Ferromagnetic resonance line width detection device for microwave ferrite material

Abstract

The invention discloses a ferromagnetic resonance line width detection device for a microwave ferrite material. Relates to the technical field, is arranged on an active vibration isolation platform, and comprises a microwave source, a first directional coupler, a variable attenuator, a second directional coupler and a resonant cavity which are connected in sequence, an isolator is arranged between the microwave source and the first directional coupler, a frequency meter is arranged on the first directional coupler, and an isolator is arranged between the second directional coupler and the resonant cavity. A crystal detector is arranged on the second directional coupler, an isolator is further arranged on the side, away from the directional couplers, of the resonant cavity, magnetic field control systems are arranged on the two sides of the resonant cavity, crystal detectors are arranged on the isolator away from the directional couplers, and an oscilloscope is arranged on each crystal detector. The microwave source is arranged to provide energy for ferromagnetic resonance of a sample; a frequency meter is arranged to monitor whether the output signal frequency of the microwave source is matched with the resonant frequency of the resonant cavity; and the ferromagnetic resonance line width can be accurately measured.

Description

Technical Field

[0001] The present invention relates to the technical field of ferromagnetic resonance linewidth detection, and more specifically, to a device for detecting the ferromagnetic resonance linewidth of microwave ferrite materials. Background Art

[0002] Microwave ferrite materials are widely used in various civilian and military fields such as communication, television, radar, artificial satellites, missile systems, electronic countermeasure systems, and high-energy particle accelerators due to their gyromagnetic properties.

[0003] Ferrite is a ferromagnetic material sintered from iron oxides and other elements (such as manganese, magnesium, nickel, copper, etc.). Its main characteristic is its very high resistivity, which is 10^6 - 10^18 times that of ordinary metals. This enables ferrite to have a very high operating frequency as a magnetic material. At microwave frequencies, electromagnetic waves can no longer penetrate ordinary metals, but can pass through ferrite with high resistivity. In addition, ferrite with gyromagnetic properties can also change the propagation characteristics of microwave signals. Therefore, using ferrite with gyromagnetic properties to make microwave devices has unique advantages, so such ferrite is also called microwave ferrite. Currently, microwave devices made of microwave ferrite have been widely used in various aspects of civilian and military applications such as communication, television, radar, artificial satellites, missile systems, electronic countermeasure systems, and high-energy particle accelerators, and occupy an important position in the communication field. Therefore, research on microwave ferrite materials and devices at home and abroad has never stopped. For microwave ferrite materials, it is generally required to have low losses, a high Curie temperature, good consistency, and stability. Among them, the losses of microwave ferrite consist of magnetic losses and electrical losses, and magnetic losses often dominate. Among the various parameters of microwave ferrite, the ferromagnetic resonance linewidth is directly related to magnetic losses. Therefore, measuring the ferromagnetic resonance linewidth is of great significance for evaluating the performance of microwave ferrite materials.

[0004] To adapt to the development of current 5G communication technology, microwave ferrite materials need to have a smaller ferromagnetic resonance linewidth. Therefore, accurately measuring the ferromagnetic resonance linewidth has become an important task in the research and development of microwave ferrite and the design of 5G electronic devices.

[0005] Therefore, how to provide a device for detecting the ferromagnetic resonance linewidth of microwave ferrite materials that can accurately measure the ferromagnetic resonance linewidth is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a device for detecting the ferromagnetic resonance linewidth of microwave ferrite materials, aiming to solve one of the problems in the above background art and achieve accurate measurement of the ferromagnetic resonance linewidth.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A device for detecting the ferromagnetic resonance linewidth of a microwave ferrite material, which is arranged on an active vibration isolation platform and includes:

[0009] A microwave source, a first directional coupler, a variable attenuator, a second directional coupler and a resonant cavity connected in sequence. An isolator is provided between the microwave source and the first directional coupler. A frequency meter is provided on the first directional coupler. An isolator is provided between the second directional coupler and the resonant cavity. A crystal detector is provided on the second directional coupler. An isolator is also provided on the side of the resonant cavity away from the directional coupler. Magnetic field control systems are provided on both sides of the resonant cavity. A crystal detector is provided on the isolator away from the directional coupler. An oscilloscope is provided on each crystal detector.

[0010] Further, the resonant cavity is set to be rectangular, flange plates are provided at both ends of the resonant cavity, a sample hole is provided at the center position of the narrow side of the resonant cavity, and tuning rod holes are respectively provided on both sides of the sample hole.

[0011] Further, the tuning rod holes are located at the 1 / 4 and 3 / 4 positions of the side wall of the resonant cavity.

[0012] Further, it also includes a sample holder and a tuning rod. The sample holder is divided into upper and lower parts. The inner diameter of the upper part of the sample holder is smaller than that of the lower part. A sample cavity is provided at the top of the upper part of the sample holder. The sample cavity extends into the sample hole. A through hole is provided at the bottom of the sample holder. The tuning rod is divided into upper and lower parts. The inner diameter of the upper part of the tuning rod is smaller than that of the lower part. The upper part of the tuning rod extends into the tuning rod hole.

[0013] Further, it also includes a temperature control system. The temperature fluctuation of the resonant cavity is controlled within ±0.1 °C through the temperature control system. The temperature control system includes a cooling module, and the cooling module is used for low-temperature experiments to ensure the temperature stability of the sample.

[0014] Further, it also includes a vacuum system, and the vacuum system includes a vacuum pump.

[0015] Further, it also includes a gaussmeter, and the output frequency of the microwave source is detected through the gaussmeter.

[0016] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a device for detecting the ferromagnetic resonance linewidth of a microwave ferrite material. By setting the output frequency of the wave source to match the resonance frequency of the resonant cavity, microwave signals are provided to supply energy for the ferromagnetic resonance of the sample. By setting a frequency meter to monitor whether the output signal frequency of the microwave source matches the resonance frequency of the resonant cavity. By setting a crystal detector, high-frequency microwave signals can be detected. Utilizing its unidirectional conductivity and non-linear characteristics, a unidirectional intermediate-frequency carrier can be extracted. Then, through capacitance filtering and a de-emphasis circuit, an envelope can be obtained, which is approximately equal to the original low-frequency waveform of the modulation signal. By using an oscilloscope to measure the level of the output low-frequency signal, the relative magnitude of the signal pattern can be characterized. By setting an isolator, reflected signals can be isolated, avoiding measurement errors caused by reflected signals and playing a role in protecting the device. By setting a first directional coupler to distribute the input signal power in a certain proportion, a small part of the input signal is coupled out for monitoring the frequency or relative power magnitude of the input signal. By setting a variable attenuator to continuously adjust the attenuation value. The device has a reasonable structural design, is convenient to operate, has good flexibility and high stability, and can accurately measure the ferromagnetic resonance linewidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0018] Figure 1 It is a system diagram of the device for detecting the ferromagnetic resonance linewidth of the microwave ferrite material provided by the present invention;

[0019] Figure 2 It is a schematic structural diagram of the resonant cavity provided by the present invention;

[0020] Figure 3 It is a schematic structural diagram of the sample holder provided by the present invention;

[0021] Figure 4 It is a schematic structural diagram of the tuning rod provided by the present invention;

[0022] Figure 5 It is a schematic internal structure diagram of the sample holder provided by the present invention;

[0023] Figure 6 It is a schematic structural diagram of the tuning rod located in the resonant cavity provided by the present invention.

[0024] Wherein: 1 is a resonant cavity; 2 is a flange; 3 is a sample hole; 4 is a tuning rod hole; 5 is a sample holder; 6 is a tuning rod; 7 is a through hole; 8 is a friction layer; 9 is a sample cavity. Specific embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] See Figures 1-6 , an apparatus for detecting the ferromagnetic resonance linewidth of a microwave ferrite material disclosed in an embodiment of the present invention is disposed on an active vibration isolation platform and includes a microwave source, a first directional coupler, a variable attenuator, a second directional coupler, and a resonant cavity 2 connected in sequence. An isolator is provided between the microwave source and the first directional coupler. A frequency meter is provided on the first directional coupler. An isolator is provided between the second directional coupler and the resonant cavity 2. A crystal detector is provided on the second directional coupler. An isolator is further provided on the side of the resonant cavity 2 away from the directional coupler. Magnetic field control systems are provided on both sides of the resonant cavity 2. A crystal detector is provided on the isolator away from the directional coupler. An oscilloscope is provided on each crystal detector; by setting the microwave signal output by the wave source to match the resonant frequency of the resonant cavity 2, energy is provided for the ferromagnetic resonance of the sample; by setting the frequency meter to monitor whether the output signal frequency of the microwave source matches the resonant frequency of the resonant cavity 2; by setting the crystal detector, the high-frequency microwave signal can be detected. Using its unilateral conductivity and non-linear characteristics, the unidirectional intermediate-frequency carrier can be extracted, and then the envelope can be obtained through capacitor filtering and de-emphasis circuit, which is approximately equal to the original low-frequency waveform of the modulation signal. Then, by using the oscilloscope to measure the level of the output low-frequency signal, the relative magnitude of the signal law can be characterized; by setting the isolator, the reflected signal can be isolated, avoiding the measurement error caused by the reflected signal and playing a role in protecting the device; by setting the first directional coupler to distribute the input signal power according to a certain ratio and couple out a small part of the input signal for monitoring the frequency or relative power magnitude of the input signal; by setting the variable attenuator to continuously adjust the attenuation value.

[0027] In this embodiment, the resonant cavity 2 is set to be rectangular, and flange plates 2 are provided at both ends of the resonant cavity 2. A sample hole 3 is provided at the center position of the narrow side of the resonant cavity 2, and tuning rod holes 4 are provided on both sides of the sample hole 3; since the wide side of the resonant cavity 2 is required to load a steady magnetic field, the sample hole 3 is provided at the center position of the narrow side of the resonant cavity 2; the diameter of the sample hole 3 is not greater than 2 mm, which can ensure that the sample reaches the position where the magnetic field in the cavity is the largest and the electric field is the smallest, and the influence of the entry of the sample on the original electromagnetic field in the resonant cavity 2 is within an acceptable range; in order to facilitate the connection of the resonant cavity 2, the flange plate 2 structure is adopted at both ends of the resonant cavity 2 to ensure the stable connection between the resonant cavity 2 and the front and rear components, and a small hole coupling can also be formed between the resonant cavity 2 and the excitation signal.

[0028] In this embodiment, the tuning rod holes 4 are located at the 1 / 4 and 3 / 4 positions of the side wall of the resonant cavity 2; the tuning rod 6 can enter the two positions where the electric field in the resonant cavity 2 is the largest, achieving the best adjustment effect.

[0029] In this embodiment, a sample holder 5 and a tuning rod 6 are further included. The sample holder 5 is divided into upper and lower parts. The inner diameter of the upper part of the sample holder 5 is smaller than that of the lower part. A sample cavity 9 is provided at the top of the upper part of the sample holder 5, and the sample cavity 9 extends into the sample hole 3. A through hole 7 is provided at the bottom of the sample holder 5. The tuning rod 6 is divided into upper and lower parts. The inner diameter of the upper part of the tuning rod 6 is smaller than that of the lower part. The upper part of the tuning rod 6 extends into the tuning rod hole 4; the upper part of the sample holder 5 is used to guide the sample into the hole, and the lower part of the sample holder 5 is used to extend into the resonant cavity 2 to send the sample to the designated position; in order to prevent the situation that the air pressure inside and outside the sample holder 5 is different during the process of placing the sample, resulting in the sample not being able to reach the bottom smoothly, a through hole 7 is provided at the bottom of the sample holder 5 to keep the air pressure inside and outside the sample holder 5 balanced; by setting the tuning rod 6 to be divided into upper and lower parts, the diameter of the upper part of the tuning rod 6 is smaller than that of the lower part. The upper part is used to enter the resonant cavity 2 to adjust the resonant frequency, and the lower part can prevent the tuning rod 6 from falling into the resonant cavity 2.

[0030] In this embodiment, a temperature control system is further included. The temperature fluctuation of the resonant cavity 2 is controlled within ±0.1 °C through the temperature control system. The temperature control system includes a cooling module. The cooling module is used for low-temperature experiments to ensure the temperature stability of the sample; the cooling module is a cooling water circulation machine. The heat generated by the electromagnet during operation needs to be taken away by cooling water to ensure that the electromagnetic field can work normally for a long time.

[0031] In this embodiment, a vacuum system is further included. The vacuum system includes a vacuum pump; it is used for high-vacuum or ultra-high-vacuum experiments.

[0032] In this embodiment, a gaussmeter is further included. The output frequency of the microwave source is detected through the gaussmeter; the gaussmeter has high precision, resolution and stability.

[0033] In addition, in this embodiment, there are two positions where the signal power needs to be measured, so the oscilloscope requires at least two channels.

[0034] Friction layers 8 are provided on both the lower parts of the sample holder 5 and the tuning rod 6 for easy grasping and use.

[0035] Since a crystal detector is used in the system, to ensure that the crystal detector detects the microwave signal according to the square law, the output power of the microwave source should not be too large. Therefore, to enable the measurement results to be clearly observed, the devices used in the signal transmission line should have a small insertion loss; and to improve the quality of signal transmission and reduce signal reflection during transmission, devices with a small voltage standing wave ratio are selected.

[0036] A variable attenuator with a spiral adjustment is adopted to ensure the accuracy of attenuation value adjustment.

[0037] The production material of the resonant cavity 2 is copper, and aluminum or other metals can also be used.

[0038] It also includes a programmable power supply that can control the electromagnet to generate the required magnetic field; to ensure precise adjustment of the magnetic field and avoid measurement errors, the programmable power supply used needs to be able to finely adjust the output current, and the output current of the power supply needs to match the working current of the electromagnet.

[0039] The measurement steps are as follows:

[0040] (1) Connect all the instruments and microwave devices, and connect the signals sent from the front and back of the resonant cavity 2 to the CH1 and CH2 channels of the oscilloscope respectively, and check whether the interfaces between all the devices and cables are tightened;

[0041] (2) Turn on the microwave source, frequency meter, oscilloscope, programmable power supply and gaussmeter, calibrate the probe of the gaussmeter, and set the output frequency of the microwave source to 9.98 GHz and the signal power to 8 dBm;

[0042] (3) Adjust the variable attenuator to an appropriate attenuation value a 0 , and load the tuning rod 6 on the resonant cavity 2, adjust the tuning rod 6 to make the signal on the CH2 channel have the maximum output, and take the signal level at this time as the reference value;

[0043] (4) Place the sample into the resonant cavity 2 through the sample holder 5, adjust the magnetic field strength until the signal on the CH2 channel has the minimum output (at this time, the sample reaches the ferromagnetic resonance state and absorbs the maximum power), record the magnetic field value H 0 , adjust the variable attenuator to make the signal level return to the reference level, and record the attenuation value a r of the variable attenuator at this time;

[0044] (5) According to the formula: Calculate the attenuation value a corresponding to the half-power point of the sample 1 / 2 ;

[0045] (6) Adjust the attenuation value of the variable attenuator to a 1 / 2 , slowly reduce the magnetic field to restore the signal level of the CH2 channel to the reference level; then adjust the tuning rod 6 again until the signal has the maximum output, and then adjust the magnetic field strength to restore the signal level to the reference level. Repeat this operation until the signal has the maximum output without adjusting the tuning rod 6; record the magnetic field value H 1 , which is called the left magnetic field;

[0046] (7) Slowly increase the magnetic field and repeat the operation in (6) to find the right magnetic field H 2 ;

[0047] (8) Finally, according to the formula: ΔH = H 2 - H 1 , obtain the ferromagnetic resonance linewidth ΔH.

[0048] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and reference can be made to the description of the method part for related parts.

[0049] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A microwave ferrite material ferromagnetic resonance line width detection device, characterized in that: The device is arranged on an active vibration isolation platform, and comprises a microwave source, a first directional coupler, a variable attenuator, a second directional coupler and a resonant cavity connected in sequence, an isolator is arranged between the microwave source and the first directional coupler, a frequency meter is arranged on the first directional coupler, an isolator is arranged between the second directional coupler and the resonant cavity, a crystal detector is arranged on the second directional coupler, the isolator is further arranged on the side of the resonant cavity away from the directional coupler, a magnetic field control system is arranged on both sides of the resonant cavity, a crystal detector is arranged on the isolator away from the directional coupler, and an oscilloscope is arranged on each of the crystal detectors.

2. A microwave ferrite material ferromagnetic resonance line width detection device according to claim 1, characterized in that: The resonant cavity is arranged in a rectangular shape, flanges are arranged at both ends of the resonant cavity, a sample hole is arranged at the center of a narrow side of the resonant cavity, and tuning rod holes are arranged on both sides of the sample hole.

3. A microwave ferrite material ferromagnetic resonance line width detection device according to claim 2, characterized in that: The tuning rod holes are located at 1 / 4 and 3 / 4 of the side wall of the resonant cavity.

4. A microwave ferrite material ferromagnetic resonance line width detection device according to claim 3, characterized in that: It also includes a sample rack and a tuning rod, wherein the sample rack is divided into an upper and lower part, the inner diameter of the upper part of the sample rack is smaller than the inner diameter of the lower part, a sample cavity is arranged at the top of the upper part of the sample rack, and the sample cavity extends into the sample hole, a through hole is arranged at the bottom of the sample rack, and the tuning rod is divided into an upper and lower part, the inner diameter of the upper part of the tuning rod is smaller than the inner diameter of the lower part, and the upper part of the tuning rod extends into the tuning rod hole.

5. The microwave ferrite material ferromagnetic resonance line width detection device according to claim 1, characterized in that: It also includes a temperature control system, through which the temperature fluctuation of the resonance cavity is controlled within ±0.1°C. The temperature control system includes a cooling module, which is used for low-temperature experiments to ensure the temperature stability of the sample.

6. The microwave ferrite material ferromagnetic resonance line width detection device according to claim 1, characterized in that: Also included is a vacuum system including a vacuum pump.

7. The microwave ferrite material ferromagnetic resonance line width detection device according to claim 1, characterized in that: A gaussmeter is also included, and the output frequency of the microwave source is detected by the gaussmeter.

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