CN111460697A - Coaxial connector passive intermodulation prediction method with different corrosion degrees - Google Patents
Coaxial connector passive intermodulation prediction method with different corrosion degrees Download PDFInfo
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Abstract
The invention discloses a coaxial connector passive intermodulation prediction method with different corrosion degrees. The invention comprises the following steps: step one), selecting an uncorroded coaxial connector to carry out contact resistance and passive intermodulation third harmonic power test, and carrying out theoretical analysis modeling on the nonlinear effect of the uncorroded coaxial connector by adopting a polynomial model; step two), designing and carrying out an accelerated test on the coaxial connector in the step one to obtain coaxial connectors with different corrosion degrees; step three), testing the contact resistance and the passive intermodulation third harmonic power of the coaxial connectors with different corrosion degrees, and establishing passive intermodulation power prediction models of the coaxial connectors with different corrosion degrees. The invention obtains the coaxial connector passive intermodulation prediction method with different corrosion degrees by various testing means and analysis methods, and the method is suitable for analyzing the coaxial connectors in all radio frequency communication systems.
Description
Technical Field
The invention relates to a passive intermodulation prediction method of coaxial connectors with different corrosion degrees, which obtains passive intermodulation power prediction models of the coaxial connectors with different corrosion degrees based on analysis methods such as theoretical modeling and experimental measurement and belongs to the crossing field of an electrical contact theory and a communication technology.
Background
Passive intermodulation refers to a phenomenon in which, when signals of two or more frequencies are input into a passive device, harmonics of other frequencies are generated in the output signal. These harmonics may fall into the reception band with a non-negligible impact on the quality of the communication system. Passive intermodulation is due to the nonlinear effects of passive devices.
Coaxial connectors are the most used and most varied of important components in the overall radio frequency communication system. Coaxial connectors complete the connection by means of metal contacts, generally considered linear, but in the case of high power passing, will exhibit slight nonlinear effects. Particularly, under the conditions of poor contact, improper use of magnetic materials, poor quality of metal coatings and the like, the passive intermodulation phenomenon is very serious, and strong interference is generated on communication signals. In addition, the use environment of many connectors is the field, and the alternating of temperature and humidity, weather such as wind, rain and thunder and lightning arouse the vibration, the dust and the mutual action of corrosive gas, these all make the connector lose efficacy because of the combined action of environmental factor, further bring more serious passive intermodulation problem. Nonlinear effects in coaxial connectors are the main cause of passive intermodulation problems. Therefore, the analysis of the nonlinear effect and the passive intermodulation problem of the coaxial connector is a problem which is closely concerned and needs to be solved in the communication field at present.
At present, the research work on the nonlinear effect of the coaxial connector mainly stays in modeling analysis and passive intermodulation performance analysis of the nonlinear effect of the non-corroded connector, and basically obtains a passive intermodulation test method and a prediction model of passive intermodulation power of the non-corroded connector. The analysis on the nonlinear effect and the passive intermodulation of the corroded connector and the analysis on the influence of the corrosion of the connector on the passive intermodulation performance are rare, and the method has very important application prospect and practical value on the research on the nonlinear effect and the passive intermodulation prediction of coaxial connectors with different corrosion degrees.
Disclosure of Invention
Aiming at the one-sided and limited conditions of passive intermodulation performance analysis and prediction of the corroded coaxial connector in the prior art, the invention aims to analyze and establish the nonlinear effect models and the passive intermodulation power prediction models of the coaxial connector with different corrosion degrees on the basis of combining theoretical analysis and experimental measurement.
To achieve the above object, the present invention provides the following analysis scheme:
step one) research on non-linear effect of non-corroded connector
A connector pair consisting of an unetched female-to-female N-type connector and a revolute female N-type connector was selected as a sample. The contact resistance was measured for the connector pair using the four-point method and the two-tone passive intermodulation third harmonic power was measured for the connector pair using a passive intermodulation analyzer, where the two frequencies input were 935MHz and 960MHz, respectively, and the two input powers were simultaneously stepped from 35dBm to 44 dBm. The measured third order passive intermodulation frequency was 910 MHz. A polynomial mathematical model is adopted to carry out theoretical analysis modeling on the nonlinear effect of the non-corroded coaxial connector, and the model is as follows:
iout＝a3v3+a5v5+a7v7
wherein ioutIs a non-linear current through the connectorV is the voltage input to the connector, a3，a5，a7Are coefficients of a polynomial mathematical model, which can be obtained by fitting the passive intermodulation third harmonic power test results.
Step two) carrying out accelerated test on the connector
The accelerated test is a test method for accelerating the failure of a tested product by strengthening test conditions on the premise of ensuring that the failure mechanism of the product is not changed so as to obtain necessary information in a short time to evaluate the reliability or service life index of the product under normal conditions. The coaxial connector in step one was subjected to an accelerated test using nitric acid vapor, wherein the concentration of nitric acid was 69%. In the acceleration test, only the male portion of the revolution female N-type connector was corroded, and the female portion of the revolution female connector was protected by a rubber cap and a teflon anti-corrosion tape. The corroded male connector is then connected to the female connector of the non-corroded female-to-female connector. Such a connector pair can be used to study passive intermodulation performance variations due to corrosion of the male and female contact portions. In addition, it can prevent the corroded portion of the connector from directly contacting the test instrument. To make connectors of different corrosion levels, the connector pairs were divided into 5 groups, and the duration of the accelerated test of these 5 groups was set to 1 hour, 2 hours, 4 hours, 6 hours, and 8 hours, respectively. Then, the 5 groups of connectors with different corrosion degrees are respectively tested for contact resistance and passive intermodulation third harmonic power.
Step three) passive intermodulation analysis and prediction of connectors with different corrosion degrees
The contact resistance is used as an index for measuring the corrosion degree of the connector, and the nonlinear effect models and the passive intermodulation third harmonic power prediction models of the coaxial connectors with different corrosion degrees are quantitatively provided by analyzing the change rule of the contact resistance and the passive intermodulation third harmonic power values of the connectors with different corrosion degrees, wherein the nonlinear effect models of the coaxial connectors with different corrosion degrees can be expressed as:
wherein idFor nonlinear current through the corroded connector, v is the voltage input into the corroded connector, R is the contact resistance of the corroded connector, R0The standard contact resistance of the non-corroded connector is the average value of the contact resistances of all samples of the non-corroded connector, r is a correction coefficient and can be obtained by fitting the test results of the contact resistance of the corroded connector and the passive intermodulation third harmonic power, a3、a5、a7Are coefficients of a polynomial mathematical model. The model is described in the specification of R ═ R0The model of the nonlinear effect is the same as that of the un-corroded coaxial connector.
The passive intermodulation third harmonic current amplitudes of coaxial connectors of different corrosion levels can be expressed as:
wherein I3rdFor passive intermodulation third harmonic current amplitude, V is the voltage amplitude of the input connector.
The passive intermodulation third harmonic power prediction model of the coaxial connectors with different corrosion degrees is as follows:
wherein P isIM3For passive intermodulation third harmonic power, the unit is dBm, | Z | is the connector impedance mode value, lg represents the base-10 logarithm.
And then comparing the model result with the passive intermodulation third harmonic power experimental data of the connector with different corrosion degrees, verifying the correctness of the model and obtaining the passive intermodulation prediction method of the corrosion coaxial connector.
The passive intermodulation prediction method of the coaxial connectors with different corrosion degrees, which is provided by the invention, manufactures the connectors with different corrosion degrees by designing and implementing an accelerated test. And through the combination of theoretical modeling analysis and experimental verification, obtaining the nonlinear effect models of the coaxial connectors with different corrosion degrees and the passive intermodulation third harmonic power prediction models. Theoretical support is provided for analyzing the influence of the corrosion of the coaxial connector on the passive intermodulation performance of the coaxial connector and predicting the passive intermodulation power of the coaxial connector with different corrosion degrees. Compared with a passive intermodulation analysis method of a coaxial connector, the passive intermodulation analysis method of the coaxial connector mainly has the following advantages:
1) the nonlinear effects of corroded coaxial connectors were analyzed.
2) An accelerated test in which only the male portion of the revolution female N-type connector is corroded to avoid the introduction of unnecessary errors and the corroded portion of the connector is prevented from directly contacting with a test instrument is designed and implemented.
3) The nonlinear effect model and the passive intermodulation third harmonic power prediction model of the coaxial connector with different corrosion degrees are quantitatively provided, and the model is also suitable for the non-corroded connector.
Drawings
FIG. 1 is a general schematic diagram of the technical route of the method.
Detailed Description
The invention is described in further detail below with reference to the following description of the drawings. The following description case takes an N-type coaxial connector as an example for analysis, but this embodiment is not intended to limit the present invention, and the analysis method of the present invention can be used to predict the nonlinear effect and the passive intermodulation power of coaxial connectors with different corrosion degrees, as long as the coaxial connectors with similar structure and similar changes of the present invention are used as the analysis objects.
The general schematic diagram of the technical route is shown in FIG. 1, the invention selects a non-corroded connector, and measures the contact resistance and the third-order intermodulation power of the connector; designing and implementing an accelerated test to manufacture coaxial connectors with different corrosion degrees; the contact resistance is used as an index for measuring the corrosion degree of the connector, and the relation between the passive intermodulation third harmonic power of the coaxial connector and the contact resistance and the input power is quantitatively given.
In the first step, a connector pair consisting of an unetched female-to-female N-type connector and a revolute female N-type connector was selected as a sample. The contact resistance of the connector pair was measured using a microohm microvolt using the four point method. The connector pair was tested for two-tone passive intermodulation third harmonic power using a passive intermodulation analyzer, where the two frequencies input were 935MHz and 960MHz, respectively, and the two input powers were simultaneously stepped from 35dBm to 44 dBm. The measured third order passive intermodulation frequency was 910 MHz. A polynomial mathematical model is adopted to carry out theoretical analysis modeling on the nonlinear effect of the non-corroded coaxial connector, and the model is as follows:
iout＝a3v3+a5v5+a7v7
wherein ioutIs the nonlinear current through the connector, v is the voltage input to the connector, a3，a5，a7Are coefficients of a polynomial mathematical model, which can be obtained by fitting the passive intermodulation third harmonic power test results.
In the second step, the coaxial connector in the first step was subjected to an accelerated test using nitric acid vapor, in which the concentration of nitric acid was 69%. The accelerated test is a test method for accelerating the failure of a tested product by strengthening test conditions on the premise of ensuring that the failure mechanism of the product is not changed so as to obtain necessary information in a short time to evaluate the reliability or service life index of the product under normal conditions. In the acceleration test, only the male portion of the revolution female N-type connector was corroded, and the female portion of the revolution female connector was protected by a rubber cap and a teflon anti-corrosion tape. The corroded male connector is then connected to the female connector of the non-corroded female-to-female connector. Such a connector pair can be used to study passive intermodulation performance variations due to corrosion of the male and female contact portions. In addition, it can prevent the corroded portion of the connector from directly contacting the test instrument. To make connectors of different corrosion levels, the connector pairs were divided into 5 groups, and the duration of the accelerated test of these 5 groups was set to 1 hour, 2 hours, 4 hours, 6 hours, and 8 hours, respectively. Then, the 5 groups of connectors with different corrosion degrees are respectively tested for contact resistance and passive intermodulation third harmonic power.
And thirdly, analyzing the change rule of the contact resistance and the passive intermodulation third harmonic power value of the connector with different corrosion degrees by taking the contact resistance as an index for measuring the corrosion degree of the connector, and quantitatively providing a nonlinear effect model and a passive intermodulation third harmonic power prediction model of the coaxial connector with different corrosion degrees, wherein the nonlinear effect model of the coaxial connector with different corrosion degrees can be expressed as:
wherein idFor nonlinear current through the corroded connector, v is the voltage input into the corroded connector, R is the contact resistance of the corroded connector, R0The standard contact resistance of the non-corroded connector is the average value of the contact resistances of all samples of the non-corroded connector, r is a correction coefficient and can be obtained by fitting the test results of the contact resistance of the corroded connector and the passive intermodulation third harmonic power, a3、a5、a7Are coefficients of a polynomial mathematical model. The model is described in the specification of R ═ R0The model of the nonlinear effect is the same as that of the un-corroded coaxial connector.
The voltage v input to the connector from the passive intermodulation analyzer can be expressed as:
v＝V[cos(ω1t)+cos(ω2t)]
where V is the amplitude of the input voltage, ω1And ω2Respectively, the angular frequency of the two input signals, and t is an argument representing time.
Substituting the input voltage v into the nonlinear effect model of the corroded coaxial connector to obtain:
extracting the angular frequency of (2 omega)1-ω2) The coefficients of the terms (a) and (b) can obtain the passive intermodulation third harmonic current amplitudes of the coaxial connectors with different corrosion degrees, and can be expressed as:
wherein I3rdFor passive intermodulation third harmonic current amplitude, V is the voltage amplitude of the input connector.
The passive intermodulation third harmonic power prediction model of the coaxial connectors with different corrosion degrees is as follows:
wherein P isIM3For passive intermodulation third harmonic power, the unit is dBm, | Z | is the connector impedance mode value, lg represents the base-10 logarithm.
And then comparing the model result with the passive intermodulation third harmonic power experimental data of the connector with different corrosion degrees, verifying the correctness of the model and obtaining the passive intermodulation prediction method of the corrosion coaxial connector.
Claims (4)
1. A passive intermodulation prediction method of coaxial connectors with different corrosion degrees is characterized by comprising the following steps:
selecting a connector pair consisting of an un-corroded female-to-female N-type connector and a male-to-female N-type connector as a sample; designing and implementing an accelerated test to manufacture coaxial connectors with different corrosion degrees; the contact resistance is used as an index for measuring the corrosion degree of the connector, and the relation between the passive intermodulation third harmonic power of the coaxial connector and the contact resistance and the input power is quantitatively given. The specific implementation steps are as follows:
in the first step, a connector pair consisting of an unetched female-to-female N-type connector and a revolute female N-type connector was selected as a sample. Measuring the passive intermodulation performance of the coaxial connector by using the third harmonic power, measuring the contact resistance of a sample and testing the passive intermodulation third harmonic power, and performing theoretical analysis modeling on the non-linear effect of the non-corroded coaxial connector by using a polynomial mathematical model;
in the second step, the coaxial connector in the first step was subjected to an accelerated test using nitric acid vapor, in which the concentration of nitric acid was 69%. In the acceleration test, only the male portion of the revolution female N-type connector was corroded, and the female portion of the revolution female connector was protected by a rubber cap and a teflon anti-corrosion tape. The corroded male connector is then connected to the female connector of the non-corroded female-to-female connector. Such a connector pair can be used to study passive intermodulation performance variations due to corrosion of the male and female contact portions. In addition, it can prevent the corroded portion of the connector from directly contacting the test instrument. To make connector pairs of different corrosion levels, the connector pairs were divided into 5 groups, and the duration of the accelerated test of these 5 groups was set to 1 hour, 2 hours, 4 hours, 6 hours, and 8 hours, respectively.
And thirdly, testing the contact resistance and the passive intermodulation third harmonic power of the coaxial connectors with different corrosion degrees obtained in the second step. And (3) theoretically analyzing and modeling the nonlinear effect of the coaxial connectors with different corrosion degrees by taking the contact resistance as an index for measuring the corrosion degree of the coaxial connectors and combining the polynomial mathematical model in the step one, and obtaining the passive intermodulation third harmonic power prediction models of the coaxial connectors with different corrosion degrees.
2. The passive intermodulation prediction method of coaxial connectors with different corrosion degrees as claimed in claim 1, wherein the first step is to select a non-corroded connector pair as the sample to be tested, so as to study the change of passive intermodulation performance caused by corrosion of the contact parts of the male and female connectors and prevent the corroded part of the connector from directly contacting the test instrument, and in addition, the contact resistance and the passive intermodulation third harmonic power of the non-corroded sample are selected to be basically the same.
3. The passive intermodulation prediction method of coaxial connectors with different corrosion degrees as claimed in claim 1, wherein the second step should only corrode the male portion of the revolution female N-type connector, care should be taken to protect the female portion of the revolution female connector, and in addition, coaxial connectors with different corrosion degrees should be made with different accelerated test durations.
4. The passive intermodulation prediction method of coaxial connectors with different corrosion degrees as claimed in claim 1, wherein the third step quantitatively gives the nonlinear effect model and the passive intermodulation third harmonic power prediction model of coaxial connectors with different corrosion degrees by using the contact resistance as an index for measuring the corrosion degree of the connector, wherein the nonlinear effect model of coaxial connectors with different corrosion degrees can be expressed as:
wherein idFor nonlinear current through the corroded connector, v is the voltage input into the corroded connector, R is the contact resistance of the corroded connector, R0The standard contact resistance of the non-corroded connector is the average value of the contact resistances of all samples of the non-corroded connector, r is a correction coefficient, a3、a5、a7Are coefficients of a polynomial mathematical model.
The passive intermodulation third harmonic current amplitudes of coaxial connectors of different corrosion levels can be expressed as:
wherein I3rdFor passive intermodulation third harmonic current amplitude, V is the voltage amplitude of the input connector.
The passive intermodulation third harmonic power prediction model of the coaxial connectors with different corrosion degrees is as follows:
wherein P isIM3For passive intermodulation third harmonic power, the unit is dBm, | Z | is the connector impedance mode value, lg represents the base-10 logarithm.
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| CN113176461A (en) * | 2020-10-22 | 2021-07-27 | 西南交通大学 | Passive intermodulation prediction method integrating contact and material nonlinearity |
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