CN101483273A

CN101483273A - Calibration method for amplitude and phase variable array antenna

Info

Publication number: CN101483273A
Application number: CNA2009100782722A
Authority: CN
Inventors: 田步宁; 敬红勇
Original assignee: 504 INSTITUTE OF FIVE INSTITUTE OF CASIC
Current assignee: 504 INSTITUTE OF FIVE INSTITUTE OF CASIC
Priority date: 2009-02-24
Filing date: 2009-02-24
Publication date: 2009-07-15
Anticipated expiration: 2029-02-24
Also published as: CN101483273B

Abstract

The invention discloses a calibration method of an array antenna with alterable amplitude and phase. A power response of the array antenna at an auxiliary antenna is obtained by altering the states of an alterable digital phase shifter and an alterable digital attenuator in each channel of the array, an equation is formed by the power response corresponding to a response of a specific channel at multiple different states, a relative amplitude and a relative phase to a reference signal of the channel is obtained by solving the equation, and an phase-amplitude consistency error of each channel of the array is obtained, then the calibration is realized. Aiming at each channel, the calibration method of the invention can obtain the relative amplitude and phase of the channel only through three amplitude states and one phase state, the needed state parameter is small, the algorithm is simple and the operation process is easy.

Description

The calibration steps of the array antenna of a kind of amplitude and phase variable

Technical field

The invention belongs to the space flight measurement and control field, relate to the calibration steps of a kind of amplitude and phase variable array antenna.

Background technology

Array antenna is made up of a lot of antenna elements, and to form specific wave beam and to realize beam scanning, the signal stack of each antenna element forms the signal of array antenna to the feedback of each antenna element with the signal of certain amplitude and phase place.Array antenna for amplitude and phase variable, the signal amplitude of its each antenna element and phase place are all adjustable, generally speaking, by control behind each unit connect attenuator needed wave beam is regulated and formed to the amplitude of antenna element signal, by changing the phase place that connects phase shifter behind each unit the phase place of antenna element signal is controlled to realize beam scanning.

For the sensing of accurate control wave beam, need to determine the phase response of each antenna element reality of array antenna.Yet phase response is subjected to the influence of various inevitable errors and manufacturing tolerance and is the function of time and temperature, so need calibrate and phase place is compensated the error of phase response.Equally, the amplitude response of each antenna element is also relevant with the sum of errors manufacturing tolerance, need calibrate and amplitude is recompensed the amplitude response error.

At present, the calibration steps of array antenna is had a lot, the different paths that its signal injects during according to calibration can be divided into internal calibration and external calibration two big classes.External calibration is to set up auxiliary antenna in distance antenna to be measured a distance to carry out signal injection or sampling, auxiliary antenna can be erected near field, midfield and the far field of array antenna, the process width of cloth is monitored mutually and is compared again, draw the antenna element passage (calibration is at whole passage, comprised antenna element and with this electric wire unit place passage in phase shifter, attenuator) amplitude phase error.Compare with the internal calibration method, the external calibration method need not be provided with a large amount of directional couplers and matrix switch element (some external calibration method requires each monitored road should have HF switch to be used to connect tested passage) in antenna array, therefore easy and simple to handle.The external calibration method that occurs has near field measurement, middle field measurement, far-field measurement, commutation measurement and REV method etc. at present.

Near field measurement is meant in the array antenna near field range, in a certain lip-deep distribution, utilizes the anti-distribution that pushes away the antenna aperture field of BTM (Backward Transformation Method) according to the field.As the matrix method (MM) of phased array antenna near field measurement, this method can restore the excitation width of cloth phase of each unit of phased array antenna, and can be used in the array antenna of random geometry.The subject matter that the near field matrix method will solve is the matrix ill-conditioning problem, and this blocks problem and non-homogeneous scanning problem with regard to requiring to solve the limited scanning face, also needs to solve the rapid solving problem of matrix.This method is in the experimental study stage at present, and much remains to be done apart from the engineering application.

The midfield mensuration is to utilize the mutual coupling principle that phased array antenna is proofreaied and correct, and phase array has one dimension to sweep the branch of sweeping with two-dimensional phase mutually, and corresponding with it, the midfield alignment technique also can be divided into midfield two-point method and midfield line-of-sight course.This method requires phased array antenna to have single channel and receives/send out function, and when promptly an active cell (or passage) was in emission or accepting state, other active cell (or passage) was in closed condition, and isolated mutually between each unit (or passage).The bearing calibration of phased array antenna midfield utilizes a reference antenna to be placed on several ad-hoc locations of a distance, tested array the place ahead array is tested, and obtains correction parameter by data correlation process.The shortcoming of this method is, requires antenna to have HF switch and is used for the tested passage of gating, and through existing measuring system checking, the precision of this method still remains to be improved.

Require during far-field measurement on the distance of far field, phased array antenna to be measured, Dan Davis has proposed the model of a far-field measurement phased array antenna, it needs Distance Test field, auxiliary antenna and a turret systems, tested antenna is contained on the rotary positioning apparatus of a precision, and reception far-field radiation signal, for different predetermined angle positions, measure the amplitude-phase value of antenna accurately at the antenna port place, then carry out phase place and range value that matrix inversion operation obtains the aperture.The key of this method is that accurate rotary positioning apparatus will be arranged.

The commutation mensuration is proposed by Russian scientist, its basic thought be exactly under all fixing condition of probe and tested antenna to phased array antenna different join phase, it is the matrix equation (claiming to measure equation again) of unknown number that the signal that utilizes probe to receive is set up with the element excitation, obtains the excitation of each unit by finding the solution matrix equation then.The outstanding advantage of this method is just can obtain all by one-shot measurement to join radiation characteristic under the phase state, and the measurement that does not need to add just can obtain characteristics such as the directional diagram, gain of antenna, and measuring period is short, is a kind of method of measurement very efficiently.But this method needs extremely complicated control, and it is very expensive to set up the required software and hardware of measurement.The disadvantage of this method is a probe sampling amount of information deficiency, for trying to achieve the unique solution of matrix equation, must utilize the prior information of phase shifter---the assembly average of transmission coefficient mould and phase shift variations during the phase shifter commutation, the engineering versatility that this has influenced this method has greatly restricted the development of this technology.

REV (Rotating-element Electric Field Vector) method is that Mitsubishi electric corporation (Mitsubishi Electric Corporation) a kind of phased array antenna that last century, the eighties proposed in the development process of airborne active phase array antenna detects bearing calibration.This method is a kind of method based on power measurement, by continuously changing the phase place of tested passage phase shifter, all the other all passage phase shifter phase states are constant, measure the variation of received power, then according to the power maximin and obtain the phase-shift phase of the peaked phase shifter of power, the electric field that calculates each unit generation can be determined the amplitude-phase consistency of each passage thus with respect to initial synthetic relative amplitude and relative phase.For digital phase shifter, phase-shift value and resulting power are discrete magnitude, and the algorithm that the phase-shift value of phase shifter can adopt when obtaining the power maximum and obtaining maximum has linear interpolation, least square approximation and Fourier transform.Though REV method data processing is simple, there is the fuzzy problem of separating, promptly exist and separate more, the judgement that the size with the field that utilize out of Memory to produce as all unit of field and all the other that are calibrated the unit generation is separated.

In addition, Ron Sorace has proposed a kind of method of carrying out element amplitude and phasing under four quadrature phase states according to the power samples result, and this method can realize the phasing of satellite antenna under the rail operating state.Concrete calibration steps is: for the width of cloth phase of n passage of calibration arrays, the phase place of all passages is arranged to array beam points to a certain particular orientation (as the base station), phase state note work 0 state this moment, under n all phase states of passage, measure received or institute's emitted power, the difference of the setting that produces maximum power and the 0 state setting of being supposed as calibrated offset.Each passage in the array is repeated this process, and adjust the last time phasing of each passage according to detecting error.The phase alignment of repeat array and correction reach convergence up to phase error when being lower than receivable degree, so just formed the new corrected value of each passage.The method of Ron Sorace needn't be measured under all phase states, only measures under four quadrature phase states (0 °, 180 °, 90 ° and 270 °), just can obtain the likelihood valuation of maximum calibration offset according to measured value.But the data handling procedure complexity of this method, and spended time is longer.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, provide that a kind of calibration algorithm is easy, the calibration steps of the array antenna of the simple amplitude of operating process and phase variable.

Technical solution of the present invention is: the calibration steps of the array antenna of a kind of amplitude and phase variable, and step is as follows:

(1) at place, array antenna far field the auxiliary reception antenna is set;

(2) to the array antenna feed, this moment, each antenna element of array antenna produced the initial field vector at auxiliary reception antenna place Thereby obtain the initial synthetic field vector that array antenna produces at auxiliary reception antenna place

N=1 wherein, 2,3...... is the numbering of each antenna element in the array antenna, E _nWith

Be amplitude and the phase place of each antenna element at the initial field vector of auxiliary reception antenna place generation, E ₀With

Be amplitude and the phase place of array antenna at the initial synthetic field vector of auxiliary reception antenna place generation;

(3) n antenna element and coupled attenuator and the phase shifter conduct of choosing in the array antenna is calibrated passage, and the described attenuation coefficient that is calibrated the channel attenuation device is become a by initial value ₁, again by a ₁Become a ₂, obtaining attenuation coefficient respectively is a ₁And a ₂The time array antenna synthetic field vector that produces at auxiliary reception antenna place

With

(4) the attenuation coefficient value is a in the initial condition of step (2) and the step (3) when array antenna is in ₁, the attenuation coefficient value is a ₂During three kinds of different conditions, the signal that the auxiliary antenna receiving array antenna produces, and obtain three kinds of signal powers under the state through power detection and be respectively P _N0, P _N1And P _N2:

P_{n 0} = {| {\overset{&RightArrow;}{E}}_{0} |}^{2} = E_{0}^{2},

And obtain to be calibrated the relative amplitude of passage thus

A_{n} = \frac{E_{n}}{E_{0}} = \sqrt{\frac{a_{2} (R_{2} - 1) - a_{1} (R_{2} - 1) + R_{2} - R_{1}}{(a_{1} - 1) (a_{2} - 1) (a_{1} - a_{2})}}

And relative phase

Wherein

(5) attenuation coefficient that keeps being calibrated passage is a ₂Constant, will be calibrated the phase change of passage phase shifter simultaneously And obtain the signal power that auxiliary antenna receives under this state

Obtain thus

(6), obtain being calibrated the relative phase of passage according to the result of calculation of step (4) and step (5)

(7) choose again and be calibrated passage, repeating step (3)～(6) obtain the relative amplitude and the relative phase of each passage in the array antenna;

(8) if the relative amplitude and the relative phase of each passage that step (7) obtains are inconsistent, then adjust the attenuation coefficient of attenuator in each antenna channels and the phase coefficient of phaser, make the relative amplitude of each passage consistent with relative phase.

The present invention's advantage compared with prior art is: at first, the inventive method has made full use of this characteristic of array antenna variable-magnitude of amplitude and phase variable, and, under amplitude and phase place multimode, realize calibration to array antenna according to the power response of array signal in conjunction with these characteristics of phase variable.With regard to present calibration steps, be to utilize this characteristic of phase place multimode to realize calibration mostly, also do not unite and utilize amplitude and phase place multimode to realize Calibration Method.Secondly, this method only needs to measure the power that is calibrated array antenna emission or received signal under three amplitude state of attenuator and phase state of phase shifter, calculate the relative amplitude and the relative phase of each passage relative reference signal according to measured performance number, and obtain each passage inconsistency error, the width of cloth that can finish each passage of array antenna is calibrated mutually thus, operating process is simple, compare with other calibration steps, find the solution easy, do not need a large amount of computational processes, do not have the fuzzy problem of separating yet.

Description of drawings

Fig. 1 is the structure chart of array antenna;

Fig. 2 is the schematic diagram of array antenna calibration steps of the present invention;

Fig. 3 is the FB(flow block) of array antenna calibration steps of the present invention.

Embodiment

As shown in Figure 1, be the structure chart of the array antenna of amplitude and phase variable.3 is antenna element among the figure, and 1 is attenuator, and 2 is phase shifter, by changing the state of attenuator and phase shifter, can change the amplitude and the phase place of the signal of each antenna element of feeding, and this work is finished by controller 5.

4 is power source, and when array antenna was in emission mode, power source gave each antenna element feed with the emission array signal by corresponding attenuator and phase shifter.Power source comprises that a power splitter is with one road signal demultiplexing each antenna element of feeding.Phase place and amplitude that each antenna element signal is set by controller can form the wave beam of desired given shape and realize beam scanning.Can be provided with auxiliary antenna 7 this moment in the far-field range of array antenna, when array antenna is in emission mode, auxiliary antenna as reception antenna to receive calibrating signal.Detect by the signal that auxiliary antenna is received, can obtain the amplitude and the phase characteristic of each antenna element.

6 are power termination among Fig. 1, when array antenna is in receiving mode, auxiliary antenna as outside source to the array antenna transmitted reference signal, reference signal is delivered to power termination through the phase shifter and the attenuator of each antenna element of array antenna, power termination comprises a power combiner as receiving system, and the multiple signals that are used for receiving synthesize one road signal.In like manner, amplitude and phase place that each antenna element signal is set by controller can form the wave beam of desired given shape and realize beam scanning, the reference signal that receives according to load detects, and also can obtain the amplitude and the phase characteristic of each antenna element.

As shown in Figure 3, be the FB(flow block) of the inventive method, the inventive method is utilized the change information of attenuator and phaser array signal under different conditions, the multi-mode joint calibration of realization amplitude and phase place.Calibration steps is as follows:

At first need the auxiliary reception antenna be set at place, array antenna far field.During calibration, array antenna to be measured transmits, and remembers that the field vector that n antenna element produces at auxiliary reception antenna place is

When the position between array antenna to be measured and the auxiliary reception antenna and other boundary condition were constant, this field vector was constant, the stack of the field vector that the field vector that array antenna then to be measured produces at auxiliary reception antenna place produces for each antenna element with, be designated as

As shown in Figure 2, n=1 wherein, 2,3...... is the numbering of each antenna element in the array antenna, E _nWith

Be amplitude and the phase place of array antenna at the initial synthetic field vector of auxiliary reception antenna place generation.

N passage choosing array antenna to be measured supposes that as being calibrated passage the attenuation coefficient of attenuator was l (l=a when attenuator state changed ₀, a ₁, a ₂..., a _m), an operating state of the corresponding attenuator of each attenuation coefficient value, the initial condition of attenuator is designated as a ₀, when the attenuation coefficient that is calibrated attenuator that passage connects (being the state of attenuator) becomes a respectively ₁And a ₂The time array antenna vector field that produces be respectively (principle as shown in Figure 2):

Then attenuator is at a ₀, a ₁, a ₂The signal power that auxiliary antenna receives during three different conditions can be expressed as:

P_{n 0} = {| {\overset{&RightArrow;}{E}}_{0} |}^{2} = E_{0}^{2},

If the relative amplitude of tested passage initial condition

\frac{E_{n}}{E_{0}} = A_{n},

Relative phase

The state of attenuator is a so ₁And a ₂The time, the normalized value of the relative initial power of power that the auxiliary reception antenna receives is respectively R ₁And R ₂, expression formula is as follows:

According to attenuator at a ₀, a ₁, a ₂Signal response result under three different conditions can be in the hope of A _nWith

, expression formula is as follows:

A_{n} = \sqrt{\frac{a_{2} (R_{2} - 1) - a_{1} (R_{2} - 1) + R_{2} - R_{1}}{(a_{1} - 1) (a_{2} - 1) (a_{1} - a_{2})}}

Obviously in order to obtain Exact value, need additional information, can consider that at this state that changes phase shifter obtains enough information, suppose that in attenuator state be a ₂The time, be calibrated the phase shifter phase shift of passage

This moment, the received signal power of auxiliary reception antenna was designated as

Then by aforementioned various getting:

Three state (a according to attenuator ₀, a ₁, a ₂) and the state (90 °) of phase shifter, can obtain the relative phase of tested passage

Expression formula is as follows:

By as can be seen aforementioned, only need add a phase state following inconsistency error that just can obtain tested passage initial amplitude of array antenna and phase place of totally 4 states (comprising initial condition) 3 amplitude state.

Again choose and be calibrated passage, repeat said process, can obtain the relative amplitude and the relative phase of each antenna element in the array antenna, if the relative amplitude and the relative phase of each antenna element that obtains are inconsistent, then adjust the attenuation coefficient and the phase coefficient of each antenna element place passage, the state of promptly adjusting corresponding attenuator and phaser makes it consistent.

The content that is not described in detail in the specification of the present invention belongs to this area professional and technical personnel's known technology.

Claims

1, the calibration steps of the array antenna of a kind of amplitude and phase variable is characterized in that step is as follows:

(1) at place, array antenna far field the auxiliary reception antenna is set;

(2) to the array antenna feed, this moment, each antenna element of array antenna produced the initial field vector at auxiliary reception antenna place

Thereby obtain the initial synthetic field vector that array antenna produces at auxiliary reception antenna place

N=1 wherein, 2,3...... is the numbering of each antenna element in the array antenna, E _nWith Be amplitude and the phase place of each antenna element at the initial field vector of auxiliary reception antenna place generation, E ₀With

P_{n 0} = {| {\overset{&RightArrow;}{E}}_{0} |}^{2} = E_{0}^{2},

And obtain to be calibrated the relative amplitude of passage thus

A_{n} = \frac{E_{n}}{E_{0}} = \sqrt{\frac{a_{2} (R_{2} - 1) - a_{1} (R_{2} - 1) + R_{2} - R_{1}}{(a_{1} - 1) (a_{2} - 1) (a_{1} - a_{2})}}

And relative phase

Wherein

(5) attenuation coefficient that keeps being calibrated passage is a ₂Constant, will be calibrated the phase change of passage phase shifter simultaneously

And obtain the signal power that auxiliary antenna receives under this state

Obtain thus