An active magnetic field probe

Abstract

The application discloses an active magnetic field probe and relates to the technical field of electromagnetic compatibility and electromagnetic field near field testing. After detecting the magnetic field change of a to-be-detected object, a detection part generates an electromagnetic signal. A horizontal switching structure realizes smooth transition of the electromagnetic signal from a strip line to an artificial surface plasmon and impedance matching between the strip line and the artificial surface plasmon. An active amplification circuit amplifies the electromagnetic signal, and the sensitivity of the active magnetic field probe is greatly improved.

Description

Technical Field

[0001] This invention relates to the fields of electromagnetic compatibility and electromagnetic field near-field testing technology, and in particular to an active magnetic field probe. Background Technology

[0002] With the rapid development of electronic technology, operating frequencies are increasing rapidly, layout complexity is increasing dramatically, and chip size is constantly shrinking, posing new challenges to the electromagnetic compatibility (EMC) design of electronic devices. Utilizing near-field probes combined with point-by-point near-field scanning can help us accurately measure the intensity of electromagnetic fields radiated from circuit boards, chips, antennas, and other devices, thus solving electromagnetic interference problems.

[0003] Near-field magnetic field probes can be used to measure the intensity of magnetic fields radiated by devices such as circuit boards. Their main performance characteristics include bandwidth, sensitivity, and spatial resolution. Bandwidth refers to the frequency range within which the magnetic field probe can operate normally; sensitivity refers to the probe's ability to couple magnetic field energy; and spatial resolution refers to the probe's ability to locate electromagnetic interference sources.

[0004] Based on their internal components, magnetic field probes can be divided into two types: passive probes and active probes. Patent document (CN105717466A) discloses a passive magnetic field probe structure. However, to achieve high spatial resolution performance with passive magnetic field probes, the probe size must be reduced, but reducing the size deteriorates the probe's sensitivity performance. The proposed active magnetic field probe structure effectively solves this problem. Journal article (IEEE Microwave and Wireless Components Letters: Design of Miniature Active Magnetic Probe for Near-Field Weak Signal Measurement in ICs) proposes an active magnetic field probe composed of four metal layers: a first signal layer, a first ground plane, a second signal layer, and a second ground plane, from top to bottom. The induced signal is transmitted from the second signal layer to the first signal layer through a vertical transition structure, i.e., a through-hole structure. As the frequency increases, the resonance phenomenon caused by the parasitic capacitance of the through-hole structure becomes increasingly apparent, deteriorating the probe's high-frequency response. A journal article (International Journal of RF and Microwave Computer-Aided Engineering: A miniature shielded-loop active H-field probe design with high spatial resolution for near-field measurement) proposed a similar active magnetic field probe composed of four metal layers. However, it also suffers from the problem of resonance caused by the parasitic capacitance of the vertical transition structure, which degrades the high-frequency response of the probe and limits the operating bandwidth of the active magnetic field probe.

[0005] Currently available passive magnetic field probes suffer from a contradiction between spatial resolution and sensitivity, while existing active magnetic field probes suffer from a limitation on the probe's operating bandwidth due to the vertical adapter structure. Summary of the Invention

[0006] The purpose of this invention is to provide an active magnetic field probe that can improve the sensitivity of the magnetic field probe and broaden its operating bandwidth.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] An active magnetic field probe, the active magnetic field probe comprising: a detection unit, a horizontal transition structure, and an active amplifier circuit;

[0009] The detector, horizontal adapter structure, and active amplifier circuit are cascaded in sequence.

[0010] The detection unit is used to induce and generate a transverse electromagnetic wave mode electromagnetic signal in the time-varying magnetic field of the device under test.

[0011] The horizontal transition structure is used to connect the stripline of the detection unit to the artificial surface plasmon of the active amplifier circuit, converting the electromagnetic signal from the transverse electromagnetic wave mode to the artificial surface plasmon mode.

[0012] The active amplifier circuit is used to amplify the electromagnetic signal of the artificial surface plasmon mode and then output it.

[0013] Optionally, the detection unit is a strip-shaped structure.

[0014] Optionally, the detection unit includes: a first upper outer conductor, an inner conductor, a first lower outer conductor, a first transmission conductor, and a shorting through hole;

[0015] The first upper outer conductor, inner conductor, and first lower outer conductor are arranged alternately in sequence;

[0016] The first upper outer conductor and the first lower outer conductor have the same shape; a groove is formed on the first upper outer conductor and the first lower outer conductor, which are in the shape of an open ring; the groove of the first upper outer conductor is set to correspond to the groove of the first lower outer conductor.

[0017] The shorting via is located between the first upper outer conductor and the first lower outer conductor. One end of the shorting via is connected to the first upper outer conductor, and the other end of the shorting via is connected to the first lower outer conductor.

[0018] The inner conductor is an open metal ring. The open metal ring, the groove of the first upper outer conductor, and the groove of the first lower outer conductor are all correspondingly provided. The opening direction of the open metal ring is different from the opening direction of the groove of the first upper outer conductor and the opening direction of the groove of the first lower outer conductor.

[0019] The short-circuit through hole is connected to one end of the open metal ring;

[0020] One end of the first transmission conductor is connected to the other end of the open metal ring, and the other end of the first transmission conductor is connected to the horizontal transition structure.

[0021] The inner conductor induces an electromagnetic signal in the transverse electromagnetic wave mode in the time-varying magnetic field of the device under test, and transmits it to the horizontal transition structure through the first transmission conductor.

[0022] Optionally, the probe further includes: a first dielectric substrate, a second dielectric substrate, and a plurality of shielding vias;

[0023] The first upper outer conductor and the inner conductor are connected through the first dielectric substrate, and the inner conductor and the first lower outer conductor are connected through the second dielectric substrate.

[0024] Each shielding via penetrates the first dielectric substrate and the second dielectric substrate; one end of each shielding via is connected to the first upper outer conductor, and the other end of each shielding via is connected to the first lower outer conductor; the shielding vias are arranged in two rows on both sides of the first transmission conductor and do not contact the first transmission conductor; the shielding vias are used to shield noise.

[0025] Optionally, the horizontal transition structure includes: a second upper outer conductor, a second lower outer conductor, a second transmission conductor, a third dielectric substrate, and a fourth dielectric substrate;

[0026] The second upper outer conductor, the second transmission conductor, and the second lower outer conductor are arranged alternately in sequence.

[0027] One end of the second transmission conductor is connected to the other end of the first transmission conductor, and the other end of the second transmission conductor is connected to the active amplifier circuit; the second upper outer conductor is connected to the first upper outer conductor, and the second lower outer conductor is connected to the first lower outer conductor.

[0028] The second transmission conductor gradually widens non-linearly from one end to the other; a tapered groove is formed on the second upper outer conductor, and the tapered groove gradually widens non-linearly along the direction of the widening of the second transmission conductor;

[0029] The second transmission conductor is used to ensure impedance matching between the stripline and the artificial surface plasmon, while the tapered slot is used to convert the electromagnetic signal from the transverse electromagnetic wave mode to the artificial surface plasmon mode, and transmit the electromagnetic signal of the artificial surface plasmon mode to the active amplifier circuit.

[0030] The second upper outer conductor and the second transmission conductor are connected through a third dielectric substrate, and the second transmission conductor and the second lower outer conductor are connected through a fourth dielectric substrate; the third dielectric substrate is connected to the first dielectric substrate, and the fourth dielectric substrate is connected to the second dielectric substrate.

[0031] Optionally, the active amplifier circuit includes: a DC power supply terminal, a low-noise amplifier, an input conductor, and an output conductor;

[0032] The DC power supply terminal is connected to the power supply ports of an external DC voltage source device and a low-noise amplifier, respectively. The DC power supply terminal is used to provide DC bias voltage for the low-noise amplifier.

[0033] One end of the input conductor is connected to the other end of the second transmission conductor, and the other end of the input conductor is connected to the signal input terminal of the low-noise amplifier; the input conductor is used to input the electromagnetic signal of the artificial surface plasmon mode to the low-noise amplifier;

[0034] The signal output terminal of the low-noise amplifier is connected to one end of the output conductor. The low-noise amplifier is used to amplify the electromagnetic signal of the artificial surface plasmon mode and output the amplified electromagnetic signal to an external receiver device via the output conductor. Optionally, the active amplifier circuit further includes: a noise reduction capacitor circuit, a third lower outer conductor, multiple grounding vias, and a fifth dielectric substrate;

[0035] The noise reduction capacitor circuit is located between the DC power supply terminal and the low noise amplifier. The noise reduction capacitor circuit is used to reduce the noise component of the DC bias voltage input to the DC power supply terminal and input the noise-reduced DC bias voltage to the low noise amplifier.

[0036] One end of the third lower outer conductor is connected to the second lower outer conductor;

[0037] One end of each of the multiple grounding vias is connected to a corresponding grounding terminal of the noise reduction capacitor circuit, and the other end of each of the multiple grounding vias is disposed on the third lower outer conductor; the grounding vias are used to provide a return path for the noise signal;

[0038] The noise reduction capacitor circuit is connected to the third lower layer outer conductor through the fifth dielectric substrate, and the fifth dielectric substrate is connected to the fourth dielectric substrate.

[0039] Optionally, the noise reduction capacitor circuit includes: three noise reduction capacitor groups;

[0040] The input terminal of each noise reduction capacitor bank is connected to the DC power supply terminal, and the output terminal of each noise reduction capacitor bank is connected to the three power supply ports of the low noise amplifier one by one.

[0041] Each noise reduction capacitor bank consists of three capacitors connected in parallel.

[0042] Optionally, the input conductor is provided with multiple rectangular teeth, which constitute an artificial surface plasmon. The artificial surface plasmon is used to enhance the transmission of electromagnetic signals in the artificial surface plasmon mode.

[0043] Optionally, the active magnetic field probe is based on a three-layer printed circuit board design and fabrication, wherein the three-layer printed circuit board consists of a bottom metal layer, a middle metal layer, and a top metal layer in sequence.

[0044] The first upper outer conductor and the second upper outer conductor are integrally formed based on the top metal layer;

[0045] The inner conductor, the first transmission conductor, the second transmission conductor, the input conductor, and the output conductor are integrally formed based on the intermediate metal layer; the DC power supply terminal, the low-noise amplifier, and the noise reduction capacitor circuit are all disposed on the intermediate metal layer;

[0046] The first lower outer conductor, the second lower outer conductor, and the third lower outer conductor are integrally formed based on the bottom metal layer.

[0047] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0048] This invention discloses an active magnetic field probe. After the detection unit senses the change in the magnetic field of the test object, it generates an electromagnetic signal. The horizontal transition structure realizes the smooth transition of the electromagnetic signal from the stripline to the artificial surface plasmon and the impedance matching between the two. The active amplifier circuit amplifies the electromagnetic signal, which greatly improves the sensitivity of the magnetic field probe.

[0049] In this invention, the inner conductor of the detection unit, the first transmission conductor, the second transmission conductor of the horizontal transition structure, and the input and output conductors of the active amplifier circuit are located in the same metal layer and are designed with shielded vias, which reduces the resonance interference caused by the via structure and widens the working bandwidth of the magnetic field probe. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the structure of the active magnetic field probe provided by the present invention;

[0052] Figure 2 This is a schematic diagram showing the relative positions of the dielectric substrate, outer conductor, and inner conductor provided by the present invention.

[0053] Figure 3 A schematic diagram of conductor layering provided by the present invention;

[0054] Figure 4 This is a schematic diagram of the dielectric substrate provided by the present invention;

[0055] Figure 5 This invention provides a schematic diagram of frequency characteristic simulation and test curves.

[0056] Figure 6 A schematic diagram illustrating the sensitivity performance test provided by this invention.

[0057] Symbol Explanation: 1a-First dielectric substrate, 1b-Second dielectric substrate, 1c-Third dielectric substrate, 1d-Fourth dielectric substrate, 1e-Fifth dielectric substrate, 2a-Upper outer conductor, 2b-Lower outer conductor, 3-Inner conductor, 4-Short-circuit via, 5-Shielding via, 6-Tapered slot, 7-DC power supply terminal, 8-Noise reduction capacitor, 9-Grounding via, 10-Low noise amplifier, 11-First transmission conductor, 12-Second transmission conductor, 13-Input conductor, 14-Output conductor. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] The purpose of this invention is to provide an active magnetic field probe that can improve the sensitivity of the magnetic field probe and broaden its operating bandwidth.

[0060] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] like Figure 1 As shown, this invention provides an active magnetic field probe, comprising: a detection unit, a horizontal transition structure, and an active amplifier circuit. The detection unit, the horizontal transition structure, and the active amplifier circuit are cascaded in sequence. The detection unit is used to induce and generate a transverse electromagnetic wave (TEM) mode electromagnetic signal in the time-varying magnetic field of the device under test. The horizontal transition structure is used to convert the electromagnetic signal from the TEM mode to an artificial surface plasmon mode. The active amplifier circuit is used to amplify the electromagnetic signal of the artificial surface plasmon mode before outputting it.

[0062] The following is combined with Figures 1 to 3 This section provides a detailed introduction to the various structures within an active magnetic field probe.

[0063] (I) Detection Department

[0064] The detection unit has a strip-shaped structure.

[0065] The detection unit includes: a first upper outer conductor, an inner conductor 3, a first lower outer conductor, a first transmission conductor 11, and a short-circuit hole 4. The first upper outer conductor, inner conductor 3, and first lower outer conductor are arranged sequentially at intervals. The first upper outer conductor and the first lower outer conductor have the same shape; each of the first upper and first lower outer conductors has a groove, forming an open ring shape; the groove of the first upper outer conductor corresponds to the groove of the first lower outer conductor. The short-circuit hole 4 is located between the first upper outer conductor and the first lower outer conductor, with one end connected to the first upper outer conductor and the other end connected to the first lower outer conductor. The inner conductor 3 is an open metal ring, and the open metal ring, the groove of the first upper outer conductor, and the groove of the first lower outer conductor are all correspondingly arranged, with the opening direction of the open metal ring being different from the opening direction of the groove of the first upper outer conductor and the opening direction of the groove of the first lower outer conductor. The short-circuit hole 4 is connected to one end of the open metal ring. One end of the first transmission conductor 11 is connected to the other end of the open metal ring, and the other end of the first transmission conductor 11 is connected to the horizontal transition structure. The inner conductor 3 induces an electromagnetic signal in TEM mode in the time-varying magnetic field of the device under test, and transmits it to the horizontal transition structure through the first transmission conductor 11.

[0066] Both the upper and lower outer conductors of the detector have openings with the same area. The inner conductor 3 of the open ring section of the detector is located outside the opening of the outer conductor, and the area enclosed by them is equal to the area of ​​the opening of the outer conductor. In addition, a short-circuit through-hole 4 is designed in the open ring section of the detector. The short-circuit through-hole 4 is located outside the opening of the outer conductor of the detector and passes through the lower outer conductor of the open ring section, the end of the inner conductor 3 of the open ring section, and the upper outer conductor of the open ring section from bottom to top, forming a closed loop in the open ring section.

[0067] The detection unit also includes: a first dielectric substrate 1a, a second dielectric substrate 1b, and a plurality of shielding vias 5.

[0068] The first upper outer conductor and the inner conductor are connected through a first dielectric substrate 1a, and the inner conductor and the first lower outer conductor are connected through a second dielectric substrate 1b. Each shielding via 5 penetrates through the first dielectric substrate 1a and the second dielectric substrate 1b. Multiple shielding vias 5 are disposed between the first upper outer conductor and the first lower outer conductor, with one end of each via 5 connected to the first upper outer conductor and the other end connected to the first lower outer conductor. The multiple shielding vias 5 are arranged in two rows on both sides of the first transmission conductor 11 and do not contact the first transmission conductor 11. Figure 3 As shown, the shielding through-holes 5 are evenly placed on the left and right sides of the transmission section of the detection unit. The function of the shielding through-holes 5 is to reduce external interference to signal transmission. For example, the spacing between adjacent shielding through-holes 5 is less than λ / 10.

[0069] The first dielectric substrate 1a is rectangular in shape, and the outer edge shape of the first dielectric substrate 1a is the same as that of the first upper outer conductor. That is, the first upper outer conductor has an open ring, but the first dielectric substrate 1a does not have an open ring. The second dielectric substrate 1b has the same shape as the first dielectric substrate 1a.

[0070] Figure 2 The diagram shows the relative positions of a dielectric substrate, two outer conductors and an inner conductor 3. The relative positions of the dielectric substrate, the two outer conductors and the inner conductor 3 are not limited to... Figure 2 The positional relationships and dimensions are shown. The total thickness of the first dielectric substrate 1a located above the inner conductor 3 is h1, the total thickness of the second dielectric substrate 1b located below the inner conductor 3 is h1, and the thickness of the metal layer of both the outer conductor and the inner conductor 3 is t.

[0071] (II) Horizontal transition structure

[0072] The horizontal transition structure includes: a second upper outer conductor, a second lower outer conductor, a second transmission conductor 12, a third dielectric substrate 1c, and a fourth dielectric substrate 1d.

[0073] The second upper outer conductor, the second transmission conductor 12, and the second lower outer conductor are arranged alternately. One end of the second transmission conductor 12 is connected to the other end of the first transmission conductor 11, and the other end of the second transmission conductor 12 is connected to the active amplifier circuit; the second upper outer conductor is connected to the first upper outer conductor, and the second lower outer conductor is connected to the first lower outer conductor. The second transmission conductor 12 gradually widens non-linearly from one end to the other; a tapered groove 6 is formed on the second upper outer conductor, and the tapered groove 6 gradually widens non-linearly along the direction of the widening of the second transmission conductor 12.

[0074] Reference Figure 4 The second upper outer conductor and the second transmission conductor are connected through the third dielectric substrate 1c, and the second transmission conductor and the second lower outer conductor are connected through the fourth dielectric substrate 1d; the third dielectric substrate 1c is connected to the first dielectric substrate 1a, and the fourth dielectric substrate 1d is connected to the second dielectric substrate 1b.

[0075] The third dielectric substrate 1c is rectangular in shape, and its outer edge shape is the same as that of the second upper outer conductor. That is, the second upper outer conductor has a non-linearly widening gap, but the third dielectric substrate 1c does not have a non-linearly widening gap. The fourth dielectric substrate 1d has the same shape as the third dielectric substrate 1c.

[0076] The upper outer conductor of the horizontal transition section is designed with a non-linearly tapered gap for transitioning from TEM mode to artificial surface plasmon mode. The second transmission conductor 12 is configured with a non-linearly tapered shape to ensure impedance matching between the stripline and the artificial surface plasmon.

[0077] (III) Active Amplifier Circuit

[0078] The active amplifier circuit includes: a DC power supply terminal 7, a low-noise amplifier 10, an input conductor 13, and an output conductor 14.

[0079] The DC power supply terminal 7 is connected to both an external DC voltage source and the power supply port of the low-noise amplifier 10, providing a DC bias voltage to the low-noise amplifier 10. One end of the input conductor 13 is connected to the other end of the second transmission conductor 12, and the other end of the input conductor 13 is connected to the signal input terminal of the low-noise amplifier 10; the input conductor 13 is used to input the electromagnetic signal of the artificial surface plasmon mode to the low-noise amplifier 10. The signal output terminal of the low-noise amplifier 10 is connected to one end of the output conductor 14, amplifying the electromagnetic signal of the artificial surface plasmon mode and outputting the amplified electromagnetic signal through the output conductor 14.

[0080] The low-noise amplifier 10 is an active integrated low-noise amplifier module, designed using a microstrip structure rather than a three-layer printed circuit board. This integrated low-noise amplifier features wide bandwidth and miniaturization. The function of the low-noise amplifier 10 is to amplify the energy of the induced electromagnetic signal, thereby improving the sensitivity of the probe.

[0081] Reference Figure 1 The active amplifier circuit also includes: a noise reduction capacitor circuit, a third lower outer conductor, multiple grounding vias 9 and a fifth dielectric substrate 1e.

[0082] A noise reduction capacitor circuit is disposed between the DC power supply terminal 7 and the low-noise amplifier 10. This circuit reduces the noise component of the DC bias voltage input to the DC power supply terminal 7 and inputs the denoised DC bias voltage to the low-noise amplifier 10. One end of the third lower outer conductor is connected to the second lower outer conductor. One end of each of the multiple grounding vias 9 is connected to a corresponding grounding terminal of the noise reduction capacitor circuit, and the other ends of the multiple grounding vias 9 are disposed on the third lower outer conductor. The grounding vias 9 provide a return path for the noise signal. The noise reduction capacitor circuit and the third lower outer conductor are connected through a fifth dielectric substrate 1e, which is connected to a fourth dielectric substrate 1d. The shape of the fifth dielectric substrate 1e is the same as that of the third lower outer conductor.

[0083] For example, the noise reduction capacitor circuit includes three noise reduction capacitor groups. The input terminal of each noise reduction capacitor group is connected to the DC power supply terminal 7, and the output terminal of each noise reduction capacitor group is connected to the three power supply ports of the low noise amplifier 10 in a corresponding manner. Each noise reduction capacitor group consists of three capacitors connected in parallel (noise reduction capacitors 8).

[0084] like Figure 3 As shown, multiple rectangular teeth are provided on the input conductor 13. These multiple rectangular teeth constitute an artificial surface plasmon, which is used to enhance the transmission of electromagnetic signals in the artificial surface plasmon mode.

[0085] Figure 3 This is a schematic diagram of the conductor layers in an active magnetic field probe, from left to right: upper outer conductor, inner conductor layer, and lower outer conductor. In the active magnetic field probe structure provided by this invention, the height of the opening ring portion of the detection section is 'a'; the width is 'b'; the height of the slit is 'c'; and the width is 'd'. These dimensions should be designed to be as small as possible under manufacturing conditions to minimize errors. In the active amplifier circuit section, the capacitance values ​​of the noise reduction capacitors are c1, c2, c3, c4, c5, c6, c7, c8, and c9.

[0086] The active magnetic field probe is designed and fabricated based on a three-layer printed circuit board, consisting of a bottom metal layer, a middle metal layer, and a top metal layer. The first and second upper outer conductors are integrally formed on the top metal layer, constituting the upper outer conductor 2a. The inner conductor 3, the first transmission conductor 11, the second transmission conductor 12, the input conductor 13, and the output conductor 14 are integrally formed on the middle metal layer; the DC power supply terminal 7, the low-noise amplifier 10, and the noise reduction capacitor circuit are all located on the middle metal layer. The first, second, and third lower outer conductors are integrally formed on the bottom metal layer, constituting the lower outer conductor 2b.

[0087] The first dielectric substrate 1a and the third dielectric substrate 1c are integrally formed, and the second dielectric substrate 1b, the fourth dielectric substrate 1d and the fifth dielectric substrate 1e are integrally formed.

[0088] The entire working process of the active magnetic field probe of the present invention is as follows: the detection unit is placed above the device under test, and the detection unit is a single metal ring with its end grounded. After sensing the change in the magnetic field of the device under test, it generates an electromagnetic signal. Since the short-circuit hole 4 in the detection unit connects the upper outer conductor, the lower outer conductor, and the inner conductor 3, forming a loop, an induced signal is generated on the inner conductor. The induced signal is transmitted backward from the inner conductor, flowing through the first transmission conductor 11 to the second transmission conductor 12. After reaching the second transmission conductor 12, since the signal exists inside the upper and lower outer conductors, the induced signal that is ultimately to be measured needs to be transmitted to the surface. Traditionally, a vertical transition structure, i.e., a through-hole structure, is used to transmit the internal induced signal to the surface. However, this method generates resonance, which is more pronounced at high frequencies, limiting the probe's operating bandwidth. This invention introduces a horizontal transition structure. Through a conical groove 6 on the horizontal transition structure, the induced signal is converted from a stripline structure to an artificial surface plasmon structure. As a result, the active amplifier circuit no longer needs an upper outer conductor and an upper dielectric substrate; only a lower outer conductor and a lower dielectric substrate are used. Therefore, the induced signal in the artificial surface plasmon mode passes through the input conductor 13, is amplified by the low-noise amplifier 10, and is output from the output conductor 14.

[0089] In this embodiment, a microstrip line is used as the device under test (DUT) to test the performance of the magnetic field probe, and a vector network analyzer is used as the receiving device to receive the output signal. One end of the microstrip line is connected to Port 1 of the vector network analyzer, and the other end is connected to a matching load; the output end (output conductor 14) of the magnetic field probe is connected to Port 2 of the vector network analyzer. When measuring the microstrip line using the active magnetic field probe of this invention, the openings of the grooves in the upper and lower outer conductors of the probe are placed above the microstrip line, and the plane of the openings is perpendicular to the magnetic field direction of the microstrip line.

[0090] Figure 5 The simulation and test curves of the frequency characteristics of the active magnetic field probe are shown. The results indicate that the bandwidth of the active magnetic field probe is 16 GHz to 43.5 GHz. The low-frequency and high-frequency nonlinearities of the low-noise amplifier 10 limit the probe's bandwidth. 21 The magnetic field strength detected by the corresponding magnetic field probe.

[0091] Figure 6 This is a performance test graph showing the sensitivity of an active magnetic field probe. Sensitivity is defined as the minimum excitation signal energy that the probe can couple to when it is positioned directly above a microstrip line. The results show that the sensitivities of the reference magnetic field probe (without active amplifier circuit design) and the active magnetic field probe are approximately -70 dBm and -90 dBm, respectively. Compared to the reference magnetic field probe (without active amplifier circuit design), the active magnetic field probe exhibits a 20 dB increase in sensitivity. Figure 6The horizontal axis, Frequency, represents frequency, and the vertical axis, Sensitivity, represents sensitivity.

[0092] The inner conductor 3 of the detection unit and the conductor of the active amplifier circuit are located in the same metal layer and are designed with shielded vias 5, which reduces the resonance interference caused by the via structure and widens the operating bandwidth of the magnetic field probe. The active amplifier circuit introduces a low-noise amplifier 10, which improves the sensitivity of the magnetic field probe. The structural implementation scheme of each part of the magnetic field probe is simple, making it easy for engineers and R&D personnel to master the design scheme of the magnetic field probe in this invention. At the same time, it is low in cost and easy to promote and apply in engineering.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0094] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An active magnetic field probe, characterized in that, The active magnetic field probe includes: a detection unit, a horizontal transition structure, and an active amplifier circuit; The detector, horizontal adapter structure, and active amplifier circuit are cascaded in sequence. The detection unit is used to induce electromagnetic signals in the transverse electromagnetic wave mode in the time-varying magnetic field of the device under test. The horizontal transition structure is used to connect the stripline of the detection unit to the artificial surface plasmon of the active amplifier circuit, converting the electromagnetic signal from the transverse electromagnetic wave mode to the artificial surface plasmon mode. The active amplifier circuit is used to amplify the electromagnetic signal of the artificial surface plasmon mode and then output it. The detection unit includes: a first upper outer conductor, an inner conductor, a first lower outer conductor, a first transmission conductor, and a short-circuit through-hole; The first upper outer conductor, inner conductor, and first lower outer conductor are arranged alternately in sequence; The first upper outer conductor and the first lower outer conductor have the same shape; a groove is formed on the first upper outer conductor and the first lower outer conductor, which are in the shape of an open ring; the groove of the first upper outer conductor is set to correspond to the groove of the first lower outer conductor. The shorting via is located between the first upper outer conductor and the first lower outer conductor. One end of the shorting via is connected to the first upper outer conductor, and the other end of the shorting via is connected to the first lower outer conductor. The inner conductor is an open metal ring. The open metal ring, the groove of the first upper outer conductor, and the groove of the first lower outer conductor are all correspondingly provided. The opening direction of the open metal ring is different from the opening direction of the groove of the first upper outer conductor and the opening direction of the groove of the first lower outer conductor. The short-circuit through hole is connected to one end of the open metal ring; One end of the first transmission conductor is connected to the other end of the open metal ring, and the other end of the first transmission conductor is connected to the horizontal transition structure. The inner conductor induces an electromagnetic signal in the transverse electromagnetic wave mode in the time-varying magnetic field of the device under test, and transmits it to the horizontal transition structure through the first transmission conductor. The detection unit further includes: a first dielectric substrate, a second dielectric substrate, and a plurality of shielding vias; The first upper outer conductor and the inner conductor are connected through the first dielectric substrate, and the inner conductor and the first lower outer conductor are connected through the second dielectric substrate. Each shielding via penetrates the first dielectric substrate and the second dielectric substrate; one end of each shielding via is connected to the first upper outer conductor, and the other end of each shielding via is connected to the first lower outer conductor; the shielding vias are arranged in two rows on both sides of the first transmission conductor and do not contact the first transmission conductor; the shielding vias are used to shield noise. The horizontal transition structure includes: a second upper outer conductor, a second lower outer conductor, a second transmission conductor, a third dielectric substrate, and a fourth dielectric substrate; The second upper outer conductor, the second transmission conductor, and the second lower outer conductor are arranged alternately in sequence. One end of the second transmission conductor is connected to the other end of the first transmission conductor, and the other end of the second transmission conductor is connected to the active amplifier circuit; the second upper outer conductor is connected to the first upper outer conductor, and the second lower outer conductor is connected to the first lower outer conductor. The second transmission conductor gradually widens non-linearly from one end to the other; a tapered groove is formed on the second upper outer conductor, and the tapered groove gradually widens non-linearly along the direction of the widening of the second transmission conductor; The second transmission conductor is used to ensure impedance matching between the stripline and the artificial surface plasmon, while the tapered slot is used to convert the electromagnetic signal from the transverse electromagnetic wave mode to the artificial surface plasmon mode, and transmit the electromagnetic signal of the artificial surface plasmon mode to the active amplifier circuit. The second upper outer conductor and the second transmission conductor are connected through a third dielectric substrate, and the second transmission conductor and the second lower outer conductor are connected through a fourth dielectric substrate; the third dielectric substrate is connected to the first dielectric substrate, and the fourth dielectric substrate is connected to the second dielectric substrate.

2. The active magnetic field probe according to claim 1, characterized in that, The detection unit has a strip-shaped structure.

3. The active magnetic field probe according to claim 1, characterized in that, The active amplifier circuit includes: a DC power supply terminal, a low-noise amplifier, an input conductor, and an output conductor; The DC power supply terminal is connected to the power supply ports of an external DC voltage source device and a low-noise amplifier, respectively. The DC power supply terminal is used to provide DC bias voltage for the low-noise amplifier. One end of the input conductor is connected to the other end of the second transmission conductor, and the other end of the input conductor is connected to the signal input terminal of the low-noise amplifier; the input conductor is used to input the electromagnetic signal of the artificial surface plasmon mode to the low-noise amplifier; The signal output terminal of the low-noise amplifier is connected to one end of the output conductor. The low-noise amplifier is used to amplify the electromagnetic signal of the artificial surface plasmon mode and output the amplified electromagnetic signal to an external receiver device via the output conductor.

4. The active magnetic field probe according to claim 3, characterized in that, The active amplifier circuit also includes: a noise reduction capacitor circuit, a third lower outer conductor, multiple grounding vias, and a fifth dielectric substrate; The noise reduction capacitor circuit is located between the DC power supply terminal and the low noise amplifier. The noise reduction capacitor circuit is used to reduce the noise component of the DC bias voltage input to the DC power supply terminal and input the noise-reduced DC bias voltage to the low noise amplifier. One end of the third lower outer conductor is connected to the second lower outer conductor; One end of each of the multiple grounding vias is connected to a corresponding grounding terminal of the noise reduction capacitor circuit, and the other end of each of the multiple grounding vias is disposed on the third lower outer conductor; the grounding vias are used to provide a return path for the noise signal; The noise reduction capacitor circuit is connected to the third lower layer outer conductor through the fifth dielectric substrate, and the fifth dielectric substrate is connected to the fourth dielectric substrate.

5. The active magnetic field probe according to claim 4, characterized in that, The noise reduction capacitor circuit includes: three noise reduction capacitor groups; The input terminal of each noise reduction capacitor bank is connected to the DC power supply terminal, and the output terminal of each noise reduction capacitor bank is connected to the three power supply ports of the low noise amplifier one by one. Each noise reduction capacitor bank consists of three capacitors connected in parallel.

6. The active magnetic field probe according to claim 3, characterized in that, The input conductor is provided with multiple rectangular teeth, which constitute an artificial surface plasmon. The artificial surface plasmon is used to enhance the transmission of electromagnetic signals in the artificial surface plasmon mode.

7. The active magnetic field probe according to claim 4, characterized in that, The active magnetic field probe is designed and manufactured based on a three-layer printed circuit board, which consists of a bottom metal layer, a middle metal layer, and a top metal layer. The first upper outer conductor and the second upper outer conductor are integrally formed based on the top metal layer; The inner conductor, the first transmission conductor, the second transmission conductor, the input conductor, and the output conductor are integrally formed based on the intermediate metal layer; the DC power supply terminal, the low-noise amplifier, and the noise reduction capacitor circuit are all disposed on the intermediate metal layer; The first lower outer conductor, the second lower outer conductor, and the third lower outer conductor are integrally formed based on the bottom metal layer.

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