CN102904015A - Short-wave small circular receiving antenna array - Google Patents

Abstract

The invention relates to a short-wave small circular receiving antenna array. The short-wave small circular receiving antenna array comprises a small uniform circular array which consists of monopole antennae, a matching network, a radar radio frequency receiving channel, a weighted generator, a cross-coupling corrector and a weighting device, wherein the radius of the circular array is less than or equal to a quarter of wavelength; the quantity of antennae and the radius of the circular array are determined according to the characteristic of a directional diagram which is required to be formed; the matching network is in impedance matching with the receiving channel; the weighted generator generates a weight according to the distribution condition of the circular array and the characteristic of the directional diagram; the cross-coupling corrector forms correction data by measuring the cross-coupling condition of the antennae to correct the generated weight; and the weighting device weights an antenna unit. On the premise that signal to noise ratio and angular resolution are ensured, occupation area is greatly decreased, a portable high-frequency ground wave radar antenna array is realized, and sea surface kinetic parameters can be effectively detected.

Description

A kind of shortwave miniature circular receiving antenna array

Technical field

The invention belongs to antenna technical field, particularly the high-frequency ground wave radar receiving antenna array.

Background technology

High-frequency ground wave radar is a kind of important detecting devices that can carry out the continuous large-area marine environmental monitoring, main drive marine mathematic(al) parameter and the sea low-altitude low-speed moving targets such as ocean surface wind, wave, stream, tide surveyed are of great significance national economy and national defense construction.In order to obtain narrower antenna main lobe width, namely in order to obtain higher angular resolution, the bore of receiving antenna array is often very large, array length reaches tens meters even upper km, therefore need to take very large " Gold Coast " area, greatly increase construction difficulty and construction cost, seriously hindered the promotion and application of high-frequency ground wave radar.

Summary of the invention

For the large problem of traditional high-frequency ground wave radar antenna aperture, the present invention proposes a kind of shortwave miniature circular receiving antenna array, this antenna array can obtain directivity factor and the main lobe width identical with traditional large aperture antenna battle array in the situation that guarantee certain signal to noise ratio, generate required directional diagram, and be easy to realize 360 ° of omnidirectional's scannings.

Technical scheme of the present invention is a kind of shortwave miniature circular receiving antenna array, comprises the little spacing monopole antenna of circle battle array, matching network, radar radio frequency reception channel, weighting generator, mutual coupling calibration device and a weighter;

Circular little spacing monopole antenna battle array comprises a plurality of monopole antennas, and each monopole antenna is evenly arranged on the circumference, and the radius of circular little spacing monopole antenna battle array is less than or equal to 1/4th of radar operation wavelength;

The output of each monopole antenna connects the input of corresponding matching network, and the output of each matching network is through corresponding radar radio frequency reception channel difference weighted input device;

The weights that the weighting generator produces output to the mutual coupling calibration device; The mutual coupling calibration device forms correction data according to the mutual coupling situation between each monopole antenna, proofread and correct weights and weighted input device that the weighting generator produces, weighter is weighted each monopole antenna according to the input by weights and corresponding radar radio frequency reception channel after the correction of mutual coupling calibration device input, form specific directional diagram, support 360 ° of omnidirectional's scannings.

And matching network is five rank broadband matching networks.

And the radius of monopole antenna number and circular little spacing monopole antenna battle array is determined according to the characteristics of the default directional diagram that will form; The characteristics of described directional diagram comprise main lobe direction, main lobe width and sidelobe level inhibiting value.

And, the weighting generator is according to the characteristics of the radius of monopole antenna number, circular little spacing monopole antenna battle array and the directional diagram that will form, utilize maximization directivity factor method under the secondary lobe constraint to calculate the weighted value of each antenna element, computational process comprises following substep

Step 1, input parameter comprises radius r, the operating frequency f of monopole antenna number N, circular little spacing monopole antenna battle array ₀, main lobe direction

With secondary lobe constraints Wherein, θ _sWith

Represent respectively the angle of pitch and azimuth, secondary lobe constraints

Represent the amplitude that i secondary lobe will retrain;

Step 2 is according to array number N, circle battle array radius r, operating frequency f ₀And main lobe direction

Obtain one group of weight w with maximization directivity factor method _D

Step 3 is with weight w _DWeighing vector calculated direction figure as array;

Step 4, whether the sidelobe level of directional diagram all is less than or equal to the sidelobe level inhibiting value in the directional diagram characteristics in the determining step 3

Then to organize weights output, process ends, otherwise enter step 5;

Step 5, find out backlog demand secondary lobe the position and add secondary lobe constraints;

Step 6 is obtained weights with maximization directivity factor method under current secondary lobe constraints, obtain new w _D, return step 3 and calculate, until sidelobe level all meets the demands, export current weight w _D

And the mutual coupling calibration device forms correction data according to the mutual coupling situation between each monopole antenna, and implementation is proofreaied and correct the weights that the weighting generator produces as correction data with mutual resistance matrix for generate the mutual resistance matrix of array with the S parameter; Described S parameter be antenna with adopt before matching network is connected the two-port network analyzer directly in actual working environment, to measure.

The invention has the beneficial effects as follows, under the prerequisite that guarantees certain signal to noise ratio and angular resolution, greatly reduced floor space, realized the portable high frequency groundwave radar antenna array, can effectively survey the ocean surface kinetic parameter.

Description of drawings

Fig. 1 is the structural representation of the embodiment of the invention.

Fig. 2 is the matching network structural representation of the embodiment of the invention.

Fig. 3 is 8 yuan of embodiment of the invention circle battle array main lobes array element weighting schematic diagrames when pointing to 15 °.

Fig. 4 is array element weighting schematic diagram when main lobe points to 60 ° after the counterclockwise by turns weighting of the round battle array of 8 yuan of the embodiment of the invention.

Fig. 5 is the lower maximization directivity factor of the sidelobe level constraint synthesis calculation flow chart of the embodiment of the invention.

Fig. 6 be the embodiment of the invention measure S parameter schematic diagram between two antennas with network analyzer.

8 yuan of radius 2.5m circle battle array main lobes pointed to 90 ° directional diagram when Fig. 7 was the frequency 10MHz of the embodiment of the invention.

8 yuan of radius 2.5m circle battle array Sidelobe Suppression values were that 10dB, main lobe point to 90 ° directional diagram when Fig. 8 was the frequency 10MHz of the embodiment of the invention.

Embodiment

Describe technical solution of the present invention in detail below in conjunction with drawings and Examples.

Referring to Fig. 1, the shortwave miniature circular receiving antenna array that the embodiment of the invention provides comprises the little spacing monopole antenna of circle battle array, matching network, radar radio frequency reception channel, weighting generator, mutual coupling calibration device and a weighter.Circular little spacing monopole antenna battle array comprises a plurality of monopole antennas, and each monopole antenna is evenly arranged on the circumference, and the radius of circular little spacing monopole antenna battle array is less than or equal to 1/4th of radar operation wavelength.For ease of outlines device, below shortwave miniature circular receiving antenna array is called for short the circle battle array.Matching network is used for and the radar radio frequency reception channel is carried out impedance matching; The weighting generator produces weights according to circle battle array distribution situation and directional diagram characteristics, and the weights that produce output to the mutual coupling calibration device; The mutual coupling calibration device forms correction data according to the mutual coupling situation between each monopole antenna, proofreaies and correct weights and weighted input device that the weighting generator produces; Weighter is weighted each monopole antenna according to the input by weights and corresponding radar radio frequency reception channel after the correction of mutual coupling calibration device input, forms specific directional diagram, supports 360 ° of omnidirectional's scannings.

Each monopole antenna is established total N monopole antenna D1, D2, D3, D4 as an antenna element ... DN is arranged on the circumference equably, and circle battle array radius is less than or equal to 1/4th of radar operation wavelength, and is propped up by support.Circle battle array radius is less than or equal to the spacing requirement that 1/4th of wavelength belongs to the Superdirective antenna array, therefore can obtain the directivity factor identical with the wide aperture array antenna.The height of monopole antenna and diameter can require to select according to gain size, weight requirement and wind resistance.

Antenna number and a circle battle array radius determined by the characteristics of the directional diagram that will form, for example main lobe direction, main lobe width and sidelobe level inhibiting value, and those skilled in the art can preset the characteristics of the directional diagram that will form according to demand.Can require to determine antenna main lobe direction and Sidelobe Suppression value according to radar performance first, then in the situation that can reach required main lobe width, optimize fate number and circle battle array radius with existing maximization directivity factor method with Computer Simulation, maximization directivity factor method is in following derivation and the step that detailed description is arranged.Namely elder generation is according to the requirement of antenna array miniaturization, select the antenna of right quantity and suitable circle battle array radius, and circle battle array radius is less than or equal to 1/4th of radar operation wavelength, in computer, obtain the directional diagram of antenna with maximization directivity factor method, see that whether the main lobe width of directional diagram is less than required main lobe width, if less than namely meeting the demands, otherwise need to increase the antenna number or increase circle battle array radius (but can not surpass radar operation wavelength 1/4th).Theoretical proof suitably increases the antenna number and can reduce main lobe width.Until main lobe width meets the demands.

Among the embodiment, the circle battle array is as the receiving antenna array of high-frequency ground wave radar, and operating frequency is 7.5MHz-25MHz, the height of each antenna element is 2m, adopts broadband omni directional monopoles sub antenna, in 7.5MHz-25MHz frequency band, its standing-wave ratio is less than 2, and variation is mild.Before a burst of type of circle was determined, embodiment optimized number of antennas and circle battle array radius according to the characteristics of directional diagram.In high-frequency ground wave radar, when operating frequency during at 7.5MHz-10MHz, require main lobe width on each scanning direction less than 35 °.Find when comprehensive, circle battle array radius is during less than 3m, can allow the main lobe width be 8 less than 35 ° of required minimum array numbers, so adopt 8 antennas, a circle battle array radius can be according to the degree of miniaturization and the variation comprehensive selection of main lobe width.

Because at high band, external noise is greater than the internal system noise, therefore when aerial array dwindles, antenna reception to signal and noise reduce in proportion, namely signal to noise ratio is constant, this is the theoretical foundation of high frequency antenna battle array miniaturization.The weighting scheme of circle battle array is fairly simple, because each antenna element is evenly distributed, the directional diagram that points to all directions is period profile, and therefore a demand goes out the weighted value of required antenna pattern in the one-period, then array element is rotated weighting, can form the directional diagram that points to other directions.For this reason, embodiment provides weighting generator and mutual coupling calibration device.

Described weighting generator namely according to antenna number, circle battle array radius and directional diagram characteristics, utilizes the superdirectivity synthesis to calculate the weighted value of each antenna element.Embodiment is according to formation distribution, main lobe direction and sidelobe level inhibiting value, and the maximization directivity factor synthesis under the constraint of employing secondary lobe is obtained the weighted value of each antenna.During implementation, can adopt computer software technology to realize the automatic operation of maximization directivity factor synthesis, namely the weighting generator can adopt computer or chip microcontroller, perhaps adopts the realizations such as software solidification module, integrated circuit.

Described mutual coupling calibration device, generate the mutual resistance matrix of array with the S parameter, weighted value is proofreaied and correct as correction data with mutual resistance matrix, weighter is then with the output multiplication of the weighted value after proofreading and correct to the respective radio-frequency receive path, realization is weighted each antenna element, by by turns weighting, realize 360 ° of omnidirectional's scannings.During implementation, can adopt computer software technology to generate mutual resistance matrix, the weighted calculation of array, namely the weighting generator can adopt computer or chip microcontroller, perhaps adopts the realizations such as software solidification module, integrated circuit.Weighter can adopt logical integrated circuit, for example adopts adder and multiplier to realize weighting.Described S parameter, can antenna with adopt before matching network is connected the two-port network analyzer directly in actual working environment, to measure.Because each antenna distance is less, the mutual coupling degree between antenna is very large, therefore must carry out mutual coupling calibration, to eliminate the interference between antenna.After antenna number and circle battle array radius are determined, be after the formation distribution is determined, the circle battle array is placed on the work-yard, measure S parameter between each antenna with network analyzer, again the S parameter is converted to mutual resistance matrix, according to the input impedance value of radar radio frequency reception channel, mutual resistance matrix is carried out normalization, proofread and correct the weights that the weighting generator generates with the normalization mutual resistance matrix that obtains.

Matching network is used for and receive path carries out impedance matching.The output of each monopole antenna connects the input of corresponding matching network, and the output of each matching network is connected with corresponding radar radio frequency reception channel; Each radar radio frequency reception channel is distinguished the weighted input device again.Described radar radio frequency reception channel can be various radar receivers, has expressed the annexation of signal, and its internal structure is not at the row of content of the present invention.The output of each antenna is matching connection network 1,2 respectively ... N is used for and the radar radio frequency reception channel input impedance of rear end 50 Ω is complementary.N receive path 1,2 ... N respectively N output with the mutual coupling calibration device is corresponding, and the mutual coupling calibration device links to each other with the weighting generator.Matching network can have multiple design, and scheme shown in Figure 2 is five rank matching networks, is made of capacitor C 1=52.9pF wherein, C2=97.1pF, C3=51.6pF, inductance L 1=689.5nH, L2=1.7uH three electric capacity and two inductance.Series capacitance C1 and inductance L 1 between port P1, the P2; Capacitor C 2 one ends are connected between capacitor C 1 and the inductance L 1, other end ground connection; Capacitor C 3 and inductance L 2 homogeneous end connectivity port P2, other end ground connection.Capacitance and inductance value are only in this scheme.Port P1 connects the feedback point of monopole antenna, and port P2 connects receive path.During implementation, the invention technician can arrange matching network voluntarily as the case may be.

For the purpose of efficient is provided, can based on asking for the weights in the scan period, obtain 360 ° weights during implementation of the present invention.In 8 yuan of circle battle arrays shown in Figure 3, the central angle alpha of two adjacent array elements is 45 °, therefore the scan period is 45 °, therefore only need calculate the weights that main lobe points to all assigned directions in 0 ° to 44 °, when then needing to point to other directions, only get final product with the weighted value of rotating certain number of times.When namely needing orientation angle β, calculate first γ wherein ₁For

The merchant, γ ₂For

Remainder, and γ ₂＜α.Then in 0 to α, find out and point to γ ₂The time corresponding weights, again with the counterclockwise γ by turns successively of the weights on each array element ₁Inferior, main lobe can orientation angle β.So both can by by turns weighting, realize 360 ° of omnidirectional's scannings.When pointing to 60 ° such as needs, calculate first 60 divided by 45, the merchant is 1, and remainder is 15.Weights corresponding to each array element when then finding out main lobe and pointing to 15 °, as shown in Figure 3, antenna D1, D2, D3, D4, D5, D6, the corresponding weighted value of D7, D8 are respectively W1, W2, W3, W4, W5, W6, W7, W8.All weights are rotated 1 time counterclockwise successively again, namely W1 is assigned to D2 to D8 successively to W7, W8 is assigned to D1, as shown in Figure 4, then main lobe points to 60 °, and the characteristics of directional diagram are constant.In high-frequency ground wave radar, main lobe is every 15 ° of run-downs, then only needs to calculate the weighted value that main lobe points to 0 °, 15 ° and 30 °, only need rotate weighted value by above-mentioned rule when needing other to point to, and is simple and convenient.

Maximization directivity factor method is prior art, for ease of implementing reference, provides related description as follows:

By the theory of Array Signal Processing as can be known, the directional diagram of N element array is:

Wherein, w=[w ₁, w ₂..., w _N] ^TBe the weighing vector of array, Be the steering vector of array, subscript H and T represent respectively conjugate transpose and transposition, θ and

Represent respectively the angle of pitch and azimuth.

For isotropism array element, have:

Wherein, f ₀Be the incident wave frequency,

Arrive the time delay of each array element for the wavefront of incident plane wave, r is circle battle array radius, and c is electromagnetic wave propagation speed in the air, and N is element number of array.Exp (j2 π f ₀τ _k) (k=1,2 ..., N) expression is by corresponding phase term of the time of this delay, and j is imaginary unit.

The directivity factor of array is defined as:

Be the greatest irradiation direction of array, i.e. main lobe direction.

Directivity factor is as follows with the quotient representation of broad sense Rayleigh:

$D=\frac{w^H\mathrm{Bw}}{w^H\mathrm{Aw}}---\left(4\right)$

Wherein,

That main lobe points to.

The method of available generalized eigenvalue decomposition obtains the corresponding weighing vector of maximum D, but is not easy to add constraints.The method travel direction of using numerical value is comprehensive, namely is converted into following problem:

$\underset{w}{\min }{w}^H\mathrm{Aw}$

(5)

Wherein Re represents to get real part, subscript θ and

Expression is respectively to its differentiate.Then this problem equivalence is:

$\underset{w}{\min }{w}^H\mathrm{Aw}$ (6)

st.C ^Hw＝f

Wherein, C is the row non-singular matrix of N * M, and f is the column vector of M * 1, and M is the number of constraints.

Constrained optimization problem has a variety of methods, and such as quadratic programming, method of Lagrange multipliers etc., it is as follows that embodiment draws weight coefficient with method of Lagrange multipliers:

w _D＝A ^-1C(C ^HA ^-1C) ^-1f (7)

w _DBe the corresponding weighing vector of array maximum directivity coefficient.

For to anti-interference, need to suppress sidelobe level in practice.Make the arithmetic number function

Be the amplitude function of expectation secondary lobe in the secondary lobe to be optimized zone, the weighing vector of establishing the front array of each iteration is w _c, its corresponding directional diagram is

Then the weighing vector that obtains of each iteration is the solution of following problems.

$\underset{w}{\min }{w}^H\mathrm{Aw}$

Last formula is illustrated in m the Linear Constraints that newly increases on the basis of M constraints in the following formula.f _iBe the complex representation of Sidelobe Suppression value, use in this median as computing.This m Linear Constraints is used for controlling current directional diagram

In the amplitude at m side lobe peak point place to set-point

F then _iValue be:

Wherein,

Currency for this m some place.

This problem also can equivalence be

$\underset{w}{\min }{w}^H\mathrm{Aw}$ (10)

st.C ₁ ^Hw＝g

C wherein ₁Be the complex matrix of N * (M+m), g is the column vector of M+m dimension.The side lobe peak point of current directional diagram in searching target zone during each iteration

Be total to m _sIndividual.Because the number of Linear Constraints can not surpass N, so can add m at most in the iteration _Max=N-M secondary lobe constraints.If m _s＞m _Max, then choose wherein m _sIndividual large secondary lobe is as constraint object, so the number m=min (m of secondary lobe constraint _s, m _Max).

Still use method of Lagrange multipliers, draw weighing vector and be:

w _D＝A ^-1C ₁(C ₁ ^HA ^-1C ₁) ^-1g (11)

By

Can form main lobe points to

Wave beam.

The calculation process explanation of the maximization directivity factor method under the secondary lobe constraint of embodiment is provided for the sake of ease of implementation.As shown in Figure 5, in an embodiment step is as follows:

Step 1, input parameter comprises that array number N(is the monopole antenna number), a circle battle array radius r (being the radius of circular little spacing monopole antenna battle array), operating frequency f ₀, main lobe direction

(θ _sWith

Represent respectively the angle of pitch and azimuth), secondary lobe constraints

(representing the amplitude that i secondary lobe will retrain);

Step 2 is obtained one group of weights with maximization directivity factor method, and (1) to (7) formula has provided the derivation of maximization directivity factor method, will can obtain one group of weight w in other parameter substitutions (7) except secondary lobe constraints s in the step 1 _D, namely according to array number N, circle battle array radius r, operating frequency f ₀, main lobe direction

Obtain one group of weight w with maximization directivity factor method _D, the formula of asking for employing is w _D=A ^-1C (C ^HA ^-1C) ^-1F, wherein

C is the row non-singular matrix of N * M;

Step 3 is with the weight w of obtaining _DCalculate directional diagram, the weight w of namely obtaining according to step 2 in the substitution (1) _DMake up the weighing vector w=[w of array ₁, w ₂..., w _N] ^T, calculate F is the column vector of M * 1, and M is the number of secondary lobe constraints;

Step 4, whether the sidelobe level of directional diagram all is less than or equal to the sidelobe level inhibiting value in the directional diagram characteristics in the determining step 3

If it is should organize weights output, process ends, otherwise enter step 5;

Step 5, find out backlog demand (namely greater than the sidelobe level inhibiting value in the directional diagram characteristics) secondary lobe the position and add secondary lobe constraints, soon do not satisfy in the location point substitution (9) of secondary lobe requirement, calculate median f _iAfter, in the again substitution (8), and finally be reduced to (10) formula;

Step 6 is obtained weights with maximization directivity factor method under current secondary lobe constraints, namely use (11) formula w _D=A ^-1C ₁(C ₁ ^HA ^-1C ₁) ^-1G obtains the solution w of (10) formula _DReturn step 3 and calculate, until sidelobe level all meets the demands.

For the sake of ease of implementation, provide the method for measurement of S parameter for reference: as shown in Figure 6, when adopting the two-port network analyzer to measure S parameter (being the microwave scattering parameter) between two antennas, if two antennas are designated as respectively array element 1 and array element 2, in the environment of circle battle array work, instrument is calibrated coupling first, then port one is connected the feedback point that connects respectively array element 1 and array element 2 with port, network analyzer is set to the single port mode of operation, can measure respectively S11 and S22 parameter under each Frequency point.Network analyzer is set to the dual-port transmission mode again, can measure respectively S12 and S21 parameter under each Frequency point.Owing to can not make the characteristic of two monopoles just the same in the manufacturing process, therefore the numerical value of S12 and S21 is understood some difference, be unequal.According to microwave network theory, the conversion relation of S parameter and mutual resistance matrix is as follows:

Z＝Z ₀(S+I)(I-S) ^-1 (12)

Wherein, Z ₀Being characteristic impedance, is 50 Ω at this.

$Z=\left(\begin{array}{cc}{Z}_{11}& Z_{12}\\ Z_{21}& Z_{22}\end{array}\right)$ Be mutual resistance matrix, $I=\left(\begin{array}{cc}1& 0\\ 0& 1\end{array}\right)$ Be the second order unit matrix; $S=\left(\begin{array}{cc}{S}_{11}& S_{12}\\ S_{21}& S_{22}\end{array}\right)$ Be the S parameter matrix.

In mutual resistance matrix, Z ₁₁And Z ₂₂The self-impedance that represents respectively array element 1 and array element 2, Z ₁₂The mutual impedance of 2 pairs of array elements 1 of expression array element, Z ₂₁The mutual impedance of 1 pair of array element 2 of expression array element.In the S parameter matrix, S ₁₁During expression port 2 coupling, the reflection coefficient of port one; S ₂₂During expression port one coupling, the reflection coefficient of port 2; S ₁₂During expression port one coupling, port 2 is to the reverse transfer coefficient of port one; S ₂₁During expression port 2 coupling, port one is to the forward transmission coefficient of port 2.

Measure the S parameter of all per two antennas according to above method, and be converted into mutual resistance matrix, finally form the mutual resistance matrix of array:

$Z=\left(\begin{array}{cccc}{Z}_{11}& Z_{12}& ...& Z_{1N}\\ Z_{21}& Z_{22}& ...& Z_{2N}\\ .& .& & .\\ .& .& & .\\ .& .& & .\\ Z_{N1}& {\mathrm{<figure-callout\; id="2"\; label="Z\; N"\; filenames="121107114451.png"\; state="\{\{state\}\}">Z</figure-callout>}}_N& ...& Z_{\mathrm{NN}}\end{array}\right)---\left(13\right)$

Then the antenna array that proposes according to Gupta receives equivalent network model, draws normalized mutual resistance matrix and is:

$Z_u=\left(\begin{array}{cccc}1+\frac{Z_{11}}{Z_L}& \frac{Z_{12}}{Z_L}& ...& \frac{Z_{1N}}{Z_L}\\ \frac{Z_{21}}{{\mathrm{<figure-callout\; id="1"\; label="Z\; L"\; filenames="121107114451.png"\; state="\{\{state\}\}">Z</figure-callout>}}_L}& 1+\frac{Z_{22}}{Z_L}& ...& \frac{Z_{2N}}{Z_L}\\ .& .& & .\\ .& .& & .\\ .& .& & .\\ \frac{Z_{N1}}{Z_L}& \frac{Z_{N2}}{Z_L}& ...& 1+\frac{Z_{\mathrm{NN}}}{Z_L}\end{array}\right)---\left(14\right)$

Wherein, Z _LBe load impedance, be the input impedance of receiver at this, be i.e. 50 Ω.Z _uBe final correction data.Weighing vector after then proofreading and correct is w _L=w _D ^HZ _uUse w _LEach antenna is weighted, can obtains required directional diagram.

Fig. 7 and shown in Figure 8 be that said method is used in 8 yuan of radius 2.5m circle battle arrays, be 10MHz, main lobe when pointing to 90 ° in operating frequency, secondary lobe is in the situation of 10dB without constraint and constraint level, the directional diagram that obtains respectively.Among Fig. 7, main lobe width is 32.49 °, and directivity factor is 12.21dB, and the highest sidelobe level is-8.2dB; Main lobe width is 31.34 ° among Fig. 8, and directivity factor is 11.71dB, and the highest sidelobe level is-10dB.Can find out, the superdirective antenna battle array is because antenna distance is very little, and mutual coupling is very large on the impact of directional diagram, must be proofreaied and correct, and the invention provides the effective scheme of mutual coupling calibration.

Specific embodiment described herein only is to the explanation for example of the present invention's spirit.Those skilled in the art can make various modifications or replenish or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present invention or surmount the defined scope of appended claims.

Claims (5)

1. a shortwave miniature circular receiving antenna array is characterized in that: comprise the little spacing monopole antenna of circle battle array, matching network, radar radio frequency reception channel, weighting generator, mutual coupling calibration device and a weighter;

Circular little spacing monopole antenna battle array comprises a plurality of monopole antennas, and each monopole antenna is evenly arranged on the circumference, and the radius of circular little spacing monopole antenna battle array is less than or equal to 1/4th of radar operation wavelength;

The output of each monopole antenna connects the input of corresponding matching network, and the output of each matching network is through corresponding radar radio frequency reception channel difference weighted input device;

The weights that the weighting generator produces output to the mutual coupling calibration device; The mutual coupling calibration device forms correction data according to the mutual coupling situation between each monopole antenna, proofread and correct weights and weighted input device that the weighting generator produces, weighter is weighted each monopole antenna according to the input by weights and corresponding radar radio frequency reception channel after the correction of mutual coupling calibration device input, form specific directional diagram, support 360 ° of omnidirectional's scannings.

2. shortwave miniature circular receiving antenna array according to claim 1, it is characterized in that: matching network is five rank broadband matching networks.

3. shortwave miniature circular receiving antenna array according to claim 1 is characterized in that: the radius of monopole antenna number and circular little spacing monopole antenna battle array is definite according to the characteristics of the default directional diagram that will form; The characteristics of described directional diagram comprise main lobe direction, main lobe width and sidelobe level inhibiting value.

4. shortwave miniature circular receiving antenna array according to claim 3, it is characterized in that: the weighting generator is according to the characteristics of the radius of monopole antenna number, circular little spacing monopole antenna battle array and the directional diagram that will form, utilize maximization directivity factor method under the secondary lobe constraint to calculate the weighted value of each antenna element, computational process comprises following substep

Step 1, input parameter comprises radius r, the operating frequency f of monopole antenna number N, circular little spacing monopole antenna battle array ₀, main lobe direction

With secondary lobe constraints

Wherein, θ _sWith

Represent respectively the angle of pitch and azimuth, secondary lobe constraints

Represent the amplitude that i secondary lobe will retrain;

Step 2 is according to array number N, circle battle array radius r, operating frequency f ₀And main lobe direction

Obtain one group of weight w with maximization directivity factor method _D

Step 3 is with weight w _DWeighing vector calculated direction figure as array;

Step 4, whether the sidelobe level of directional diagram all is less than or equal to the sidelobe level inhibiting value in the directional diagram characteristics in the determining step 3

Then to organize weights output, process ends, otherwise enter step 5;

Step 5, find out backlog demand secondary lobe the position and add secondary lobe constraints;

Step 6 is obtained weights with maximization directivity factor method under current secondary lobe constraints, obtain new w _D, return step 3 and calculate, until sidelobe level all meets the demands, export current weight w _D

5. according to claim 1 and 2 or 3 or 4 described shortwave miniature circular receiving antenna arrays, it is characterized in that: the mutual coupling calibration device forms correction data according to the mutual coupling situation between each monopole antenna, implementation is proofreaied and correct the weights that the weighting generator produces as correction data with mutual resistance matrix for generate the mutual resistance matrix of array with the S parameter; Described S parameter be antenna with adopt before matching network is connected the two-port network analyzer directly in actual working environment, to measure.

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