CN102412441A - Vector averaging calibration method for phased-array antenna - Google Patents

Abstract

The invention provides a vector averaging calibration method for a phased-array antenna, and aims to provide a vector averaging calibration method capable of improving calibration accuracy and avoiding the influence of phase-shifting errors of branch phase shifters. The method comprises the following steps of: (1) serially/parallelly connecting the phase-array antenna with N units and N transmitter-receiver (TR) components comprising N phase shifters to obtain a calibration feed network, and connecting each phase-array antenna feed branch to a calibration amplitude phase receiver through a beam-forming network and the calibration feed network to obtain a transmitter-receiver circuit; (2) setting a phase-array antenna feed branch consisting of the beam-forming network and the TR components comprising the phase shifters as an object to be calibrated, and performing phase shift on the phase shifters by using a wave shaper; and (3) obtaining the initial phase and amplitude distribution of each branch by using a vector averaging algorithm, wherein the difference between the phase and the amplitude distribution and the designed phase and amplitude distribution is a calibration parameter. The calibration method has the advantages of high accuracy and engineering applicability.

Description

Phased array antenna vector average calibration method

Technical field

The invention relates to phased array antenna vector average calibration method.

Background technology

Phased array antenna is except that causing that because of front machinery, thermal deformation antenna performance descends, and its critical component---T/R assembly also can cause the variation of each bay exciting current amplitude, phase place owing to reasons such as environmental change, device agings.These variations will cause that indexs such as antenna side lobe, beam-pointing accuracy descend.So the amplitude of each antenna feed branch road, the calibration of phase place and compensation are the keys that can Connectors for Active Phased Array Radar work long-term effectively.Simultaneously more accurate precision receives the influence of the phase shift error of self phase shifter.

A lot of about the calibration research method at present, representational have:

Zou Yongqing, Cao Jun, Li Guangzhong. based on the angle Selection [J] of FFT Calibration for Phased Array Antenna. the microwave journal; 2003; 19 (3): 10-13, this method improves calibration accuracy from angle Selection, satisfies relational expression (1) and obtains high-precision calibration result through scanning angle is set:

θ _k＝sin ^-1{λ[2k-(N+1)]/(2Nd)}(1)

In the formula: θ _k: controlling antenna wave beam to point, k:1～N, N: antenna element number, d: antenna element distance

This method is carried out the phased array antenna calibration based on the FFT method; Calibration accuracy is influenced by the phase shift error of all TR assemblies; When branch road is uneven; Close coupling branch road TR phase shift error will produce considerable influence to weak coupling branch road calibration accuracy, so this method calibration accuracy is not so good as calibration steps of the present invention with engineering adaptability.

Open good 1996,18 (1): 62-74, be published in " modern radar ", name is called " the amplitude phase error impact analysis of Multi-mode Solid-state Phased Array Radar radar and calibration steps research [J] ", with and the feedback mode realize high-precision calibration.The document analyzed and the feedback mode under the factor of calibration error influence, obtained following result:

$\underset{\‾}{{\mathrm{\σ}}_a={\mathrm{\σ}}_p=\frac{1}{\sqrt{2\·L\·M_0\·(S/N)}}}---\left(2\right)$

In the formula: σ _a :The calibration amplitude error, σ _p :The calibration phase error, L: sampling number in the pulse, M ₀: average time, S/N: the signal to noise ratio during this paths test.

This method needs each bar phase array branch road that a receiver is all arranged, and is higher to the insulated degree requirement of switch when array element is a lot, therefore bad for the calibration engineering adaptability of highly integrated phased array antenna and large-scale phased array antenna.

Ge Jianjun etc. are published in " modern radar ", the 3rd phase of June calendar year 2001: 52-59, and name is called " based on the AESA alignment technique [J] of array row ripple feed " 2.3 calibrations based on array row ripple feed.This techniques make use row ripple feed technology and through and add load condition L at the TR assembly, and with (4) as the accuracy Design foundation.

This method algorithm is with the algorithm basically identical in " the amplitude phase error impact analysis of Multi-mode Solid-state Phased Array Radar radar and calibration steps research [J] ", and difference is that the TR assembly that non-calibration branch road is set is in the purpose that load condition realizes testing separately each branch road.This method need be for load condition of each TR component design, and is higher to the insulated degree requirement of switch simultaneously.

Lu Bin is published in " spacecraft engineering "; The 4th phase of December in 2006: 43-45; Name is called that " the simple bearing calibration [J] of phased array antenna amplitude and phase correction; rotating vector method collimation technique, this method be through phase change 360 degree of the single phase-shifting unit of control, the amplitude maximum through detecting composite signal and the amplitude of recently calibrating each passage and the phase error of amplitude minimum value.

This method reality has only utilized two kinds of phase shift states of phase shifter to calculate, and the amplitude of test signal only, shifts to all states of device with utilization of the present invention and the phase place of test signal is calculated obviously different.

East, Tangshan etc. is published in " play arrow and instruct journal " the 2nd phase of April in 2008: 303-306; Name is called " a kind of phased array antenna phase alignment [J] based on curve fit "; The curve-fitting method collimation technique; To the phase place traversal of the phase-shifting unit of each passage, the phase value corresponding through the composite signal maximum carries out this passage correction this method through one by one.This process iteration is carried out, and realizes the purpose to each channel correcting.

This method mainly is applicable to the experimental stage calibration, is not suitable for the antenna on-line calibration.

Summary of the invention

The objective of the invention is weak point, provide a kind of and can improve more accurate precision, can effectively avoid the vector averaging method calibration steps of branch road phase shifter phase shift error effect to above-mentioned prior art.

Above-mentioned purpose of the present invention can reach through following measure, and a kind of phased array antenna vector average calibration method is characterized in that comprising the steps:

(1) establishes N antenna element and N TR assembly that contains phase shifter and form phased array antenna by beam-forming network; Each TR assembly series, parallel or spacing wireless mode are formed the correction feeding network; Each phased array antenna feed leg is connected calibration width of cloth Phase Receiver machine by beam-forming network with the correction feeding network, form the transmitting-receiving test loop;

(2) with above-mentioned beam-forming network, contain phase shifter the TR assembly and or add that phased array antenna branch road that antenna constitutes is made as and be calibrated object, by the ripple control device that is connected between TR assembly and the width of cloth Phase Receiver machine antenna phasing unit is carried out phase shift; With calibration width of cloth Phase Receiver machine test amplitude-phase value;

(3) obtain the initial phase and the amplitude distribution of above-mentioned each bar branch road through the vector average algorithm, the difference between the phase amplitude of this phase place and amplitude distribution and design distributes is calibration parameter; Through revising the calibration that this parameter difference can realize phased array antenna.

The present invention has following beneficial effect than prior art.

Because calibration accuracy is basic only relevant with the phase shifter phase shift state error of phased array antenna feed leg; Irrelevant with other branch road phase shifter phase shift state error; Therefore, can effectively avoid the influence of other branch road phase shifter phase shift state error, reduce this fractional error greatly through the vector averaging method calibration steps; Also make calibration accuracy reduced by inconsistent the influence greatly of coupling factor of branch, can carry out Project Realization easily.Simultaneously, because average effect, more accurate precision has also been reduced by the influence of the phase shift error of self phase shifter widely.

Phased array antenna vector average calibration method of the present invention; Utilization is calibrated the vector of branch road and on average realizes the amplitude of each antenna feed branch road, the calibration and the compensation of phase place; The influence of phase shift error in calibration of phase shifter reduce owing to can improve the precision of calibration effectively.Adopt this calibration steps, precision is high, engineering adaptability is good.

Description of drawings

Fig. 1 is that the typical case of vector average calibration of the present invention system forms sketch map.

Embodiment

Consult Fig. 1.In the typical case of the vector average calibration system that Fig. 1 describes forms, establish phased array antenna and N TR assembly series and parallel or spacing wireless mode that contains phase shifter of N unit and form the correction feeding network, and form phased array antenna through beam-forming network.Beam-forming network, the TR assembly that contains phase shifter and above-mentioned antenna constitute the phased array antenna feed leg, and this feed leg is for being calibrated object.Each phased array antenna feed leg is connected to two microwave signal ports calibrating width of cloth Phase Receiver machine through beam-forming network and correction feeding network, forms the transmitting-receiving loop; Each TR assembly is connected to two signal ports of calibration width of cloth Phase Receiver machine through calibration network (and presenting network, series feed network, wireless feedback network) and beam-forming network and forms the closed loop of test; During calibration, with beam-forming network, contain the TR assembly of phase shifter or add that phased array antenna feed leg that antenna constitutes is made as and be calibrated object, antenna phasing unit is carried out phase shift by the ripple control device that is connected between TR assembly and the width of cloth Phase Receiver machine; Amplitude-phase value with calibration width of cloth Phase Receiver machine test composite signal.Under each phase shift state of width of cloth Phase Receiver machine test, arrive the complex signal of width of cloth Phase Receiver machine; Obtain the initial phase and the amplitude distribution of above-mentioned each bar branch road through the vector average algorithm, the difference between the phase amplitude of this phase place and amplitude distribution and design distributes is calibration parameter; Utilize vector average calibration algorithm to obtain the amplitude phase error of each branch road,, can realize the calibration of phased array antenna through revising this error.

Above-mentioned correction feeding network can be the coupling network of other form, as and present forms such as network, space electricity-feeding network, near field antenna coupling.The calibration coupling network can have various ways: series coupled calibration feeding network, parallel coupled calibration feeding network, wireless coupling calibration feeding network.

Then have during calibration

$A_k=S_m\·a_m\·e^{-j\frac{2\mathrm{\π}\·k}{N}}+\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{S}_i\·a_i\·e^{j\·0}---\left(3\right)$

$S_m\·a_m=\frac{1}{N}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}{A}_i{e}^{-j\frac{2\mathrm{\π}\·i}{N}}---\left(4\right)$

In the formula:

a _m: the transmission S parameter of m branch road is the value of needs detection and calibration;

S _m, S _i: the transmission S parameter of i, m road calibration coupling network;

A _k: the complex values that measures for the k time;

N; N=2 ^b, b is smaller or equal to the figure place of phase shifter, and when b equaled the figure place of phase shifter, calibration accuracy was the highest in theory.

In the calibration process:

Make the phase shifter phase shift of m road

Δ θ _{M, k}Be m road branch road, the phase shift error during the k next state, k=0～N-1, other phase shifter phase shift value is constant, can obtain N test data A ₁～A _k

Then, with A _kMultiply by

And, get its mean value with N results added.Because last is indeclinable under N phase shift state for (3) formula the right, this multiply by

Addition equals zero, thus final itself and be (4) formula left-hand component, owing to S _mBe the transmission coefficient of m road coupling branch road, known in advance, a so _mJust can obtain.

Change phase shifted branch again, repeat above calibration process, can obtain a of other branch road _i

Therefore an average process of vector that above algorithm reality is corresponding can be referred to as the vector mean emendation.

By analysis, consider that its calibration error is under the phase shifter phase shift error condition:

${{\mathrm{\σ}}_{\mathrm{\Δa},a}}^{\′}{\left(m\right)}^2={{\mathrm{\σ}}_{\mathrm{\Δa},\mathrm{\θ}}}^{\′}{\left(m\right)}^2=\frac{{\mathrm{\σ}}^2}{{2N}^2\·{b_m}^2}\·\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{d}_i\·{b_i}^2---\underset{\‾}{\left(5\right)}$

${{\mathrm{\σ}}_{\mathrm{\Δ\θ},a}}^{\′}{\left(m\right)}^2={{\mathrm{\σ}}_{\mathrm{\Δ\θ},\mathrm{\θ}}}^{\′}{\left(m\right)}^2=\frac{{{\mathrm{\σ}}_{\mathrm{\θ}}}^2}{{2N}^2\·{b_m}^2}\·\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{d}_i\·{b_i}^2---\underset{\‾}{\left(6\right)}$

σ _{Δ a, a}' (m), σ _{Δ a, θ}' (m): range error produces during phase shifter phase shift state variation more accurate phase place and amplitude root-mean-square error.

σ _{Δ θ, a}' (m), σ _{Δ θ, θ}' (m): phase error produces during phase shifter phase shift state variation more accurate phase place and amplitude root-mean-square error.

M is the calibration port number.Can know that by (5), (6) formula the N value is big more, error is more little, but the N value is greater than 2 ⁿAfter, the every increase by 1 of n, the N value doubles, but continuous item can double.By the amplitude of phase shift state, calibration error that phase error causes with constant.Simultaneously owing to work as the N value greater than 2 ⁿThe quantization error of back phase shifter will be considered, in this case, quantize the error term except overall error can increase, and test volume is increased, and therefore, under the situation of testing time permission, get N=2 ⁿCan obtain minimum calibration error.

Claims (6)

1. a phased array antenna vector average calibration method is characterized in that comprising the steps:

(1) establishes N antenna element and N TR assembly that contains phase shifter and form phased array antenna by beam-forming network; Each TR assembly series, parallel or spacing wireless mode are formed the correction feeding network; Each phased array antenna feed leg is connected calibration width of cloth Phase Receiver machine by beam-forming network with the correction feeding network, form the transmitting-receiving test loop;

(2) with above-mentioned beam-forming network, contain phase shifter the TR assembly and or add that phased array antenna branch road that antenna constitutes is made as and be calibrated object, by the ripple control device that is connected between TR assembly and the width of cloth Phase Receiver machine antenna phasing unit is carried out phase shift; With calibration width of cloth Phase Receiver machine test amplitude-phase value;

(3) obtain the initial phase and the amplitude distribution of above-mentioned each bar branch road through the vector average algorithm, the difference between the phase amplitude of this phase place and amplitude distribution and design distributes is calibration parameter; Through revising the calibration that this parameter difference can realize phased array antenna.

2. phased array antenna vector average calibration method as claimed in claim 1 is characterized in that described correction feeding network comprises the coupling network of other form: and present network, space electricity-feeding network or near field antenna coupled mode.

3. phased array antenna vector average calibration method as claimed in claim 2 is characterized in that described calibration coupling network has various ways: series coupled calibration feeding network, parallel coupled calibration feeding network and wireless coupling calibration feeding network.

4. phased array antenna vector average calibration method as claimed in claim 1 is characterized in that having during calibration

In the formula:

a _m: the transmission S parameter of m branch road is the value of needs detection and calibration;

S _m, S _i: the transmission S parameter of i, m road calibration coupling network;

A _k: the complex values that measures for the k time;

N; N=2 ^b, b is smaller or equal to the figure place of phase shifter, and when b equaled the figure place of phase shifter, calibration accuracy was the highest in theory.

5. phased array antenna vector average calibration method as claimed in claim 4 is characterized in that, in the calibration process:

Make the phase shifter phase shift of m road

, Δ θ _{M, k} ForM road branch road, the phase shift error during the k next state, k=0～N-1, other phase shifter phase shift value is constant, can obtain N test data A ₁～A _k

6. phased array antenna vector average calibration method as claimed in claim 5 is characterized in that, with A _kMultiply by

And, get its mean value with N results added, obtain a _m, change phase shifted branch again, repeat above calibration process, obtain a of other branch road _i

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