CN102013576A - Regulating method of secondary surface of modified Cassegrain type antenna - Google Patents

Abstract

The invention discloses a regulating method of the secondary surface of a modified Cassegrain type antenna, mainly solving the problem that the traditional method carries out approximate regulation only along an axial direction or a radial direction. The regulating method comprises the following steps of: carrying out segmented parabola fitting on generatrix discrete points of the primary surface of the modified Cassegrain type antenna to obtain a group of segmented standard parabolas; rotating the fitted parabola around a common axis for a round to obtain a group of parabolic tori; establishing an optimized mathematical model to calculate segmented fit parameters by taking that a root-mean-square value of the z direction deviation of nodes of the primary surface relative to the parabolic tori is minimum as a target and ensuring that the parabolic tori meet a confocal axis and the length of a focal line is not longer than that of an initial focal line; and calculating the regulating amount of two endpoints of the focal line according to focal length variation amount and vertex coordinates which are included in the fit parameters to direct the regulation of the secondary surface of the modified Cassegrain type antenna. The invention has the advantages of accurately positioning the secondary surface under multiple working conditions and enhancing the electrical property of the modified Cassegrain type antenna and can be used for regulating the secondary surface of the modified Cassegrain type antenna, thereby enhancing the electrical property of the modified Cassegrain type antenna.

Description

The secondary face method of adjustment of correction type Cassegrain formula antenna

Technical field

The invention belongs to antenna technical field, relate to the adjustment of antenna, particularly a kind of secondary face method of adjustment to correction type Cassegrain formula antenna is used to instruct the secondary face adjustment of cassette dual reflector antenna, to reduce the influence of interarea distortion to antenna electric performance.

Background technology

Correction type Cassegrain formula antenna leaks with its illumination efficiency height and edge penetrates advantages such as low, is widely used in a plurality of fields such as radar tracking, satellite communication, survey of deep space in recent years.The interarea of this type of dual reflector antenna and secondary face all are to revise curved surface, and the purpose of doing like this is that the amplitude of primary reflection surface aperture field and phase place are evenly distributed, to improve the electrical efficiency of antenna.The interarea precision of dual reflector antenna is having a strong impact on the electrical performance indexes of antenna.The effect of multiple load such as antenna structure can be conducted oneself with dignity, wind lotus, sleet makes primary reflection surface deform, and surface accuracy reduces, thereby causes the electrical property variation of antenna, and along with the change at the antenna work elevation angle, this influence also can change thereupon.

German scholar S.von Hoerner has provided the thought of guarantor's type design, can reduce the distortion of antenna interarea to a certain extent, but can't eliminate fully.Though the piecemeal panel on the antenna interarea can be done the adjustment of trace, also can improve the deviation that the back frame structure distortion is brought, degree is limited.By the moving sets face, change the relative position relation between the major-minor face, thus but the phase deviation that the distortion of cancellation part interarea forms at actinal surface.For example, the U.S.'s 100 meters GBT radio telescopes antenna has adopted adjustable secondary face, with the influence of compensation interarea distortion to electrical property.

At present, the secondary face method of adjustment of the most frequently used at home and abroad dual reflector antenna has following several:

(1) select test antenna test antenna electrical property under the operating mode of the different elevations angle for use, extrapolate the axial deviation of secondary face, test data is carried out curve fitting obtains the approximation relation that secondary over glaze changes with the elevation angle to deviation.Utilize finite element software to calculate the radial missing of the secondary face in the different elevations angle.Adjust secondary face position at certain work elevation angle by axial deviation and the radial missing of calculating gained.As at C.N.Guiar, L.W.Duff.64m Antenna Automatic Subreflector Focusing Controller.NASA JPL, TDA Progress Report 42-78 is exactly this kind method of adjustment that adopts among the April1984.

(2) according to the design principle of shaped aerial, use Image Synthesis by Ray Tracing, secondary face is adjusted a certain value vertically make interarea bore face satisfy the aplanatism condition, thereby adopt least square method to calculate the axial adjustment amount of secondary face.This method is reported in " Northwest Inst. of Telecommunication Engineering journal " the 1st phase in 1981 " guarantor's type of revising the curved surface antenna designs " (leaf Shang Huizhu) document to some extent.

(3) use the distortion that testing equipment such as laser tracker detects the antenna interareas, the distortion interarea is carried out standard is parabolic coincide, obtain the focus of best matching surface,, determine the position of secondary face according to the matching relationship of interarea and secondary face.This kind method is that the paraboloidal situation of standard is proper for antenna main reflector, and then error is bigger for correction type interarea.As B.Nikolic, R.M.Prestage.Out-of-focus holography at theGreen Bank Telescope.A﹠amp; A, 465:685-693, what adopt in 2007 is exactly this method of adjustment.

Secondary face adjustment for correction type Cassegrain antenna, existing method just in axial direction or radial direction be similar to adjustment, in fact antenna is located secondary face at the different elevations angle not only radial and axial translation, also have the rotation around reference axis, the actinal surface phase error that this type of secondary face rotation causes can have a strong impact on the electrical property of antenna.Along with the increase of antenna aperture and the raising of operating frequency, various load cause not good one of the greatest factor that influences antenna electric performance that becomes of antenna interarea and secondary face coupling, and the adjustment problem of secondary face position also can be more outstanding.

Summary of the invention

The objective of the invention is to avoid above-mentioned the deficiencies in the prior art, a kind of secondary face method of adjustment of revising the type Cassegrain antenna is provided, under the situation of considering secondary face translation and rotation at the same time, realize the accurate location of the secondary face of antenna, thereby reduce the influence of interarea distortion antenna electric performance by secondary face position compensation.

The technical scheme that realizes the object of the invention is, based on the theoretical bus discrete points data of antenna interarea, select one group of standard parabolic torus to remove to approach the distortion node, under guaranteeing, pass through to optimize the best parameter of coincideing of calculated with mathematical model segmentation with the situation of focal axis constraint, calculate the side-play amount of focal line two-end-point, thereby the position adjustment to secondary face quantizes to instruct, and concrete steps are as follows:

(1) M discrete points data with the theoretical bus of correction type Cassegrain formula antenna interarea is divided into the N section, N-1 section discrete counted identical before guaranteeing, and every section discrete counting is [M-M% (N-1)]/N on the preceding N-1 section, discrete the counting of N section is [M-M% (N-1)]/N+M% (N-1), and wherein population variance is counted M much larger than hop count N;

(2) the N section discrete points data of dividing is carried out the parabola match piecemeal, get the parabola of fit of N section discrete points data;

(3) according to the focal distance f of parabola of fit _nWith apex coordinate Δ H _n, calculate its focus region scope, promptly initial focal line length:

ΔF ₀＝max(f _n-ΔH _n)-min(f _n-ΔH _n)(n＝1，2，...，N)；

(4) set up the optimization Mathematical Modeling and seek the identical Parameter H of segmentation:

(4a) earlier N section parabola of fit is rotated a circle around its public focal axis, obtain one group of parabolic torus, parabolic torus is carried out projection with the interarea node, reject the parabolic torus that does not contain subpoint, again the parabolic torus group integral body of choosing is rotated respectively around x axle and y axle

With Angle is calculated the node z that produces because of rotation to deviation delta z ₁:

In the formula, x _Ji, y _JiBe the x coordinate and the y coordinate of i subpoint on j the parabolic torus;

(4b) with the parabolic torus group along three translation of axes amount Δ x, Δ y and Δ z, the node coordinate deviation that produces of translation as a whole;

(4c) direction vector of calculating parabolic torus group common axis:

(4d), calculate the node coordinate deviation that parabolic torus is produced along the focal axis translation according to the direction vector of common axis:

$\left[\begin{array}{ccc}{\mathrm{\Δx}}_{t_j}& {\mathrm{\Δy}}_{t_j}& {\mathrm{\Δz}}_{t_j}\end{array}\right]={}_{}\left[\begin{array}{ccc}{\mathrm{mt}}_j& {\mathrm{nt}}_j& {\mathrm{pt}}_j\end{array}\right];$

(4e) according to the whole rotation of parabolic torus group, integral translation and the node coordinate deviation that produces along the focal axis translation, calculate interarea distortion node with respect to the z of best matching surface root-mean-square value rms to deviation:

In the formula, z ' _JiIt is the z coordinate of i the corresponding interarea distortion of subpoint node on j the parabolic torus;

Be the anglec of rotation of antenna parabolic torus group around x axle and y axle,

t _jBe the translational movement of j parabolic torus of antenna along focal axis,

K is the antenna parabolic torus number of choosing,

D _jBe j the node number on the antenna parabolic torus,

Nod is an antenna interarea node sum;

(4f) guaranteeing the confocal axle of each standard parabolic torus, and focal line length is not more than initial focal line length Δ F ₀Prerequisite under, according to the criterion of root-mean-square value rms minimum, set up following optimization Mathematical Modeling and seek the segmentation Parameter H of coincideing:

In the formula, Δ f ₁, Δ f ₂..., Δ f _KBe the focal length variations amount of each parabolic torus of antenna,

t ₁, t ₂..., t _KBe the translational movement of each parabolic torus of antenna along focal axis,

Be the position vector of identical preceding j parabolic torus focus,

Be the position vector of j parabolic torus focus after coincideing,

T _jIt is the transformation matrix of matching surface focus;

(5), calculate the actual coordinate of each focus after the secondary face adjustment according to segmentation each the focal length variations amount in the Parameter H of coincideing

(6) extract focal line two-end-point coordinate, calculate focal line near-end adjustment amount d respectively ₁With far-end adjustment amount d ₂Parameter as the position adjustment of the secondary face of guidance:

${\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HSA00000280526700022.png"\; state="\{\{state\}\}">d</figure-callout>}}_1=\min (x_j^{\mathrm{FR}},y_j^{\mathrm{FR}},z_j^{\mathrm{FR}})-\min (x_j^{\mathrm{FO}},y_j^{\mathrm{FO}},x_j^{\mathrm{FO}})(j=\mathrm{1,2},...,K)$

$d_2=\max (x_j^{\mathrm{FR}},y_j^{\mathrm{FR}},z_j^{\mathrm{FR}})-\max (x_j^{\mathrm{FO}},y_j^{\mathrm{FO}},x_j^{\mathrm{FO}})(j=\mathrm{1,2},...,K).$

The present invention has following advantage:

1) the present invention carries out the sectional parabola match owing to will revise Cassegrain antenna interarea bus discrete data, and the mathematic(al) representation of the interarea bus that obtains is accurate;

2) the present invention provides a plane of reference accurately because piecewise fitting parabola is obtained one group of parabolic torus around public focal axis by rotating a circle for interarea is out of shape node;

3) the present invention rejects the parabola that does not contain subpoint because parabolic torus is carried out projection with the interarea node, has reduced unnecessary computational process;

4) the present invention rotates through integral translation, integral body owing to the parabolic torus group that will choose and removes to approach interarea distortion node along the common axis translation, has considered the influencing factor of secondary face position comprehensively;

5) the present invention is out of shape the identical parameter of segmentation of node owing to utilize optimization method to calculate the parabolic torus group with respect to interarea, thereby has guaranteed the optimum matching relation of secondary face and interarea;

6) the present invention accurately locatees secondary face owing to each focal length variations amount in the parameter of coincideing according to segmentation is calculated the adjustment amount parameter of secondary face focal line, has finally reduced the influence of interarea distortion to antenna electric performance.L-G simulation test proves, can improve the positional precision of secondary face and the electrical property of antenna with method of the present invention.

Description of drawings

Fig. 1 is that the secondary face of antenna of the present invention is adjusted flow chart;

Fig. 2 is an antenna interarea bus discrete points data piecewise fitting schematic diagram of the present invention;

Fig. 3 is the identical schematic diagram of antenna interarea distortion segmentation parabolic torus of the present invention;

Fig. 4 is existing antenna geometric parameter schematic diagram;

Fig. 5 is existing antenna interarea back frame structure FEM (finite element) model;

Fig. 6 is that the present invention rejects unnecessary parabolic torus schematic diagram;

Fig. 7 is existing antenna interarea back of the body frame distortion node distribution map;

Fig. 8 is that the secondary face of l-G simulation test of the present invention is adjusted schematic diagram.

Embodiment

Followingly the present invention is described in further detail with reference to accompanying drawing.

The matching precision of revising cassette antenna major-minor face is restricting the electrical property of antenna, and various load cause the interarea distortion, and secondary face need be adjusted to suitable position could offset the influence that the interarea distortion brings electrical the subject of knowledge and the object of knowledge.The distortion of antenna interarea can obtain by finite element analysis software, because the rigidity of interarea panel contribution is limited, generally only sets up the back frame structure model, and the distortion situation of analyzing its node that winds up replaces describing the distortion of interarea node.The present invention at first carries out the sectional parabola match to revising the theoretical bus discrete points data of cassette dual reflector antenna interarea, uses least square method and obtains one group of standard parabola to describe the theoretical bus of interarea; Piecewise fitting parabola rotated a circle around common axis obtains one group of parabolic torus, with this parabolic torus group interarea distortion node that goes to coincide; Is target with respect to standard parabolic torus z to the root-mean-square value minimum of deviation to be out of shape node, and each standard parabolic torus of while satisfies confocal axle and focal line length is not more than initial focal line length, sets up and optimizes the identical parameter of calculated with mathematical model segmentation; Calculate focal line two-end-point side-play amount according to focal length in the identical parameter of the best and apex coordinate, thereby instruct the adjustment of secondary face, adjustment process as shown in Figure 1.

With reference to Fig. 1, concrete adjustment process of the present invention is as follows:

The first step, with reference to Fig. 2, M discrete points data of the theoretical bus of correction type Cassegrain formula antenna interarea is divided into the N section, N-1 section discrete counted identical before guaranteeing, in order to make piecewise fitting parabola continuous, set two adjacent segment and have a common point, every section discrete counting is [M-M% (N-1)]/N on the then preceding N-1 section, and discrete the counting of N section is [M-M% (N-1)]/N+M% (N-1).

In second step, the N section discrete data of dividing is carried out the sectional parabola match.

2.1) equation of establishing n section parabola of fit is:

$r_n^2={4f}_n(z_n+{\mathrm{\&Delta;H}}_n)(n=\mathrm{1,2},...,N)---<1>$

In the formula, f _nBe the focal length of n section parabola of fit,

Δ H _nIt is the apex coordinate of n section parabola of fit;

2.2) calculate parabola of fit with respect to the z of discrete points data root-mean-square value σ to deviation:

$\mathrm{\&sigma;}=\sqrt{\frac{\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{D_n}{\mathrm{\&Sigma;}}}{(\frac{r_{\mathrm{ni}}^2}{{4f}_n}-z_{\mathrm{ni}}^{\&prime;}-{\mathrm{\&Delta;H}}_n)}^2}{M}}---<2>$

In the formula, D _nBe discrete the counting on the n section parabola of fit,

Z ' _NiThe z that is i discrete point on the n section is to coordinate;

2.3) according to root-mean-square value σ, find the solution the Optimization Model shown in the following formula, obtain the focal distance f of N section parabola of fit ₁, f ₂..., f _NWith apex coordinate Δ H ₁, Δ H ₂..., Δ H _N:

$\left\{\begin{array}{c}\mathrm{Find}(N,{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000280526700022.png"\; state="\{\{state\}\}">f</figure-callout>}}_1,f_2,...,f_N,{\mathrm{\&Delta;<figure-callout\; id="1"\; label="H"\; filenames="HSA00000280526700022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1,{\mathrm{\&Delta;H}}_2,...,{\mathrm{\&Delta;H}}_N)\\ \mathrm{Min\&sigma;}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{D_n}{\mathrm{\&Sigma;}}}{(\frac{r_{\mathrm{ni}}^2}{{4f}_n}-z_{\mathrm{ni}}^{\&prime;}-{\mathrm{\&Delta;H}}_n)}^2}{M}}\\ s.t.N\&le;M-1\&pound;\&not;\\ f_n>0,(n=\mathrm{1,2},...,N)\end{array}\right.---<3>$

2.4) with focal distance f ₁, f ₁..., f _NWith apex coordinate Δ H ₁, Δ H ₂..., Δ H _NBring into＜1 in parabolic equation, promptly get the parabola of fit of N section discrete points data.

In the 3rd step, according to the focal length and the apex coordinate of N section parabola of fit, calculate its focus region scope, promptly initial focal line length:

ΔF ₀＝max(f _n-ΔH _n)-min(f _n-ΔH _n)(n＝1，2，...，N)。<4>

In the 4th step, generate the parabolic torus group that is used for identical interarea node.

4.1) N section parabola of fit is rotated a circle around its public focal axis, obtain a set of segmentation standard parabolic torus, keep their focal length consistent with the focal length and the apex coordinate of aforementioned parabola of fit with apex coordinate;

4.2) use Ansys software and set up the antenna FEM (finite element) model, carry out static analysis, obtain antenna interarea distortion node data;

4.3) with reference to Fig. 6, interarea is out of shape node projects on the segmentation criteria parabolic torus, reject the unnecessary anchor ring that does not contain subpoint, utilize the standard parabolic torus group of choosing to remove identical interarea distortion node data;

4.4) the given antenna work elevation angle, generate and wait to coincide interarea distortion node data.

The 5th step, the identical parameter of the best of calculating segmentation parabolic torus group.

With reference to Fig. 3, being implemented as follows of this step:

5.1) parabolic torus group integral body is rotated respectively around x axle and y axle

With

Angle is calculated the node z that produces because of rotation to deviation delta z ₁:

In the formula, x _Ji, y _JiBe the x coordinate and the y coordinate of i subpoint on j the parabolic torus;

5.2) with the parabolic torus group along three translation of axes amount Δ x, Δ y and Δ z, the node coordinate deviation that produces of translation as a whole;

5.3) calculate the direction vector of parabolic torus group common axis:

5.4) according to the direction vector of common axis, calculate the node coordinate deviation that parabolic torus is produced along the focal axis translation:

$\left[\begin{array}{ccc}{\mathrm{\&Delta;x}}_{t_j}& {\mathrm{\&Delta;y}}_{t_j}& {\mathrm{\&Delta;z}}_{t_j}\end{array}\right]={}_{}\left[\begin{array}{ccc}{\mathrm{mt}}_j& {\mathrm{nt}}_j& {\mathrm{pt}}_j\end{array}\right]---<7>$

In the formula, t _jBe the translational movement of j parabolic torus along focal axis;

5.5) according to the whole rotation of parabolic torus group, integral translation and the node coordinate deviation that produces along the focal axis translation, calculate interarea distortion node with respect to the z of best matching surface root-mean-square value rms to deviation:

In the formula, z ' _JiBe the z coordinate of i the corresponding interarea distortion of subpoint node on j the parabolic torus,

Be the anglec of rotation of antenna parabolic torus group around x axle and y axle,

t _jBe the translational movement of j parabolic torus of antenna along focal axis,

K is the antenna parabolic torus number of choosing,

D _jBe j the node number on the antenna parabolic torus,

Nod is an antenna interarea node sum;

5.6) guaranteeing the confocal axle of each standard parabolic torus, and focal line length is not more than initial focal line length Δ F ₀Prerequisite under, according to the criterion of root-mean-square value rms minimum, set up following optimization Mathematical Modeling and seek the segmentation Parameter H of coincideing:

In the formula, Δ f ₁, Δ f ₂..., Δ f _KBe the focal length variations amount of each parabolic torus of antenna,

t ₁, t ₂..., t _KBe the translational movement of each parabolic torus of antenna along focal axis,

Be the position vector of identical preceding j parabolic torus focus,

Be the position vector of j parabolic torus focus after coincideing,

T _jIt is the transformation matrix of matching surface focus.

In the 6th step,, calculate the actual coordinate of each focus after the secondary face adjustment according to segmentation each the focal length variations amount in the Parameter H of coincideing

In the formula,

It is the focus original coordinates of parabolic torus before secondary face is adjusted.

The 7th step, with reference to Fig. 8, extract focal line two-end-point coordinate, calculate focal line near-end adjustment amount d respectively ₁With far-end adjustment amount d ₂Parameter as the position adjustment of the secondary face of guidance:

${\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HSA00000280526700022.png"\; state="\{\{state\}\}">d</figure-callout>}}_1=\min (x_j^{\mathrm{FR}},y_j^{\mathrm{FR}},z_j^{\mathrm{FR}})-\min (x_j^{\mathrm{FO}},y_j^{\mathrm{FO}},x_j^{\mathrm{FO}})(j=\mathrm{1,2},...,K)---<11>$

$d_2=\max (x_j^{\mathrm{FR}},y_j^{\mathrm{FR}},z_j^{\mathrm{FR}})-\max (x_j^{\mathrm{FO}},y_j^{\mathrm{FO}},x_j^{\mathrm{FO}})(j=\mathrm{1,2},...,K).---<12>$

After the application said method was adjusted secondary face position, the interarea of antenna and secondary face reached the matching relationship an of the best, and the phase error that the interarea distortion under different operating modes forms on actinal surface farthest is reduced, and antenna system has best electrical property.

Advantage of the present invention can further specify by following l-G simulation test:

The secondary face method of adjustment of antenna of the present invention is carried out l-G simulation test on 64m bore correction cassette antenna.This antenna is certain the 64 meters amendment type dual reflector antenna that is used for survey of deep space, and its geometric parameter as shown in Figure 4.Wherein, the interarea bore is 64000mm, and secondary face bore is 6000mm, and the centerbody internal diameter is 6100mm, and the burnt footpath of equivalence is than being 0.30.Use Ansys software and set up the FEM (finite element) model of antenna-reflected body structure, as shown in Figure 5.Comprising 6919 beam elements, 9824 shell units, and 11724 nodes.Because the piecemeal reflecting surface is very little to the rigidity contribution of entire antenna, do not set up the FEM (finite element) model of actual panel during modeling, just its gravity equivalence is loaded on the node that winds up of back frame structure for mass unit.The theoretical bus radical length of interarea is 29000mm, is made up of 5801 discrete points data, and the radial point spacing is 5mm.For satisfying the approximation ratio of revising the interarea describing function, the overall precision of choosing the sectional parabola match is 0.01mm, and is as shown in table 1, totally 107 sections of piecewise fitting parabola hop counts, and the parabolic torus that rotation obtains also is 107 rings.

In the FEM (finite element) model of antenna structure, the coordinate offset of the node that winds up has promptly been represented the distortion of antenna interarea, thus just remove to approach totally 1104 of nodes of winding up after the distortion during actual coincideing with parabolic torus, as shown in Figure 7.The number of rings of node of winding up will be less than aforesaid 107 rings, so in order to guarantee sampled data is arranged all on each parabolic torus, needs to reject unnecessary parabolic torus as shown in Figure 6.30 parabolic torus of treated needs can be carried out the identical processing of the best to the node that winds up after the distortion.Antenna structure is carried out a static analysis every 15 degree in referring to flat 0 degree and the 90 degree scopes of looking up to heaven, then with parabolic torus group go to coincide the node deformation data that winds up under each operating mode.Table 2 is depicted as the identical parameter of the best of each elevation angle distortion interarea and the adjustment parameter of secondary face focal line.

Certain 64 meters antenna bus discrete data piecewise fitting result of table 1

The best parameter of coincideing of each elevation angle distortion interarea of certain 64 meters antenna of table 2

Result of calculation from table 2 is located the focal line length of matching surface all less than focal length initial change range delta F at each elevation angle as can be seen ₀Be 2243.5678mm, this is by the decision of the matching relationship of antenna major-minor face, otherwise blooming effect will occur.Along with the rising of antenna elevation angle, the absolute value of Z direction adjustment amount increases gradually, and the Y direction reduces on the contrary, and the directions X value is very little and constant substantially.This is that gravity has similar variation at the component of three coordinate directions because antenna is turning to the attitude process of looking up to heaven from referring to put down around X-axis.Because the existence with the focal axis constraint has guaranteed

The total establishment.

For checking the contribution of secondary face adjustment to electrical property, calculate and compared the gain loss of secondary face adjustment front and back antenna, as shown in table 3.

Secondary face position compensation front and back gain loss relatively when each elevation angle interarea distortion of certain 64 meters antenna of table 3 and frequency 3GHz

RMS in the table 3 _oBe surface gravity distortion root-mean-square error, RMS _pBe the surperficial root-mean-square error of the pre-timing of interarea 35 degree, RMS _fBe the precision of coincideing, Δ G _BcBe the gain loss before the secondary face position compensation, Δ G _BcBe the gain loss behind the secondary face position compensation.

As can be seen from Table 3, antenna interarea gravity deformation raises with the elevation angle and increases, and will delay in the error with respect to design surface with respect to the error increase degree of matching surface.When antenna refers to flatly when working in 3GHz, the surperficial root-mean-square error of 1mm can cause the gain loss of about 0.2dB.Gain loss significantly decreases after the secondary face compensation, and along with the rising at the elevation angle, the effect of compensation is more and more obvious.

L-G simulation test shows, adopts the present invention to reduce the gain loss that the interarea distortion causes, and has improved the electrical property of antenna.

Claims (3)

1. a secondary face method of adjustment of revising type Cassegrain formula antenna comprises the steps:

(1) M discrete points data with the theoretical bus of correction type Cassegrain formula antenna interarea is divided into the N section, N-1 section discrete counted identical before guaranteeing, and every section discrete counting is [M-M% (N-1)]/N on the preceding N-1 section, discrete the counting of N section is [M-M% (N-1)]/N+M% (N-1), and wherein population variance is counted M much larger than hop count N;

(2) the N section discrete points data of dividing is carried out the parabola match piecemeal, get the parabola of fit of N section discrete points data;

(3) according to the focal distance f of parabola of fit _nWith apex coordinate Δ H _n, calculate its focus region scope, promptly initial focal line length:

ΔF ₀＝max(f _n-ΔH _n)-min(f _n-ΔH _n)(n＝1，2，...，N)；

(4) set up the optimization Mathematical Modeling and seek the identical Parameter H of segmentation:

(4a) earlier N section parabola of fit is rotated a circle around its public focal axis, obtains one group of parabolic torus,

Parabolic torus is carried out projection with the interarea node, reject the parabolic torus that does not contain subpoint, again the parabolic torus group integral body of choosing is rotated respectively around x axle and y axle

With

Angle is calculated the node z that produces because of rotation to deviation delta z ₁:

In the formula, x _Ji, y _JiBe the x coordinate and the y coordinate of i subpoint on j the parabolic torus;

(4b) with the parabolic torus group along three translation of axes amount Δ x, Δ y and Δ z, the node coordinate deviation that produces of translation as a whole;

(4c) direction vector of calculating parabolic torus group common axis:

(4d), calculate the node coordinate deviation that parabolic torus is produced along the focal axis translation according to the direction vector of common axis:

$\left[\begin{array}{ccc}{\mathrm{\&Delta;x}}_{t_j}& {\mathrm{\&Delta;y}}_{t_j}& {\mathrm{\&Delta;z}}_{t_j}\end{array}\right]={}_{}\left[\begin{array}{ccc}{\mathrm{mt}}_j& {\mathrm{nt}}_j& {\mathrm{pt}}_j\end{array}\right];$

(4e) according to the whole rotation of parabolic torus group, integral translation and the node coordinate deviation that produces along the focal axis translation, calculate interarea distortion node with respect to the z of best matching surface root-mean-square value rms to deviation:

In the formula, z ' _JiIt is the z coordinate of i the corresponding interarea distortion of subpoint node on j the parabolic torus;

Be the anglec of rotation of antenna parabolic torus group around x axle and y axle,

t _jBe the translational movement of j parabolic torus of antenna along focal axis,

K is the antenna parabolic torus number of choosing,

D _jBe j the node number on the antenna parabolic torus,

Nod is an antenna interarea node sum;

(4f) guaranteeing the confocal axle of each standard parabolic torus, and focal line length is not more than initial focal line length Δ F ₀Prerequisite under, according to the criterion of root-mean-square value rms minimum, set up following optimization Mathematical Modeling and seek the segmentation Parameter H of coincideing:

In the formula, Δ f ₁, Δ f ₂..., f _KBe the focal length variations amount of each parabolic torus of antenna,

t ₁, t ₂..., t _KBe the translational movement of each parabolic torus of antenna along focal axis,

Be the position vector of identical preceding j parabolic torus focus,

Be the position vector of j parabolic torus focus after coincideing,

T _jIt is the transformation matrix of matching surface focus;

(5), calculate the actual coordinate of each focus after the secondary face adjustment according to segmentation each the focal length variations amount in the Parameter H of coincideing

(6) extract focal line two-end-point coordinate, calculate focal line near-end adjustment amount d respectively ₁With far-end adjustment amount d ₂Parameter as the position adjustment of the secondary face of guidance:

$d_1=\min (x_j^{\mathrm{FR}},y_j^{\mathrm{FR}},z_j^{\mathrm{FR}})-\min (x_j^{\mathrm{FO}},y_j^{\mathrm{FO}},x_j^{\mathrm{FO}})(j=\mathrm{1,2},...,K)$

$d_2=\max (x_j^{\mathrm{FR}},y_j^{\mathrm{FR}},z_j^{\mathrm{FR}})-\max (x_j^{\mathrm{FO}},y_j^{\mathrm{FO}},x_j^{\mathrm{FO}})(j=\mathrm{1,2},...,K).$

2. the secondary face method of adjustment of antenna according to claim 1, wherein step (2) is described carries out the parabola match piecemeal to the N section discrete points data of dividing, and carries out as follows:

(2a) equation of establishing n section parabola of fit is:

$r_n^2={4f}_n(z_n+{\mathrm{\&Delta;H}}_n)(n=\mathrm{1,2},...,N)$

In the formula, f _nBe the focal length of n section parabola of fit,

Δ H _nIt is the apex coordinate of n section parabola of fit;

(2b) calculate parabola of fit with respect to the z of discrete points data root-mean-square value σ to deviation:

$\mathrm{\&sigma;}=\sqrt{\frac{\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{D_n}{\mathrm{\&Sigma;}}}{(\frac{r_{\mathrm{ni}}^2}{{4f}_n}-z_{\mathrm{ni}}^{\&prime;}-{\mathrm{\&Delta;H}}_n)}^2}{M}}$

In the formula, D _nBe discrete the counting on the n section parabola of fit,

Z ' _NiThe z that is i discrete point on the n section is to coordinate;

(2c) find the solution the Optimization Model shown in the following formula, obtain the focal distance f of N section parabola of fit ₁, f ₂..., f _NWith apex coordinate Δ H ₁, Δ H ₂..., Δ H _N:

$\left\{\begin{array}{c}\mathrm{Find}(N,f_1,f_2,...,f_N,{\mathrm{\&Delta;H}}_1,{\mathrm{\&Delta;H}}_2,...,{\mathrm{\&Delta;H}}_N)\\ \mathrm{Min\&sigma;}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{D_n}{\mathrm{\&Sigma;}}}{(\frac{r_{\mathrm{ni}}^2}{{4f}_n}-z_{\mathrm{ni}}^{\&prime;}-{\mathrm{\&Delta;H}}_n)}^2}{M}}\\ s.t.N\&le;M-1\&pound;\&not;\\ f_n>0,(n=\mathrm{1,2},...,N)\end{array}\right.$

(2d) with focal distance f ₁, f ₂..., f _NWith apex coordinate Δ H ₁, Δ H ₂..., Δ H _NBring parabolic equation in (2a) into, promptly get the parabola of fit of N section discrete points data.

3. the secondary face method of adjustment of antenna according to claim 1, the wherein actual coordinate of each focus after the secondary face adjustment of the described calculating of step (5)

Calculate by following formula:

In the formula,

It is the focus original coordinates of parabolic torus before secondary face is adjusted.

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