A ferrite ferromagnetic resonance linewidth measurement system and method based on static magnetic field accurate adjustment

Abstract

The application provides a ferrite ferromagnetic resonance line width measurement system and a test method based on accurate adjustment of a static magnetic field. The measurement system is based on a resonant cavity method for measurement, a high-Q cavity is used to improve the test sensitivity, and an n-layer Helmholtz coil device is innovatively designed. Through the combination of the n-layer Helmholtz coil device and an electromagnet, accurate adjustment of the static magnetic field loaded on the sample to be measured is realized, thereby overcoming the problem of small measurement range of a high-precision gauss meter, and improving the measurement precision.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave and millimeter wave testing, and in particular relates to a ferrite ferromagnetic resonance linewidth measurement system and a testing method based on precise adjustment of a static magnetic field. Background Art

[0002] The discovery and application of microwave ferrite materials in the mid-20th century marked a major breakthrough in microwave technology. Today, the gyromagnetic properties of ferrites enable the fabrication of a wide variety of microwave devices, such as phase shifters, circulators, and isolators. When designing and applying ferrite materials, the ferromagnetic resonance linewidth is a fundamental and crucial characteristic. This parameter directly influences the determination of the tensor permeability components within the ferromagnetic resonance frequency range and the loss of the ferrite material. Therefore, accurate measurement of the resonance linewidth of ferrite materials is essential. Furthermore, with the increasing integration of system units, the quality of raw materials used must be higher, with a key requirement being extremely low loss. Lower loss translates to a narrower resonance linewidth for the ferrite material. Accurately measuring this extremely narrow resonance linewidth requires a system with high test sensitivity and the ability to precisely control the static magnetic field, which presents challenges. Furthermore, with the increasing utilization of spectrum resources, microwave ferrite devices are increasingly operating in high-frequency bands, making the measurement of the extremely narrow resonance linewidth of microwave ferrite materials at these high frequencies even more urgent.

[0003] In current research, the mainstream methods for measuring ferromagnetic resonance linewidth are divided into two categories: the resonant cavity perturbation method and the broadband transmission line measurement method. The broadband transmission line method, which is often based on microstrip or coplanar waveguide structures, can measure the ferromagnetic resonance linewidth of materials over a wide frequency range. However, due to its inherently open structure, measurement loss and noise are excessive above 30 GHz, resulting in a decrease in measurement accuracy. For example, in his paper "Ultra-Wideband Ferromagnetic Resonance Linewidth Measurement System Based on Coplanar Waveguide," Wu Yongrui designed a ferromagnetic resonance linewidth measurement system using a common ground coplanar waveguide structure, achieving relatively accurate measurement results within 30 GHz. However, at high frequencies above 30 GHz, due to increased parasitic effects and losses, the S21 curve becomes less smooth, and measurement accuracy decreases, making it even more difficult to accurately measure samples with extremely narrow linewidths. The resonant cavity perturbation method, with its higher sensitivity and accuracy, offers advantages for measuring the ferromagnetic resonance linewidth of samples with extremely narrow linewidths. In his paper "Research on Ferromagnetic Resonance Linewidth Measurement Technology of Ferroelectric Thin Film Materials," Zhou Shu designed a double-ridge waveguide rectangular cavity test fixture and completed the measurement of ferromagnetic resonance linewidth up to 18 GHz. However, due to the low Q value of the double-ridge waveguide rectangular cavity, high-precision measurement cannot be achieved. In addition, as the frequency increases, the static magnetic field required to excite ferromagnetic resonance increases, and high-precision gaussmeters often have a small range, which is far from meeting the index requirements of the magnetic field required to measure the high-frequency ferromagnetic resonance linewidth.

[0004] Therefore, how to design a measurement system that can accurately measure the extremely narrow resonance linewidth of microwave ferrite materials and achieve a maximum test frequency of over 30 GHz is of great practical significance. Summary of the Invention

[0005] In response to the problems existing in the background technology, the purpose of the present invention is to provide a ferrite ferromagnetic resonance linewidth measurement system and testing method based on precise adjustment of the static magnetic field. The measurement system uses the resonant cavity method for measurement, adopts a high-Q cavity to improve the test sensitivity, and innovatively designs a Helmholtz coil. Through the combination of the Helmholtz coil and the electromagnet, the static magnetic field applied to the sample to be measured can be precisely adjusted, thereby overcoming the problem of the limited range of high-precision Gauss meters and improving measurement accuracy.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A ferrite ferromagnetic resonance linewidth measurement system based on precise adjustment of a static magnetic field comprises a vector network analyzer 1, a cylindrical resonant cavity 2, an electromagnet 3, an electromagnet power supply 4, a power supply group, a first coupling ring 8, a second coupling ring 9, an n-layer Helmholtz coil device 10, a data processing unit 12, a Gauss meter 13, and a coupling amount adjustment device 14;

[0008] The main body of the n-layer Helmholtz coil device is a cylindrical cavity, with grooves symmetrically arranged on both sides of the cavity. The radius of the grooves on each side increases from the inside to the outside, and a coil is wound in the grooves. The grooves with the same radius on both sides of the cylindrical cavity constitute a layer, with a total of n layers, and each layer forms a Helmholtz coil. A cylindrical through hole with a diameter identical to that of the cylindrical resonant cavity is provided at the center of the cylindrical cavity wall, so that the cylindrical resonant cavity is precisely embedded in the main body of the n-layer Helmholtz coil device. A rectangular through hole is provided on the side wall perpendicular to the side wall at 90° to the cylindrical through hole, facilitating the adjustment of the first coupling ring 8 and the second coupling ring, as well as the placement of the material to be tested 11. The power supply group includes n power supplies, each power supply supplies power to a group of coils, and n is a positive integer.

[0009] The first power supply is used to supply power to the electromagnet 3 so that the electromagnet generates a magnetic field; the n-layer Helmholtz coil device is fixedly arranged in the uniform magnetic field area of ​​the electromagnet 3;

[0010] The first coupling ring 8 and the second coupling ring are fixedly arranged on the side wall of the cylindrical resonant cavity 2. The coupling amount adjustment device is used to adjust the depth of the coupling ring extending into the cylindrical resonant cavity 2, thereby adjusting the coupling amount. A sample hole is set in the center of the side wall of the cylindrical resonant cavity 2 on which the first coupling ring 8 and the second coupling ring 9 are arranged. The material 11 to be tested is placed in the center of the cylindrical resonant cavity 2 through the sample hole.

[0011] The two ports of the vector network analyzer 1 are respectively connected to the first coupling ring 8 and the second coupling ring. The data processing unit 12 is respectively connected to the vector network analyzer 1, the Gaussmeter, the electromagnet power supply 4 and the power pack. The Gaussmeter 13 is used to measure the magnetic field generated by the electromagnet.

[0012] Furthermore, the different number of coils wound in each layer of grooves and the difference in groove radius determine that each layer of coils provides a different magnetic field per unit current, thereby achieving fine control of the magnetic field in a small range.

[0013] Furthermore, the cylindrical resonant cavity 2 operates at TE 01p Mode, p is odd, TE 01p In this mode, the magnetic field at the center of the cavity is the strongest and the quality factor is higher.

[0014] Furthermore, by designing the cavity size of the cylindrical resonant cavity 2 and adjusting the working mode of the cylindrical resonant cavity 2, the test frequency of the resonance linewidth measurement system can be adjusted; the smaller the cavity size of the cylindrical resonant cavity and the larger the p value, the higher the working frequency, up to 34 GHz.

[0015] Furthermore, the electromagnet power supply 4 is used to provide a high-power power supply of more than 1000W, used to provide a strong static magnetic field, and the maximum static magnetic field strength can reach 18000Gs; each power supply in the power supply group is used to provide a low-power power supply within 100W.

[0016] Furthermore, the data processing unit controls the power supply of the electromagnet power supply 4, thereby controlling the size of the static magnetic field generated by the electromagnet 3 to achieve coarse adjustment; the data processing unit controls the power supply of the power supply group, thereby controlling the n-layer Helmholtz coil device to fine-tune the size of the static magnetic field to achieve high-precision control of the static magnetic field.

[0017] Furthermore, n is preferably 3; the power supply group includes a second power supply 5, a third power supply 6 and a fourth power supply 7, and the second power supply 5, the third power supply 6 and the fourth power supply 7 respectively power the three layers of coils. The magnetic field size of the coil controlled by the second power supply 5 is 0.1Gs per 0.2A step, the magnetic field size of the coil controlled by the third power supply 6 is 1Gs per 0.4A step, and the magnetic field size of the coil controlled by the fourth power supply 7 is 10Gs per 1A step. The three layers of coils superimposed can provide a maximum of 100Gs.

[0018] Furthermore, the material to be tested 11 is a pellet sample or a thin film sample; wherein, when the thin film sample is placed in the center of the cylindrical resonant cavity, the surface of the film should be parallel to both the static magnetic field direction and the microwave magnetic field direction in the cavity.

[0019] The present invention also provides a measurement method based on the above-mentioned test system, comprising the following steps:

[0020] Step 1. Obtain the current-magnetic field intensity curve of each layer of the Helmholtz coil device with n layers. The specific process is as follows:

[0021] Before measurement, a certain number of coils were wound into the grooves of each layer of an n-layer Helmholtz coil assembly. Current was applied to each set of coils, and the current flowing through each set of coils was varied. A gaussmeter was used to record the strength of the uniform static magnetic field generated by each set of Helmholtz coils. The current-magnetic field strength curve for each layer of Helmholtz coils was then fitted.

[0022] The static magnetic field strength H generated by the n-layer Helmholtz coil device h for:

[0023]

[0024] Among them, a i is the fitting coefficient;

[0025] Step 2. Perform port calibration on the vector network analyzer and find the TE of the cylindrical resonator 01p Mode corresponds to frequency;

[0026] Step 3. Place the material to be tested in the cylindrical resonant cavity and record the S21 peak value, which is recorded as S210. Then adjust the electromagnet to generate the static magnetic field. Observe the peak value of the S21 curve on the vector network analyzer and find the minimum value of the S21 peak value, which is the rough ferromagnetic resonance point. Record the Gauss meter reading H at this time. e ;

[0027] Step 4. Keep the current of the electromagnet power supply 4 unchanged, that is, keep the electromagnet generating a uniform static magnetic field strength H e The magnitude remains unchanged, and the current of each power supply in the power supply group is adjusted, that is, the uniform static magnetic field strength H generated by the n-layer Helmholtz coil device is adjusted. h , find the precise ferromagnetic resonance point and record the current value I of each power supply at this time ic and the minimum S21 peak S21 at this time c ;

[0028] Step 5. Pass S210 and S21 c Calculate the half-power point transmission coefficient S21 half , the calculation formula is as follows:

[0029]

[0030] Step 6. S21 obtained based on step 5 half , keep the electromagnet generating a static magnetic field H e The size remains unchanged, only the static magnetic field H generated by the n-layer Helmholtz coil device is changed h The specific process is:

[0031] First, gradually reduce the current of each layer of the Helmholtz coil device until the resonance peak S21 rises to S21 half , record the current value I of each power supply at this time iR ; Then adjust the current value of each power supply in the power group to the original value I ic Then gradually increase the current of each layer of the Helmholtz coil device until the resonance peak S21 rises to S21 half , record the current value I of each power supply in the power supply group at this time iL , then the static magnetic field intensity corresponding to the two points is:

[0032]

[0033] Then the resonance linewidth ΔH can be expressed as:

[0034] ΔH=H L -H R (4).

[0035] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0036] This invention innovatively designs a multilayer Helmholtz coil. By combining an electromagnet and the coil, it achieves precise adjustment of the static magnetic field within a small range, improving measurement accuracy while reducing instrument costs. Furthermore, a ferrite ferromagnetic resonance linewidth measurement system designed with a cylindrical high-Q cavity employs the power method (transmission coefficient S21) to achieve high-precision measurement of extremely narrow linewidth materials. Furthermore, the system enables automated testing by programmable control of each power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the overall structure of the ferrite ferromagnetic resonance linewidth measurement system of the present invention.

[0038] Figure 2 Schematic diagram of the structure of the cylindrical resonant cavity in the ferrite ferromagnetic resonance linewidth measurement system of the present invention.

[0039] Figure 3 Schematic diagram of the structure of the three-layer Helmholtz coil device in the ferrite ferromagnetic resonance linewidth measurement system of the present invention.

[0040] Figure 4 This is a simulation result diagram of the magnetic field uniformity of the Helmholtz coil of the present invention.

[0041] Figure numerals: 1 is a vector network analyzer, 2 is a cylindrical resonant cavity, 3 is an electromagnet, 4 is a first power supply, 5 is a second power supply, 6 is a third power supply, 7 is a fourth power supply, 8 is a first microwave coupling ring, 9 is a second microwave coupling ring, 10 is a three-layer Helmholtz coil device, 11 is a material to be tested, 12 is a computer, 13 is a Gauss meter, and 14 is a coupling amount adjustment device. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the implementation methods and drawings.

[0043] A ferrite ferromagnetic resonance linewidth measurement system based on precise adjustment of static magnetic field, the overall structure diagram is as follows Figure 1 As shown, it includes a vector network analyzer 1, a cylindrical resonant cavity 2, an electromagnet 3, a first power supply 4, a power supply group, a first coupling ring 8, a second coupling ring 9, a three-layer Helmholtz coil 10, a computer (data processing unit) 12, a Gauss meter 13, and a coupling amount adjustment device 14;

[0044] The schematic diagram of the cylindrical resonant cavity is as follows: Figure 2 As shown, the first microwave coupling ring 8 and the second microwave coupling ring 9 are fixedly arranged on the side wall of the cylindrical resonant cavity 2. The coupling amount adjustment device 14 is used to adjust the depth of the coupling ring extending into the cylindrical resonant cavity 2, thereby adjusting the coupling amount. A sample hole is set in the center of the side wall of the cylindrical resonant cavity 2 on which the first coupling ring 8 and the second coupling ring 9 are provided. The material to be tested 11 is placed in the center of the cylindrical resonant cavity 2 through the sample hole.

[0045] The structural diagram of the three-layer Helmholtz coil 10 is as follows Figure 3As shown, its main body is a cylindrical cavity, and grooves are symmetrically arranged on both sides of the cavity. The radius of the grooves on each side increases from the inside to the outside. Coils are wound in the grooves, and a notch is arranged at the center of the grooves. The coils of the two grooves in the same layer are wound through the notch, so that only one power supply can be used to power one layer of coils. The grooves with the same radius on both sides of the cylindrical cavity form a layer, and there are 3 layers in total. Each layer forms a Helmholtz coil, that is, the distance between the two grooves in each layer of grooves is equal to the radius of the group of grooves, so as to maintain a larger magnetic field uniform area between the two coils; the power supply group includes 3 power supplies, and the second power supply 5 supplies power to the first layer of coils. The third power supply 6 supplies power to the second layer coil, and the fourth power supply 7 supplies power to the third layer coil. The first power supply is used to supply power to the electromagnet 3, causing it to generate a magnetic field. The Helmholtz coil is fixedly disposed in the uniform magnetic field region of the electromagnet 3. A cylindrical through-hole with the same diameter as the cylindrical resonant cavity 2 is provided at the center of the cylindrical cavity wall of the three-layer Helmholtz coil 10, so that the cylindrical resonant cavity 2 fits neatly into the three-layer Helmholtz coil 10. A rectangular through-hole is provided on the side wall at 90 degrees perpendicular to the side wall where the cylindrical through-hole is located to facilitate adjustment of the first microwave coupling ring 8 and the second microwave coupling ring 9, as well as placement of the test material 11.

[0046] The two ports of the vector network analyzer 1 are respectively connected to the first microwave coupling ring 8 and the second microwave coupling ring 9, and the computer 12 is respectively connected to the vector network analyzer 1, the gaussmeter 13, the first power supply 4 and the power supply group; the gaussmeter 13 is used to measure the magnetic field generated by the electromagnet.

[0047] Example 1

[0048] The cavity radius of cylindrical resonant cavity 2 is 15mm, the cavity length is 23mm, and it works at TE 013 The frequency is about 23.1GHz in TE mode. 015 The frequency in this mode is around 34.83GHz.

[0049] The three-layer Helmholtz coil is used to provide a small range of magnetic field. The coil controlled by power supply 2 5 has a magnetic field size of 0.1Gs per 0.2A step, the coil controlled by power supply 3 6 has a magnetic field size of 1Gs per 0.4A step, and the coil controlled by power supply 4 7 has a magnetic field size of 10Gs per 1A step. The three-layer coil stack can provide a maximum of 100Gs.

[0050] A method for measuring the ferromagnetic resonance linewidth of ferrite by accurately adjusting the static magnetic field of the test system described above comprises the following steps:

[0051] Step 1. Obtain the current-magnetic field strength curve of each layer of the Helmholtz coil. The specific process is as follows:

[0052] Before measurement, a certain number of coils were wound into each groove on the Helmholtz coil. Current was applied to each set of coils, and the current passing through each set of coils was varied. A gaussmeter was used to record the strength of the uniform static magnetic field generated by each set of coils. The current-magnetic field strength curve for each layer of coils was then fitted.

[0053] The static magnetic field strength generated by the Helmholtz coil under different currents is:

[0054]

[0055] Among them, H h is the magnetic field generated by the Helmholtz coil, a i is the fitting coefficient;

[0056] Step 2. Perform port calibration on the vector network analyzer and find the TE of the cylindrical resonator 013 The corresponding frequency of the mode is around 23.1GHz;

[0057] Step 3. Place the material to be tested in the cylindrical resonant cavity and record the S21 peak value, which is recorded as S210. Then adjust the electromagnet to generate the static magnetic field. Observe the peak value of the S21 curve on the vector network analyzer and find the minimum value of the S21 peak value, which is the rough ferromagnetic resonance point. Record the Gauss meter reading H at this time. e ;

[0058] Step 4: Keep the current of the first power supply 4 constant, that is, keep the electromagnet generating a uniform static magnetic field strength H e The size remains unchanged, and the current of each power supply in the power supply group is adjusted, that is, the uniform static magnetic field strength H generated by the three-layer Helmholtz coil is adjusted. h , find the exact ferromagnetic resonance point and record the current I of the second power supply at this time 1c , the current of the third power supply I 2c , the current of the fourth power supply I 3c and minimum S21 peak S21 c ;

[0059] Step 5. Pass S210 and S21 c Calculate the half-power point transmission coefficient S21 half , the calculation formula is as follows:

[0060]

[0061] Step 6. S21 obtained based on step 5 half , keep the electromagnet generating a static magnetic field H e The size remains unchanged, only the static magnetic field H generated by the Helmholtz coil changes h The specific process is:

[0062] First, gradually reduce the current of the Helmholtz coil until the peak value of the resonance peak S21 rises to S21 half , record the current I of the second power supply at this time 1R , the current of the third power supply I 2R , the current of the fourth power supply I 3R ; Then adjust the second power supply, the third power supply and the fourth power supply to their original size I 1c , I 2c , I 3c Then gradually increase the current of the electromagnet power supply until the resonance peak S21 rises to S21 half , record the current I of the second power supply at this time 1L , the current of the third power supply I 2L , the current of the fourth power supply I 3L , then the static magnetic field intensity corresponding to the two points is:

[0063]

[0064] Then the resonance linewidth ΔH can be expressed as:

[0065] ΔH=H L -H R (4).

[0066] Figure 4 These are simulation results for the magnetic field uniformity of a Helmholtz coil. The radius of the simulated Helmholtz coil is 33 mm, and the current is 1.8 A. The horizontal axis represents the distance from the midpoint of the line connecting the two coil centers, while the vertical axis represents the magnetic field intensity. It can be seen that the magnetic field is uniformly distributed within a 40 mm area, approximately 20 mm to the left and right of the center of the line.

[0067] The above description is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A ferrite ferromagnetic resonance linewidth measurement system based on precise adjustment of static magnetic field, characterized in that: It includes a vector network analyzer, a cylindrical resonant cavity, an electromagnet, an electromagnet power supply, a power supply group, a first coupling ring, a second coupling ring, an n-layer Helmholtz coil device, a data processing unit, a Gauss meter, and a coupling amount adjustment device; The main body of the n-layer Helmholtz coil device is a cylindrical cavity, with grooves symmetrically arranged on both sides of the cavity. The radius of the grooves on each side increases from the inside to the outside, and a coil is wound in the grooves. Grooves with the same radius on both sides of the cylindrical cavity constitute a layer, with a total of n layers, and each layer forms a Helmholtz coil. A cylindrical through-hole with a diameter identical to that of the cylindrical resonant cavity is provided at the center of the cylindrical cavity wall, so that the cylindrical resonant cavity is precisely embedded in the main body of the n-layer Helmholtz coil device. A rectangular through-hole is provided on the side wall at a 90° angle to the side wall where the cylindrical through-hole is located, to facilitate adjustment of the first coupling ring and the second coupling ring, as well as placement of the material to be tested. The power supply group includes n power supplies, each power supply supplies power to a group of coils, and n is a positive integer. The first power supply is used to supply power to the electromagnet so that the electromagnet generates a magnetic field; the n-layer Helmholtz coil device is fixedly arranged in the uniform magnetic field area of ​​the electromagnet; The first coupling ring and the second coupling ring are fixedly arranged on the side wall of one side of the cylindrical resonant cavity, and the coupling amount adjustment device is used to adjust the depth of the coupling ring extending into the cylindrical resonant cavity, thereby adjusting the coupling amount; a sample hole is set in the center of the side wall of the cylindrical resonant cavity on which the first coupling ring and the second coupling ring are arranged, and the material to be tested is placed in the center of the cylindrical resonant cavity through the sample hole; The two ports of the vector network analyzer are respectively connected to the first coupling ring and the second coupling ring, and the data processing unit is respectively connected to the vector network analyzer, the Gaussmeter, the electromagnet power supply and the power supply group; the Gaussmeter is used to measure the magnetic field generated by the electromagnet.

2. The ferrite ferromagnetic resonance linewidth measurement system according to claim 1, wherein: The different number of coils wound in each layer of grooves and the difference in groove radius determine that each layer of coils provides different magnetic fields per unit current, achieving fine control of the magnetic field in a small range.

3. The ferrite ferromagnetic resonance linewidth measurement system according to claim 1, wherein: The cylindrical resonant cavity operates at TE 01p mode, p is an odd number.

4. The ferrite ferromagnetic resonance linewidth measurement system according to claim 1, wherein: By designing the cylindrical resonant cavity size and adjusting the cylindrical resonant cavity working mode, the test frequency of the resonance linewidth measurement system can be adjusted; the smaller the cylindrical resonant cavity size and the larger the p value, the higher the working frequency.

5. The ferrite ferromagnetic resonance linewidth measurement system according to claim 1, wherein: The electromagnet power supply is used to provide a high-power power supply of more than 1000W, and is used to provide a strong static magnetic field; each power supply in the power supply group is used to provide a low-power power supply within 100W.

6. The ferrite ferromagnetic resonance linewidth measurement system according to claim 1, wherein: The data processing unit controls the power supply of the electromagnet to control the size of the static magnetic field generated by the electromagnet to achieve coarse adjustment; the data processing unit controls the power supply of the power supply group to control the n-layer Helmholtz coil device to fine-tune the size of the static magnetic field to achieve high-precision control of the static magnetic field.

7. The ferrite ferromagnetic resonance linewidth measurement system according to claim 1, wherein: n is 3; the power supply group includes a second power supply, a third power supply and a fourth power supply. The second power supply, the third power supply and the fourth power supply respectively power the three layers of coils. The magnetic field size of the coil controlled by the second power supply is 0.1Gs per 0.2A step, the magnetic field size of the coil controlled by the third power supply is 1Gs per 0.4A step, and the magnetic field size of the coil controlled by the fourth power supply is 10Gs per 1A step. The superposition of the three layers of coils can provide a maximum of 100Gs.

8. The ferrite ferromagnetic resonance linewidth measurement system according to claim 1, wherein: The material to be tested is a small ball sample or a thin film sample; wherein, when the thin film sample is placed in the center of the cylindrical resonant cavity, the surface of the film should be parallel to both the direction of the static magnetic field and the direction of the microwave magnetic field in the cavity.

9. A measurement method based on the ferrite ferromagnetic resonance linewidth measurement system according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1. Obtain the current-magnetic field intensity curve of each layer of the Helmholtz coil device with n layers. The specific process is as follows: Before the measurement, a certain number of coils are wound in the grooves of each layer of the n-layer Helmholtz coil device, and current is applied to each set of coils, and the current magnitude I passing through each set of coils is changed. i , use a Gauss meter to record the strength of the uniform static magnetic field generated by each set of Helmholtz coils, and fit the current-magnetic field strength curve of each layer of Helmholtz coils; The static magnetic field strength H generated by the n-layer Helmholtz coil device h for: Among them, a i is the fitting coefficient; Step 2. Perform port calibration on the vector network analyzer and find the TE of the cylindrical resonator 01p Mode corresponds to frequency; Step 3. Place the material to be tested in the cylindrical resonant cavity and record the S21 peak value, which is recorded as S210. Then adjust the electromagnet to generate the static magnetic field. Observe the peak value of the S21 curve on the vector network analyzer and find the minimum value of the S21 peak value, which is the rough ferromagnetic resonance point. Record the Gauss meter reading H at this time. e ; Step 4. Keep the power supply current of the electromagnet unchanged, that is, keep the electromagnet generating a uniform static magnetic field strength H e The magnitude remains unchanged, and the current of each power supply in the power supply group is adjusted, that is, the uniform static magnetic field strength H generated by the n-layer Helmholtz coil device is adjusted. h , find the precise ferromagnetic resonance point and record the current value I of each power supply at this time ic and the minimum S21 peak S21 at this time c ; Step 5. Pass S210 and S21 c Calculate the half-power point transmission coefficient S21 half , the calculation formula is as follows: Step 6. S21 obtained based on step 5 half , keep the electromagnet generating a static magnetic field H e The size remains unchanged, only the static magnetic field H generated by the n-layer Helmholtz coil device is changed h The specific process is: First, gradually reduce the current of each layer of the Helmholtz coil device until the resonance peak S21 rises to S21 half , record the current value I of each power supply at this time iR , and the static magnetic field intensity corresponding to this point is H R ; Then adjust the current value of each power supply in the power group to the original value I ic Then gradually increase the current of each layer of the Helmholtz coil device until the resonance peak S21 rises to S21 half , record the current value I of each power supply in the power supply group at this time iL , and the static magnetic field intensity corresponding to this point is H L ; The calculation formulas for the static magnetic field strength corresponding to the two points are: Then the resonance linewidth ΔH can be expressed as: ΔH=H L -H R (4)。

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