CN115219815A - Waveguide port S parameter calibration method and device based on inscribed circle center - Google Patents

Abstract

The invention provides a method and device for calibrating S parameters of a waveguide port based on the inscribed circle center. The method includes: acquiring a first reflection coefficient of a load calibration piece. Obtain the second reflection coefficient of the load calibration element under the first phase offset. Obtain the third reflection coefficient of the load calibration piece at the second phase offset. The coordinates of the inscribed circle center of the triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart are calculated as the corrected reflection coefficient of the load calibration piece. The S-parameters of the VNA waveguide ports are calibrated based on the corrected reflection coefficients. The present invention can obtain the correction value through the reflection coefficient of the load calibration piece under different phase offsets, and use 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 reflection coefficient is not ideal 0, and a more accurate measurement result of the S-parameter of the waveguide port is obtained.

Description

A method and device for calibrating S-parameters of waveguide ports based on inscribed circle center

technical field

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

Background technique

With the development of high-power microwave technology, waveguide devices that can withstand high power are widely used. Vector network analyzers are used to measure network parameters of waveguide devices, such as S-parameters. Before measurement, the vector network analyzer needs to be systematically calibrated according to the port type of the waveguide device to be tested, in order to eliminate the system error of the vector network analyzer itself. 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, it is necessary to perform waveguide calibration for the corresponding frequency band. For waveguide two-port vector network analyzers, short-circuit calibration, λ/4 offset short-circuit calibration, load calibration and thru calibration are usually used for calibration. According to the measurement results of each calibration piece, the vector network analyzer is calibrated based on a twelve-term error model, wherein during the calibration process, the S-parameters of the used calibration piece must be known. Usually, the reflection coefficient Γ (ie, the _S11 parameter) of the short-circuit calibration piece is defined as -1; the reflection coefficient Γ of the load calibration piece is defined as 0; the _S11 parameter and the _S22 parameter of the straight-through calibration piece are defined as 0, the _S21 parameter and The S ₁₂ parameter is defined as 1; the definition of the λ/4 bias short-circuit calibration piece is defined as different data as a function of frequency.

During single-port load calibration, connect the load calibration component to a port of the vector network analyzer to measure the reflection coefficient. The theoretical reflection coefficient of the load calibration piece is usually defined as 0 during calibration. The load calibration piece is made by inserting the wedge absorbing material into the waveguide cavity. Due to factors such as the unsatisfactory absorption performance of the absorbing material itself, and the deviation in manufacturing and assembly, the actual reflection coefficient of the load calibration piece is not an ideal 0, but a very 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 part is not 0 is used as the reflection coefficient measured when the actual reflection coefficient of the load calibration part is 0 to calibrate the vector network analyzer, which affects the calibration accuracy of the vector network analyzer and thus affects the subsequent The accuracy of the S-parameter measurements in use.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method and device for calibrating S-parameters of a waveguide port based on the inscribed circle center to solve the problem that the deviation between the actual reflection coefficient of the load calibration piece and the theoretical reflection coefficient affects the calibration accuracy of the vector network analyzer.

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 inscribed circle center, including:

Obtain the first reflection coefficient of the load calibration piece measured by the vector network analyzer without phase offset.

Obtain the second reflection coefficient of the load calibration element measured by the vector network analyzer under the first phase offset.

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

The center coordinates of the inscribed circle of the triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart are calculated as the corrected reflection coefficient of the load calibration piece.

The S-parameters of the waveguide port of the vector network analyzer are calibrated according to the corrected reflection coefficient of the load calibration piece.

In a possible implementation manner, the calculation of the coordinates of the inscribed circle center of the triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart is used as the corrected reflection of the load calibration piece coefficients, including:

calculate

Γ _{Load_M} = e _{Load_M} +m _{Load_}

Γ _{Load_M} is the corrected reflection coefficient of the load calibration element, wherein Re _{Load_M} is the real part of the corrected reflection coefficient, Im _{Load_} is the imaginary part of the corrected 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} is the third reflection coefficient the imaginary part of .

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

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

The load calibration element cascaded with the λ/6 waveguide transmission line is measured by a vector network analyzer, and the second reflection coefficient of the load calibration element under the first phase offset is obtained.

The acquiring the third reflection coefficient of the load calibration element under the second phase offset measured by the vector network analyzer includes:

Measure the load calibration piece cascaded with the λ/3 waveguide transmission line by a vector network analyzer, and obtain the third reflection coefficient of the load calibration piece under the second phase offset.

In a possible implementation manner, the calibration of the S-parameters of the waveguide port of the vector network analyzer according to the corrected reflection coefficient of the load calibration component includes:

Obtain the short-circuit reflection coefficient of the short-circuit calibration piece measured by a vector network analyzer.

Obtain the λ/4 bias short-circuit reflection coefficient of the λ/4 bias short-circuit calibration piece measured by a vector network analyzer.

According to the corrected reflection coefficient, short-circuit reflection coefficient and λ/4 bias short-circuit reflection coefficient of the load calibration piece, the directivity error, source matching error and reflection tracking error of the waveguide port of the vector network analyzer are obtained.

The S-parameters of the waveguide ports of the vector network analyzer are calibrated based on the directivity error, source matching error and reflection tracking error.

In a second aspect, an embodiment of the present invention provides a device for calibrating the S-parameter of a waveguide port based on an inscribed circle center, including:

The first acquisition module is configured to acquire the first reflection coefficient of the load calibration element measured by the vector network analyzer without phase offset.

The second acquisition module is configured to acquire the second reflection coefficient of the load calibration element measured by the vector network analyzer under the first phase offset.

The third acquisition module is configured to acquire the third reflection coefficient of the load calibration element measured by the vector network analyzer under the second phase offset, wherein the second phase offset is not equal to the first phase offset.

The calculation module is used to calculate the center coordinates of the inscribed circle 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 coefficient after the correction of the load calibration piece.

The calibration module is used for calibrating the S-parameters of the waveguide port of the vector network analyzer according to the corrected reflection coefficient of the load calibration piece.

In a possible implementation manner, the computing module is specifically used for computing

Γ _{Load_M} = e _{Load_M} +m _{Load_}

Γ _{Load_M} is the corrected reflection coefficient of the load calibration element, wherein Re _{Load_M} is the real part of the corrected reflection coefficient, Im _{Load_} is the imaginary part of the corrected 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} is the third reflection coefficient the imaginary part of .

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

In a possible implementation manner, the second acquisition module is specifically configured to measure the load calibration part cascaded with the λ/6 waveguide transmission line through a vector network analyzer, and obtain the load calibration part under the first phase offset. second reflection coefficient.

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

In a possible implementation, the calibration module includes

The short-circuit reflection coefficient acquiring unit is used to acquire the short-circuit reflection coefficient of the short-circuit calibration piece measured by the vector network analyzer.

The λ/4 offset short-circuit reflection coefficient acquisition unit is used to obtain the λ/4 offset short-circuit reflection coefficient of the λ/4 offset short-circuit calibration piece measured by the vector network analyzer.

An error calculation unit, configured to obtain the directivity error, source matching error and reflection tracking error of the waveguide port of the vector network analyzer according to the corrected reflection coefficient, short-circuit reflection coefficient and λ/4 bias short-circuit reflection coefficient of the load calibration piece .

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

In a third aspect, an embodiment of the present invention provides a calibration apparatus, including a memory, a processor, and a computer program stored in the memory and executable on the processor, when the processor executes the computer program Implement the steps of the method for calibrating the S-parameters of the waveguide port based on the inscribed circle center as described in the first aspect or any possible implementation manner of the first aspect.

In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, implements the first aspect or any of the first aspect above. A possible implementation means the steps of the method for calibrating the S-parameters of the waveguide port based on the inscribed circle center.

Embodiments of the present invention provide a method and device for calibrating S-parameters of a waveguide port based on the inscribed circle center. The method includes acquiring a first reflection coefficient of a load calibration element measured by a vector network analyzer without phase offset. Obtain the second reflection coefficient of the load calibration element measured by the vector network analyzer under the first phase offset. Obtain the third reflection coefficient of the load calibration element measured by the vector network analyzer under the second phase offset, wherein the second phase offset is not equal to the first phase offset. The center coordinates of the inscribed circle of the triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart are calculated as the corrected reflection coefficient of the load calibration piece. The S-parameters of the waveguide port of the vector network analyzer are calibrated according to the corrected reflection coefficient of the load calibration piece. By measuring the reflection coefficients of the load calibration piece under different phase offsets, the coordinates of the center of the inscribed circle of the triangle formed by each reflection coefficient are taken as the correction value, and the correction value is taken as the reflection coefficient measured when the actual reflection coefficient of the load calibration piece is 0 , to correct the calibration error caused by the fact that the reflection coefficient of the load calibration element is not ideal 0 during the waveguide port calibration process in the prior art, so as to obtain more accurate waveguide port S-parameter measurement results.

Description of drawings

In order to explain the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only for the present invention. In some embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the schematic diagram of the forward transmission error model of the twelve-term error model;

Fig. 2 is the schematic diagram of the reverse transmission error model of the twelve-term error model;

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

Fig. 4 is a schematic diagram of the straight-through calibration of the waveguide port of the vector network analyzer;

Fig. 5 is the schematic diagram of vector network analyzer measuring DUT;

6 is a schematic diagram of the internal structure of the load calibration piece;

7 is an implementation flow chart of a method for calibrating the S-parameters of a waveguide port based on an inscribed circle center provided by an embodiment of the present invention;

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

9 is a schematic structural diagram of a waveguide transmission line provided by an embodiment of the present invention;

Fig. 10 is the schematic diagram of the obtaining method of Γ _{Load_M} on the Smith chart provided by the embodiment of the present invention;

11 is a schematic structural diagram of a short-circuit calibration member provided by an embodiment of the present invention;

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

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

14 is a schematic structural diagram of an apparatus for calibrating the S-parameter of a waveguide port based on an inscribed circle center provided by an embodiment of the present invention;

FIG. 15 is a schematic diagram of a calibration apparatus provided by an embodiment of the present invention.

Detailed ways

In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are set forth in order to provide a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without 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 objectives, technical solutions and advantages of the present invention clearer, the following descriptions will be given through specific embodiments in conjunction with the accompanying drawings.

With the development of high-power microwave technology, waveguide devices that can withstand high power are widely used. Vector network analyzers are used to measure network parameters of waveguide devices, such as S-parameters. Before the measurement, the vector network analyzer needs to be systematically calibrated according to the port type of the waveguide device to be tested, in order to eliminate the system error of the vector network analyzer itself. Waveguide devices have different waveguide sizes for transmitting electromagnetic waves of different frequencies. In practical applications, it is difficult to realize the configuration of waveguide calibration parts and corresponding calibration procedures for all frequency bands. At the same time, the lower the operating frequency band of the waveguide device, the larger the size of the waveguide, and the worse the operability. In order to accurately measure the network parameters of the waveguide device, it is necessary to perform the waveguide calibration for the corresponding frequency band of the vector network analyzer.

Different from the calibration of coaxial vector network analyzers, for waveguide two-port vector network analyzers, short-circuit calibration parts, λ/4 offset short-circuit calibration parts (λ/4 transmission line cascade short-circuit calibration parts), and load calibration parts are usually used. Calibrate with thru calibration. In the calibration process, the S-parameters of the calibration piece used must be known. Usually, the reflection coefficient Γ of the short-circuit calibration piece, namely S ₁₁ , is defined as -1; the reflection coefficient Γ of the load calibration piece, namely S ₁₁ , is defined as 0; the two ports of the straight-through calibration piece are directly connected to S ₁₁ and S ₂₂ are defined is 0, S ₂₁ and S ₁₂ are defined as 1; the definition of the λ/4 bias short-circuit calibration piece is defined as different data as the frequency changes. According to the measurement results of each calibration piece, the vector network analyzer is calibrated based on the twelve-term error model.

FIG. 1 is a schematic diagram of the forward transmission error model of the twelve-term error model. FIG. 2 is a schematic diagram of the reverse transmission error model of the twelve-term error model. Referring to Figures 1 and 2:

The forward transmission error model includes 6 error terms, namely: forward directivity error (EDF), forward source matching error (ESF), forward reflection tracking error (ERF), forward isolation error (EXF), forward error Forward Load Matching Error (ELF) and Forward Transmission Tracking Error (ETF). The reverse transmission error model includes 6 error terms, namely: reverse directivity error EDR, reverse source matching error ESR, reverse reflection tracking error ERR, reverse isolation error EXR, reverse load matching error ELR and reverse Transmission tracking error ETR. The calibration piece is measured through the waveguide port of the vector network analyzer, and twelve errors are obtained according to the measurement results. Vector network analyzer waveguide port measurement calibration kits include single port calibration, isolation calibration and thru calibration.

Forward directionality error EDF, forward source matching error ESF, forward reflection tracking error ERF, reverse directionality error EDR, backward source matching error ESR, and backward reflection tracking error ERR are obtained through single-port calibration.

Taking forward transmission as an example, three single-port calibration parts are respectively connected to the first port, that is, a short-circuit calibration part, a λ/4 offset short-circuit calibration part, and a load calibration part. Three single-port calibration pieces are respectively measured to obtain three reflection coefficients Γ, namely S ₁₁ , namely short-circuit reflection coefficient Γ _{Short_M} , λ/4 offset short-circuit reflection coefficient Γ _{OffsetShort_M} and load reflection coefficient Γ _{Load_M} . The actual reflection coefficient Γ values of the short-circuit calibration part, the λ/4 offset short-circuit calibration part and the load calibration part are known in advance, respectively, and are correspondingly recorded as Γ _{Short_A} , Γ _{OffsetShort_A} and Γ _{Load_A} . The forward directivity error EDF, the forward source matching error ESF and the forward reflection tracking error ERF in the forward transmission error model can be obtained by the following formula.

Taking the reverse transmission as an example, connect three single-port calibration parts to the second port respectively, namely the short-circuit calibration part, the λ/4 bias short-circuit calibration part and the load calibration part, measure the corresponding reflection coefficient, and use the same calculation as above. The method can obtain the reverse directivity error EDR, the reverse source matching error ESR and the reverse reflection tracking error ERR in the reverse transmission error model.

Error EXF and Error EXR are obtained by isolating calibration. Figure 3 is a schematic diagram of a vector network analyzer waveguide port isolation calibration. Referring to Figure 3: the first port and the second port of the vector network analyzer are connected to the load calibration element at the same time, and the transmission coefficients S ₂₁ and S ₁₂ obtained by measurement at this time are respectively recorded 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}

Another simplification method is that, because EXF and EXR are usually small and negligible, EXF and EXR can be directly considered to be 0 without being obtained by the above measurement.

The ELF and ETF in the forward transmission error model and the ELR and ETR in the reverse transmission error model are obtained through the pass-through calibration. Figure 4 is a schematic diagram of a vector network analyzer waveguide port through calibration. Referring to Figure 4: Connect the first port and the second port of the vector network analyzer directly to each other through a thru-calibrator. The S-parameters measured by the vector network analyzer are denoted as S _{Thru_M} , including four S-parameters, S _{11 Thru_M} , S _{21 Thru_M} , S _{12 Thru_M} and S _{22 Thru_M} . ELF and ETF in the forward transmission error model and ELR and ETR in the reverse transmission error model can be obtained by the following formula.

ETF=(S _{21Thru_M} -EXF)(1-ESF·ELF)

ETR=(S _{12Thru_M} -EXR)(1-ESR·ELR)

Through the single-port calibration, isolation calibration, and shoot-through calibration procedures described above, the values of all twelve-term errors in the forward transmission error model and the reverse transmission error model are obtained. These twelve error values are the twelve systematic errors of the vector network analyzer.

Through the above twelve systematic errors combined with twelve error models, the measured value of the DUT is corrected to obtain the true value of the DUT after correction. Figure 5 is a schematic diagram of a vector network analyzer measuring DUT. Referring to Figure 5: Connect the DUT (Device Under Test, DUT for short) to the first port and the second port of the vector network analyzer. The original data of the S-parameters of the DUT can be obtained by measurement, that is, the S-parameters of the uncorrected DUT, which are denoted as S _M . The real S parameter of the DUT, that is, the S parameter of the modified DUT, is denoted as S _A , and the real S parameter of the DUT can be obtained by the following formula:

in,

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 diagram of the internal structure of the load calibration element. Referring to FIG. 6 : the load calibration element is made by inserting the wedge-shaped wave absorbing material 12 into the waveguide cavity 11 . One end of the load calibration piece waveguide cavity 11 is closed. During single-port load calibration, connect the unclosed end of the load calibration piece to a port of the vector network analyzer, and measure the reflection coefficient. The theoretical reflection coefficient of the load calibration piece is usually defined as 0 during calibration. Due to factors such as unsatisfactory absorption performance of the wave absorbing material 12 itself, and deviations in manufacturing and assembly, the actual reflection coefficient of the load calibration element is not ideally 0, but rather 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 part is not 0 is used as the reflection coefficient measured when the actual reflection coefficient of the load calibration part is 0 to calibrate the vector network analyzer, which affects the calibration accuracy of the vector network analyzer and thus affects the subsequent The accuracy of the S-parameter measurements in use.

The embodiment of the present invention provides a waveguide port S parameter calibration method based on the inscribed circle center, so as to solve the problem that the deviation between the actual reflection coefficient of the load calibration piece and the theoretical reflection coefficient affects the calibration accuracy of the vector network analyzer.

FIG. 7 is an implementation flowchart of a method for calibrating the S-parameter of a waveguide port based on the inscribed circle center provided by an embodiment of the present invention. Referring to Figure 7: The calibration method includes:

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

To measure the first reflection coefficient of the load calibration part without phase offset, directly connect the load calibration part to a certain waveguide port of the vector network analyzer for measurement. One end of the load calibration piece is closed, the other end is provided with a waveguide port, and a wave absorbing material 12 is provided inside. During single-port calibration, a waveguide port of the vector network analyzer is connected to the waveguide port of the load calibration element. FIG. 8 is a schematic diagram of a single-port load calibration of a waveguide port of a vector network analyzer according to an embodiment of the present invention. Referring to Figure 8: The wave guide port of the vector network analyzer emits electromagnetic waves and enters the wave guide port of the load calibration element. The electromagnetic wave is absorbed by the wave absorbing material 12 and then reflected at the closed end of the load calibration piece, and is again absorbed by the wave absorbing material 12 and then reflected back to the waveguide port of the vector network analyzer.

The reflection coefficient is the 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 element from the waveguide port of the vector network analyzer. The reflected wave amplitude is the reflected wave amplitude that is absorbed and reflected by the load calibration element. Theoretically, the amplitude of the reflected wave is 0, that is, the electromagnetic wave is completely absorbed by the wave absorbing material 12 . In fact, due to the unsatisfactory load calibration element, the electromagnetic wave is not completely absorbed.

In step S2, the second reflection coefficient of the load calibration element measured by the vector network analyzer under the first phase offset is obtained. Exemplarily, the first phase offset is not 0.

In step S3, the third reflection coefficient of the load calibration element measured by the vector network analyzer under the second phase offset is obtained, wherein the second phase offset is not equal to the first phase offset. Exemplarily, the second phase offset is not 0.

Illustratively, the phase offset is achieved by adding a waveguide transmission line between the load calibration element and the vector network analyzer. FIG. 9 is a schematic structural diagram of a waveguide transmission line provided by an embodiment of the present invention. Referring to Figure 9: a and b in the figure are waveguide transmission lines of different lengths, and c is a load calibration piece. The port of the waveguide transmission line is the same as that of the load calibration piece and the waveguide port of the vector network analyzer. When measuring, connect the load calibration piece, the waveguide transmission line and the vector network analyzer in sequence. The length of the waveguide transmission line in the transmission direction corresponds to the center frequency of the calibration band.

Exemplarily, 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. Exemplarily, the first phase offset is λ/4, and the second phase offset is λ3/8. Exemplarily, the first phase offset is λ/8, and the second phase offset is λ3/8.

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

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

The load calibration element cascaded with the λ/6 waveguide transmission line is measured by a vector network analyzer, and the second reflection coefficient of the load calibration element under the first phase offset is obtained.

Obtain the third reflection coefficient of the load calibration element measured by the vector network analyzer under the second phase offset, including:

Measure the load calibration piece cascaded with the λ/3 waveguide transmission line by a vector network analyzer, and obtain the third reflection coefficient of the load calibration piece under the second phase offset.

Exemplarily, according to the specifications of the waveguide ports and the center frequency of the calibration frequency band, the specifications of the λ/3 waveguide transmission line and the λ/6 waveguide transmission line are obtained. Exemplarily, the waveguide port adopts a rectangular square waveguide of WR-10 specification, the calibration frequency range is 75GHz-110GHz, and the cross-sectional size of the inner cavity of the waveguide cavity 11 of the waveguide port is 0.1in×0.05in, that is, 2.54mm×1.27mm. Using the LineCalc tool in the ADS software, the lengths of the λ/3 waveguide transmission line and the λ/6 waveguide transmission line with the rectangular square waveguide of this specification are calculated to be 1.5mm and 0.75mm, respectively.

In step S4, the center coordinates of the inscribed circle of the triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart are calculated as the reflection coefficient after correction of the load calibration element.

The Smith chart, also known as the impedance circle, is formed by superimposing the normalized equal-resistance circle and the normalized equal-reactance circle on the complex plane of reflection coefficients. The Smith chart contains complex planes. The reflection coefficients are complex numbers that correspond to the coordinates of a 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. 10 is a schematic diagram of a method for obtaining Γ _{Load_M} on a Smith chart provided by an embodiment of the present invention. Referring to Figure 10: Three different reflection coefficients correspond to three points in the complex plane, forming a triangle. The reflection coefficient corresponding to the coordinates of the center of the inscribed circle of the triangle is taken as the corrected reflection coefficient of the load calibration piece. Exemplarily, the corrected reflection coefficient of the load calibration element is used to participate in the calculation of the error term of the twelve-term error model. Exemplarily, the corrected reflection coefficient of the load calibration element is used to participate in the calculation of the directional error, the source matching error and the reflection tracking error in the twelve-term error model.

In a possible implementation manner, the coordinates of the inscribed circle center of the triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in the Smith chart are calculated as the reflection coefficient after correction of the load calibration piece, Include: Computing

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

Γ _{Load_M} is the corrected reflection coefficient of the load calibration element, wherein Re _{Load_M} is the real part of the corrected reflection coefficient, Im _{Load_M} is the imaginary part of the corrected 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} is the third reflection coefficient the imaginary part of .

In step S5, the S-parameters of the waveguide port of the vector network analyzer are calibrated according to the corrected reflection coefficient of the load calibration element.

In a possible implementation manner, the S-parameter of the waveguide port of the vector network analyzer is calibrated according to the reflection coefficient corrected by the load calibration element, including:

Obtain the short-circuit reflection coefficient of the short-circuit calibration piece measured by a vector network analyzer. FIG. 11 is a schematic structural diagram of a short-circuit calibration member provided by an embodiment of the present invention. In FIG. 11 , d is a schematic structural diagram of a short-circuit calibration member provided by an embodiment of the present invention. FIG. 12 is a schematic diagram of a single-port short-circuit calibration of a waveguide port of a vector network analyzer according to an embodiment of the present invention. In FIG. 12, exemplarily, the short-circuit calibration element is connected to the waveguide port of the vector network analyzer, and the short-circuit reflection coefficient is obtained by measurement.

Obtain the λ/4 bias short-circuit reflection coefficient of the λ/4 bias short-circuit calibration piece measured by a vector network analyzer. e in FIG. 11 is a schematic structural diagram of a λ/4 biased waveguide transmission line provided by an embodiment of the present invention. 13 is a schematic diagram of a single-port λ/4 bias short-circuit calibration of a waveguide port of a vector network analyzer according to an embodiment of the present invention. In FIG. 13 , exemplarily, the short-circuit calibration member is formed by connecting the short-circuit calibration member to the λ/4 biased waveguide transmission line to form the λ/4-biased short-circuit calibration member. The λ/4 offset short-circuit calibration piece is then connected to the waveguide port of the vector network analyzer, and the λ/4 offset short-circuit reflection coefficient is obtained by measurement.

According to the above corrected reflection coefficient, short-circuit reflection coefficient and λ/4 bias short-circuit reflection coefficient, the directivity error, source matching error and reflection tracking error of the waveguide port of the vector network analyzer are obtained.

Calibrate the S-parameters of the VNA waveguide port based on the directivity error, source matching error, and reflection tracking error.

The embodiment of the present invention provides a method for calibrating the S-parameter of a waveguide port based on the inscribed circle center. By measuring the reflection coefficients of the load calibration element under different phase offsets, the inscribed circle center coordinates of the triangle formed by each reflection coefficient are used as the correction. The correction value is taken as the reflection coefficient measured when the actual reflection coefficient of the load calibration piece is 0 to correct the calibration error caused by the fact that the reflection coefficient of the load calibration piece is not ideal 0 during the calibration process of the waveguide port in the prior art, so as to achieve more accurate The calibration can improve the accuracy of the S-parameter measurement of the waveguide port, so as to obtain more accurate measurement results of the S-parameter of the waveguide port.

It should be understood that the size of the sequence numbers of the steps in the above embodiments does not mean the sequence of execution, and the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

The following are apparatus embodiments of the present invention, and for details that are not described in detail, reference may be made to the above-mentioned corresponding method embodiments.

FIG. 14 is a schematic structural diagram of an apparatus for calibrating an S-parameter of a waveguide port based on an inscribed circle center provided by an embodiment of the present invention. For the convenience of description, only the part related to the embodiment of the present invention is shown. Referring to FIG. 14 : an embodiment of the present invention provides a waveguide port S-parameter calibration device 2 based on the inscribed circle center, including:

The first acquisition module 21 is configured to acquire the first reflection coefficient of the load calibration element measured by the vector network analyzer without phase offset.

The second acquisition module 22 is configured to acquire the second reflection coefficient of the load calibration element measured by the vector network analyzer under the first phase offset.

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

The calculation module 24 is configured to calculate the center coordinates of the inscribed circle 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 coefficient after the correction of the load calibration piece.

The calibration module 25 is used for calibrating the S-parameters of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibration element.

In a possible implementation, the calculation module 24 is specifically used to calculate

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

Γ _{Load_M} is the corrected reflection coefficient of the load calibration element, wherein Re _{Load_M} is the real part of the corrected reflection coefficient, Im _{Load_M} is the imaginary part of the corrected 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} is the third reflection coefficient the imaginary part of .

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

In a possible implementation manner, the second acquisition module 22 is specifically configured to measure the load calibration piece cascaded with the λ/6 waveguide transmission line by using a vector network analyzer, and obtain the first phase offset of the load calibration piece under the first phase offset. Two reflection coefficients.

The third acquisition module 23 is specifically configured to measure the load calibration part with the λ/3 waveguide transmission line cascaded with the vector network analyzer, and obtain the third reflection coefficient of the load calibration part under the second phase offset.

In one possible implementation, the calibration module 25 includes

The short-circuit reflection coefficient acquiring unit is used to acquire the short-circuit reflection coefficient of the short-circuit calibration piece measured by the vector network analyzer.

The λ/4 offset short-circuit reflection coefficient acquisition unit is used to obtain the λ/4 offset short-circuit reflection coefficient of the λ/4 offset short-circuit calibration piece measured by the vector network analyzer.

The error calculation unit is used to obtain the directivity error, source matching error and reflection tracking error of the waveguide port of the vector network analyzer according to the corrected reflection coefficient, short-circuit reflection coefficient and λ/4 bias short-circuit reflection coefficient of the load calibration element.

A calibration unit for calibrating the S-parameters of the waveguide port of the vector network analyzer according to the directivity error, source matching error and reflection tracking error.

FIG. 15 is a schematic diagram of a calibration apparatus provided by an embodiment of the present invention. As shown in FIG. 15 , the calibration apparatus 3 of this embodiment includes: a processor 30 , a memory 31 , and a computer program 32 stored in the memory 31 and executable on the processor 30 . When the processor 30 executes the computer program 32 , the steps in each of the above-mentioned embodiments of the method for calibrating the S-parameter of the waveguide port based on the inscribed circle center are implemented, for example, the steps S1 to S5 shown in FIG. 7 . Alternatively, when the processor 30 executes the computer program 32, the functions of the modules/units in each of the foregoing apparatus embodiments, for example, the functions of the modules 21 to 25 shown in FIG. 11, are implemented.

Exemplarily, the computer program 32 can be divided into one or more modules/units, and the one or more modules/units are stored in the memory 31 and executed by the processor 30 to complete the this invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program 32 in the calibration device 3 . For example, the computer program 32 may be divided into modules 21 to 25 shown in FIG. 11 .

The calibration device 3 may be a computing device such as a desktop computer, a notebook, a handheld computer, and a cloud server. The calibration device 3 may include, but is not limited to, a processor 30 and a memory 31 . Those skilled in the art can understand that FIG. 15 is only an example of the calibration device 3, and does not constitute a limitation to the calibration device 3, and may include more or less components than the one shown, or combine some components, or different components For example, the calibration apparatus may further include an input and output device, a network access device, a bus, and the like.

The so-called processor 30 may be a central processing unit (Central Processing Unit, CPU), and may also be other general-purpose processors, digital signal processors (Digital Signal Processors, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), Field-Programmable Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, 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 device 3 , such as a hard disk or a memory of the calibration device 3 . The memory 31 may also be an external storage device of the calibration device 3, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) equipped on the calibration device 3 card, flash card (Flash Card) and so on. Further, the memory 31 may also include both an internal storage unit of the calibration apparatus 3 and an external storage device. The memory 31 is used to store the computer program and other programs and data required by the calibration device. The memory 31 can also be used to temporarily store data that has been output or will be output.

Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned functions can be allocated to different functional units, Module completion, that is, dividing the internal structure of the device into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment may be integrated in one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit, and the above-mentioned integrated units may adopt hardware. It can also be realized in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing from each other, and are not used to limit the protection scope of the present application. For the specific working processes of the units and modules in the above-mentioned system, reference may be made to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

In the foregoing embodiments, the description of each embodiment has its own emphasis. For parts that are not described or described in detail in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of the present invention.

In the embodiments provided by the present invention, it should be understood that the disclosed apparatus/calibration apparatus and method may be implemented in other manners. For example, the device/calibration device embodiments described above are only illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units. Or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units.

The integrated modules/units, if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium. Based on this understanding, the present invention can implement all or part of the processes in the methods of the above embodiments, and can also be completed by instructing relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium. When the program is executed by the processor, the steps of each of the foregoing embodiments of the method for calibrating the S-parameter of the waveguide port based on the inscribed circle center can be implemented. Wherein, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate form, and the like. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, removable hard disk, magnetic disk, optical disk, computer memory, Read-Only Memory (ROM), Random Access Memory (Random Access Memory, RAM), electric carrier signal, telecommunication signal, software distribution medium, etc.

The above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it is still possible to implement the foregoing implementations. The technical solutions described in the examples are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the within the protection scope of the present invention.

Claims (10)

1. A waveguide port S parameter calibration method based on an inscribed circle center 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 bias, wherein the second phase bias is not equal to the first phase bias;

calculating the center coordinates of an inscribed circle of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in a Smith chart, and taking the coordinates as the reflection coefficients 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.

2. The method according to claim 1, wherein the calculating the coordinates of the center of the inscribed circle 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 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.

3. The method as claimed in 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 calibration frequency band of the S parameter of the waveguide port.

4. The method according to claim 3, wherein the obtaining of the second reflection coefficient of the load calibration piece measured by the vector network analyzer under the first phase offset includes:

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;

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.

5. The method for calibrating the S parameter of the waveguide port based on the inscribed center according to claim 1, wherein the calibrating the S parameter of the waveguide port of the vector network analyzer according to the reflection coefficient corrected by the load calibrating element 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;

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.

6. The utility model provides a waveguide port S parameter calibration device based on inscribe 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 calculating module is used for calculating the circle center coordinates of an inscribed circle of a triangle formed by the first reflection coefficient, the second reflection coefficient and the third reflection coefficient in a Smith chart, and the circle center 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.

7. The waveguide port S parameter calibration device based on the inscribed circle center of claim 6, wherein 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 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 third reflectionReal part of coefficient, im _{Load_M3} The imaginary part of the third reflection coefficient.

8. The inscribe-center-based waveguide port S-parameter calibration device according to claim 7, wherein 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 a 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 method for calibrating S parameter of an inscribe center-based waveguide port according to any one of claims 1 to 5.

10. A computer readable storage medium storing a computer program, wherein the computer program when executed by a processor implements the steps of the inscribe circle center based waveguide port S parameter calibration method as claimed in any one of claims 1 to 5 above.

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