A method for comprehensive performance analysis of passive intermodulation and scattering characteristics of radio frequency connectors

Abstract

The application discloses a kind of comprehensive performance analysis methods of passive intermodulation and scattering characteristics of radio frequency connector, the method first selects a radio frequency connector as measured piece and performance evaluation object, then in turn establishes the transmission performance equivalent model of radio frequency connector, the nonlinear equivalent model of radio frequency connector contact surface, the complete contact surface equivalent model of radio frequency connector, the complete radio frequency connector equivalent model, scattering performance and intermodulation performance simulation are carried out to complete radio frequency connector equivalent model by parameter setting, finally the simulation results of scattering performance and intermodulation performance are analyzed.The application is simple to operate, can effectively establish complete radio frequency connector equivalent model using convenient test, obtain radio frequency connector performance prediction under different signal excitation, provide a good analysis approach for practical application of radio frequency connector, with engineering practical value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radio frequency connector performance analysis, and particularly relates to a radio frequency connector passive intermodulation and scattering characteristic comprehensive performance analysis method. BACKGROUND

[0002] Radio frequency connector is a component for realizing electrical connection, separation or conversion of different types of transmission lines, and belongs to mechatronic product, which plays a bridge role in communication circuit. The electrical performance of radio frequency connector is usually measured by scattering characteristics such as return loss and insertion loss. With the increase of communication signal power, passive intermodulation interference caused by some weak passive nonlinear effects cannot be ignored. Therefore, in addition to the scattering characteristics, the nonlinear characteristics of the radio frequency connector also need to be evaluated, which is usually measured by the third-order passive intermodulation product power. However, through engineering tests, it is found that the relationship between passive intermodulation and scattering performance is not clear, and some connectors with good scattering performance show poor intermodulation performance. Therefore, modeling the relationship between the passive intermodulation performance and the scattering performance of the radio frequency connector is the key to solving the correct selection problem of the connector in engineering application.

[0003] The research on the scattering characteristics of radio frequency connector mainly focuses on the influence of the structure, material and contact surface impedance change of the radio frequency connector on the return loss, insertion loss and standing wave ratio. However, the structure, material and contact surface impedance of the radio frequency connector also affect the passive intermodulation performance. However, current test research shows that the relationship between intermodulation level and standing wave ratio is not obvious, which is related to the unclear theoretical model of the generation principle of scattering parameters and intermodulation level. Therefore, in order to predict the comprehensive performance of the intermodulation performance and the scattering characteristics of the radio frequency connector in the actual communication system in advance, the relationship between the passive nonlinear and scattering characteristics of the connector needs to be modeled. SUMMARY

[0004] In view of the above problems in the prior art, the present application provides a radio frequency connector passive intermodulation and scattering characteristic comprehensive performance analysis method, which can realize synchronous prediction of the transmission characteristics and nonlinear effects of the radio frequency connector.

[0005] In order to achieve the above application purpose, the technical scheme adopted by the present application is as follows:

[0006] A radio frequency connector passive intermodulation and scattering characteristic comprehensive performance analysis method, comprising the following steps:

[0007] S1, selecting a radio frequency connector as a test piece and a performance evaluation object;

[0008] S2, testing the scattering performance of the radio frequency connector in step S1 and establishing a transmission performance equivalent model of the radio frequency connector;

[0009] S3, test the passive intermodulation performance of the radio frequency connector in step S1 and establish a nonlinear equivalent model of the contact surface of the radio frequency connector;

[0010] S4, calculate the impedance effect equivalent model of the contact surface of the radio frequency connector in step S1 according to the contact impedance effect;

[0011] S5, cascade the nonlinear equivalent model in step S3 with the impedance effect equivalent model in step S4 to obtain a complete contact surface equivalent model of the radio frequency connector;

[0012] S6, connect the transmission performance equivalent model in step S2 with the complete contact surface equivalent model in step S5 to obtain a complete radio frequency connector equivalent model;

[0013] S7, simulate the scattering performance and intermodulation performance of the complete radio frequency connector equivalent model in step S6 through parameter setting;

[0014] S8, analyze the simulation results of the scattering performance and intermodulation performance obtained in step S7.

[0015] Further, step S2 includes the following sub-steps:

[0016] S21, measure the return loss value and insertion loss value of the radio frequency connector, record and save the sweep measurement results;

[0017] S22, equivalently model the transmission performance of the radio frequency connector as a cascade circuit model of capacitor C1 and inductor L1;

[0018] S23, set the capacitor C1 and inductor L1 in the circuit as tunable parameters to be determined;

[0019] S24, perform S-parameter simulation on the circuit model in sub-step S22 to obtain the simulation results of return loss and insertion loss;

[0020] S25, determine whether the difference between the simulation results in sub-step S24 and the measurement results in sub-step S21 is within the error range, if yes, save the values of capacitor C1 and inductor L1, otherwise adjust the values of capacitor C1 and inductor L1 and jump to sub-step S24;

[0021] S26, establish the transmission performance equivalent model of the radio frequency connector according to the values of capacitor C1 and inductor L1 saved in sub-step S25.

[0022] Further, step S3 includes the following sub-steps:

[0023] S31, measure the reflected third-order intermodulation value of the radio frequency connector, and record the measurement results;

[0024] S32, measure the reflection five-order intermodulation value of the radio frequency connector, and record the measurement result;

[0025] S33, calculate the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient according to the measurement result in the sub-step S31 and the measurement result in the sub-step S32;

[0026] S34, determine the nonlinear transfer function according to the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient obtained in the sub-step S33;

[0027] S35, obtain the nonlinear resistance model and establish the nonlinear equivalent model of the contact surface of the radio frequency connector according to the nonlinear transfer function determined in the sub-step S34.

[0028] Further, the calculation equation of the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient is:

[0029]

[0030] wherein c3 is the third-order nonlinear transmission coefficient, P0 is the input power of the two double-tone signals, R is the responsible impedance value, c5 is the fifth-order nonlinear transmission coefficient, P IM3 is the reflection three-order intermodulation value of the radio frequency connector, and P IM5 is the reflection five-order intermodulation value of the radio frequency connector.

[0031] Further, the nonlinear transfer function is:

[0032]

[0033] wherein i is the nonlinear transfer function, c1 is the linear transmission term of the connector, c3 is the third-order nonlinear transmission coefficient, v is the amplitude of the input signal, and c5 is the fifth-order nonlinear transmission coefficient.

[0034] Further, the impedance effect equivalent model comprises the contraction resistance R c of the contact surface, the contact capacitance C c caused by the contact gap, and the inductance L c caused by the current path lengthening of the contact surface, and the values of the resistance R c , the capacitance C c and the inductance L c are calculated according to the electric contact theory.

[0035] Further, in S7, the scattering performance and the intermodulation performance under different frequency bands and different signal combination frequencies are simulated by setting the parameters of the S parameter simulation space and the harmonic balance simulation control.

[0036] The present application has the following beneficial effects:

[0037] (1) The present application is simple in operation, and can effectively establish the transmission characteristic equivalent model and the nonlinear characteristic equivalent model of the radio frequency connector by using convenient tests, and obtain the performance prediction of the radio frequency connector under different signal excitations;

[0038] (2) In addition to considering the transmission characteristic and the nonlinear characteristic of the radio frequency connector, the present application also considers the electrical contact effect of the radio frequency connector, and realizes the research on the influence of the contact performance of the radio frequency connector on the transmission characteristic and the nonlinear characteristic;

[0039] (3) The present application can perform multi-dimensional simulation prediction under other application conditions (different frequencies and power signal excitations), and provides a good analysis approach for the actual application of the radio frequency connector, and has engineering practical value;

[0040] (4) In addition, the present application is also applicable to other passive radio frequency components except the radio frequency connector. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 It is a flow chart of a radio frequency connector passive intermodulation and scattering characteristic comprehensive performance analysis method;

[0042] Figure 2 It is a complete radio frequency connector equivalent model circuit diagram;

[0043] Figure 3 It is a complete radio frequency connector equivalent model S parameter scanning simulation diagram, wherein Fig. a is a return loss performance simulation diagram of different contact resistances, different body resistances and different impedance mismatches under the change of frequency, and Fig. b is an insertion loss performance simulation diagram of different contact resistances, different body resistances and different impedance mismatches under the change of frequency;

[0044] Figure 4 It is a complete radio frequency connector equivalent model harmonic balance simulation diagram, wherein Fig. a is a simulation diagram of the influence of the change of the contact resistance and the body resistance on the third-order intermodulation power, and Fig. b is a simulation diagram of the influence of the signal frequency on the intermodulation power under the condition of different contact resistances and different body resistances. DETAILED DESCRIPTION

[0045] The specific embodiments of the present application are described below to facilitate the understanding of the present application by those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

[0046] The research on the scattering characteristics of the passive radio frequency component can be generally based on the equivalent circuit modeling of the passive radio frequency component and the S parameter simulation for the estimation. In addition to the intermodulation caused by the nonlinear effect of the magnetic plating, the nonlinearity of the radio frequency connector is mainly concentrated in the contact surface. Therefore, considering a circuit model combining the passive transmission scattering characteristics and the contact nonlinearity modeling can realize the comprehensive performance analysis and prediction of the passive intermodulation and scattering characteristics of the radio frequency connector. Moreover, after the modeling is completed, various signals can be parameterized scanning, and the comprehensive prediction of the application performance of the actual connector can be made.

[0047] As shown in Figure 1 , a radio frequency connector passive intermodulation and scattering characteristic comprehensive performance analysis method of the present application comprises steps S1-S8:

[0048] S1, select a radio frequency connector as a test piece and a performance evaluation object.

[0049] In an optional embodiment of the present application, a radio frequency connector commonly used in a communication circuit is selected as a case demonstration and also as a test piece and a performance evaluation object in the present case demonstration, the use frequency range of the radio frequency connector is 0 to 3 GHz, and the characteristic impedance is 50 ohms.

[0050] S2, test the scattering performance of the radio frequency connector in step S1 and establish an equivalent model of the transmission performance of the radio frequency connector.

[0051] In an optional embodiment of the present application, the scattering performance of the connector is first tested, that is, a vector network analyzer is used, the frequency range is set to be consistent with the use frequency range of the radio frequency connector, after calibration, the radio frequency connector is connected to the vector network analyzer, the scattering performance of the radio frequency connector is tested, and an equivalent model of the transmission performance of the radio frequency connector is established, step S2 comprises the following steps:

[0052] S21, measure the return loss value and the insertion loss value of the radio frequency connector, and record and save the sweep measurement results.

[0053] In an optional embodiment of the present application, the return loss value of the radio frequency connector is first measured, and the sweep measurement results curve1 are recorded and saved. Then, the insertion loss value of the connector is measured, and the sweep measurement results curve2 are recorded and saved.

[0054] S22, equivalent the transmission performance of the radio frequency connector into a cascade circuit model of a capacitor C1 and an inductor L1.

[0055] In an optional embodiment of the present application, according to the transmission line theory, the transmission performance of the radio frequency connector can be equivalent to a small section of transmission line, and then can be equivalent to a cascade model of a capacitor and an inductor in the circuit, as shown in area A in Figure 2 .

[0056] S23, set the capacitance C1 and the inductance L1 in the circuit to be able to tune the pending parameters.

[0057] S24, obtain the simulation results of return loss and insertion loss by performing S parameter simulation on the circuit model in sub-step S22.

[0058] In an optional embodiment of the present application, the return loss curve curve_S11 and the insertion loss curve curve_S21 of the cascaded circuit model are simulated by performing S parameter simulation on the cascaded circuit model in sub-step S22.

[0059] S25, determine whether the difference between the simulation results in sub-step S24 and the measurement results in sub-step S21 is within the error range, if yes, save the values of the capacitance C1 and the inductance L1, otherwise adjust the values of the capacitance C1 and the inductance L1 and jump to sub-step S24.

[0060] In an optional embodiment of the present application, the difference between the return loss curve curve_S11 and the insertion loss curve curve_S21 of the cascaded circuit model simulated in S24 and the measured results curve1 and curve2 in step S21 is calculated, an error range is set and it is determined whether the difference between the simulation results in sub-step S24 and the measurement results in sub-step S21 is within the error range, if yes, save the values of the capacitance C1 and the inductance L1, otherwise adjust the values of the capacitance C1 and the inductance L1 and jump to sub-step S24.

[0061] S26, establish the transmission performance equivalent model of the radio frequency connector according to the values of the capacitance C1 and the inductance L1 saved in sub-step S25.

[0062] S3, test the passive intermodulation performance of the radio frequency connector in step S1 and establish the nonlinear equivalent model of the contact surface of the radio frequency connector.

[0063] In an optional embodiment of the present application, the passive intermodulation analyzer is used, the power of the double-tone signal used for testing is set to 43dBm according to the passive device intermodulation performance test standard specification, one end of the radio frequency connector in step S1 is connected to the passive intermodulation analyzer and the other end is connected to the intermodulation load, the passive intermodulation performance of the radio frequency connector is tested and the nonlinear equivalent model of the contact surface of the radio frequency connector is established, and step S3 includes the following sub-steps:

[0064] S31, measure the reflected third-order intermodulation value of the radio frequency connector and record the measurement result P IM3 .

[0065] S32, measure the reflected fifth-order intermodulation value of the radio frequency connector and record the measurement result P IM5 ;

[0066] S33, calculating the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient according to the measurement result in the sub-step S31 and the measurement result in the sub-step S32.

[0067] In an optional embodiment of the present application, the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient can be calculated according to the following binary first-order equation:

[0068]

[0069] wherein c3 is the third-order nonlinear transmission coefficient, P0 is the input power of the two double-tone signals, R is the resistance value, and c5 is the fifth-order nonlinear transmission coefficient.

[0070] S34, determining the nonlinear transfer function according to the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient obtained in the sub-step S33.

[0071] In an optional embodiment of the present application, the nonlinear model of the contact surface of the radio frequency connector is simulated by a fifth-order odd polynomial, and the nonlinear transfer function is:

[0072]

[0073] wherein i is the nonlinear transfer function, c1 is the linear transmission term of the connector, c3 is the third-order nonlinear transmission coefficient, v is the amplitude of the input signal, and c5 is the fifth-order nonlinear transmission coefficient.

[0074] The contact resistance of the connector is measured by a micro-ohm micro-volt meter, and the contact resistance is measured as R0, so the coefficient c1 of the polynomial linear part is 1 / R0.

[0075] And the third-order nonlinear transmission coefficient c3 and the fifth-order nonlinear transmission coefficient c5 obtained through the sub-step S33 can determine the nonlinear transfer function.

[0076] S35, obtaining the nonlinear resistance model according to the nonlinear transfer function determined in the sub-step S34 and establishing the nonlinear equivalent model of the contact surface of the radio frequency connector.

[0077] In an optional embodiment of the present application, the nonlinear of the radio frequency connector is set to be the contact nonlinearity generated by the contact surface, so the nonlinear resistance model can be obtained according to the nonlinear transfer function determined in the sub-step S33, that is, Figure 2 Z nonlinear in the model, so as to establish the equivalent nonlinear model of the contact surface of the radio frequency connector.

[0078] S4, calculating the impedance effect equivalent model of the contact surface of the radio frequency connector according to the contact impedance effect.

[0079] In an optional embodiment of the present application, the RF connector contact surface contains contact impedance effects in addition to the nonlinear effects, wherein the contact impedance effects include the constriction resistance R c of the contact surface, the contact gap-induced contact capacitance C c , and the inductance L c caused by the contact surface-induced current path lengthening. The corresponding values can be calculated in combination with the electrical contact theory, and the impedance effect equivalent model of the RF connector contact surface can be determined.

[0080] S5, the nonlinear equivalent model in step S3 is cascaded with the impedance effect equivalent model in step S4 to obtain a complete contact surface equivalent model of the RF connector.

[0081] In an optional embodiment of the present application, the nonlinear equivalent model is cascaded with the impedance effect equivalent model to obtain a complete contact surface equivalent model of the RF connector, as shown in the B region of Figure 2 .

[0082] S6, the transmission performance equivalent model in step S2 and the complete contact surface equivalent model in step S5 are connected in series to obtain a complete RF connector equivalent model.

[0083] In an optional embodiment of the present application, a circuit model combining the transmission performance equivalent model and the complete contact surface equivalent model can realize comprehensive performance analysis and prediction of the passive intermodulation and scattering characteristics of the RF connector. Therefore, the transmission performance equivalent model and the complete contact surface equivalent model are connected in series, i.e., the A region part in Figure 2 is connected in series with the B region part in Figure 2 to obtain a complete RF connector equivalent model.

[0084] S7, the scattering performance and intermodulation performance of the complete RF connector equivalent model in step S6 are simulated through parameter setting.

[0085] In an optional embodiment of the present application, through parameter setting of the S-parameter simulation space and the harmonic balance simulation control, the scattering performance and intermodulation performance of the RF connector under different frequency bands and different signal combination frequencies can be simulated, and the influence of the contact characteristics of the RF connector on the electrical characteristics can be predicted.

[0086] S8, the simulation results of the scattering performance and intermodulation performance obtained in step S7 are analyzed.

[0087] In an optional embodiment of the present invention, based on the complete equivalent model of the RF connector established in S6, the relationship between signal transmission characteristics and nonlinear characteristics at different frequencies can be analyzed. Furthermore, this method can also be extended to other passive components with similar transmission structures.

[0088] like Figure 3 As shown, by changing the contact resistance Rc (i.e., the linear resistance of the RF connector) in the complete equivalent model of the RF connector, it was found that the linear resistance has a significant impact on the insertion loss, while changing the contact surface of the RF connector causes the inductance L to be extended by the current path. C Contact capacitance Cc caused by contact gaps can lead to impedance mismatch, which in turn has a significant impact on return loss.

[0089] like Figure 4 As shown, an increase in the contact resistance Rc of the RF connector means an increase in the linear resistance of the RF connector, leading to an increase in intermodulation caused by the linear effect. However, when the contact surface of the RF connector is changed, the inductance L caused by the extension of the current path is reduced. C The contact capacitance Cc caused by the contact gap results in impedance mismatch. However, due to the superposition effect of reflection intermodulation, the reflection intermodulation does not necessarily increase with the increase of the reflected signal at the contact part.

[0090] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for comprehensive performance analysis of passive intermodulation and scattering characteristics of radio frequency connectors, characterized in that, The method comprises the following steps: S1, selecting a radio frequency connector as a test object and a performance evaluation object; S2, testing the scattering performance of the radio frequency connector in step S1 and establishing a transmission performance equivalent model of the radio frequency connector; S3, testing the passive intermodulation performance of the radio frequency connector in step S1 and establishing a nonlinear equivalent model of the contact surface of the radio frequency connector; S4, calculating an impedance effect equivalent model of the contact surface of the radio frequency connector in step S1 according to the contact impedance effect; S5, cascading the nonlinear equivalent model in step S3 and the impedance effect equivalent model in step S4 to obtain a complete contact surface equivalent model of the radio frequency connector; S6, connecting the transmission performance equivalent model in step S2 and the complete contact surface equivalent model in step S5 in series to obtain a complete radio frequency connector equivalent model; S7, simulating the scattering performance and the intermodulation performance of the complete radio frequency connector equivalent model in step S6 through parameter setting; S8, analyzing the simulation results of the scattering performance and the intermodulation performance obtained in step S7.

2. The method of claim 1, wherein, Step S2 comprises the following sub-steps: S21, measuring the return loss value and the insertion loss value of the radio frequency connector, recording and saving the sweep measurement results; S22, equivalent the transmission performance of the radio frequency connector into a cascaded circuit model of a capacitor C1 and an inductor L1; S23, setting the capacitor C1 and the inductor L1 in the circuit as tunable parameters to be determined; S24, obtaining the simulation results of the return loss and the insertion loss by S-parameter simulation on the circuit model in sub-step S22; S25, judging whether the difference between the simulation results in sub-step S24 and the measurement results in sub-step S21 is within the error range, if yes, saving the values of the capacitor C1 and the inductor L1, otherwise, adjusting the values of the capacitor C1 and the inductor L1 and jumping to sub-step S24; S26, establishing the transmission performance equivalent model of the radio frequency connector according to the values of the capacitor C1 and the inductor L1 saved in sub-step S25.

3. The method of claim 1, wherein, Step S3 comprises the following sub-steps: S31, measuring the reflected third-order intermodulation value of the radio frequency connector, recording the measurement results; S32, measuring the reflected fifth-order intermodulation value of the radio frequency connector, recording the measurement results; S33, calculating the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient according to the measurement results in sub-step S31 and the measurement results in sub-step S32; S34, determining the nonlinear transfer function according to the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient obtained in sub-step S33; S35, obtaining a nonlinear resistance model according to the nonlinear transfer function determined in sub-step S34 and establishing a nonlinear equivalent model of the contact surface of the radio frequency connector.

4. The method of claim 3, wherein the method further comprises: The calculation equation of the third-order nonlinear transmission coefficient and the fifth-order nonlinear transmission coefficient is: wherein: c3 is the third order nonlinear transmission coefficient, P0 is the input power of the two dual tone signals, R is the responsible impedance value, c5 is the fifth order nonlinear transmission coefficient, P IM3 is the reflected third order intermodulation value of the radio frequency connector, P IM5 is the reflected fifth order intermodulation value of the radio frequency connector.

5. The method of claim 3, wherein the method further comprises: The nonlinear transfer function is: Wherein: i is the nonlinear transfer function, c1 is the linear transmission term of the connector, c3 is the third-order nonlinear transmission coefficient, v is the amplitude of the input signal, and c5 is the fifth-order nonlinear transmission coefficient.

6. The method of claim 1, wherein, The impedance effect equivalent model includes a constriction resistance R of the contact surface c , a contact gap-caused contact capacitance C c , and an inductance L caused by the current path lengthening of the contact surface c The values of the resistance R c , the capacitance C c , and the inductance L c are calculated according to the electrical contact theory.

7. The method of claim 1, wherein, In S7, the scattering performance and the intermodulation performance under different frequency bands and different signal combination frequencies are simulated through parameter setting of the S-parameter simulation space and the harmonic balance simulation control.

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