Resonant cavity and test method for 5G components

Abstract

A resonant cavity and testing method for 5G components, belonging to the field of resonant cavity testing technology. The scheme is as follows: program initialization, input of test parameters; input of resonant cavity calibration parameters; search for the frequencies of the first to eighth resonant points in sequence, reduce the scan time, narrow the scan range, rescan, and read the frequency and Q value of each resonant point respectively; calculate the ESR value, Corrected ESR value, Cp value, and Q value of each resonant point respectively. Beneficial effect: The resonant cavity testing method for 5G components described in the present invention can calculate parameters such as the ESR value of each resonant point below 3.5GHz of a high-Q capacitor by using a vector network analyzer, achieving higher test accuracy and faster test efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of resonant cavity testing technology, and in particular relates to a resonant cavity and a testing method for 5G frequency band components. Background Art

[0002] The fifth generation of mobile communication technology is the latest generation of cellular mobile communication technology and is an extension of 4G LTE-A, WiMax, 3G UMTS, LTE, and 2G GSM systems. The performance goals of 5G are high data rates, reduced latency, energy savings, cost reduction, increased system capacity, and large-scale device connectivity.

[0003] 5G frequency bands are broadly divided into two segments: 1. The low-band Sub6G FR1: 450MHz-6000MHz; 2. The high-band millimeter wave FR2: 24250MHz-52600MHz. China Mobile: 2515MHz-2675MHz and 4800MHz-4900MHz, totaling 260MHz; China Telecom: 3400MHz-3500MHz, totaling 100MHz; and China Unicom: 3500MHz-3600MHz, totaling 100MHz.

[0004] Commercially available instruments for measuring ESR (equivalent series resistance) are typically impedance analyzers. While these devices are effective for measuring low-Q capacitors, they struggle to accurately measure the ESR of high-Q capacitors or those with high capacitive reactance due to inherent instrument accuracy issues. Consequently, negative values ​​or confusing test results are often obtained. A resonant cavity inherently possesses a very high Q at high frequencies, enabling accurate measurement of the ESR, Q, and capacitance of high-Q capacitors at these frequencies. However, due to its size and structure, the existing Boonton 34A resonant cavity has a limited test range of 100 MHz to 2 GHz, making it inadequate for component testing in the 5G application band. The testing method provided by the 34A resonant cavity manufacturer uses millivoltmeters and RF sources to calculate the ESR, Q, and capacitance of capacitors at a single frequency. This method, however, is outdated, inaccurate, and time-consuming, making it far from sufficient for factory testing. Existing resonant cavities are sealed in metal housings, which can easily leak electromagnetic waves, introducing errors during testing and compromising test stability and accuracy. Summary of the Invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a resonant cavity testing method applied to the 5G frequency band. This method can calculate parameters such as the ESR value of each resonant point below the 3.5GHz frequency band of high-Q capacitors by using a vector network analyzer. The test frequency band is higher and the scope of application is wider. It prevents electromagnetic wave leakage, effectively reduces test errors, and improves test stability.

[0006] The technical solution is as follows:

[0007] A resonant cavity applied to 5G components, characterized in that it includes: a fixture plunger, a central conductor, an attenuator, a precision resistor, a connection vector network port 1, a connection vector network port 2, and a resonant cavity body, wherein the fixture plunger is movably mounted at one end of the resonant cavity body, the central conductor is built into the resonant cavity body, and the fixture plunger and the central conductor are arranged opposite to each other; the attenuator is mounted at the other end of the resonant cavity body, the connection vector network port 1 and the connection vector network port 2 are connected to the resonant cavity body, and the precision resistor is connected to the connection vector network port 1.

[0008] Furthermore, a sealing ring is included, and the sealing ring is provided at the connection between the attenuator and the resonant cavity body.

[0009] Furthermore, the central conductor includes an inner conductor and an outer conductor, both of which are cylindrical structures, and the diameter of the inner conductor is smaller than the diameter of the outer conductor.

[0010] Furthermore, the inner conductor and the outer conductor are integrally formed.

[0011] The present invention also includes a resonant cavity testing method applied to the 5G frequency band, the scheme is as follows:

[0012] Design the resonant cavity according to the 3.5GHz frequency band requirements

[0013] S1. Use vector network analyzer and control program written in Labview to control the test

[0014] S2. Find the frequencies of the first to eighth resonance points, shorten the scanning time, reduce the scanning range, rescan, and read the frequencies and Q values ​​of each resonance point respectively;

[0015] S3. Calculate the ESR value, Corrected ESR value, C value, and Q value of each resonance point.

[0016] Furthermore, the ESR value is calculated as follows:

[0017]

[0018]

[0019]

[0020] Where: ESR is the equivalent series resistance, M is the test reactance, Q M represents the Q value at the test frequency, Q1' represents the Q value at frequency f1, R frepresents the loss of the resonant cavity at frequency f, Z0 represents the characteristic impedance, Z0=75.75Ω, f M Indicates the test frequency, f0' indicates the frequency value of short circuit, represents the contact resistance, f0 represents the resonant frequency of the resonant cavity under ideal conditions, and x' represents the intermediate variable.

[0021] Furthermore, the Corrected ESR value is calculated as follows:

[0022]

[0023]

[0024] Among them: ESR CORR represents the corrected equivalent series resistance, R T is the uncorrected equivalent series resistance, C F Indicates the capacitance of the adjustment capacitor, C indicates the capacitance of the test capacitor, ε0 indicates the dielectric constant, r indicates the radius of the center conductor, d indicates the length of the test fixture, b indicates the radius of the capacitor to be tested, and A UUT Indicates the cross-sectional area of ​​the capacitor being measured.

[0025] Furthermore, the C value is calculated as follows:

[0026] C=-1 / [2πf1Z0cot(β1l)]

[0027] β1l=(f1 / f0)90°

[0028] Where: β1 represents the phase of the capacitor being measured, l represents the capacitor length, and f1 represents the actual test resonant frequency.

[0029] Furthermore, the Q value is calculated as follows:

[0030] Q=1 / 2πf1C×ESR CORR

[0031] Where: f1 represents the actual test resonant frequency.

[0032] The beneficial effects of the present invention are:

[0033] The 5G frequency band resonant cavity test described in the present invention can calculate parameters such as the ESR value of each resonant point of high-Q capacitors below 3.5 GHz through the design of the resonant cavity size and structure, a vector network analyzer, and an automatic control program. The test frequency band is higher and the test efficiency is faster. The attenuator is set to prevent electromagnetic wave leakage, effectively reduce test errors, and improve test stability and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1This is a diagram of the resonant cavity structure for the 5G application frequency band test of the present invention;

[0035] Figure 2 This is a flow chart of the test procedure of the present invention;

[0036] Figure 3 The Q value curves of the resonant cavity of the 5G component when the present invention is applied to the open circuit and short circuit are shown;

[0037] The reference numerals in the figures are as follows:

[0038] 1-fixture plunger, 2-measured capacitor, 3-center conductor, 4-attenuator, 5-precision resistor, 6-connection to the first port of the vector network, 7-connection to the second port of the vector network, 8-resonant cavity body. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1-3 The automatic testing method of the resonant cavity for 5G applications is further explained.

[0040] Example 1

[0041] Resonant cavity design:

[0042] A resonant cavity applied to 5G components, characterized in that it includes: a fixture plunger 1, a central conductor 3, an attenuator 4, a precision resistor 5, a connection vector network port 6, a connection vector network port 7, and a resonant cavity body 8, wherein the fixture plunger 1 is movably mounted at one end of the resonant cavity body 8, the central conductor 3 is built into the resonant cavity body 8, and the fixture plunger 1 and the central conductor 3 are arranged opposite to each other; the attenuator 4 is mounted at the other end of the resonant cavity body 8, the connection vector network port 6 and the connection vector network port 7 are connected to the resonant cavity body 8, and the precision resistor 5 is connected to the connection vector network port 6.

[0043] Furthermore, a sealing ring is included, and the sealing ring is provided at the connection between the attenuator 4 and the resonant cavity body 8.

[0044] Furthermore, the central conductor 3 includes an inner conductor and an outer conductor, both of which are cylindrical structures, and the diameter of the inner conductor is smaller than the diameter of the outer conductor.

[0045] Furthermore, the inner conductor and the outer conductor are integrally formed.

[0046] The attenuator 4 is connected to the resonant cavity body 8 by threads, and the clamp plunger 1 is also connected by threads. The distance from the center conductor 3 is adjusted by rotation. The measured capacitor 2 is placed between the two and clamped and fixed by the clamp plunger 1.

[0047] The resonant cavity test frequency band range is mainly determined by the conductor size in the cavity. The resonant cavity needs to be tested to the 3.5GHz frequency band, and the 1 / 4 wavelength resonant frequency needs to fall in the 0.42GHz frequency band. In this way, the resonant frequency at the eighth resonant point, i.e., the 15 / 4 wavelength resonant frequency, is around 3.5GHz, which can cover the 3.5GHz frequency band test requirements of 5G applications.

[0048] C=λ / T=λ·f

[0049] Where C is the speed of light, λ is the wavelength, T is the period, and f is the frequency.

[0050] It can be obtained that when the 1 / 4 wavelength resonant frequency is 0.42 GHz, it is calculated that λ = 19.1 cm. When the conductor size in the resonant cavity is the wavelength, it can be achieved at 1 / 4 wavelength resonance, that is, the resonant frequency of the first resonance point is 0.42 GHz. At the eighth resonance point, the test frequency can reach 3.5 GHz, which meets the 5G frequency band requirements.

[0051] The resonant cavity itself has its own resonant frequency. After the capacitor is clamped in the cavity, the resonant frequency of the cavity itself is changed. The ESR of the capacitor can be obtained through the formula based on the test data.

[0052] The attenuator 4 is used to prevent leakage of electromagnetic waves from the open-circuit end at high frequencies. One end of the resonant cavity is a short-circuit end, that is, the end of the fixed capacitor, and the other end is an open-circuit end.

[0053] The specific dimensions of the inner and outer conductors of the resonant cavity should be debugged and designed according to the capacitance and dimensions of the specific test components.

[0054] Example 2

[0055] A resonant cavity automatic testing method, the steps are as follows:

[0056] S1. Initialize the program and input test parameters;

[0057] S2, input the calibration parameters of the resonant cavity;

[0058] S3, sequentially searching for the frequencies of the first to eighth resonance points, reducing the scanning time, narrowing the scanning range, rescanning, and reading the frequency and Q value of each resonance point respectively;

[0059] S4. Calculate the ESR value, Corrected ESR value, Cp value, and Q value of each resonance point.

[0060] Furthermore, the ESR value is calculated as follows:

[0061]

[0062]

[0063]

[0064] Where: Q M is the Q value at the test frequency, Z0=75.75Ω,

[0065] Furthermore, the Corrected ESR value is calculated as follows:

[0066]

[0067]

[0068] Furthermore, the C value is calculated as follows:

[0069] C=-1 / [2πf1Z0cot(β1l)]

[0070] β1l=(f1 / f0)90°

[0071] Where: β1 represents the phase of the capacitor being measured, l represents the capacitor length, and f1 represents the actual test resonant frequency.

[0072] Furthermore, the Q value is calculated as follows:

[0073] Q=1 / 2πf1C×ESR CORR

[0074] Where: f1 represents the actual test resonant frequency.

[0075] Example 3

[0076] This application develops an automatic testing system suitable for resonant cavities.

[0077] Product functions and main technical indicators

[0078] This software can be used to test the ESR value, Q value and capacitance value of high Q capacitors at high frequencies. The technical indicators are as follows:

[0079] Test frequency range:

[0080] The test frequency of the 5G resonant cavity is approximately 100 to 3500 MHz.

[0081] a) Minimum test frequency: The electrical length of the resonant cavity is about 17.8 cm and the total length is 19.1 cm. The resonant frequency calculation formula at λ / 4 of the resonant cavity is V p =3×10 8 m / s, λ = 4 × 0.178 = 0.714 m, so f = 420 MHz;

[0082] Test capacitance range:

[0083] The 5G resonant cavity specification specifies a test capacitance range of 1pF to 1000pF. The actual test capacitance range is as low as 0.1pF, with no upper limit. However, when the capacitance is less than 1pF, the measurement results are inconsistent due to the large capacitive reactance.

[0084] Product design plan

[0085] Resonant cavity placement:

[0086] The resonant cavity is designed vertically. When the DUT is small, especially in sizes like 0402 or 0603, it's difficult to position it completely parallel to the center conductor. This can cause the DUT to fall into the resonant cavity. Removing the DUT requires moving or even removing the resonant cavity, which can affect the consistency of the resonant cavity test. This problem is eliminated by standing the resonant cavity upright. If the DUT is not properly clamped, it will naturally fall below the short-circuit end of the resonant cavity, making it easier to remove.

[0087] Calculation method

[0088] ESR value calculation method:

[0089]

[0090]

[0091]

[0092] Where: ESR is the equivalent series resistance, M is the test reactance, Q M represents the Q value at the test frequency, Q1' represents the Q value at frequency f1, R f represents the loss of the resonant cavity at frequency f, Z0 represents the characteristic impedance, Z0=75.75Ω, f M Indicates the test frequency, f0' indicates the frequency value of short circuit, represents the contact resistance, f0 represents the resonant frequency of the resonant cavity under ideal conditions, and x' represents the intermediate variable;

[0093] Intermediate variable calculation method:

[0094]

[0095]

[0096]

[0097] Where: Qoc2 is the Q value at the second open circuit resonant frequency, Qoc1 is the Q value at the first open circuit resonant frequency, foc1 represents the first open circuit resonant frequency, foc2 represents the second open circuit resonant frequency, and Q0' represents the Q value at the resonant frequency after the copper block is loaded;

[0098] Corrected ESR (equivalent series resistance) calculation method:

[0099]

[0100]

[0101] Among them: ESR CORR represents the corrected equivalent series resistance, R T is the uncorrected equivalent series resistance, C F Indicates the capacitance of the adjustment capacitor, C indicates the capacitance of the test capacitor, ε0 indicates the dielectric constant, r indicates the radius of the center conductor, d indicates the length of the test fixture, b indicates the radius of the capacitor to be tested, and A UUT Indicates the cross-sectional area of ​​the capacitor being measured;

[0102] Calculation method of capacitance value C and quality factor Q value:

[0103] Capacitance: C = -1 / [2πf1Z0cot(β1l)]

[0104] β1l=(f1 / f0)90°

[0105] Q value: Q = 1 / 2πf1C × ESR CORR

[0106] Where: f1 represents the actual test resonant frequency, β1 represents the phase of the measured capacitor, and l represents the capacitor length.

[0107] The test procedure flow chart is as follows Figure 2 shown.

[0108] Key process issues and solutions

[0109] Impact of cable shaking on test results:

[0110] To maximize the consistency and repeatability of the measurement results, the resonant cavity is placed vertically so that if the object under test is not clamped properly, it can be easily removed without moving the cavity or reconnecting the high-frequency cable.

[0111] The impact of different testers and different test times on test results:

[0112] Different testers' varying force levels can lead to significant deviations in test results. Greater force typically results in lower ESR values. Excessive force can also permanently damage the resonant cavity. It's also difficult to ensure consistent force levels even for the same person at different times. Therefore, using a torque wrench with a fixed torque rating can effectively improve measurement consistency and repeatability.

[0113] New product identification and acceptance standards and test plans:

[0114] The results measured by this test system are considered to be qualified if they are close to the results of Modelithics.

[0115] Adoption of relevant new technologies, new materials and new processes in design and development:

[0116] This project uses the programming software Labview and ENA communication method to perform sampling calculations.

[0117] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A resonant cavity testing method for 5G components, characterized in that: A resonant cavity for testing 5G components, comprising: a fixture plunger (1), a central conductor (3), an attenuator (4), a precision resistor (5), a connection vector network port (6), a connection vector network port (7), and a resonant cavity body (8), wherein the fixture plunger (1) is movably mounted on one end of the resonant cavity body (8), the central conductor (3) is built into the resonant cavity body (8), and the fixture plunger (1) and the central conductor (3) are arranged opposite to each other; the attenuator (4) is mounted on the other end of the resonant cavity body (8), the connection vector network port (6) and the connection vector network port (7) are connected to the resonant cavity body (8), and the precision resistor (5) is connected to the connection vector network port (6). When the size of the conductor in the resonant cavity is a wavelength and the resonant cavity test frequency band is 3.5 GHz, the following steps are performed: S1, use vector network analyzer and control program written in Labview to control the test; S2. Search for the frequencies of the first to eighth resonance points in sequence, reduce the scanning time, reduce the scanning range, rescan, and read the frequency and Q value of each resonance point respectively; S3. Calculate the ESR value, Corrected ESR value, C value and Q value of each resonance point respectively; The ESR value is calculated as follows: Where: ESR is the equivalent series resistance, M is the test reactance, Q M represents the Q value at the test frequency, f1 represents the actual test resonant frequency, Q1' represents the Q value at the frequency f1, R f represents the loss of the resonant cavity at frequency f, Z0 represents the characteristic impedance, Z0=75.75Ω, f M Indicates the test frequency, f0' indicates the frequency value of short circuit, represents the contact resistance, f0 represents the resonant frequency of the resonant cavity under ideal conditions, and x' represents the intermediate variable; Intermediate variable calculation method: Wherein: Qoc2 is the Q value at the second open circuit resonant frequency, Qoc1 is the Q value at the first open circuit resonant frequency, foc1 represents the first open circuit resonant frequency, and foc2 represents the second open circuit resonant frequency; Corrected ESR value is calculated as follows: Among them: ESR CORR represents the corrected equivalent series resistance, R T is the uncorrected equivalent series resistance, C F represents the adjustment capacitance value, C represents the test capacitance value, ε0 represents the dielectric constant, r represents the center conductor radius, d represents the test fixture length, b represents the test capacitor radius, A UUT Indicates the cross-sectional area of ​​the test capacitor; The C value is calculated as follows: C=-1 / [2πf1Z0cot(β1l)] β1l=(f1 / f0)90° Where: β1 represents the test capacitor phase, l represents the capacitor length, f1 represents the actual test resonant frequency, Z0 represents the characteristic impedance, and f0 represents the resonant frequency of the resonant cavity under ideal conditions. The Q value is calculated as follows: Q=1 / 2πf1C×ESR CORR Where: f1 represents the actual test resonant frequency, and C represents the test capacitor value.

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