CN115219816A

CN115219816A - Waveguide port S parameter calibration method and device based on external circle center

Info

Publication number: CN115219816A
Application number: CN202210743221.2A
Authority: CN
Inventors: 刘晨; 吴爱华; 孙静; 栾鹏; 邹学锋; 霍晔; 王一帮; 张立飞; 张晓云; 孙晓颖; 蒋赞勤
Original assignee: CETC 13 Research Institute
Current assignee: CETC 13 Research Institute
Priority date: 2022-06-27
Filing date: 2022-06-27
Publication date: 2022-10-21

Abstract

The invention provides a method and a device for calibrating S parameters of a waveguide port based on an external circle center. The method comprises the following steps: a load calibration piece first reflection coefficient is obtained. A second reflection coefficient of the load calibration piece at the first phase offset is obtained. A third reflection coefficient of the load calibration piece at the second phase offset is obtained. And calculating the coordinates of the circumscribed circle center of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart to be used as the reflection coefficient after the load calibration piece is corrected. And calibrating the S parameter of the waveguide port of the vector network analyzer according to the corrected reflection coefficient. According to the invention, a correction value can be obtained through the reflection coefficients of the load calibration piece under different phase biases, the correction value is taken as the reflection coefficient measured when the actual reflection coefficient of the load calibration piece is 0, and the calibration error caused by the fact that the reflection coefficient of the load calibration piece is not ideal 0 in the waveguide port calibration process is corrected, so that a more accurate measurement result of the S parameter of the waveguide port is obtained.

Description

Waveguide port S parameter calibration method and device based on external circle center

Technical Field

The invention relates to the technical field of vector network analyzer calibration, in particular to a waveguide port S parameter calibration method and device based on an external circle center.

Background

With the development of high-power microwave technology, waveguide devices with large bearing power are widely applied. Vector network analyzers are used to measure network parameters, such as S-parameters, of waveguide devices. Before measurement, the vector network analyzer needs to be calibrated according to the port type of the waveguide device to be measured, and the purpose is to eliminate the system error of the vector network analyzer. The waveguide devices have different waveguide sizes for transmitting electromagnetic waves of different frequencies. In order to accurately measure the network parameters of the waveguide device, waveguide calibration needs to be performed for the corresponding frequency band. For a waveguide two-port vector network analyzer, calibration is typically performed using a short circuit calibration piece, a λ/4 bias short circuit calibration piece, a load calibration piece, and a pass-through calibration piece. The vector network analyzer is calibrated based on a twelve-term error model based on the measurement results of each calibration piece, wherein the S-parameters of the calibration piece used must be known during the calibration process. Typically, the reflection coefficient of the shorting calibration piece is Γ (i.e., S) ₁₁ Parameter) is defined as-1; the reflection coefficient gamma of the load calibration member is defined as 0; s of straight calibration piece ₁₁ Parameter and S ₂₂ The parameter is defined as 0,S ₂₁ Parameters and S ₁₂ The parameter is defined as 1; the definition of the lambda/4 bias short circuit calibration piece is different along with the change of the frequencyThe data of (2).

When the single-port load is calibrated, the load calibration piece is connected with a certain port of the vector network analyzer, and the reflection coefficient is measured. The theoretical reflection coefficient of the load calibration piece is usually defined as 0 at the time of calibration. The load calibration piece is made by inserting a wedge wave-absorbing material into the waveguide cavity. Due to factors such as non-ideal absorption performance of the wave-absorbing material, deviation in manufacturing and assembling and the like, the actual reflection coefficient of the load calibration piece is not ideal 0 but is a small value. The actual reflection coefficient of the load calibration piece deviates from the theoretical reflection coefficient. The reflection coefficient measured when the actual reflection coefficient of the load calibration piece is not 0 is used as the reflection coefficient measured when the actual reflection coefficient of the load calibration piece is 0 to calibrate the vector network analyzer, and the calibration precision of the vector network analyzer is influenced, so that the accuracy of the S parameter measurement result in subsequent use is influenced.

Disclosure of Invention

The embodiment of the invention provides a waveguide port S parameter calibration method and device based on an external circle center, and aims to solve the problem that the calibration precision of a vector network analyzer is influenced by the deviation of an actual reflection coefficient and a theoretical reflection coefficient of a load calibration piece.

In a first aspect, an embodiment of the present invention provides a method for calibrating an S parameter of a waveguide port based on an external circle center, including:

a first reflection coefficient of the load calibration piece measured by the vector network analyzer under the condition of no phase bias is obtained.

And acquiring a second reflection coefficient of the load calibration piece under the first phase bias measured by the vector network analyzer.

And acquiring a third reflection coefficient of the load calibration piece measured by the vector network analyzer under a second phase offset, wherein the second phase offset is not equal to the first phase offset.

And calculating the coordinates of the circumscribed circle center of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart to be used as the reflection coefficient after the load calibration piece is corrected.

And calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration piece.

In a possible implementation manner, the calculating, as the reflection coefficient corrected by the load calibration piece, the circumscribed circle center coordinates of a triangle formed by the first reflection coefficient, the second reflection coefficient, and the third reflection coefficient in the smith chart includes:

calculating out

Γ _{Load_M} ＝Re _{Load_M} +Im _{Load_M}

Γ _{Load_M} As corrected reflection coefficient of the load calibration member, wherein _{Load_M} For the real part of the modified reflection coefficient, im _{Load_M} For the imaginary part of the modified reflection coefficient, re _{Load_M1} Is the real part of the first reflection coefficient, im _{Load_M1} Is the imaginary part of the first reflection coefficient, re _{Load_M2} Is the real part of the second reflection coefficient, im _{Load_M2} Is the imaginary part of the second reflection coefficient, re _{Load_M3} Is the real part of the third reflection coefficient, im _{Load_M3} The imaginary part of the third reflection coefficient.

In one possible implementation, the first phase bias is λ/6, and the second phase bias is λ/3, where λ is a wavelength corresponding to a center frequency of the S parameter calibration band of the waveguide port.

In a possible implementation manner, the obtaining a second reflection coefficient of the load calibration piece measured by the vector network analyzer under the first phase offset includes:

and measuring the load calibration piece connected with the lambda/6 waveguide transmission line through a vector network analyzer to obtain a second reflection coefficient of the load calibration piece under the first phase bias.

The obtaining of the third reflection coefficient of the load calibration piece measured by the vector network analyzer at the second phase offset includes:

and measuring the load calibration piece connected with the lambda/3 waveguide transmission line through a vector network analyzer to obtain a third reflection coefficient of the load calibration piece under the second phase bias.

In a possible implementation manner, the calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration piece includes:

and acquiring the short circuit reflection coefficient of the short circuit calibration piece measured by the vector network analyzer.

And acquiring the lambda/4 offset short-circuit reflection coefficient of the lambda/4 offset short-circuit calibration piece measured by the vector network analyzer.

And obtaining the directivity error, the source matching error and the reflection tracking error of the waveguide port of the vector network analyzer according to the reflection coefficient, the short-circuit reflection coefficient and the lambda/4 bias short-circuit reflection coefficient after the load calibration part is corrected.

And calibrating the S parameter of the waveguide port of the vector network analyzer according to the directivity error, the source matching error and the reflection tracking error.

In a second aspect, an embodiment of the present invention provides a waveguide port S parameter calibration apparatus based on an external center, including:

the first acquisition module is used for acquiring a first reflection coefficient of the load calibration piece measured by the vector network analyzer under the condition of no phase offset.

And the second acquisition module is used for acquiring a second reflection coefficient of the load calibration piece measured by the vector network analyzer under the first phase offset.

And the third acquisition module is used for acquiring a third reflection coefficient of the load calibration piece measured by the vector network analyzer under a second phase offset, wherein the second phase offset is not equal to the first phase offset.

And the calculation module is used for calculating the coordinates of the center of a circumscribed circle of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart, and the coordinates are used as the reflection coefficients after the load calibration piece is corrected.

And the calibration module is used for calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration piece.

In a possible implementation, the calculation module is specifically configured to calculate

Γ _{Load_M} ＝Re _{Load_M} +Im _{Load_M}

Γ _{Load_M} As a corrected reflection coefficient of the load calibration memberIn, re _{Load_M} For the real part of the modified reflection coefficient, im _{Load_M} For the imaginary part, re, of the modified reflection coefficient _{Load_M1} Is the real part of the first reflection coefficient, im _{Load_M1} Is the imaginary part of the first reflection coefficient, re _{Load_M2} Is the real part of the second reflection coefficient, im _{Load_M2} Is the imaginary part of the second reflection coefficient, re _{Load_M3} Is the real part of the third reflection coefficient, im _{Load_M3} The imaginary part of the third reflection coefficient.

In a possible implementation manner, the second obtaining module is specifically configured to measure, by using a vector network analyzer, a load calibration element connected to a λ/6 waveguide transmission line, and obtain a second reflection coefficient of the load calibration element under the first phase offset.

The third obtaining module is specifically configured to measure the load calibration element with the λ/3 waveguide transmission line through the vector network analyzer, and obtain a third reflection coefficient of the load calibration element under the second phase bias.

In one possible implementation, the calibration module includes

And the short circuit reflection coefficient acquisition unit is used for acquiring the short circuit reflection coefficient of the short circuit calibration piece measured by the vector network analyzer.

And the lambda/4 offset short-circuit reflection coefficient acquisition unit is used for acquiring the lambda/4 offset short-circuit reflection coefficient of the lambda/4 offset short-circuit calibration piece measured by the vector network analyzer.

And the error calculation unit is used for obtaining the directivity error, the source matching error and the reflection tracking error of the waveguide port of the vector network analyzer according to the reflection coefficient, the short-circuit reflection coefficient and the lambda/4 bias short-circuit reflection coefficient corrected by the load calibration piece.

And the calibration unit is used for calibrating the S parameter of the waveguide port of the vector network analyzer according to the directivity error, the source matching error and the reflection tracking error.

In a third aspect, an embodiment of the present invention provides a calibration apparatus, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor, when executing the computer program, implements the steps of the method for calibrating S parameters of a waveguide port based on an external center of circle as described in the first aspect or any one of the possible implementations of the first aspect.

In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, where a computer program is stored, and the computer program, when executed by a processor, implements the steps of the circumscribed waveguide port S parameter calibration method according to the first aspect or any one of the possible implementations of the first aspect.

The embodiment of the invention provides a method and a device for calibrating S parameters of a waveguide port based on an external circle center. And acquiring a second reflection coefficient of the load calibration piece under the first phase bias measured by the vector network analyzer. And acquiring a third reflection coefficient of the load calibration piece measured by the vector network analyzer under a second phase offset, wherein the second phase offset is not equal to the first phase offset. And calculating the coordinates of the circumscribed circle center of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart to be used as the reflection coefficient after the load calibration piece is corrected. And calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration piece. By measuring the reflection coefficients of the load calibration piece under different phase offsets, taking the circumcircle center coordinate of a triangle formed by all the reflection coefficients as a correction value and taking the correction value as the reflection coefficient measured when the actual reflection coefficient of the load calibration piece is 0, the calibration error caused by the fact that the reflection coefficient of the load calibration piece is not ideal 0 in the waveguide port calibration process in the prior art is corrected, and therefore a more accurate measurement result of the S parameter of the waveguide port is obtained.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the embodiments or the prior art description will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings may be obtained according to these drawings without inventive labor.

FIG. 1 is a schematic diagram of a forward transmission error model of a twelve term error model;

FIG. 2 is a schematic diagram of a reverse transmission error model of a twelve term error model;

FIG. 3 is a schematic diagram of a vector network analyzer waveguide port isolation calibration;

FIG. 4 is a schematic diagram of a vector network analyzer waveguide port pass-through calibration;

FIG. 5 is a schematic diagram of a vector network analyzer measuring a DUT;

FIG. 6 is a schematic view of the internal structure of the load calibration member;

fig. 7 is a flowchart illustrating an implementation of a method for calibrating S parameters of a waveguide port based on an external center according to an embodiment of the present invention;

FIG. 8 is a schematic view of a vector network analyzer waveguide port single port load calibration provided by an embodiment of the present invention;

FIG. 9 is a schematic diagram of a waveguide transmission line according to an embodiment of the present invention;

FIG. 10 is a chart of gamma rays on a Smith chart provided by embodiments of the invention _{Load_M} Schematic diagram of the method for obtaining;

FIG. 11 is a schematic structural diagram of a short circuit calibration piece according to an embodiment of the present invention;

FIG. 12 is a schematic diagram of a calibration of a single-port short circuit at a waveguide port of a vector network analyzer according to an embodiment of the present invention;

FIG. 13 is a schematic diagram of a calibration of a single-port λ/4 bias short circuit at a waveguide port of a vector network analyzer according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of a waveguide port S parameter calibration apparatus based on an external circle center according to an embodiment of the present invention;

fig. 15 is a schematic diagram of a calibration apparatus according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is made by way of specific embodiments with reference to the accompanying drawings.

With the development of high-power microwave technology, waveguide devices with large bearing power are widely applied. Vector network analyzers are used to measure network parameters, such as S-parameters, of waveguide devices. Before measurement, the vector network analyzer needs to be subjected to system calibration according to the port type of the waveguide device to be measured, so that the system error of the vector network analyzer is eliminated. The waveguide devices have different waveguide sizes for transmitting electromagnetic waves of different frequencies. In practical application, it is difficult to implement waveguide calibration pieces and corresponding calibration procedures for configuring all frequency bands. Meanwhile, the lower the operating frequency band of the waveguide device, the larger the waveguide size, and the worse the operability. In order to accurately measure the network parameters of the waveguide device, waveguide calibration needs to be performed for the corresponding frequency band of the vector network analyzer.

Unlike calibrating a coaxial vector network analyzer, for a waveguide two-port vector network analyzer, calibration is typically performed using a short calibration piece, a λ/4 bias short calibration piece (λ/4 transmission line cascade short calibration piece), a load calibration piece, and a pass-through calibration piece. Wherein the S-parameters of the calibration piece used must be known during the calibration process. In general, the reflection coefficient of the shorting alignment member is Γ, i.e., S ₁₁ Defined as-1; the reflection coefficient of the load calibration member is Γ, i.e. S ₁₁ Defined as 0; s with two directly connected ports of straight-through calibration part ₁₁ And S ₂₂ Is defined as 0,S ₂₁ And S ₁₂ Is defined as 1; the definition of the lambda/4 bias short calibration is defined as different data as the frequency changes. And calibrating the vector network analyzer based on the twelve-term error model according to the measurement result of each calibration piece.

Fig. 1 is a schematic diagram of a forward transmission error model of a twelve term error model. Fig. 2 is a schematic diagram of a twelve term error model of the inverse transmission error model. Referring to fig. 1 and 2:

the forward transmission error model includes 6 error terms, which are: forward directional Error (EDF), forward source matching Error (ESF), forward reflection tracking Error (ERF), forward isolation Error (EXF), forward load matching Error (ELF), and forward transmission tracking Error (ETF). The inverse transmission error model includes 6 error terms, which are: an inverse directivity error EDR, an inverse source match error ESR, an inverse reflection tracking error ERR, an inverse isolation error EXR, an inverse load match error ELR, and an inverse transmission tracking error ETR. And measuring the calibration piece through the waveguide port of the vector network analyzer, and obtaining twelve errors according to the measurement result. The vector network analyzer waveguide port measurement calibration piece comprises single-port calibration, isolation calibration and through calibration.

And obtaining a forward directional error EDF, a forward source matching error ESF, a forward reflection tracking error ERF, a reverse directional error EDR, a reverse source matching error ESR and a reverse reflection tracking error ERR through single-port calibration.

Taking forward transmission as an example, three single-port calibration pieces, namely a short circuit calibration piece, a lambda/4 bias short circuit calibration piece and a load calibration piece, are respectively connected to the 1 st port. Measuring three single-port calibration pieces separately to obtain three reflection coefficients, i.e. S ₁₁ I.e. short-circuit reflection coefficient Γ _{Short_M} λ/4 bias short circuit reflection coefficient Γ _{OffsetShort_M} And load reflection coefficient Γ _{Load_M} . The actual reflection coefficients gamma of the short-circuit calibration piece, the lambda/4 bias short-circuit calibration piece and the load calibration piece are known in advance and are correspondingly recorded as gamma _{Short_A} 、Γ _{OffsetShort_A} And Γ _{Load_A} . The forward directional error EDF, the forward source matching error ESF and the forward inverse in the forward transmission error model can be obtained by the following formulasThe tracking error ERF.

Taking reverse transmission as an example, three single-port calibration pieces, namely a short-circuit calibration piece, a lambda/4 offset short-circuit calibration piece and a load calibration piece, are respectively connected to the 2 nd port, corresponding reflection coefficients are measured, and the reverse directivity error EDR, the reverse source matching error ESR and the reverse reflection tracking error ERR in the reverse transmission error model can be obtained by using the same calculation method as the above.

Error EXF and error EXR are obtained by isolation calibration. FIG. 3 is a schematic diagram of vector network analyzer waveguide port isolation calibration. Referring to fig. 3: the 1 st port and the 2 nd port of the vector network analyzer are simultaneously connected with a load calibration piece, and the transmission coefficient S obtained by measurement at the moment ₂₁ And S ₁₂ Are respectively marked as S _{21 Load} And S _{12 Load} . EXF and EXR can be obtained according to the following formulas.

EXF＝S _{21Load_M}

EXR＝S _{12Load_M}

As another simplified method, EXF and EXR can be directly considered as 0 in the normal case because they are small and negligible, and are not obtained by the above measurement.

ELF and ETF in the forward transmission error model and ELR and ETR in the reverse transmission error model are obtained through-calibration. FIG. 4 is a schematic diagram of vector network analyzer waveguide port pass-through calibration. Referring to fig. 4: the 1 st port and the 2 nd port of the vector network analyzer are directly connected with each other through a pass-through calibration piece. The S parameter measured by the vector network analyzer is recorded as S _{Thru_M} Including S _{11 Thru_M} 、S _{21 Thru_M} 、S ₁₂ _{Thru_M} And S _{22 Thru_M} And (4) four S parameters. The ELF and the ETF in the forward transmission error model and the ELR and the ETR in the reverse transmission error model can be obtained through the following formulas.

ETF＝(S _{21Thru_M} -EXF)(1-ESF·ELF)

ETR＝(S _{12Thru_M} -EXR)(1-ESR·ELR)

Through the single-port calibration, the isolation calibration and the direct calibration, the numerical values of all twelve errors in the forward transmission error model and the reverse transmission error model are obtained. The twelve error numerical values are twelve system errors of the vector network analyzer.

And correcting the measured value of the measured piece by combining the twelve systematic errors with the twelve error model to obtain the real value of the corrected measured piece. FIG. 5 is a schematic diagram of a vector network analyzer measuring a DUT. Referring to FIG. 5: the 1 st port and the 2 nd port of the vector network analyzer are connected with a DUT (Device Under Test). Raw data of the S parameters of the DUT, namely the unmodified S parameters of the DUT, which are recorded as S, can be obtained through measurement _M . The actual S parameter of the DUT, i.e. the modified S parameter of the DUT, is denoted as S _A The actual S-parameters of the DUT can be obtained by the following formula:

wherein, the first and the second end of the pipe are connected with each other,

D＝(1+S _11N ·ESF)(1+S _22N ·ESR)-ELF·ELR·S _21N ·S _12N

in the above calibration method, since the actual reflection coefficient of the load calibration piece is not ideally 0, the calibration accuracy is affected. Fig. 6 is a schematic view of the internal structure of the load calibration member. Referring to fig. 6: the load calibration member is made by inserting a wedge-shaped wave-absorbing material 12 into the waveguide cavity 11. The load-leveling waveguide cavity 11 is closed at one end. When the single-port load is calibrated, the unsealed end of the load calibration piece is connected with a certain port of the vector network analyzer, and the reflection coefficient is measured. The theoretical reflection coefficient of the load calibration piece is usually defined as 0 at the time of calibration. Due to factors such as non-ideal absorption properties of the absorbing material 12 itself, variations in manufacturing and assembly, etc., the actual reflection coefficient of the load calibration member is not ideally 0, but rather some small value. The actual reflection coefficient of the load calibration piece deviates from the theoretical reflection coefficient. The reflection coefficient measured when the actual reflection coefficient of the load calibration piece is not 0 is used as the reflection coefficient measured when the actual reflection coefficient of the load calibration piece is 0 to calibrate the vector network analyzer, so that the calibration precision of the vector network analyzer is influenced, and the accuracy of the S parameter measurement result in subsequent use is influenced.

The embodiment of the invention provides a waveguide port S parameter calibration method based on an external circle center, which aims to solve the problem that the calibration precision of a vector network analyzer is influenced by the deviation of the actual reflection coefficient and the theoretical reflection coefficient of a load calibration piece.

Fig. 7 is a flowchart illustrating an implementation of a method for calibrating S parameters of a waveguide port based on an external center according to an embodiment of the present invention. Referring to fig. 7: the calibration method comprises the following steps:

in step S1, a first reflection coefficient of the load calibration piece measured by the vector network analyzer is obtained without phase offset.

And measuring the first reflection coefficient of the load calibration piece under the condition of no phase offset, namely directly connecting the load calibration piece with a certain waveguide port of the vector network analyzer for measurement. One end of the load calibration piece is closed, the other end of the load calibration piece is provided with a waveguide port, and the inside of the load calibration piece is provided with a wave-absorbing material 12. During single-port calibration, a certain waveguide port of the vector network analyzer is connected with a waveguide port of the load calibration piece. Fig. 8 is a schematic view of a vector network analyzer waveguide port single-port load calibration provided by an embodiment of the present invention. Referring to fig. 8: the waveguide port of the vector network analyzer emits electromagnetic waves, and the electromagnetic waves are input into the waveguide port of the load calibration piece. The electromagnetic wave is absorbed by the wave-absorbing material 12, reflected at the closed end of the load calibration member, and then absorbed by the wave-absorbing material 12 again, and then reflected back to the waveguide port of the vector network analyzer.

The reflection coefficient is a complex ratio of the reflected wave amplitude to the incident wave amplitude. The incident wave amplitude is the amplitude of the incident wave received by the load calibration piece to the waveguide port from the vector network analyzer. The amplitude of the reflected wave is the amplitude of the reflected wave that is absorbed back by the load calibration member. Theoretically, the amplitude of the reflected wave is 0, i.e. the electromagnetic wave is completely absorbed by the wave-absorbing material 12. In practice, the electromagnetic waves are not fully absorbed due to imperfections in the load leveling member.

In step S2, a second reflection coefficient of the load calibration member at the first phase offset measured by the vector network analyzer is obtained. Illustratively, the first phase offset is other than 0.

In step S3, a third reflection coefficient of the load calibration member measured by the vector network analyzer is obtained under a second phase offset, where the second phase offset is not equal to the first phase offset. Illustratively, the second phase bias is other than 0.

Illustratively, phase biasing is achieved by adding a waveguide transmission line between the load calibration piece and the vector network analyzer. Fig. 9 is a schematic structural diagram of a waveguide transmission line according to an embodiment of the present invention. Referring to fig. 9: in the figure, a and b are waveguide transmission lines with different lengths, and c is a load calibration piece. The port of the waveguide transmission line is consistent with the waveguide port specification of the load calibration piece and the vector network analyzer. And during measurement, the load calibration piece, the waveguide transmission line and the vector network analyzer are connected in sequence. The length of the waveguide transmission line in the transmission direction corresponds to the center frequency of the calibration band.

Illustratively, the first phase offset is greater than 0 and less than λ/2 and the second phase offset is greater than 0 and less than λ/2. Illustratively, the first phase bias is λ/4 and the second phase bias is λ 3/8. Illustratively, the first phase bias is λ/8 and the second phase bias is λ 3/8.

In one possible implementation, the first phase bias is λ/6 and the second phase bias is λ/3, where λ is a wavelength corresponding to a center frequency of the S parameter calibration band of the waveguide port.

In one possible implementation, obtaining a second reflection coefficient of the load calibration piece measured by the vector network analyzer at the first phase offset includes:

Obtaining a third reflection coefficient of the load calibration piece measured by the vector network analyzer at a second phase offset, comprising:

Illustratively, the specifications of the λ/3 waveguide transmission line and the λ/6 waveguide transmission line are obtained according to the specification of the waveguide port and the center frequency of the calibration band. Illustratively, the waveguide port adopts a rectangular square waveguide of WR-10 specification, the calibration frequency range is 75 GHz-110 GHz, and the cross-sectional dimension of the inner cavity of the waveguide cavity 11 of the waveguide port is 0.1in multiplied by 0.05in, namely 2.54mm multiplied by 1.27mm. The lengths of the rectangular square waveguide lambda/3 waveguide transmission line and the lambda/6 waveguide transmission line of the specification are respectively 1.5mm and 0.75mm through calculation by using a LineCalc tool in ADS software.

In step S4, the circumscribed circle center coordinates of the triangle formed by the first reflection coefficient, the second reflection coefficient, and the third reflection coefficient on the smith chart are calculated as the reflection coefficients corrected by the load calibration member.

The smith chart is also called an impedance chart and is formed by drawing a normalized equal-resistance circle, which is superimposed on a reflection coefficient complex plane. The smith chart contains a plurality of planes. The reflection coefficient is a complex number corresponding to the coordinates of a certain point in the complex plane. The real part of the reflection coefficient corresponds to the horizontal axis of the complex number plane and the imaginary part of the reflection coefficient corresponds to the vertical axis of the complex number plane. FIG. 10 is a chart of gamma rays on a Smith chart provided by embodiments of the invention _{Load_M} Schematic diagram of the obtaining method. Referring to fig. 10: the three different reflection coefficients correspond to three points in the complex plane to form a triangle. And the reflection coefficient corresponding to the coordinate of the circle center of the triangle circumscribed circle is used as the reflection coefficient after the load calibration piece is corrected. Illustratively, the corrected reflection coefficients of the load calibration piece are used for participating in the error term solving calculation of the twelve-term error model. Illustratively, the corrected reflection coefficients of the load calibration piece are used for solving and calculating the directional error, the source matching error and the reflection tracking error in the twelve-term error model.

In one possible implementation manner, calculating the circumscribed circle center coordinates of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the smith chart as the reflection coefficient corrected by the load calibration member includes: calculating out

Γ _{Load_M} ＝Re _{Load_M} +Im _{Load_M}

Γ _{Load_M} As a corrected reflection coefficient of a load calibration member, wherein Re _{Load_M} For the real part of the modified reflection coefficient, im _{Load_M} For the imaginary part of the modified reflection coefficient, re _{Load_M1} Is the real part of the first reflection coefficient, im _{Load_M1} Is the imaginary part of the first reflection coefficient, re _{Load_M2} Is the real part of the second reflection coefficient, im _{Load_M2} Is the imaginary part, re, of the second reflection coefficient _{Load_M3} Is the real part of the third reflection coefficient, im _{Load_M3} The imaginary part of the third reflection coefficient.

And in step S5, calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration piece.

In one possible implementation manner, calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration piece includes:

and acquiring the short circuit reflection coefficient of the short circuit calibration piece measured by the vector network analyzer. Fig. 11 is a schematic structural diagram of a short circuit calibration piece according to an embodiment of the present invention. Fig. 11 d is a schematic structural diagram of a short circuit calibration component according to an embodiment of the present invention. Fig. 12 is a schematic diagram of a calibration of a single-port short circuit of a waveguide port of a vector network analyzer according to an embodiment of the present invention. In fig. 12, the short circuit reflection coefficient is measured by connecting the short circuit calibration piece to the waveguide port of the vector network analyzer, as an example.

And acquiring the lambda/4 offset short-circuit reflection coefficient of the lambda/4 offset short-circuit calibration piece measured by the vector network analyzer. Fig. 11 e is a schematic diagram of a λ/4 biased waveguide transmission line structure according to an embodiment of the present invention. FIG. 13 is a schematic diagram of a calibration of a single-port λ/4 bias short circuit of a waveguide port of a vector network analyzer according to an embodiment of the present invention. In fig. 13, the λ/4 biased short circuit calibration piece is illustratively formed after connecting the short circuit calibration piece to a λ/4 biased waveguide transmission line. And the lambda/4 offset short-circuit calibration piece is connected with a waveguide port of the vector network analyzer, and the lambda/4 offset short-circuit reflection coefficient is obtained through measurement.

According to the waveguide port S parameter calibration method based on the circumscribed circle center, provided by the embodiment of the invention, by measuring the reflection coefficients of the load calibration piece under different phase offsets, taking the coordinates of the circumscribed circle center of a triangle formed by all the reflection coefficients as a correction value, and taking the correction value as the reflection coefficient measured when the actual reflection coefficient of the load calibration piece is 0, the calibration error caused by the fact that the reflection coefficient of the load calibration piece is not ideal 0 in the waveguide port calibration process in the prior art is corrected, more accurate calibration is realized, the waveguide port S parameter measurement accuracy is improved, and thus more accurate waveguide port S parameter measurement results are obtained.

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

The following are embodiments of the apparatus of the invention, reference being made to the corresponding method embodiments described above for details which are not described in detail therein.

Fig. 14 is a schematic structural diagram of a waveguide port S parameter calibration device based on an external center according to an embodiment of the present invention. For convenience of explanation, only a part related to the embodiment of the present invention is shown, and fig. 14: the embodiment of the invention provides a waveguide port S parameter calibration device 2 based on an external circle center, which comprises:

the first obtaining module 21 is configured to obtain a first reflection coefficient of the load calibration component measured by the vector network analyzer without phase offset.

And a second obtaining module 22, configured to obtain a second reflection coefficient of the load calibration component measured by the vector network analyzer under the first phase offset.

A third obtaining module 23, configured to obtain a third reflection coefficient of the load calibration component measured by the vector network analyzer under a second phase offset, where the second phase offset is not equal to the first phase offset.

And the calculating module 24 is configured to calculate a circumscribed circle center coordinate of a triangle formed by the first reflection coefficient, the second reflection coefficient, and the third reflection coefficient in the smith chart, as the reflection coefficient after the load calibration is corrected.

And the calibration module 25 is configured to calibrate the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration component.

In one possible implementation, the calculation module 24 is specifically used for calculating

Γ _{Load_M} ＝Re _{Load_M} +Im _{Load_M}

Γ _{Load_M} As a corrected reflection coefficient of a load calibration member, wherein Re _{Load_M} For the real part of the modified reflection coefficient, im _{Load_M} For the imaginary part of the modified reflection coefficient, re _{Load_M1} Is the real part of the first reflection coefficient, im _{Load_M1} Is the imaginary part of the first reflection coefficient, re _{Load_M2} Is the real part of the second reflection coefficient, im _{Load_M2} Is the imaginary part of the second reflection coefficient, re _{Load_M3} Is the real part of the third reflection coefficient, im _{Load_M3} The imaginary part of the third reflection coefficient.

In a possible implementation manner, the second obtaining module 22 is specifically configured to measure, by a vector network analyzer, a load calibration element associated with a λ/6 waveguide transmission line, and obtain a second reflection coefficient of the load calibration element under the first phase offset.

The third obtaining module 23 is specifically configured to measure, by using a vector network analyzer, a load calibration element with a λ/3 waveguide transmission line, and obtain a third reflection coefficient of the load calibration element under the second phase bias.

In a possible implementation, the calibration module 25 comprises

Fig. 15 is a schematic diagram of a calibration apparatus according to an embodiment of the present invention. As shown in fig. 15, the calibration device 3 of this embodiment includes: a processor 30, a memory 31 and a computer program 32 stored in said memory 31 and executable on said processor 30. The processor 30 executes the computer program 32 to implement the steps in each circumscribed-circle-center-based waveguide port S parameter calibration method embodiment, such as steps S1 to S5 shown in fig. 7. Alternatively, the processor 30, when executing the computer program 32, implements the functions of the modules/units in the device embodiments described above, such as the functions of the modules 21 to 25 shown in fig. 11.

Illustratively, the computer program 32 may be partitioned into one or more modules/units that are stored in the memory 31 and executed by the processor 30 to implement the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 32 in the calibration apparatus 3. For example, the computer program 32 may be divided into the modules 21 to 25 shown in fig. 11.

The calibration device 3 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The calibration device 3 may include, but is not limited to, a processor 30 and a memory 31. It will be appreciated by those skilled in the art that fig. 15 is merely an example of the calibration apparatus 3, and does not constitute a limitation of the calibration apparatus 3, and may include more or less components than those shown, or combine some components, or different components, for example, the calibration apparatus may further include an input-output device, a network access device, a bus, etc.

The Processor 30 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory 31 may be an internal storage unit of the calibration apparatus 3, such as a hard disk or a memory of the calibration apparatus 3. The memory 31 may also be an external storage device of the calibration apparatus 3, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like provided on the calibration apparatus 3. Further, the memory 31 may also include both an internal storage unit and an external storage device of the calibration apparatus 3. The memory 31 is used for storing the computer program and other programs and data required by the calibration device. The memory 31 may also be used to temporarily store data that has been output or is to be output.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/calibration apparatus and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/calibration apparatus are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the method according to the embodiments of the present invention may also be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned each circumscribed-circle-center-based waveguide port S parameter calibration method embodiment may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims

1. A waveguide port S parameter calibration method based on external circle centers is characterized by comprising the following steps:

acquiring a first reflection coefficient of a load calibration piece measured by a vector network analyzer under the condition of no phase offset;

acquiring a second reflection coefficient of the load calibration piece measured by the vector network analyzer under the first phase offset;

obtaining a third reflection coefficient of the load calibration piece measured by the vector network analyzer under a second phase offset, wherein the second phase offset is not equal to the first phase offset;

calculating the coordinates of the centers of the circumscribed circles of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart, and taking the coordinates as the reflection coefficients after the load calibration piece is corrected;

2. The method according to claim 1, wherein the calculating the circumscribed circle center coordinates of the triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the smith chart as the reflection coefficients corrected by the load calibration member comprises:

computing

Γ _{Load_M} ＝Re _{Load_M} +Im _{Load_M}

Γ _{Load_M} As a corrected reflection coefficient of a load calibration member, wherein Re _{Load_M} For the real part of the modified reflection coefficient, im _{Load_M} For the imaginary part, re, of the modified reflection coefficient _{Load_M1} Is the real part of the first reflection coefficient, im _{Load_M1} Is the imaginary part of the first reflection coefficient, re _{Load_M2} Is the real part of the second reflection coefficient, im _{Load_M2} Is the imaginary part of the second reflection coefficient, re _{Load_M3} Is the real part of the third reflection coefficient, im _{Load_M3} The imaginary part of the third reflection coefficient.

3. The circumscribed waveguide port S parameter calibration method according to claim 1, wherein the first phase offset is λ/6, and the second phase offset is λ/3, where λ is a wavelength corresponding to a center frequency of a waveguide port S parameter calibration band.

4. The method for calibrating the S parameter of the waveguide port based on the circumscribed circle center of the claim 3, wherein the obtaining the second reflection coefficient of the load calibration piece measured by the vector network analyzer under the first phase offset comprises:

measuring a load calibration piece connected with a lambda/6 waveguide transmission line through a vector network analyzer, and acquiring a second reflection coefficient of the load calibration piece under the first phase offset;

5. The method for calibrating the S parameter of the waveguide port based on the circumscribed circle center according to claim 1, wherein calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration member comprises:

obtaining a short circuit reflection coefficient of a short circuit calibration piece measured by a vector network analyzer;

acquiring a lambda/4 offset short circuit reflection coefficient of a lambda/4 offset short circuit calibration piece measured by a vector network analyzer;

obtaining a directional error, a source matching error and a reflection tracking error of a waveguide port of the vector network analyzer according to the reflection coefficient, the short-circuit reflection coefficient and the lambda/4 bias short-circuit reflection coefficient corrected by the load calibration piece;

6. The utility model provides a waveguide port S parameter calibrating device based on external centre of a circle which characterized in that includes:

the first acquisition module is used for acquiring a first reflection coefficient of the load calibration piece measured by the vector network analyzer under the condition of no phase offset;

the second acquisition module is used for acquiring a second reflection coefficient of the load calibration piece measured by the vector network analyzer under the first phase offset;

the third obtaining module is used for obtaining a third reflection coefficient of the load calibration piece measured by the vector network analyzer under a second phase offset, wherein the second phase offset is not equal to the first phase offset;

the calculation module is used for calculating the coordinates of the center of a circumscribed circle of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart, and the coordinates are used as the reflection coefficients after the load calibration piece is corrected;

7. The waveguide port S parameter calibration device based on external circle center of claim 6, wherein the calculation module is specifically configured to calculate

Γ _{Load_M} ＝Re _{Load_M} +Im _{Load_M}

8. The circumscribed waveguide port S parameter calibration device of claim 7, wherein the first phase offset is λ/6 and the second phase offset is λ/3, where λ is a wavelength corresponding to a center frequency of the waveguide port S parameter calibration band.

9. A calibration apparatus comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor when executing the computer program implements the steps of the circumscribed waveguide port S parameter calibration method according to any one of claims 1-5 above.

10. A computer readable storage medium storing a computer program, wherein the computer program when executed by a processor implements the steps of the circumscribed waveguide port S parameter calibration method as set forth in any one of claims 1-5 above.