CN1773307A - Small size antenna array aperture expanding and space signal processing method - Google Patents

Abstract

The present invention relates to a small type antenna array aperture expanding and space signal processing method. Said method includes the following steps: making antenna array into any array form: dividing scanning area of whole antenna into several subregions, finely-dividing any one subregion of said several subregions; in the finely-divided subregion constructing actual array flow form of antenna array and array flow form of expanded array so as to further obtain the array expansion conversion matrix; utilizing the obtained array expansion conversion matrix to reconstitute the signal of expanded antenna array; then making said signal undergo the process of digital beam formation or adaptive beam formation or utilizing space high resolution algorithm to obtain space arrival angle of signal.

Description

Small size antenna array aperture expansion and space signal processing method

Technical field

The present invention relates to a kind of small size antenna array aperture expansion and empty ask signal disposal route.

Background technology

According to the antenna theory of classics, the angular resolution of radar is relevant with antenna beamwidth, and radar antenna beam angle and antenna electrical length are approximated to inverse ratio, promptly

${\mathrm{\θ}}_{3\mathrm{dB}}\∝\frac{\mathrm{\λ}}{L}$ (radian)

Wherein, θ _3dBBe the antenna beam half-power width, λ is the radar operation wavelength, and L is an aerial array length.When the spacing between the antenna unit is half left and right sides of radar operation wavelength, obtain high angular resolution, just need to adopt large-scale phased array antenna and a large amount of receiving cables.But in radar antenna position occasions with limited, for example, for high-frequency ground wave or high frequency sky-wave OTH radar, in order to obtain high-resolution ocean surface stream and sea-surface target azimuth information, high-resolution algorithms such as general employing (multiple signal classification algorithm) MUSIC, in order to obtain high-resolution sea stormy waves information, generally adopt the DBF technology.For example, be 5MHz if higher-frequency radar work is frequency, seek out 1 ° angular resolution, the radar antenna battle array is long will to reach 3000 meters.And, in order to evoke the surface wave of coastal propagation effectively, the radar antenna battle array should be positioned as close to the seawater setting, this distance requires 1～2 radar wavelength usually, this is under actual seashore condition, not only be difficult to find the antenna farm that can match, and greatly increased radar build a station expense and daily maintenance expense with the large-scale antenna battle array.Because the radar antenna battle array is excessive, its far-field range reaches thousands of rice simultaneously, and is also very difficult to the calibration of radar system.All these will limit applying of many radars of comprising high frequency surface wave radar.

Summary of the invention

At the limitation of existing hyperchannel Large Phased Array Radar, the purpose of this invention is to provide a kind of small size antenna array aperture expansion and space signal processing method, this method utilizes the array extension technology to realize the function of having only Large Phased Array Radar to realize.

To achieve these goals, the invention provides a kind of small size antenna array aperture expansion and space signal processing method, aerial array is set to any array format; The entire antenna scanning area is divided into several regions, wherein any subregion segmentation: the actual battle array stream shape A=[a (θ that in the subregion of segmentation, makes up aerial array ₁), a (θ ₁+ Δ θ), a (θ ₂+ 2 Δ θ) ..., a (θ _r)] and the battle array stream shape A=[a (θ of array extending ₁), a (θ ₁+ Δ θ), a (θ ₂+ 2 Δ θ) ..., a (θ _r)], and then obtain array extension transformation matrix B=AA ^-1, wherein, θ ₁, θ _rBe respectively the border, the left and right sides of subregion, Δ θ is the step-length of subregion segmentation; Utilize acquired array extension transformation matrix to reconstruct the signal Z=BX of array extending antenna, wherein, X is the signal that original antenna array receives; The signal Z of the array extending antenna of reconstruct carried out digital beam forms or adaptive beam forms or utilize the space high resolution algorithm to obtain the space angle of arrival of signal.

According to the present invention, when actual battle array stream shape A is non-square matrix, matrix A is carried out the diagonal angle load.

In addition, the present invention can utilize the norm minimum value of ‖ A-BA ‖, determines the unit number of array extending.

Advantage of the present invention is the Practical Performance that it is outstanding: (1) has expanded the bore and the bay number of antenna array greatly by said method; (2) utilize the software special advantages, the signal of reconstruct extended antenna unit enables to use neatly the modern digital signal processing technology, and the change, space super-resolution direction finding and the antenna self-adaptive that carry out digital beam formation, beam shape are anti-interference; (3) because the antenna aperture expansion is to be based upon on the basis of software, can significantly reduce antenna element number and receiving cable, greatly reduce R﹠D costs and the expense of building a station; (4) by small-sized any antenna array is implemented transform expansion, compare with original battle array, it has not only increased detectable information source number, has improved the overload capacity of antenna array, and can overcome the signal ambiguity problem that array may occur, improved the relevant ability of separating of array.

The present invention is directed to the radar antenna restricted special occasions of structuring the formation, break the old formula of general phased-array radar design, proposed a kind of by the miniature compact phased array antenna being implemented transform expansion to increase the method in antenna array aperture, be that phased-array radar reduces antenna element and receiving cable, reduce cost, be simple and easy to build new way is provided.The present invention not only is suitable for uniform array, also is suitable for any non-homogeneous array, and the antenna aperture after the expansion is equivalent to the performance that the primary antenna bore more than three times is reached.It is applied to the high-frequency ground wave over-the-horizon radar,, not only can obtains the azimuth information of high-resolution ocean surface stream and sea-surface target, can also form narrow relatively wave beam, obtain to satisfy the stormy waves information that oceanographic engineering requires by the aerial array after the expansion.The present invention provides theory and engineering basis for the miniaturization of radar antenna battle array.

The present invention is applied to engineering reality, and not only research and development are relative with equipment maintenance cost cheap, under the flexible cooperation of software, also have the function that present traditional Large Phased Array Radar does not have.The present invention is to using phased array in antenna position and electromagnetic compatibility occasions with limited, to national defense construction and economic construction such as Aeronautics and Astronautics, air defence, coast defence, and makes the phased-array radar miniaturization and reduces cost, and has important theory value and engineering significance.

A large amount of theoretical analysis and radar tests show, array extension by the present invention's proposition, realized effective expansion of bay number, promptly make array extending have more array number by the array extension conversion, its advantage is tangible, it has not only increased the overload capacity that detectable signal number has promptly improved array, and can overcome the signal ambiguity problem that array may occur, improved the relevant ability of separating of array, significantly reduce the bore and the receiving cable number of actual antennas, reduce the radar development cost, satisfied the requirement that utilizes array extension technology implementation space super-resolution that the present invention proposes.

Description of drawings

Fig. 1, Fig. 2 and Fig. 3 are respectively the Doppler spectrum of former battle array, expansion battle array and the traditional large-sized array of scan angle when being 40 °;

Fig. 4, Fig. 5 and Fig. 6 are respectively the Doppler spectrum of former battle array, expansion battle array and the traditional large-sized array of scan angle when being 60 °;

Fig. 7, Fig. 8 and Fig. 9 are respectively the Doppler spectrum of former battle array, expansion battle array and the traditional large-sized array of scan angle when being 80 °;

Figure 10, Figure 11 and Figure 12 are respectively the Doppler spectrum of former battle array, expansion battle array and the traditional large-sized array of scan angle when being 100 °;

Figure 13, Figure 14 and Figure 15 are respectively the Doppler spectrum of former battle array, expansion battle array and the traditional large-sized array of scan angle when being 120 °;

Figure 16, Figure 17 and Figure 18 are respectively the Doppler spectrum of former battle array, expansion battle array and the traditional large-sized array of scan angle when being 140 °;

It is 25dB that Figure 19, Figure 20 and Figure 21 are respectively signal to noise ratio (S/N ratio), the Doppler spectrum of the former battle array when scan angle is 40 °, expansion battle array and traditional large-sized array;

It is 25dB that Figure 22, Figure 23 and Figure 24 are respectively signal to noise ratio (S/N ratio), the Doppler spectrum of the former battle array when scan angle is 60 °, expansion battle array and traditional large-sized array;

It is 25dB that Figure 25, Figure 26 and Figure 27 are respectively signal to noise ratio (S/N ratio), the Doppler spectrum of the former battle array when scan angle is 80 °, expansion battle array and traditional large-sized array;

It is 25dB that Figure 28, Figure 29 and Figure 30 are respectively signal to noise ratio (S/N ratio), the Doppler spectrum of the former battle array when scan angle is 100 °, expansion battle array and traditional large-sized array;

It is 25dB that Figure 31, Figure 32 and Figure 33 are respectively signal to noise ratio (S/N ratio), the Doppler spectrum of the former battle array when scan angle is 120 °, expansion battle array and traditional large-sized array;

It is 25dB that Figure 34, Figure 35 and Figure 36 are respectively signal to noise ratio (S/N ratio), the Doppler spectrum of the former battle array when scan angle is 140 °, expansion battle array and traditional large-sized array;

Figure 37 is that former array beam points to 60 ° Doppler spectrum;

Figure 38 is the echo spectrum of 60 ° of beam positions after the array extension;

Figure 39 is that former array beam points to 120 ° Doppler spectrum;

Figure 40 is the echo spectrum of 120 ° of beam positions after the array extension;

Figure 41 is the MUSIC spectrum before the array extension;

Figure 42 is the MUSIC spectrum after the array extension.

Embodiment

Below in conjunction with drawings and Examples, the present invention is done more detailed explanation.

To achieve these goals, the present invention adopts a kind of any aerial array bore expansion and space ultra-resolution method, and aerial array is set to any array format; The entire antenna scanning area is divided into several regions, again with certain sub regions segmentation; Relation by between actual array stream shape A and the expansion battle array stream shape A obtains array extension transformation matrix B=AA ^-1Utilize acquired array extension matrix to reconstruct the signal Z=BX (wherein, X is the signal that original antenna array receives) of array extending antenna; The data Z that the reconstruct array extending is received carries out wave beam formation, or utilizes the space high resolution algorithm to obtain the space super-resolution angle of arrival of signal.

1, original array signal model

Be without loss of generality, the hypothesis space battle array is made up of m array element, and d signal source arranged, and signal incides on the array with the plane wave form.Then the data of i array element reception are:

$x_i=\underset{k=1}{\overset{d}{\mathrm{\&Sigma;}}}{e}^{-\mathrm{<figure-callout\; id="0"\; label="j\; w"\; filenames="A20051001963300155.png"\; state="\{\{state\}\}">j</figure-callout>}{w}_{}{}_0{\mathrm{\&tau;}}_{\mathrm{ik}}}{s}_k\left(t\right)+n_i\left(t\right),i=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,m---\left(1\right)$

Then m array element is as follows at the vector that the fast beat of data of t output constantly constitutes:

X(t)＝[x ₁(t)，x ₂(t)，...，x _m(t)] ^T (2)

A is an array manifold

A＝[a(θ ₁)，a(θ ₂)，...，a(θ _d)] (3)

θ wherein _kThe deflection of k incoming signal, a (θ _i) as shown in the formula expression:

$a\left({\mathrm{\&theta;}}_i\right)=[e^{-j{w}_0{\mathrm{\&tau;}}_{1i}},e^{-j{w}_0{\mathrm{\&tau;}}_{2i}},...,e^{-j{w}_0{\mathrm{\&tau;}}_{\mathrm{mi}}}{]}^{T---\left(4\right)}$

τ _Ki=(x _kCos (θ _i)+y _kSin (θ _i))/c is i the delay of signal on k array element, (x _k, y _k) position coordinates of array element for this reason, c is the light velocity.

Be the data matrix of array received:

X＝AS (5)

2. the design of array extending

2.1 array extension transform method

For irregular Phalanx or non-homogeneous array, the existing output that former array data is transformed to the even linear array of an expansion by the method for digital conversion.

If the sense vector of the even linear array after the expansion is

A (θ)=[1, exp (jkd cos θ) ..., exp (jk (N-1) dcos θ)] (6) wherein d for the expansion day after tomorrow linear array array element distance.Be provided with a N * N rank nonsingular matrix T (Θ) and satisfy following relation

B (Θ) A (Θ)=[a (θ ₁), a (θ ₂) ..., a (θ _P)]=A (Θ) (7) is by the following formula change action, matrix B (Θ) has just become a new evenly direction matrix of battle array with the direction matrixing of former array, we are referred to as array extending the new uniform array that obtains like this, and in case obtain B (Θ) matrix, the output vector of the even linear array that can be expanded

z(t)＝B(Θ)x(t) (8)

2.2 the acquisition of array transformation matrix

The processing thought of array extension is that the entire antenna scanning area is divided into plurality of sub-regions, again with certain sub regions segmentation.Suppose that signal is positioned at regional Θ, is divided into regional Θ

Θ＝[θ ₁，θ ₁+Δθ，θ ₁+2Δθ，...，θ _r] (9)

θ ₁, θ _rFor Θ is border, the left and right sides, Δ θ is a step-length. then the array manifold matrix of actual array is

A＝[a(θ ₁)，a(θ ₁+Δθ)，a(θ ₂+2Δθ)，...，a(θ _r)] (10)

And the array manifold matrix A of the expansion even linear array in the same area Θ is

A＝[ a(θ ₁)， a(θ ₁+Δθ)， a(θ ₂+2Δθ)，…， a(θ _r)] (11)

A (θ _i) as shown in the formula expression:

$\stackrel{\&OverBar;}{a}\left({\mathrm{\&theta;}}_i\right)=[e^{-\mathrm{<figure-callout\; id="0"\; label="j\; w"\; filenames="A20051001963300155.png"\; state="\{\{state\}\}">j</figure-callout>}{w}_{}{}_0{\mathrm{\&Delta;}}_{1i}},e^{-\mathrm{<figure-callout\; id="0"\; label="j\; w"\; filenames="A20051001963300155.png"\; state="\{\{state\}\}">j</figure-callout>}{w}_{}{}_0{\mathrm{\&Delta;}}_{2i}},...,e^{-\mathrm{<figure-callout\; id="0"\; label="j\; w"\; filenames="A20051001963300155.png"\; state="\{\{state\}\}">j</figure-callout>}{w}_{}{}_0{\mathrm{\&Delta;}}_{\mathrm{ni}}}{]}^T---\left(12\right)$

Wherein, n is the element number of array of array extending, Δ k _i=(xx _kCos (θ _i)+yy _kSin (θ _i))/c is the delay of i signal on k array element of array extending, (xx _k, yy _k) expanding the position coordinates of array element for this reason, c is the light velocity.

Then there is a fixing transformation relation B (T) between Kuo Zhan array and the real array, makes BA=A_B=AA ^-1(13)

In following formula, relate to inverting to A.Generally speaking, matrix A is not a square formation, can not directly invert, so we adopts the diagonal angle loading technique, and a is a loading coefficient.

C＝A′*A

A ^-1≈(C+a*eye(size(C，1))) ^-1*A′ (14)

Suppose that a certain matrix Z satisfies Z=BX,

Z＝BX＝ AA ^-1X＝ AA ^-1AS＝ AS (15)

Then Z can see the data that received by array extending as.

2.3 determining of initial angle and array extension unit

From above analysis as can be known, the matter of utmost importance that the transform method of array extending faces is exactly determining of initial angle and antenna element number, and the position angle of signal source is a parameter to be estimated, therefore, before the tectonic transition matrix, need the position angle is estimated, directly influence the good and bad of transformation matrix and finally influence estimated result and estimate the fine or not of quality.In actual applications, a kind of simple method is when each distance element spacing wave is handled, the entire antenna scanning area can be divided into several radar units by the array extending beam angle, suppose that signal is positioned at the digital beam zone at digital antenna battle array place, calculate then ${\left|\right|\stackrel{\&OverBar;}{A}\left(\widehat{\mathrm{\&Theta;}}\right)-B\left(\widehat{\mathrm{\&Theta;}}\right)A\left(\widehat{\mathrm{\&Theta;}}\right)\left|\right|}_F$ Norm, if this value is not enough little, can adjust extended antenna unit number, select suitable lobe width and signal initial angle, and then recomputate the transform expansion matrix

So that ${\left|\right|\stackrel{\&OverBar;}{A}\left(\widehat{\mathrm{\&Theta;}}\right)-B\left(\widehat{\mathrm{\&Theta;}}\right)A\left(\widehat{\mathrm{\&Theta;}}\right)\left|\right|}_F$ It is minimum that norm reaches.

2.4 determining of antenna element spacing

Carry out array extension and at first will know the inceptive direction of signal, and initial angle is estimated

Error is always arranged, therefore, during design expansion even linear array, should select as far as possible error mapping fault least responsive, that form that initial angle is estimated also minimum array be array extending.In the practical application, what we were concerned about is matrix

With

Column space whether consistent.On the meaning of column space, vector And the available angle between the two of the distance between a (θ)

Expression:

$\mathrm{\&gamma;}(\mathrm{\&theta;};\widehat{\mathrm{\&theta;}})=\arccos \frac{\left|{\stackrel{\&OverBar;}{a}}^H\left(\mathrm{\&theta;}\right)B\left(\widehat{\mathrm{\&theta;}}\right)a\left(\mathrm{\&theta;}\right)\right|}{{\left|\right|\stackrel{\&OverBar;}{a}\left(\mathrm{\&theta;}\right)\left|\right|}_2\&CenterDot;{\left|\right|B\left(\widehat{\mathrm{\&theta;}}\right)a\left(\mathrm{\&theta;}\right)\left|\right|}_2}---\left(16\right)$ ‖ ‖ ₂With || represent spectral norm and absolute value respectively.Square d between best array element should make

Minimum, promptly

$d_{\mathrm{opt}}=\arg \underset{d}{\min }\mathrm{\&gamma;}(\mathrm{\&theta;};\widehat{\mathrm{\&theta;}})---\left(17\right)$

General d _OptTo θ and Not very sensitive, therefore for the sake of simplicity, θ can be chosen as the maximum outbound course of Beam-former.However, d _OptCalculating still inconvenient.According to the discussion of front, should try one's best near consistent with the magnitude-phase characteristics of the main beam of expansion even linear array for reducing the former array of mapping fault.So if the 3dB main beam width of former array is W, then a kind of simple selection of even linear array array element distance is ^[7]

$d=0.886\frac{\mathrm{\&lambda;}}{N\&CenterDot;W}---\left(18\right)$

Wherein, λ is a wavelength.The 3dB main beam width of former array and expansion even linear array is equated.Computer simulation shows that d generally approaches d _Opt

2.5 transform expansion error analysis

Be to investigate the error of unitary transformation matrix, this with $\widehat{\mathrm{\&Theta;}}=\{{\widehat{\mathrm{\&theta;}}}_1,{\widehat{\mathrm{\&theta;}}}_2\}$ A kind of simple scenario be example.When array element is omnidirectional's array element, it be easy to show that

${\left|\right|\stackrel{\&OverBar;}{A}({\widehat{\mathrm{\&theta;}}}_1,{\widehat{\mathrm{\&theta;}}}_2)-B({\widehat{\mathrm{\&theta;}}}_1,{\widehat{\mathrm{\&theta;}}}_2)A({\widehat{\mathrm{\&theta;}}}_1,{\widehat{\mathrm{\&theta;}}}_2)\left|\right|}_F$

Wherein,

Research (18) formula as can be known, when _ _a→ _ _bOr when _ _a→ 0 and _ _b→ 0 o'clock, (19) formula left side leveled off to zero.This that is to say, when

With

In the time of in a beam angle, make transformation matrix error minimum, the amplitude characteristic of the main beam of former array and array extending and phase propetry should be tried one's best approaching; And work as

With

Interval when surpassing a beam angle, two array secondary lobes are low more, then the transformation matrix error is more little.When selecting unitary transformation matrix (15) formula, this conclusion has not only been pointed out the requirement of array data converter technique to former array, and the design of expansion even linear array has also been indicated direction.

2.6 transform expansion is to The noise

The data covariance matrix of supposing actual battle array is R, and noise covariance matrix is R _N, then the data covariance matrix of array extending is

R _T＝NRB ^H＝B(AR _sA ^H+R _N)T ^H

＝BAR _sA ^HT ^H+BR _NT ^H (21)

When neighbourhood noise is white noise, then

BR _NB ^H＝σ ²BB ^H (22)

As can be seen from the above equation, after the array extension conversion, the white noise of former array received has become coloured noise.

The super-resolution algorithm of 3, expansion battle array

From above analysis as can be known since to array by after the array extending conversion, the white noise of former array received has become coloured noise, therefore when the noise of each array element reception is separate, can be by following method estimate covariance matrix:

$R_T=\frac{1}{M}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}x(i:L-M+i-1)x^H(i+1:L-M+i)---\left(23\right)$

M is the level and smooth number of times of time domain in the formula, and L is fast umber of beats, and wherein x (i:j) expression was photographed fast beat of data the j time the i time soon.Obviously, when each array element noise was separate, the noise item of the covariance matrix that estimates should be 0.To R _TCarry out feature decomposition, utilize MUSIC Estimation of Spatial Spectrum device then, can obtain the super-resolution estimation of signal DOA.

4, algorithm performance emulation

Simulation test 1: even linear array bore expansion

The omnidirectional's array element that is provided with N=8 is evenly distributed on the straight line that length is λ.Existing 6 signals deviate from the radar direction motion, its radial velocity and direction of motion be respectively 4,8,12,16,20,24}m/s and { 40 °, 60 °, 80 °, 100 °, 120 °, 140 ° }.Data sampling point 256.The echo Doppler spectrum of 40 °, 60 °, 80 °, 100 °, 120 ° of (former battle array) beam positions and 140 ° before representing array extension respectively as Fig. 1,4,7,10,13 and 16.Now former battle array is extended to the array that antenna distance is d=0.5 λ.Represent respectively that as Fig. 2,5,8,11,14 and 17 array beam after the array extension points to the echo Doppler spectrum of 40 °, 60 °, 80 °, 100 °, 120 ° and 140 °.As Fig. 3,6,9,12,15 and 18 expression array element distance is 8 yuan of uniform straight line arrays of half-wavelength.From then on the result can know and finds out, before the array extension, former battle array can't be differentiated the several senses that exist in the wave beam, but after the scheme of utilizing this paper to propose is expanded array, can most clearly tell the direction and the Doppler of each signal, and the array after the expansion is about the same with the resolving effect of the actual battle array that equates bore.Further analyze its reason as can be known, before the array extension, about 60 ° of the beam angle of former battle array, and the beam angle of array is reduced to about 15 ° after the array extension, promptly this Phalanx resolution is equivalent to the aperture of three times of former battle arrays.

Simulation test 2: signal to noise ratio (S/N ratio) is to the influence of even linear array bore expansion

Be provided with N=8 omnidirectional array element and be evenly distributed on the straight line that length is λ, the incident wave signal is with simulation test 1, and different is that each Signal-to-Noise is 25dB.The echo Doppler spectrum of 40 °, 60 °, 80 °, 100 °, 120 ° of (former battle array) beam positions and 140 ° before representing array extension respectively as Figure 19,22,25,28,31 and 34.Now former battle array is extended to the array that antenna distance is d=0.5 λ.Represent respectively that as Figure 20,23,26,29,32 and 35 array beam after the array extension points to the echo Doppler spectrum of 40 °, 60 °, 80 °, 100 °, 120 ° and 140 °.As Figure 21,24,27,30,33 and 36 expression array element distance is the large-scale uniform straight line array of half-wavelength.The same with the conclusion of simulation test 1 gained, before the array extension, former battle array can't be differentiated the several senses that exist in the wave beam, but after utilizing this paper to propose a plan array expanded, can most clearly tell the direction and the Doppler of each signal, further analyze as can be known, along with the raising of signal to noise ratio (S/N ratio) or the increase of former array element antenna distance, its resolving effect also can improve greatly.

Simulation test 3: big spacing even linear array bore expansion

Be provided with N=8 omnidirectional array element and be evenly distributed on (obviously antenna distance is much larger than half-wavelength, and graing lobe will appear in former battle array directional diagram) on the straight line that length is 10 λ.Signal to noise ratio (S/N ratio) 25dB.The incident wave signal is with simulation test 1.The typical simulation result is: the echo Doppler spectrum of representing 60 ° of beam positions before the array extension as Figure 37.Now former battle array is extended to the array that antenna distance is d=0.5 λ.The echo spectrum of representing 60 ° of beam positions after the array extension as Figure 38.From then on the result can obviously find out, before the array extension, a plurality of angles of arrival occurred in a wave beam, and this obviously is because primary antenna battle array spacing is excessive, and graing lobe appears in antenna radiation pattern and the direction finding that produces is fuzzy.But after utilizing this paper to propose a plan array expanded, antenna distance significantly reduces, and has eliminated the graing lobe that antenna radiation pattern occurs, and therefore can most clearly tell the direction and the Doppler of signal in the wave beam.

Simulation test 4: the unnecessary actual array number of expansion array number

Be provided with N=8 omnidirectional array element and be evenly distributed on the straight line that length is λ, the incident wave signal is with simulation test 1, and different is that each Signal-to-Noise is 20dB.The typical simulation result is: the echo Doppler spectrum of representing 120 ° of beam positions before the array extension as Figure 39.Now former battle array is extended to 12 yuan of front's battle arrays that antenna distance is d=0.5 λ.The echo spectrum of representing 120 ° of beam positions after the array extension as Figure 40.The experiment of a large amount of random pattern shows that before the array extension, former battle array can't be differentiated the several senses that exist in the wave beam, but after utilizing this paper to propose a plan array expanded, can most clearly tell the direction and the Doppler of each signal.Further analyze also as can be known, this moment, the beam angle of antenna array was narrower than the wave beam of 8 even linear arrays, but the result more is subjected to influence on signal-to-noise ratio (SNR), and signal to noise ratio (S/N ratio) is high more, and effect is good more.

Simulation test 5: nonuniform array bore expansion

Be provided with N=8 omnidirectional array element and be randomly dispersed in (or being evenly distributed on the semicircle that radius is r=0.5 λ) on the straight line that length is λ.The incident wave signal is with simulation test 1.Now former battle array is extended to the array that antenna distance is d=0.5 λ.A large amount of stochastic simulation experiments show that before the array extension, former battle array can't be differentiated the several senses that exist in the wave beam, but after utilizing technical solution of the present invention that array is expanded, can most clearly tell the direction and the Doppler of each signal.

Simulation test 6: the high resolution algorithm of expansion battle array

Being provided with N=8 omnidirectional array element is evenly distributed on the straight line that length is 5 λ.The incident wave signal is with simulation test 1, and signal to noise ratio (S/N ratio) is 25dB.Now former battle array is extended to the array that antenna distance is d=0.5 λ.Figure 41 represents the super-resolution spatial spectrum that utilizes before the array extension MUSIC algorithm to obtain.Figure 42 represents the super-resolution spatial spectrum that utilizes after the array extension MUSIC algorithm to obtain.Thus the result as can be known, before the antenna array expansion, it is fuzzy that direction finding appears in antenna array, but the method for utilizing this paper to propose expands former battle array, the resolution of antenna is not only high, but also it is fuzzy to have eliminated direction finding.

5, discuss

The bore extended method based on small size antenna array that the present invention goes out has following characteristics:

(a) conversion process needn't be known the accurate direction of signal, only needs the initial incidence angle of hypothesis signal, can obtain the array manifold matrix of former array and array extending, and then realizes the conversion battle array of array.In actual applications, can store conversion battle array T in advance, and realize the expansion of array.

(b) general array antenna spacing requires less than half-wavelength, if surpass half-wavelength, it is fuzzy direction finding to occur, and by the array extension conversion, the non-equidistance antenna array can be become the antenna array of array element distance, can solve the signal ambiguity of array like this less than half-wavelength.

(c) increased the dirigibility of array, because array extending has increased array number (degree of freedom), like this at the digital array number that carries out to select flexibly according to actual environment when DOA estimates array extending, as number of signals when fewer, can select the little array extending in aperture, can suitably increase array number for the high occasion of accuracy requirement and increase antenna array aperture.

(d), therefore, can estimate more signal number through the array after the expansion because the array of expansion can have more array number than actual array.

(e) the array extending unit number can not be infinitely great, and the selection of array number can only be effective within the specific limits.This be because: from energy, energy and quantity of information that antenna receives are conservations, and the conversion on any mathematical meaning can only be carried out to a certain degree improvement to traditional algorithm, can not increase energy and useful information amount; From mathematics, array number increases, and it is big that the conditional number of transform expansion matrix becomes, and it is big that the error of reconstruct array extending antenna element width of cloth phase becomes, and can bring bigger error to the result at last.And along with the increase of expanding array number, in order to obtain the result that engineering can be used, its requirement meeting to signal to noise ratio (S/N ratio) increases greatly.In actual applications, the number of expansion array element should be compromised between the factors such as conditional number of signal to noise ratio (S/N ratio), actual signal number, transform expansion matrix.

(f) because small-sized array antenna row aperture is less, this helps reducing the calibrated distance of antenna array.

(g) will invent with modern high resolution algorithm and combine, can realize the direction finding of array manifold super-resolution.

Claims (3)

1. a small size antenna array aperture is expanded and space signal processing method, and it is characterized in that: aerial array is set to any array format; The entire antenna scanning area is divided into several regions, wherein any subregion segmentation; In the subregion of segmentation, make up the actual battle array stream shape A=[a (θ of aerial array ₁), a (θ ₁+ Δ θ), a (θ ₂+ 2 Δ θ) ..., a (θ _r)] and the battle array stream shape A=[a (θ of array extending ₁), a (θ ₁+ Δ θ), a (θ ₂+ 2 Δ θ) ..., a (θ _r)], and then obtain array extension transformation matrix B=AA ^-1, wherein, θ ₁, θ _rBe respectively the border, the left and right sides of subregion, Δ θ is the step-length of subregion segmentation; Utilize acquired array extension transformation matrix to reconstruct the signal Z=BX of array extending antenna, wherein, X is the signal that original antenna array receives; The signal Z of the array extending antenna of reconstruct carried out digital beam forms or adaptive beam forms or utilize the space high resolution algorithm to obtain the space angle of arrival of signal.

2. method according to claim 1 is characterized in that: when actual battle array stream shape A is non-square matrix, matrix A is carried out the diagonal angle load.

3. method according to claim 1 and 2 is characterized in that: utilize the norm minimum value of ‖ A-BA ‖, determine the unit number of array extending.

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