathrm{hv}}\\ r_{\mathrm{vh}}& r_{\mathrm{vv}}\end{array}\right]\·\left[\begin{array}{cc}{s}_t^{\mathrm{hh}}& s_t^{\mathrm{hv}}\\ s_t^{\mathrm{vh}}& s_t^{\mathrm{vv}}\end{array}\right]\·\left[\begin{array}{cc}{t}_{\mathrm{hh}}& t_{\mathrm{hv}}\\ t_{\mathrm{vh}}& t_{\mathrm{vv}}\end{array}\right]---\left(24\right)$

Formula (24) is arranged, can obtain:

$s_t^{\mathrm{hh}}=\frac{1}{x}(\frac{m_t^{\mathrm{hh}}}{a_{\mathrm{hh}}}-{\mathrm{\ϵ}}_t^h\frac{m_t^{\mathrm{hv}}}{a_{\mathrm{hv}}}-{\mathrm{\ϵ}}_r^h\frac{m_t^{\mathrm{vh}}}{a_{\mathrm{vh}}}+{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^h\frac{m_t^{\mathrm{vv}}}{a_{\mathrm{vv}}})---\left(25a\right)$

$s_t^{\mathrm{hv}}=\frac{1}{x}(-{\mathrm{\ϵ}}_t^v\frac{m_t^{\mathrm{hh}}}{a_{\mathrm{hh}}}+\frac{m_t^{\mathrm{hv}}}{a_{\mathrm{hv}}}+{\mathrm{\ϵ}}_r^h{\mathrm{\ϵ}}_t^v\frac{m_t^{\mathrm{vh}}}{a_{\mathrm{vh}}}-{\mathrm{\ϵ}}_r^h\frac{m_t^{\mathrm{vv}}}{a_{\mathrm{vv}}})---\left(25b\right)$

$s_t^{\mathrm{vh}}=\frac{1}{x}(-{\mathrm{\ϵ}}_r^v\frac{m_t^{\mathrm{hh}}}{a_{\mathrm{hh}}}+{\mathrm{\ϵ}}_r^v{\mathrm{\ϵ}}_t^h\frac{m_t^{\mathrm{hv}}}{a_{\mathrm{hv}}}+\frac{m_t^{\mathrm{vh}}}{a_{\mathrm{vh}}}-{\mathrm{\ϵ}}_t^h\frac{m_t^{\mathrm{vv}}}{a_{\mathrm{vv}}})---\left(25c\right)$

$s_t^{\mathrm{vv}}=\frac{1}{x}({\mathrm{\ϵ}}_r^v{\mathrm{\ϵ}}_t^v\frac{m_t^{\mathrm{hh}}}{a_{\mathrm{hh}}}-{\mathrm{\ϵ}}_r^v\frac{m_t^{\mathrm{hv}}}{a_{\mathrm{hv}}}-{\mathrm{\ϵ}}_t^v\frac{m_t^{\mathrm{vh}}}{a_{\mathrm{vh}}}+\frac{m_t^{\mathrm{vv}}}{a_{\mathrm{vv}}})---\left(25d\right)$

In formulaCan according to the measured value of the systematic parameter tried to achieve and target to be calibrated, Complete the solution of the true polarization scattering matrix of target to be calibrated by formula (25a) to formula (25d).

Scheme -3:

Forwarding antenna and receiving polarization mode be mutually orthogonal and synchronous rotary.Meet relation all the time:Now, the polarization scattering matrix of parc is:

$s_{c3}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}-\sin 2{\mathrm{\θ}}_t& 1+\cos 2{\mathrm{\θ}}_t\\ \cos 2{\mathrm{\θ}}_t-1& \sin 2{\mathrm{\θ}}_t\end{array}\right]---\left(26\right)$

In this case, its Polarimetric Calibration course of work and the single antenna parc described in document [2] are equivalent, As shown in Figure 4.

Parameter up to 8 in the error model of system, in theory, the data under any three groups different attitude integrations all may be used For Polarimetric Calibration.For example, calculate for convenience, we choose θ_t,1=0 °, θ_t,2=45 °, θ_t,3=90 °, by θ_t,1、θ_t,2、 θ_t,3Bring formula (26) respectively into, then the psm corresponding to each attitude is

$s_{c3,1}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}0& 2\\ 0& 0\end{array}\right]---\left(27a\right)$

$s_{c3,2}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}-1& 1\\ -1& 1\end{array}\right]---\left(27b\right)$

$s_{c3,3}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}0& 0\\ -2& 0\end{array}\right]---\left(27c\right)$

WillSubstitute into formula (9) respectively to launch, have:

$m_{c3,1}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}{2r}_{\mathrm{hh}}\·t_{\mathrm{hh}}\·{\mathrm{\ϵ}}_t^v& 2r_{\mathrm{hh}}\·t_{\mathrm{hh}}\\ 2r_{\mathrm{hh}}\·t_{\mathrm{hh}}\·{\mathrm{\ϵ}}_r^v\·{\mathrm{\ϵ}}_t^v& 2r_{\mathrm{vv}}\·t_{\mathrm{vv}}\·{\mathrm{\ϵ}}_r^v\end{array}\right]---\left(28a\right)$

$m_{c3,2}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}{r}_{\mathrm{hh}}\·t_{\mathrm{hh}}\·({\mathrm{\ϵ}}_t^v-{\mathrm{\ϵ}}_r^h+{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_t^v-1)& r_{\mathrm{hh}}\·t_{\mathrm{vv}}\·({\mathrm{\ϵ}}_r^h-{\mathrm{\ϵ}}_t^h-{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_t^v+1)\\ r_{\mathrm{vv}}\·t_{\mathrm{hh}}\·({\mathrm{\ϵ}}_t^v-{\mathrm{\ϵ}}_r^v+{\mathrm{\ϵ}}_r^v\·{\mathrm{\ϵ}}_t^v-1)& r_{\mathrm{vv}}\·t_{\mathrm{vv}}\·({\mathrm{\ϵ}}_r^v-{\mathrm{\ϵ}}_t^h-{\mathrm{\ϵ}}_r^v\·{\mathrm{\ϵ}}_t^h+1)\end{array}\right]---\left(28b\right)$

$m_{c3,3}^p=\frac{\mathrm{\β}}{\sqrt{2}}\·\left[\begin{array}{cc}-{2r}_{\mathrm{hh}}\·t_{\mathrm{hh}}\·{\mathrm{\ϵ}}_r^h& -2r_{\mathrm{hh}}\·t_{\mathrm{vv}}\·{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_t^h\\ -2r_{\mathrm{vv}}\·t_{\mathrm{hh}}& -2r_{\mathrm{vv}}\·t_{\mathrm{vv}}\·{\mathrm{\ϵ}}_t^h\end{array}\right]---\left(28c\right)$

First element of above three matrix (hh component) is handled as follows:

$\frac{m_{c\mathrm{3,2}}^{p,\mathrm{hh}}}{(-1-{\mathrm{\ϵ}}_r^h+{\mathrm{\ϵ}}_t^v+{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_t^v)}=\frac{m_{c\mathrm{3,1}}^{p,\mathrm{hh}}}{2{\mathrm{\ϵ}}_t^v}\&doublerightarrow;2{\mathrm{\ϵ}}_t^v\·m_{c\mathrm{3,1}}^{p,\mathrm{hh}}=(-1-{\mathrm{\ϵ}}_r^h+{\mathrm{\ϵ}}_t^v+{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_t^v)\·m_{c\mathrm{3,2}}^{p,\mathrm{hh}}---\left(29\right)$

$\frac{m_{c\mathrm{3,1}}^{p,\mathrm{hh}}}{2{\mathrm{\ϵ}}_t^v}=\frac{m_{c\mathrm{3,3}}^{p,\mathrm{hh}}}{-2{\mathrm{\ϵ}}_r^h}\&doublerightarrow;{\mathrm{\ϵ}}_r^h=-\frac{m_{c\mathrm{3,3}}^{p,\mathrm{hh}}}{m_{c\mathrm{3,1}}^{p,\mathrm{hh}}}\·{\mathrm{\ϵ}}_t^v---\left(30\right)$

Formula (30) is substituted into formula (29), arrangement can obtain:

$m_{c\mathrm{3,3}}^{p,\mathrm{hh}}\·{\left({\mathrm{\ϵ}}_t^v\right)}^2+(2m_{c\mathrm{3,2}}^{p,\mathrm{hh}}-m_{c\mathrm{3,3}}^{p,\mathrm{hh}}-m_{c\mathrm{3,1}}^{p,\mathrm{hh}})\·{\mathrm{\ϵ}}_t^v+m_{c\mathrm{3,1}}^{p,\mathrm{hh}}=0---\left(31\right)$

Formula (31) is a quadratic equation with one unknown, and the solution of the equation is:

${\mathrm{\ϵ}}_t^v=\frac{-(2m_{c\mathrm{3,2}}^{p,\mathrm{hh}}-m_{c\mathrm{3,3}}^{p,\mathrm{hh}}-m_{c\mathrm{3,1}}^{p,\mathrm{hh}})\&plusminus;\sqrt{{(2m_{c\mathrm{3,2}}^{p,\mathrm{hh}}-m_{c\mathrm{3,3}}^{p,\mathrm{hh}}-m_{c\mathrm{3,1}}^{p,\mathrm{hh}})}^2-4m_{c\mathrm{3,3}}^{p,\mathrm{hh}}\·m_{c\mathrm{3,1}}^{p,\mathrm{hh}}}}{2m_{c\mathrm{3,3}}^{p,\mathrm{hh}}}---\left(32\right)$

The selection of ' ± ' in formula (32), it then follows so thatPrinciple.

The solution of system other parameters.Can directly be tried to achieve by formula (30)AndSolution can pass through following Two kinds of approach are being solved: (1) passes through similar solutionThe form solving equation solving, such solution procedure is cumbersome； (2) special relationship between using each parameter is being solved.

Here taking solved using second method as a example it is illustrated.

By in formula (28)WithAssociation type (28) can determine that

${\mathrm{\ϵ}}_t^h=\frac{m_{c\mathrm{3,1}}^{p,\mathrm{hh}}\·m_{c\mathrm{3,3}}^{p,\mathrm{hv}}}{m_{c\mathrm{3,3}}^{p,\mathrm{hh}}\·m_{c\mathrm{3,1}}^{p,\mathrm{hv}}}\·\frac{1}{{\mathrm{\ϵ}}_t^v}---\left(33\right)$

By in formula (28)WithAndCan determine that

${\mathrm{\ϵ}}_r^v=-\frac{m_{c\mathrm{3,1}}^{p,\mathrm{vh}}}{m_{c\mathrm{3,3}}^{p,\mathrm{vh}}}\·\frac{1}{{\mathrm{\ϵ}}_t^v}---\left(34\right)$

And

$r_{\mathrm{hh}}\·t_{\mathrm{hh}}=\frac{m_{c\mathrm{3,1}}^{p,\mathrm{hh}}}{2{\mathrm{\ϵ}}_t^v}---\left(35a\right)$

$r_{\mathrm{hh}}\·t_{\mathrm{vv}}=\frac{2m_{c\mathrm{3,1}}^{p,\mathrm{hv}}}{\sqrt{\frac{\mathrm{\σ}}{\mathrm{\π}}}}---\left(35b\right)$

$r_{\mathrm{vv}}\·t_{\mathrm{hh}}=\frac{m_{c\mathrm{3,1}}^{p,\mathrm{hh}}}{2{\mathrm{\ϵ}}_t^v\·{\mathrm{\ϵ}}_r^v}---\left(35c\right)$

$r_{\mathrm{vv}}\·t_{\mathrm{vv}}=\frac{m_{c\mathrm{3,1}}^{p,\mathrm{hh}}}{2{\mathrm{\ϵ}}_r^v}---\left(35d\right)$

So far, all calibration parameters of system are all obtained, can achieve the school to target arbitrarily to be calibrated by formula (18) Quasi- work.

Except three examples enumerated above, parc sending and receiving antenna can also have other various combinations, thus can obtain More multi-form polarization scattering matrix is used for Polarimetric Calibration, does not enumerate herein.

The implementation process of the present invention and applicating example are described below:

For further illustrating the bparc being proposed using this invention how concrete application in Polarimetric Calibration, now more than As a example stating scheme -2, implementation process is described.Using its measurement and calibration process all fours during other schemes.

Measurement and Polarimetric Calibration process step are as follows:

Step -1:bparc device adjustment

Adjust the sight line rotating mechanism of bparc reception antenna and forwarding antenna so that the initial polarization angle of two antennas is adjusted For consistent, and control the rotating speed of two rotating mechanisms, make dual-mode antenna keep the same rotating speed w_r(w_r=w_t, unit rad/s) at the uniform velocity Rotation, being polarized with the dual-mode antenna ensureing bparc in whole measurement process is on all four all the time.For this reason, rotating mechanism Can be using stepper motor it is ensured that antenna stop when often going to an angle, one group of data of radar surveying, then control antenna to go to Next Angle Position, such Repetitive controller and measurement, you can the polarization of guarantee dual-mode antenna is synchronous change.

Angular encoder accurately records the angle γ that antenna turns over, then the number of turns that bparc turns over can by n=γ/ 360 ° calculate.In measurement, bparc double antenna can be controlled to carry out the measurement of whole circle, this ensure that initial polarization angle Choosing does not affect on whole calibration process.

The installation of step -2:bparc device

Bparc Polarimetric Calibration device proposed by the invention is installed on calibration support, peace is according to instrumentation radar system Require to adjust its delay parameter.

For the dual station angle of current bistatic measurement, control azimuth turntable, bparc reception antenna is made to be directed at sending out of instrumentation radar Penetrate antenna, bparc forwarding antenna is directed at the reception antenna of instrumentation radar, as shown in Figure 10.When changing measurement dual station angle every time, all This step need to be repeated.

Step -3: Polarimetric Calibration measurement data admission

Maintain adjusted good azimuth rotating platform position to maintain static, control the sight line rotating mechanism of bparc, make bparc's Two antennas at the uniform velocity rotate at a slow speed it is assumed that corotation crosses n circle.Instrumentation radar transmission signal simultaneously receives the radiation of bparc forwarding antenna Echo-signal, under admission bparc antenna diverse location in instrumentation radar sight line rotary course, all the echo of POLARIZATION CHANNEL is believed Number, the whole psm measurement data obtaining are designated as

Step -4: Polarimetric Calibration parameter extraction

WillEach polarization components apply Fourier space to be launched respectively, have

$m_{c2}^{p,\mathrm{wv}}=c_{0,\mathrm{wv}}+\underset{n=1}{\overset{+\∞}{\mathrm{\σ}}}(a_{n,\mathrm{wv}}\cos n{\mathrm{\θ}}_r+b_{n,\mathrm{wv}}\sin n{\mathrm{\θ}}_r)---\left(36\right)$

Wherein wv represents all of polarized state, extracts constant term and 2 rank term coefficient, convolution (21), makes respective items Coefficient is equal, can try to achieve whole Polarimetric Calibration parameters of instrumentation radar system according to process described in aforementioned schemes -2；

Step -5: target dual station polarization measurement

Target to be measured is installed, and the target echo of all POLARIZATION CHANNEL is enrolled it is assumed that its psm measures by bistatic measurement radar It is worth for m_t；

Step -6: Polarimetric Calibration is processed

According to the target psm measured value recording in the Polarimetric Calibration parameter having obtained in step -4 and step -5, applying equation (18) Polarimetric Calibration of surveyed target can be completed, obtain true psm value s of target_t.

The measurement of dual station rcs only need to be done and calibrate if noticed, above-mentioned 6 steps can simplify further it is not necessary to carry Take Polarimetric Calibration parameter, only need to measure according to the dual station calibration equation given by formula (2) and calibrate calculating with rcs, wherein The theoretical rcs value of bparcStill calculated by formula (8), scaling constant k_bCalculating then according to bistatic measurement geometrical relationship by formula (3) Complete.Do not repeat.

In addition, other replacement schemes of the present invention are described below:

(1) electromagnetic horn that in this invention, parc is used also can be substituted by other kinds of linear polarized antenna；

(2) the dual-mode antenna polarization combination in this invention has infinitely multiple, can be designed according to different polarization combination Go out different Polarimetric Calibration measurement scheme and Polarimetric Calibration parameter extraction algorithm, 3 kinds of schemes that being not limited to has illustrated points out.

The techniques well known being related in the present invention does not elaborate.

Claims (6)

1. one kind can be used for target Bistatic RCS measurement calibration with Polarimetric Calibration device it is characterised in that: this device Drive and controller, sight line rotation including reception antenna, transmitting antenna, two orientation-sight line dual-axis rotation units, orientation rotations Drive and controller, radio frequency combining and power source combination, wherein:

Described reception antenna, for receiving the radiation signal of bistatic measurement transmitting radar antenna, is fed radio frequency by radio-frequency cable Combination；

Described radio frequency combining: it includes amplifier, wave filter, delay line and the attenuator being sequentially connected, and it completes to described Reception antenna received the amplification of bistatic measurement radar emission signal, filtering, obtain output signal after delay process, and warp After attenuator is to output signal level regulation, fed transmitting antenna by radio-frequency cable；

Described transmitting antenna, for completing radiofrequency signal to the radiation of bistatic measurement radar receiving antenna；

Two described orientation-sight line dual-axis rotation unit:, for placing described reception antenna, another is used for for one of them Place described transmitting antenna；

Described orientation rotation drives and controller: for controlling described orientation-sight line dual-axis rotation unit around orientation Rotate；

Described sight line rotation driving and controller: for controlling described orientation-sight line dual-axis rotation unit around sight line axle Rotate；

Described power source combination: for the power supply supply of this device.

2. one kind according to claim 1 can be used for the measurement calibration of target Bistatic RCS and Polarimetric Calibration dress Put it is characterised in that: described reception antenna and described transmitting antenna are respectively made up of an electromagnetic horn, meanwhile, in order to the greatest extent Antenna cross-polarization coupling error may be reduced, improve polarization isolation ratio, install micro-strip polarization filtering at each Antenna aperture additional Device device, each electromagnetic horn is installed on an orientation-sight line dual-axis rotation unit carrying angular coding, is revolved by orientation Turning to drive controls each antenna can rotate and around side independently about radar line of sight with controller and sight line rotation driving with controller Position rotates, and the orientation with angular coding-sight line dual-axis rotation unit can provide sight line corner and the orientation corner of antenna simultaneously Precise position information.

3. one kind according to claim 1 can be used for the measurement calibration of target Bistatic RCS and Polarimetric Calibration dress Put it is characterised in that: described orientation-sight line dual-axis rotation unit: main by sight line rotaty step motor, sight angle coding Device, azimuth rotating platform, orientation angles encoder and between antenna Matching installation interface composition；Wherein " sight line " means dual station Line between instrumentation radar emitter and reception antenna or between bistatic measurement radar receiver and transmitting antenna；" orientation " When meaning that instrumentation radar is set up in xoy plane, corner in xoy plane, rotated by sight line and drive control device, permissible Accurately control each antenna in real time around the rotary speed of radar antenna sight line and angle position, by orientation rotation with drive control Device processed, can accurately control each antenna in real time around the rotary speed of azimuthal plane radar antenna sight line and angle position, Under in working order, EM scattering measurement rcs calibration is turned in orientation respectively with the reception of Polarimetric Calibration device and transmitting antenna Move the transmitter and receiver antenna of be aligned bistatic measurement radar.

4. one kind according to claim 3 can be used for the measurement calibration of target Bistatic RCS and Polarimetric Calibration dress Put it is characterised in that: described orientation rotation drives and controller, by control azimuth turntable, completes to reception antenna and sends out Penetrate the rotation in orientation for the antenna, and provide the position of orientation information of each antenna by azimuth angular encoders, orientation rotation drives Dynamic and controller can be by RCI by EM scattering measuring system controller remotely control.

5. one kind according to claim 3 can be used for the measurement calibration of target Bistatic RCS and Polarimetric Calibration dress Put it is characterised in that: described sight line rotation driving and controller: by control sight line electric rotating machine, complete to reception antenna With transmitting antenna around the rotation of sight line axle, and provide the sight line angle position information of each antenna by sight line angular encoder, depending on Line rotation driving can be by RCI by EM scattering measuring system controller remotely control with controller.

6. one kind can be used for target Bistatic RCS measurement calibration steps, according to any one of Claims 1 to 5 Can be used for target Bistatic RCS measurement calibration with Polarimetric Calibration device it is characterised in that: bistatic measurement and calibration The method and steps processing is as follows:

Step -1:bparc device adjustment, comprising:

The sight line rotating mechanism adjusting bparc reception antenna with transmitting antenna is so that the initial polarization angle of two antennas is adjusted to one Cause, and control the rotating speed of two rotating mechanisms, make dual-mode antenna keep the same rotating speed w_rAt the uniform velocity rotate, wherein w_r=w_t, w_rFor connecing Receive the rotating speed of antenna, w_tFor the rotating speed of transmitting antenna, unit rad/s, to ensure the transmitting-receiving sky of bparc in whole measurement process Linear polarization is on all four all the time, for this reason, rotating mechanism can be using stepper motor it is ensured that antenna stops when often going to an angle Under, one group of data of radar surveying, then control antenna to go to next Angle Position, such Repetitive controller and measurement, you can to ensure The polarization of dual-mode antenna is synchronous change；Wherein measurement calibration is referred to as bparc with Polarimetric Calibration device；

Angular encoder accurately records the angle γ that antenna turns over, then the number of turns that bparc turns over is calculated by n=γ/360 ° Draw, in measurement, bparc double antenna can be controlled to carry out the measurement of whole circle, the selection that this ensure that initial polarization angle is to whole Individual calibration process does not affect；

The installation of step -2:bparc device, comprising:

The bparc being proposed Polarimetric Calibration device is installed on calibration support, the requirement according to instrumentation radar system adjusts it Delay parameter；

For the dual station angle of the bistatic measurement currently giving, control azimuth turntable, bparc reception antenna is made to be directed at instrumentation radar Transmitting antenna, bparc transmitting antenna is directed at the reception antenna of instrumentation radar, when changing measurement dual station angle every time, is both needed to repeat this Bparc installation steps；

Step -3: Polarimetric Calibration measurement data admission:

Maintain and maintain static according to the azimuth rotating platform position that given measurement dual station angle regulates, control the sight line rotation of bparc Mechanism, makes two antennas of bparc at the uniform velocity rotate at a slow speed it is assumed that corotation crosses n circle, instrumentation radar transmission signal simultaneously receives bparc The echo-signal of transmitting antenna radiation, whole poles under admission bparc antenna diverse location in instrumentation radar sight line rotary course Change the echo-signal of passage, obtain whole measurement data；

When changing measurement dual station angle every time, it is both needed to repeat this bparc measurement data recording step；

Step -4: Polarimetric Calibration parameter extraction:

Solve the whole Polarimetric Calibration parameters obtaining instrumentation radar system by the measurement data in step -3；

When changing measurement dual station angle every time, it is both needed to solve instrumentation radar system using to the bparc measurement data under this dual station angle Calibration parameter；

Step -5: target dual station polarization measurement:

Target to be measured is installed, and is enrolled the target echo of all POLARIZATION CHANNEL by bistatic measurement radar；

Under same dual station angle, bistatic measurement can be carried out to multiple identical or different targets using identical instrumentation radar；

Step -6: Polarimetric Calibration is processed

According to the target measurement value recording in the Polarimetric Calibration parameter having obtained in step -4 and step -5, applying equation (6-1) is i.e. The Polarimetric Calibration of surveyed target can be completed, obtain the true polarization scattering matrix value of target；

$s_t=\frac{1}{(1-{\mathrm{\ϵ}}_r^h\·{\mathrm{\ϵ}}_r^v)}\·\frac{1}{(1-{\mathrm{\ϵ}}_t^h\·{\mathrm{\ϵ}}_t^v)}\·\left[\begin{array}{cc}1& -{\mathrm{\ϵ}}_r^h\\ -{\mathrm{\ϵ}}_r^v& 1\end{array}\right]\·\left[\begin{array}{cc}\frac{m_t^{hh}}{r_{hh}\·t_{hh}}& \frac{m_t^{hv}}{r_{hh}\·t_{vv}}\\ \frac{m_t^{vh}}{r_{vv}\·t_{hh}}& \frac{m_t^{vv}}{r_{vv}\·t_{vv}}\end{array}\right]\·\left[\begin{array}{cc}1& -{\mathrm{\ϵ}}_t^h\\ -{\mathrm{\ϵ}}_t^v& 1\end{array}\right]---(6-1)$

In formulaFor the measured value under 4 polarization combination of target to be calibrated；s_tTrue for target to be calibrated Polarization scattering matrix；r_hhAnd r_vvIt is respectively the gain factor of the polarization of measuring system hh and vv polarization reception passage, t_hhAnd t_vvRespectively For measuring system hh polarization and vv polar transmitter passage gain factor,Cross-pole for measuring system Change the factor, this 8 parameters are to need by -5 pairs of bparc measurements of step -1～step and measurement data is processed to solve Measuring system Polarimetric Calibration parameter；

Under same dual station angle, when bistatic measurement is carried out to multiple identical or different targets using identical instrumentation radar, Ke Yiyong Same group of calibration parameter carries out Polarimetric Calibration process；

If only doing the measurement of dual station rcs and calibrating, above-mentioned 6 steps simplify it is not necessary to extract Polarimetric Calibration parameter further, Only need to measure to calibrate with rcs according to the dual station calibration equation given by formula (6-2) and calculate,

${\mathrm{\σ}}_t^b=k_b\·\frac{p_{rt}}{p_{rc}}\·{\mathrm{\σ}}_c^b=k_b\·|\frac{s_t}{s_c}{|}^2\·{\mathrm{\σ}}_c^b---(6-2)$

In formulaFor target dual station rcs,Theoretical dual station rcs for bparc；p_rcAnd p_rtIt is respectively and measure standard type and survey target The echo power that Shi Leida receives；s_tAnd s_cIt is respectively in single rcs measurement sampling, when measurement target and measurement calibration body The multiple echo-signal of radar；k_bIt is the corresponding scaling constant of same bistatic measurement geometrical relationship；

The theoretical dual station rcs value of bparcComputing formula is；

${\mathrm{\σ}}_c^b=g_{loop}\·\frac{g_t\·g_r\·{\mathrm{\λ}}^2}{4\mathrm{\π}}---(6-3)$

In formula, g_tAnd g_rIt is respectively the gain of bparc transmitting antenna and reception antenna, g_loopFor in bparc in addition to antenna, entirely The overall gain in loop, λ is radar operation wavelength；The theoretical rcs value of bparc also can be by using fixed known to another rcs value The method that standard type is measured by relative calibration is recording；

With the corresponding scaling constant k of bistatic measurement geometrical relationship_bCalculating then according to bistatic measurement geometrical relationship by formula (6-4) Complete:

$k_b={\left(\frac{r_{tt}{r}_{rt}}{r_{tc}{r}_{rc}}\right)}^2\·\frac{l_{tt}{l}_{rt}}{l_{tc}{l}_{rc}}---(6-4)$

R in formula_ttAnd r_tcRepresent target range and the calibration body distance of transmission channel respectively；r_rtAnd r_rcRepresent receiving channel respectively Target range and calibration body distance；l_ttAnd l_tcRepresent the total losses of transmission channel when surveying target and measuring standard type respectively；l_rtWith l_rcRepresent the total losses of receiving channel when surveying target and measuring standard type respectively；As long as target range and calibration body distance are in test Determine, dual station geometrical relationship keeps constant, then k_bThe constant that value is to determine.