A microwave magnetic sensor and its measurement method

Abstract

A microwave magnetic sensor comprises: two half-wavelength resonators, each of which is a transmission line segment with a length equal to half the wavelength corresponding to its fundamental mode resonant frequency, and the two half-wavelength resonators have the same length and the same fundamental mode resonant frequency; a magnetoresistive element located between the two half-wavelength resonators and symmetrically spaced equidistantly from the two half-wavelength resonators, the magnetoresistive element and the ends of the two half-wavelength resonators forming a coupling capacitor, and the two half-wavelength resonators are coupled via the coupling capacitor. The microwave magnetic sensor provided by the present invention can determine the external magnetic field based on changes in the first resonant frequency of the microwave magnetic sensor. Because the resonant frequency of the resonant structure can be precisely measured, the microwave magnetic sensor provided by the present invention has higher sensitivity and accuracy than existing magnetoresistive sensors based on Wheatstone bridges.

Description

Technical Field

[0001] The present invention relates to the field of sensors, and in particular to a microwave magnetic sensor and a measurement method thereof. Background Art

[0002] Magnetic sensors are widely used in consumer electronics and industrial production. They are particularly important in the Internet of Things (IoT) and Industrial Internet of Things (IIoT). They can be used to power smart home solutions, allowing users to remotely turn appliances on and off and adjust energy consumption in real time by measuring current and voltage. They can also provide angle sensing, distance sensing, motion sensing, and safety switches for robotics and factory automation.

[0003] Magnetic sensors using magnetoresistive (MR) elements are already widely used. The resistance of a MR element changes with the external magnetic field it experiences. MR elements include semiconductor MR elements such as indium antimonide (InSb) and metal MR elements such as giant magnetoresistive (GMR), tunnel magnetoresistive (TMR), and anisotropic magnetoresistive (AMR). Magnetic sensors using metal MR elements are popular due to their advantages in sensitivity and reliability.

[0004] However, because metal magnetoresistive elements are conductors, it is difficult to accurately measure changes in their resistivity. Therefore, the sensitivity and accuracy of magnetic sensors with metal magnetoresistive elements need to be further improved. Summary of the Invention

[0005] The object of the present invention is to provide a microwave magnetic sensor to solve the problems raised in the background technology.

[0006] The technical solution of the present invention is: a microwave magnetic sensor, comprising:

[0007] Two half-wavelength resonators, each of the half-wavelength resonators is a section of transmission line, the length of which is equal to half the wavelength corresponding to its fundamental mode resonant frequency, and the two half-wavelength resonators have the same length and the same fundamental mode resonant frequency;

[0008] A magnetoresistive element is located between the two half-wavelength resonators and is symmetrically spaced equidistantly from the two half-wavelength resonators. The magnetoresistive element and ends of the two half-wavelength resonators form a coupling capacitor, and the two half-wavelength resonators are coupled via the coupling capacitor.

[0009] Preferably, the magnetoresistive element is a metal magnetoresistive element, including a giant magnetoresistive element, a tunnel magnetoresistive element or an anisotropic magnetoresistive element.

[0010] Preferably, the transmission line is a planar transmission line, including a stripline, a microstrip or a coplanar line.

[0011] Preferably, the transmission line is a microstrip.

[0012] Preferably, the substrate is made of a low-loss dielectric material, including but not limited to silicon, gallium arsenide, FR-4, alumina, sapphire, quartz, or a combination thereof;

[0013] The ground wire is made of a highly conductive metal, including but not limited to gold, silver, copper or a combination thereof.

[0014] Preferably, the protective layer covers the magnetoresistive element;

[0015] The protection layer is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide or a combination thereof.

[0016] Preferably, the protection layer fills a gap between the resonator and the magnetoresistive element and covers a portion of the half-wavelength resonator.

[0017] Preferably, the magnetoresistive element has a step structure on each side;

[0018] The magnetoresistive element includes a top surface, an intermediate surface, and a bottom surface. The bottom surface of the magnetoresistive element directly contacts the top surface of the substrate. The intermediate surface and the top surface of the magnetoresistive element are located above the top surface of the half-wavelength resonator and cover a portion of the half-wavelength resonator on each side.

[0019] Preferably, the isolation element is provided between the half-wavelength resonator and the magnetoresistive element;

[0020] The isolation element has a stepped structure;

[0021] The isolation element includes a top surface, an intermediate surface and a bottom surface. The top surface of the isolation element directly contacts the intermediate surface of the magnetoresistive element, the intermediate surface of the isolation element directly contacts the top surface of the half-wavelength resonator, and the bottom surface of the isolation element directly contacts the top surface of the substrate.

[0022] The isolation element is made of low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide or a combination thereof.

[0023] Preferably, the protective layer covers the magnetoresistive element;

[0024] The protection layer is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

[0025] Preferably, the isolation element has a stepped structure on each side;

[0026] The isolation element comprises a top surface, an intermediate surface, and a bottom surface, wherein the bottom surface of the isolation element directly contacts the top surface of the substrate, the intermediate surface of the isolation element directly contacts the top surface of the half-wavelength resonator and covers a portion of the half-wavelength resonator on each side, and the magnetoresistive element is disposed on the top surface of the isolation element;

[0027] The isolation element is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide or a combination thereof.

[0028] Preferably, the protective layer covers the magnetoresistive element;

[0029] The protection layer is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

[0030] Preferably, the half-wavelength resonator includes a transition portion, and the transition portion is located on a side of the half-wavelength resonator close to the magnetoresistive element;

[0031] The width of the transition portion at one end close to the magnetoresistive element is consistent with the width of the magnetoresistive element.

[0032] Preferably, the coupling unit is used to measure the resonant frequency of the microwave magnetic sensor;

[0033] The coupling unit is made of a section of transmission line, and the characteristic impedance of the transmission line is consistent with the characteristic impedance of the external measurement circuit.

[0034] Preferably, the coupling between the coupling unit and the half-wavelength resonator is end-to-end coupling.

[0035] Preferably, the coupling between the coupling unit and the half-wavelength resonator is parallel coupling.

[0036] Preferably, the substrate, the half-wavelength resonator, the coupling unit and the ground line are made of non-magnetic materials.

[0037] A microwave magnetic sensor measurement method, comprising:

[0038] S1, obtaining a calibration curve between a first resonant frequency of the microwave magnetic sensor and an external magnetic field strength, where the first resonant frequency is the lowest resonant frequency of the microwave magnetic sensor, and the calibration curve is obtained by measuring the first resonant frequency of the microwave magnetic sensor under external magnetic fields of different intensities within a range of interest;

[0039] S2, measuring the first resonant frequency of the microwave magnetic sensor under the magnetic field to be measured, and obtaining the intensity of the magnetic field to be measured according to the calibration curve.

[0040] The beneficial effects of the present invention are:

[0041] Compared to existing technologies, the microwave magnetic sensor provided by the present invention can determine the external magnetic field based on changes in the first resonant frequency of the microwave magnetic sensor. Because the resonant frequency of the resonant structure can be precisely measured, the microwave magnetic sensor provided by the present invention has higher sensitivity and accuracy than existing Wheatstone bridge-based magnetoresistive sensors. Furthermore, the microwave magnetic sensor can be manufactured using traditional semiconductor manufacturing processes and technologies. Furthermore, because the microwave magnetic sensor operates at microwave frequencies, it can be integrated into wireless communication systems, enabling remote, wireless sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic structural diagram of a microwave magnetic sensor provided by an embodiment of the present invention;

[0043] Figure 2 for Figure 1 A partial enlarged view of the coupling capacitor CAP;

[0044] Figure 3 A diagram showing the relationship between the first resonant frequency of an exemplary microwave magnetic sensor and the resistivity of a magnetoresistive element provided by an embodiment of the present invention;

[0045] Figure 4 A top view of a microstrip magnetic sensor provided by an embodiment of the present invention;

[0046] Figure 5 For the Figure 4 A cross-sectional view of section A-A';

[0047] Figure 6 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention;

[0048] Figure 7 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention;

[0049] Figure 8 A top view of another microstrip magnetic sensor provided by an embodiment of the present invention;

[0050] Figure 9 For the Figure 8 Cross-sectional view of section BB';

[0051] Figure 10 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention;

[0052] Figure 11 A top view of another microstrip magnetic sensor provided by an embodiment of the present invention;

[0053] Figure 12 For the Figure 11 Cross-sectional view of the C-C' section;

[0054] Figure 13 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention;

[0055] Figure 14 A top view of another microstrip magnetic sensor provided by an embodiment of the present invention;

[0056] Figure 15 For the Figure 14 Cross-sectional view of section D-D';

[0057] Figure 16 A schematic structural diagram of another microwave magnetic sensor provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0059] The following description of exemplary embodiments is merely illustrative in nature and is not intended to limit the present invention, its application, or use. In all examples shown and discussed, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0060] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, these technologies, methods, and equipment should be considered part of the specification.

[0061] It should be noted that like reference numerals and letters denote similar items in the drawings, and thus, once an item is defined in one drawing, it will not be further discussed in the subsequent drawings.

[0062] As mentioned in the background art, since metal magnetoresistive elements are conductors, it is difficult to accurately measure changes in their resistivity. Therefore, the sensitivity and accuracy of magnetic sensors with metal magnetoresistive elements need to be further improved.

[0063] In view of this, the present invention provides a microwave magnetic sensor with a metal magnetoresistive element and a measurement method thereof, which effectively solves the technical problems existing in the prior art and improves the sensitivity and accuracy of the magnetic sensor with a metal magnetoresistive element.

[0064] In the microwave magnetic sensor with a metal magnetoresistive element provided by the present invention, when an external magnetic field is applied to the magnetoresistive element, the resistivity of the element changes, thereby changing the resonance characteristics of the microwave magnetic sensor. The strength of the external magnetic field can be determined based on this change in the resonance characteristics of the microwave magnetic sensor.

[0065] Figure 1 This is a schematic diagram of the structure of a microwave magnetic sensor provided by an embodiment of the present invention. Figure 1 As shown, the microwave magnetic sensor includes two half-wavelength resonators 1 and a magnetoresistive element 2. Each of the half-wavelength resonators 1 is a transmission line whose length is equal to half the wavelength corresponding to its fundamental mode resonant frequency f0. The two half-wavelength resonators have the same length and the same fundamental mode resonant frequency f0. The magnetoresistive element 2 is located between the two half-wavelength resonators 1 and is symmetrically spaced from the two half-wavelength resonators 1. The magnetoresistive element 2 and the ends of the two half-wavelength resonators 1 form a coupling capacitor CAP, as shown in FIG. Figure 1 As shown in the dotted box in FIG. The two half-wavelength resonators 1 are coupled via the coupling capacitor CAP.

[0066] Figure 2 for Figure 1 The partial enlarged diagram of the coupling capacitor CAP in FIG, including the equivalent circuit of the coupling capacitor CAP. Figure 2 As shown, the coupling capacitor CAP includes three capacitors: two capacitors C1 formed between the half-wavelength resonator 1 and the magnetoresistive element 2, and the self-capacitance C2 of the magnetoresistive element 2. The capacitance of each of the three capacitors is related to the resistivity of the magnetoresistive element 2. Therefore, the total capacitance C of the coupling capacitor CAP is related to the resistivity of the magnetoresistive element 2.

[0067] In the microwave magnetic sensor, because the two half-wavelength resonators 1 are coupled via the coupling capacitor CAP, the fundamental mode resonance of the microwave magnetic sensor degenerates into two resonances, each having a first resonant frequency f1 and a second resonant frequency f2. The first resonant frequency f1 is lower than the fundamental mode resonant frequency f0 of the half-wavelength resonator 1, while the second resonant frequency f2 is higher than the fundamental mode resonant frequency f0 of the half-wavelength resonator 1. Specifically, the first resonant frequency is the lowest resonant frequency of the microwave magnetic sensor.

[0068] The difference between the first resonant frequency f1 and the second resonant frequency f2 is related to the total capacitance C of the coupling capacitor CAP. A change in the total capacitance C will cause a change in the first resonant frequency f1 and the second resonant frequency f2. The total capacitance C can be calculated from the first resonant frequency f1 and the second resonant frequency f2:

[0069]

[0070] Where Z0 is the characteristic impedance of the transmission line constituting the half-wavelength resonator. It can be understood that when the total capacitance C increases, the difference between f1 and f2 increases, and the first resonant frequency f1 decreases.

[0071] When the resistivity of the magnetoresistive element 2 decreases, the total capacitance C increases, so the first resonant frequency f l Will decrease. Figure 3 The relationship between the first resonant frequency and the resistivity of the magnetoresistive element of an exemplary microwave magnetic sensor provided by an embodiment of the present invention is shown in FIG. The exemplary microwave magnetic sensor is made of a microstrip, and the characteristic impedance of the microstrip is 50Ω. Figure 3 As shown in FIG. 1 , when the resistivity of the magnetoresistive element decreases, the first resonant frequency f1 of the exemplary microwave magnetic sensor decreases monotonically. Therefore, the resistivity of the magnetoresistive element can be inferred based on the first resonant frequency f1.

[0072] In the present invention, the coupling capacitor CAP comprises a magnetoresistive element 2. Magnetoresistive refers to the change in resistivity of a sample under an external magnetic field of strength H:

[0073] Where δH represents magnetoresistance, R(H) is the resistivity of the sample in a magnetic field of strength H, and R(0) is the resistivity of the sample when H=0.

[0074] The magnetoresistive element 2 in the present invention is a metal magnetoresistive element. The metal magnetoresistive element can be a giant magnetoresistive (GMR) element, a tunnel magnetoresistive (TMR) element, or an anisotropic magnetoresistive (AMR) element. Generally, the δH value of the GMR element, the TMR element, and the AMR element is greater than the δH value of the semiconductor magnetoresistive element. Taking GMR as an example, GMR is a spin electronic effect, and the operation of the GMR element is based on the dependence of electron scattering on spin orientation. The thin film structure of the GMR element is composed of alternating ferromagnetic and non-magnetic conductive layers. Depending on the magnetization arrangement of adjacent ferromagnetic layers, the total resistivity of the thin film structure may vary significantly. When arranged in parallel, the total resistivity is relatively low, while when arranged in anti-parallel, the total resistivity is relatively high.

[0075] In the present invention, the transmission line used to make the half-wavelength resonator can be any type of planar transmission line, including stripline, microstrip and coplanar line. The following description takes microstrip as an exemplary planar transmission line.

[0076] Figure 4 A top view of a microstrip magnetic sensor provided in an embodiment of the present invention. Figure 5 For the Figure 4 The cross-sectional view of the A-A' section. Figure 4 and Figure 5 As shown, the microstrip magnetic sensor includes two half-wavelength resonators 101 , a magnetoresistive element 102 , a substrate 103 and a ground line 104 .

[0077] The two half-wavelength resonators 101 are made of a highly conductive metal, including but not limited to gold, silver, copper, or a combination thereof. The two half-wavelength resonators 101 may have a multi-layer structure.

[0078] The magnetoresistive element 102 is a metal magnetoresistive element, which can be a GMR element, a TMR element, or an AMR element. The magnetoresistive element 102 is located between the two half-wavelength resonators 101 and is symmetrically spaced from the two half-wavelength resonators. The magnetoresistive element 102 can have a multilayer structure.

[0079] The substrate 103 is made of a low-loss dielectric material, including but not limited to silicon, gallium arsenide, FR-4, alumina, sapphire, quartz, or a combination thereof.

[0080] The ground line 104 is made of a highly conductive metal, including but not limited to gold, silver, copper, or a combination thereof, and may have a multi-layer structure.

[0081] The magnetoresistive element 102 may be covered by a protective layer. Figure 6 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention. Figure 6 As shown, in one embodiment, the magnetoresistive element 102 is covered by a protective layer 105. The protective layer 105 is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

[0082] In one embodiment, the magnetoresistive element 102 is covered by a protective layer that fills the gap between the resonator 101 and the magnetoresistive element 102 and covers a portion of the half-wavelength resonator 101 . Figure 7 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention. Figure 7 As shown, the magnetoresistive element 102 is covered by a protective layer 106, which fills the gap between the resonator 101 and the magnetoresistive element 102 and covers a portion of the half-wavelength resonator 101. The protective layer 106 is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

[0083] In the present invention, the coupling capacitor CAP may have various structures. Figure 8 A top view of another microstrip magnetic sensor provided by an embodiment of the present invention. Figure 9 For the Figure 8 The cross-sectional view of the B-B' section. Figure 8 and Figure 9 As shown, in one embodiment, the microstrip magnetic sensor includes a magnetoresistive element 202 and two isolation elements 207 .

[0084] The magnetoresistive element 202 has a stepped structure on each side. The magnetoresistive element 202 includes a top surface, an intermediate surface, and a bottom surface. The bottom surface of the magnetoresistive element 202 directly contacts the top surface of the substrate 103. The intermediate surface and top surface of the magnetoresistive element 202 are located above the top surface of the half-wavelength resonator 101 and cover a portion of the half-wavelength resonator 101 on each side.

[0085] Isolation element 207 has a stepped structure. Isolation element 207 is disposed between half-wavelength resonator 101 and magnetoresistive element 202. Isolation element 207 includes a top surface, an intermediate surface, and a bottom surface. The top surface of isolation element 207 directly contacts the intermediate surface of magnetoresistive element 202, and the intermediate surface of isolation element 207 directly contacts the top surface of half-wavelength resonator 101. The bottom surface of isolation element 207 directly contacts the top surface of substrate 103. Isolation element 207 is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organosilicon glass, porous silicon dioxide, or a combination thereof.

[0086] The magnetoresistive element 202 is a metal magnetoresistive element, and may be one of a GMR element, a TMR element, and an AMR element. The magnetoresistive element 202 may have a multilayer structure.

[0087] In one embodiment, the magnetoresistive element is covered by a protective layer. Figure 10 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention. Figure 10 As shown, the magnetoresistive element 202 is covered by a protective layer 205. The protective layer 205 is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

[0088] In one embodiment, the isolation element 207 and the protection layer 205 are made of the same material. In other embodiments, the isolation element 207 and the protection layer 205 may be made of different materials.

[0089] Figure 11 A top view of another microstrip magnetic sensor provided by an embodiment of the present invention. Figure 12 For the Figure 11 The cross-sectional view of the C-C' section. Figure 11 and 12 As shown, in one embodiment, the magnetic sensor includes a magnetoresistive element 302 and an isolation element 307 .

[0090] Isolation element 307 has a stepped structure on each side. Isolation element 307 includes a top surface, an intermediate surface, and a bottom surface. The bottom surface of isolation element 307 directly contacts the top surface of substrate 103. The intermediate surface of isolation element 307 directly contacts the top surface of half-wavelength resonator 101 and covers a portion of half-wavelength resonator 101 on each side. Magnetoresistive element 302 is disposed on the top surface of isolation element 307. Isolation element 307 is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organosilicon glass, porous silicon dioxide, or a combination thereof.

[0091] In one embodiment, the magnetoresistive element 302 is covered by a protective layer. Figure 13 A cross-sectional view of another microstrip magnetic sensor provided by an embodiment of the present invention. Figure 13 As shown, the magnetoresistive element 302 is covered by a protective layer 305. The protective layer 305 is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

[0092] In one embodiment, the isolation element 307 and the protection layer 305 are made of the same material. In other embodiments, the isolation element 307 and the protection layer 305 may be made of different materials.

[0093] In the present invention, the width of the half-wavelength resonator near the magnetoresistive element can be adjusted to meet specific measurement requirements. In one embodiment, the half-wavelength resonator includes a transition portion located on the side of the half-wavelength resonator near the magnetoresistive element. This transition portion ensures that the width of the half-wavelength resonator near the magnetoresistive element is consistent with the width of the magnetoresistive element, thereby meeting specific measurement requirements.

[0094] Figure 14 A top view of another microstrip magnetic sensor provided by an embodiment of the present invention. Figure 15 For the Figure 14 The cross-sectional view of the D-D' section. Figure 14 and Figure 15 As shown, the microstrip magnetic sensor includes two half-wavelength resonators 401 and a magnetoresistive element 402. The half-wavelength resonator includes a transition portion 408, which is located at one end of the half-wavelength resonator near the magnetoresistive element 402. Transition portion 408 ensures that the width of the end of the half-wavelength resonator 401 near the magnetoresistive element 402 is consistent with the width of the magnetoresistive element 402. The present invention does not limit the specific structure of transition portion 408.

[0095] The microwave magnetic sensor provided by the present invention further includes a coupling unit for measuring the resonant frequency of the microwave magnetic sensor. Figure 16 This is a schematic diagram of the structure of another microwave magnetic sensor provided by an embodiment of the present invention. Figure 16As shown, in one embodiment, the magnetic sensor includes two coupling units 509 for measuring the resonant frequency of the microwave magnetic sensor. The coupling unit 509 is made of a transmission line, and the characteristic impedance of the transmission line is consistent with the characteristic impedance of the external measurement circuit, for example, 50Ω. In one embodiment, as Figure 16 As shown, the coupling between the coupling unit 509 and the half-wavelength resonator 101 is end-to-end coupling. In other embodiments, the coupling between the coupling unit 509 and the half-wavelength resonator 101 can be other types of coupling, such as parallel coupling.

[0096] In some other embodiments, the microwave magnetic sensor may include only one coupling unit.

[0097] In one embodiment, the coupling unit 509 and the half-wavelength resonator 101 are made of the same type of transmission line. In some other embodiments, the coupling unit 509 and the half-wavelength resonator 101 may be made of different types of transmission lines.

[0098] In one embodiment, the coupling unit 509 and the half-wavelength resonator 101 are made of the same material. In some other embodiments, the coupling unit 509 and the half-wavelength resonator 101 may be made of different materials.

[0099] In one embodiment, the substrate, the half-wavelength resonator, the coupling unit and the ground line are made of non-magnetic materials.

[0100] The present invention also provides a method for measuring a microwave magnetic sensor. The method includes S1, obtaining a calibration curve between a first resonant frequency of the microwave magnetic sensor and an external magnetic field strength, wherein the first resonant frequency is the lowest resonant frequency of the microwave magnetic sensor. The calibration curve can be obtained by measuring the first resonant frequency of the microwave magnetic sensor under external magnetic fields of varying intensities within a range of interest; and S2, measuring the first resonant frequency of the microwave magnetic sensor under a magnetic field to be measured, and obtaining the magnetic field strength to be measured based on the calibration curve.

[0101] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A microwave magnetic sensor, comprising: Two half-wavelength resonators, each of the half-wavelength resonators is a section of transmission line, the length of which is equal to half the wavelength corresponding to its fundamental mode resonant frequency, and the two half-wavelength resonators have the same length and the same fundamental mode resonant frequency; A magnetoresistive element is located between the two half-wavelength resonators and is symmetrically spaced equidistantly from the two half-wavelength resonators. The magnetoresistive element and ends of the two half-wavelength resonators form a coupling capacitor, and the two half-wavelength resonators are coupled via the coupling capacitor.

2. The microwave magnetic sensor according to claim 1, wherein: The magnetoresistive element is a metal magnetoresistive element, including a giant magnetoresistive element, a tunnel magnetoresistive element or an anisotropic magnetoresistive element.

3. The microwave magnetic sensor according to claim 2, wherein: The transmission line is a planar transmission line, including a stripline, a microstrip or a coplanar line.

4. The microwave magnetic sensor according to claim 3, characterized in that The transmission line is a microstrip.

5. The microwave magnetic sensor according to claim 4, further comprising: a substrate made of a low-loss dielectric material including, but not limited to, silicon, gallium arsenide, FR-4, alumina, sapphire, quartz, or a combination thereof; The ground wire is made of a highly conductive metal, including but not limited to gold, silver, copper or a combination thereof.

6. The microwave magnetic sensor according to claim 5, further comprising a protective layer, characterized in that: The protective layer covers the magnetoresistive element; The protection layer is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide or a combination thereof.

7. The microwave magnetic sensor according to claim 6, characterized in that: The protective layer fills a gap between the resonator and the magnetoresistive element and covers a portion of the half-wavelength resonator.

8. The microwave magnetic sensor according to claim 5, wherein: The magnetoresistive element has a stepped structure on each side; The magnetoresistive element includes a top surface, an intermediate surface, and a bottom surface. The bottom surface of the magnetoresistive element directly contacts the top surface of the substrate. The intermediate surface and the top surface of the magnetoresistive element are located above the top surface of the half-wavelength resonator and cover a portion of the half-wavelength resonator on each side.

9. The microwave magnetic sensor according to claim 8, further comprising an isolation element, characterized in that: The isolation element is disposed between the half-wavelength resonator and the magnetoresistive element; The isolation element has a stepped structure; The isolation element comprises a top surface, an intermediate surface, and a bottom surface, wherein the top surface of the isolation element directly contacts the intermediate surface of the magnetoresistive element, the intermediate surface of the isolation element directly contacts the top surface of the half-wavelength resonator, and the bottom surface of the isolation element directly contacts the top surface of the substrate; The isolation element is made of low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide or a combination thereof.

10. The microwave magnetic sensor according to claim 9, further comprising a protective layer, characterized in that: The protective layer covers the magnetoresistive element; The protection layer is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

11. The microwave magnetic sensor according to claim 5, further comprising an isolation element, characterized in that: The isolation element has a stepped structure on each side; The isolation element comprises a top surface, an intermediate surface, and a bottom surface, wherein the bottom surface of the isolation element directly contacts the top surface of the substrate, the intermediate surface of the isolation element directly contacts the top surface of the half-wavelength resonator and covers a portion of the half-wavelength resonator on each side, and the magnetoresistive element is disposed on the top surface of the isolation element; The isolation element is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide or a combination thereof.

12. The microwave magnetic sensor according to claim 11, further comprising a protective layer, characterized in that: The protective layer covers the magnetoresistive element; The protection layer is made of a low-k material, including but not limited to fluorine-doped silicon dioxide, organic silicon glass, porous silicon dioxide, or a combination thereof.

13. The microwave magnetic sensor according to claim 5, characterized in that: The half-wavelength resonator includes a transition portion, and the transition portion is located on a side of the half-wavelength resonator close to the magnetoresistive element; The width of the transition portion at one end close to the magnetoresistive element is consistent with the width of the magnetoresistive element.

14. The microwave magnetic sensor according to claim 5, further comprising a coupling unit, characterized in that: The coupling unit is used to measure the resonant frequency of the microwave magnetic sensor; The coupling unit is made of a section of transmission line, and the characteristic impedance of the transmission line is consistent with the characteristic impedance of the external measurement circuit.

15. The microwave magnetic sensor according to claim 14, characterized in that: The coupling between the coupling unit and the half-wavelength resonator is end-to-end coupling.

16. The microwave magnetic sensor according to claim 14, wherein: The coupling between the coupling unit and the half-wavelength resonator is parallel coupling.

17. The microwave magnetic sensor according to claim 14, wherein: The substrate, the half-wavelength resonator, the coupling unit, and the ground line are made of non-magnetic materials.

18. The microwave magnetic sensor measurement method according to claim 1, comprising: S1, obtaining a calibration curve between a first resonant frequency of the microwave magnetic sensor and an external magnetic field strength, where the first resonant frequency is the lowest resonant frequency of the microwave magnetic sensor, and the calibration curve is obtained by measuring the first resonant frequency of the microwave magnetic sensor under external magnetic fields of different intensities within a range of interest; S2, measuring the first resonant frequency of the microwave magnetic sensor under the magnetic field to be measured, and obtaining the intensity of the magnetic field to be measured according to the calibration curve.

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