A lightning broadband magnetic field signal detection antenna system

Abstract

The present application discloses a lightning broadband magnetic field signal detection antenna system, including a magnetic antenna and an amplifying circuit connected to the magnetic antenna; the magnetic antenna includes two vertically cross-distributed magnetic rings, and the magnetic rings are cross-arranged with the center line of the plane as the axis. The present application utilizes the unique magnetic field change rate (dB / dt) measurement characteristics of the magnetic ring antenna itself to control the cutoff frequency of the high-frequency end in the frequency band, and through the amplifying circuit, the entire frequency band always maintains the dB / dt gain characteristics, so that the signal at the high-frequency end can obtain a gain of more than 20dB, effectively ensuring the measurement of high-frequency pulse signals, so that the low-frequency positioning system can obtain more high-frequency radiation source positioning information, further enriching the applicable scenarios of the low-frequency positioning system.

Description

Technical Field

[0001] The invention relates to an antenna system, in particular to a lightning broadband magnetic field signal detection antenna system. Background Art

[0002] Lightning signals have a very wide radiation band, but they have extremely strong energy in the low frequency band (generally 30 kHz - 100 kHz), which can propagate thousands of kilometers on the surface of the earth. Therefore, low-frequency signals have become one of the most widely used frequency bands for long-distance measurement and positioning of lightning. Recently, with the development of technology, low-frequency electromagnetic signals have gradually been applied to the construction of local three-dimensional lightning positioning networks. The system sets up more than 5 electromagnetic measurement stations working in the low frequency band (30 kHz-300kHz) and time synchronization, and uses the time difference positioning algorithm to obtain the three-dimensional position of the lightning radiation source.

[0003] At present, most of the three-dimensional positioning systems in China use vertical electric field sensor systems. This system mainly measures the vertical electric field change characteristics of the radiation source during the lightning discharge process. This system can directly obtain the discharge polarity of the radiation source in the discharge process located, and the circuit design often controls the attenuation speed of the detected signal by adding an integral circuit with different time constants. Most electric antennas used in positioning systems have an integration time of several to more than ten milliseconds, which makes the working frequency band have an almost fixed gain characteristic. Similar to ordinary electric antennas, a few three-dimensional positioning systems that use horizontal magnetic field sensors often use magnetic field antennas to design circuits (control the size of the chopper resistor or add an integral circuit) to make the system working frequency band (3dB bandwidth) have a fixed gain band characteristic, so that the system has a gain change characteristic that is approximately consistent over a wider frequency band, which is the so-called B antenna or integral antenna (V = n*B).

[0004] According to previous measurements of lightning electromagnetic signal spectrum, the electromagnetic signal radiated by lightning has extremely strong energy in the low frequency band, and in a wider low frequency band, the spectrum of the electromagnetic wave signal generated by the discharge has the characteristic of decreasing with increasing frequency (1 / f). The specific change curve is as follows: Figure 1As shown. Therefore, the low-frequency broadband measurement system of electric and magnetic fields with consistent frequency band characteristics currently used will cause the signal strength attenuation of more than 20dB at the high-frequency end of the measurement signal within its frequency band to be lower than that at the low-frequency end. As a result, the entire measurement system generally has a strong detection capability in the low-frequency band of 30kHz, while the detection capability is relatively weakened in slightly higher frequency bands, such as 100-300kHz. This strong low-frequency signal and relatively weak high-frequency signal will cause: 1) the number of signal pulses is reduced, and the number of events that can be used for positioning in a single lightning process is reduced, and 2) the time resolution of the signal is reduced. Therefore, the low-frequency antenna with overall frequency band gain limits its application in the positioning system to a certain extent, which may cause: 1) fewer radiation sources are located in a single lightning process; 2) the positioning accuracy is low; and because the discharge process in the cloud has a relatively small spatial scale and a high radiation frequency, this type of detection antenna will also lead to weak cloud flash positioning capability. Summary of the invention

[0005] The purpose of the present application is to provide a lightning broadband magnetic field signal detection antenna system to solve the problem of low positioning accuracy or small number of positioning radiation sources caused by weak high-frequency signals during lightning broadband signal measurement.

[0006] The present application provides a lightning broadband magnetic field signal detection antenna system, which adopts the following technical solutions:

[0007] A lightning broadband magnetic field signal detection antenna system comprises a magnetic antenna and an amplifying circuit connected to the magnetic antenna; the magnetic antenna comprises two vertically cross-distributed magnetic rings, and the magnetic rings are cross-arranged with the center line of the plane where they are located as the axis.

[0008] Through the above technical solution, the unique magnetic field change rate (dB / dt) measurement characteristics of the magnetic loop antenna are utilized to control the cutoff frequency of the high-frequency end in the frequency band, and through the amplification circuit, the dB / dt gain characteristics of the entire frequency band are always maintained. In this way, the signal at the high-frequency end can obtain a gain of more than 20dB, effectively ensuring the measurement of high-frequency pulse signals, so that the low-frequency positioning system can obtain more high-frequency radiation source positioning information.

[0009] Optionally, the magnetic ring is composed of multiple turns of single-layer enameled wire.

[0010] Through the above technical solution, by making the magnetic ring with multiple turns of single-layer enameled wire, it is easy to control various parameters of the magnetic ring antenna, and select appropriate shape and parameters to control the cutoff frequency of the high-frequency end.

[0011] Optionally, the magnetic antenna includes two annular frames arranged vertically and crosswise, and multiple turns of single-layer enameled wire are wound around each annular frame.

[0012] Through the above technical solution, by providing an annular frame and winding multiple turns of single-layer enameled wire on the annular frame, the positions of the two magnetic ring antennas can be ensured to be stable and secure.

[0013] Optionally, a groove is provided on the annular frame, and the multiple turns of single-layer enameled wire are wound in the groove.

[0014] Through the above technical solution, by winding multiple turns of single-layer enameled wire in the groove, it can be ensured that the enameled wire can be stably set on the annular frame, and the enameled wire can be prevented from slipping off the annular frame when in use.

[0015] Optionally, the annular frame adopts a circular frame, and a groove concentrically arranged with the circular frame is arranged on the outer circumferential surface of the circular frame, and the two circular frames constitute a spherical frame.

[0016] Through the above technical solution, by adopting a circular frame, a groove concentrically arranged with the circular frame is arranged on the outer circumferential surface of the circular frame, and by winding multiple turns of enameled wire on the groove on the circular frame, the magnetic ring on the circular frame can be arranged.

[0017] Optionally, the spherical frame includes an upper hemisphere and a lower hemisphere, and the lower hemisphere and the upper hemisphere are fixed by a supporting connecting frame.

[0018] Through the above technical solution, the spherical frame is arranged into an upper hemisphere and a lower hemisphere, and the lower hemisphere and the upper hemisphere are fixed by a supporting connecting frame, which not only facilitates the production and installation of the spherical frame, but also ensures the strength and reliability of the spherical frame, thereby ensuring the vertical angle and shaping between the two magnetic rings.

[0019] Optionally, the diameters of the two magnetic rings are both 248 mm, and each magnetic ring is provided with 32 turns of single-layer enameled wire tightly arranged on the magnetic ring in each direction, and the diameter of the enameled wire is 0.41 mm.

[0020] Through the above technical solution and this parameter, the antenna design makes the low-frequency end and the high-frequency band have a gain difference of 100 times, so the amplification factor of the high-frequency end signal is significantly improved, so that the high-frequency end components that have a greater effect on positioning accuracy and quantity, the measurement system obtains more high-frequency components.

[0021] Optionally, the amplifier circuit includes a first amplifier circuit and a second amplifier circuit, wherein the signal input end of the first amplifier circuit is connected to one of the magnetic ring signals, and the signal input end of the second amplifier circuit is connected to the other magnetic ring signal; the first amplifier circuit includes a chopper resonance adjustment circuit, a high-pass filter amplifier circuit, a low-pass filter amplifier circuit, a matching circuit and a power supply circuit; the signal of the magnetic ring is connected to the chopper resonance adjustment circuit, the output end of the chopper resonance adjustment circuit is connected to the input end of the high-pass filter amplifier circuit, the output end of the high-pass filter amplifier circuit is connected to the input end of the low-pass filter amplifier circuit, and the output end of the low-pass filter amplifier circuit is connected to the input end of the matching circuit; the power supply circuit supplies power to the chopper resonance adjustment circuit, the high-pass filter amplifier circuit, the low-pass filter amplifier circuit and the matching circuit; the second amplifier circuit has the same structure as the first amplifier circuit.

[0022] Through the above technical solution, the first amplifier circuit is connected to the signal of one magnetic ring, and the second amplifier circuit is connected to the signal of the other magnetic ring, so that the signals of the two magnetic rings can be chopped, high-pass filtered and amplified, low-pass filtered and amplified, etc. respectively, so that the low-frequency and high-frequency ends in the frequency band have relatively consistent gain characteristics, so that the bandwidth of the entire detection system has a frequency band characteristic consistent with the magnetic field change rate measured by the magnetic ring antenna.

[0023] In summary, the present application includes at least one of the following beneficial technical effects:

[0024] 1. This application utilizes the unique magnetic field change rate (dB / dt) measurement characteristics of the magnetic loop antenna to control the cutoff frequency at the high-frequency end of the frequency band, and through the amplification circuit, the entire frequency band is always kept at the dB / dt gain characteristics, so that the signal at the high-frequency end can obtain a gain of more than 20dB, effectively ensuring the measurement of high-frequency pulse signals, so that the low-frequency positioning system can obtain more high-frequency radiation source positioning information.

[0025] 2. The present application forms a magnetic loop antenna by winding multiple turns of single-layer enameled wire in a groove, which facilitates the control of various parameters of the magnetic loop antenna and the selection of appropriate shape and parameters to control the cut-off frequency of the high-frequency end; and can ensure that the enameled wire can be stably set on the annular frame, can prevent the enameled wire from slipping off the annular frame during use, and can ensure the stability of the magnetic loop antenna.

[0026] 3. This application sets the parameters of the two magnetic rings to a diameter of 248mm, and each magnetic ring is provided with 32 turns of single-layer enameled wire tightly arranged on the magnetic ring in each direction, and the diameter of the enameled wire is 0.41mm; this antenna design makes the low-frequency end and the high-frequency band have a gain difference of 100 times, so the amplification factor of the high-frequency end signal is significantly improved, so that the high-frequency end components that have a greater effect on positioning accuracy and quantity, the measurement system obtains more high-frequency components. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the characteristic spectrum diagram of the electromagnetic wave signal of the natural lightning discharge process;

[0028] Figure 2 This is a schematic diagram of the structure of the lightning broadband magnetic field signal detection antenna of the present application;

[0029] Figure 3 It is a structural schematic diagram of the frame of the lightning broadband magnetic field signal detection antenna of the present application;

[0030] Figure 4 is a schematic diagram of the structure of the amplifier circuit of an embodiment of the present application;

[0031] Figure 5 It is a spectrum characteristic diagram of electromagnetic wave signals generated by lightning discharge process recorded by electromagnetic measurement equipment with different frequency band characteristics;

[0032] Figure 6 Figure 2. Lightning signal recorded by two electromagnetic measurement systems with different spectral characteristics.

[0033] Figure 7 It is the overall frequency band curve of the antenna and amplifier circuit.

[0034] Description of reference numerals:

[0035] 1. First annular frame; 2. Second annular frame; 3. Support connecting frame; 4. First magnetic ring; 5. Second magnetic ring; 6. Chopper resonance adjustment circuit; 7. High-pass filter amplifier circuit; 8. Low-pass filter amplifier circuit; 9. Matching circuit; 10. Power supply circuit; 11. Base; 12. Mounting hole; 101. First groove; 201. Second groove. DETAILED DESCRIPTION

[0036] The following is combined with Figure 2-7 This application is described in further detail.

[0037] Reference Figure 2 and Figure 3 The present embodiment discloses a lightning broadband magnetic field signal detection antenna system, including a magnetic antenna and an amplifying circuit connected to the magnetic antenna; the magnetic antenna includes an antenna frame, the antenna frame includes a first annular frame 1 and a second annular frame 2, the first annular frame 1 and the second annular frame 2 are both circular frames, the first annular frame 1 and the second annular frame 2 are vertically cross-distributed with the center line of the plane as the axis, so that the first annular frame 1 and the second annular frame 2 constitute a spherical frame.

[0038] The first annular frame 1 and the second annular frame 2 are also connected by a supporting connecting frame 3. The first annular frame 1 and the second annular frame 2 are generated by 3D printing of ABS engineering plastic. In the specific production process, the upper hemisphere and the lower hemisphere are combined. The upper hemisphere and the lower hemisphere are 3D printed respectively, and then spliced ​​into a complete spherical frame. The joint between the upper hemisphere and the lower hemisphere is fixed with plastic screws and nuts. A base 11 is provided at the lower part of the lower hemisphere, and a mounting hole 12 is provided on the base 11 for fixing and installing the antenna.

[0039] A first groove 1011 is provided on the outer circumferential surface of the first annular frame 1, and the first groove 1011 is arranged concentrically with the first annular frame 1. Multiple turns of single-layer enameled wire are wound in the first groove 101 to form a first magnetic ring 4. A second groove 201 is provided on the outer circumferential surface of the second annular frame 2, and the second groove 201 is arranged concentrically with the second annular frame 2. Multiple turns of single-layer enameled wire are wound in the second groove 201 to form a second magnetic ring 5. The second magnetic ring 5 and the first magnetic ring 4 are intersected and distributed perpendicularly with the center line of the plane where they are located as the axis.

[0040] When the antenna is erected, the two vertical cross rings are oriented in the east-west and north-south directions according to the magnetic field orientation, and are used to measure the magnetic field change rate signals from the east-west and north-south directions respectively.

[0041] According to Faraday's law of electromagnetic induction, the voltage generated at both ends of the magnetic loop due to the change in the magnetic field passing through the magnetic loop is:

[0042] (1)

[0043] Where N is the number of turns of the coil, A is the area of ​​the ring, is the magnetic flux, B is the magnetic induction intensity, is the signal output voltage at both ends of the coil.

[0044] Reference Figure 4 The two ends of the enameled wire of the first magnetic ring 4 are respectively connected to the first amplifier circuit, and the signal of the first magnetic ring 4 is sent to the first amplifier circuit for processing; the two ends of the enameled wire of the second magnetic ring 5 are respectively connected to the second amplifier circuit, and the signal of the second magnetic ring 5 is sent to the second amplifier circuit for processing.

[0045] The first amplifier circuit includes a chopper resonance adjustment circuit 6 , a high-pass filter amplifier circuit 7 , a low-pass filter amplifier circuit 8 , a matching circuit 9 and a power supply circuit 10 .

[0046] The output end of the chopper resonance adjustment circuit 6 is connected to the input end of the high-pass filter amplifier circuit 7, the output end of the high-pass filter amplifier circuit 7 is connected to the input end of the low-pass filter amplifier circuit 8, and the output end of the low-pass filter amplifier circuit 8 is connected to the input end of the matching circuit 9. The chopper resonance adjustment circuit 6 performs initial adjustment on the signal band of the first magnetic ring 4 to remove the resonance of the signal of the first magnetic ring 4. The high-pass filter amplifier circuit 7 performs high-pass filtering on the output signal of the chopper resonance adjustment circuit 6, removes the power frequency and its resonance frequency noise, and amplifies the signal. The low-pass filter amplifier circuit 8 performs low-pass filtering on the output signal of the high-pass filter amplifier circuit 7, removes the high-frequency noise and amplifies the signal. The matching circuit 9 performs geometric amplification on the output of the low-pass filter amplifier circuit 8 and adjusts it to an output end that matches the impedance of the long transmission line. The power supply circuit 10 supplies power to the chopper resonance adjustment circuit 6, the high-pass filter amplifier circuit 7, the low-pass filter amplifier circuit 8, and the matching circuit 9; the second amplifier circuit has the same structure as the first amplifier circuit.

[0047] The chopper resonance adjustment circuit 6 includes an instrument amplifier U1, the model of the instrument amplifier U1 is AD8429, the -IN and +IN ports of the instrument amplifier U1 are respectively connected to the two ends of the enameled wire of the first magnetic ring 4, the -IN and +IN ports of the instrument amplifier U1 are respectively connected to the two ends of the capacitor C6, the -IN and +IN ports of the instrument amplifier U1 are respectively connected to the two ends of the resistor R17, the -IN port of the instrument amplifier U1 is grounded through the resistor R1, the +IN port of the instrument amplifier U1 is grounded through the resistor R2, and the two RG ports of the instrument amplifier U1 are respectively connected to the two ends of the resistor R3. The +VS port of the instrument amplifier U1 is connected to the +VCCO port of the power supply circuit, the -VS port of the instrument amplifier U1 is connected to the -VCCO port of the power supply circuit, the REF port of the instrument amplifier U1 is grounded, and the VOUT port of the instrument amplifier U1 is connected to the high-pass filter amplifier circuit 7.

[0048] The high-pass filter amplifier circuit 7 includes an operational amplifier U2, the model of which is ADA4898. The +IN port of the operational amplifier U2 is connected to the VOUT port of the instrument amplifier U1 through a capacitor C3 to receive the output signal of the chopper resonance adjustment circuit 6, and the +IN port of the operational amplifier U2 is also grounded through a resistor R4. The +VS port of the operational amplifier U2 is connected to the +VCCO port of the power supply circuit, the -VS port of the operational amplifier U2 is connected to the -VCCO port of the power supply circuit, and the -IN port of the operational amplifier U2 is grounded through a resistor R5. The VOUT port of the operational amplifier U2 is connected to the low-pass filter amplifier circuit 8, and the VOUT port of the operational amplifier U2 is also grounded through resistors R6 and R5.

[0049] The low-pass filter amplifier circuit includes an operational amplifier U8 and an operational amplifier U7, wherein the +IN port of the operational amplifier U8 is connected to the VOUT port of the operational amplifier U2 through resistors R16 and R15, and receives the output signal of the high-pass filter amplifier circuit 7, and the +IN port of the operational amplifier U8 is also grounded through capacitor C8. The +VS port of the operational amplifier U8 is connected to the +VCCO port of the power supply circuit, and the -VS port of the operational amplifier U8 is connected to the -VCCO port of the power supply circuit. The -IN port of the operational amplifier U8 is connected to the VOUT port of the operational amplifier U2 through capacitor C9 and resistor R15, and the -IN port of the operational amplifier U8 is also connected to the VOUT port of the operational amplifier U8.

[0050] The VOUT port of the operational amplifier U8 is connected to the +IN port of the operational amplifier U7 through the resistor R19 and the resistor R20, and the +IN port of the operational amplifier U7 is also grounded through the capacitor C10. The +VS port of the operational amplifier U7 is connected to the +VCCO port of the power supply circuit, and the -VS port of the operational amplifier U7 is connected to the -VCCO port of the power supply circuit. The -IN port of the operational amplifier U7 is connected to the VOUT port of the operational amplifier U8 through the capacitor C11 and the resistor R19, and the -IN port of the operational amplifier U7 is also connected to the VOUT port of the operational amplifier U7. The VOUT port of the operational amplifier U7 is connected to the matching circuit 9, and the VOUT port of the operational amplifier U7 is also grounded through the resistor R10.

[0051] The matching circuit 9 includes an operational amplifier U15, a +IN port of the operational amplifier U15 is connected to the VOUT port of the operational amplifier U7, a +VS port of the operational amplifier U15 is connected to the +VCCO port of the power circuit, and a -VS port of the operational amplifier U15 is connected to the -VCCO port of the power circuit.

[0052] The second amplifier circuit is the same as the first amplifier circuit, and also includes a chopper resonance adjustment circuit 6, a high-pass filter amplifier circuit 7, a low-pass filter amplifier circuit 8, a matching circuit 9 and a power supply circuit 10. The second amplifier circuit is used to process the signal of the second magnetic ring 5. The processing method is the same as the signal processing method of the first amplifier circuit for the first magnetic ring 4.

[0053] Reference Figure 5 The overall frequency band gain of the measurement signal obtained by the system with different frequency bands shows that the antenna with dB / dt makes the received lightning radiation signal have a gain curve at the high frequency end that is relatively consistent with the low frequency end. In this way, the signal at the high frequency end can obtain 20 dB more gain than the ordinary B or E type antenna, which effectively guarantees the measurement of high-frequency pulse signals, so that the positioning system can theoretically obtain more radiation source positioning information.

[0054] Reference Figure 6 , intuitively showing the time domain waveforms of the lightning discharge process obtained by the electromagnetic wave recording system with two spectrum characteristics. Comparing the time periods marked by the dotted box in the figure, it can be seen that the system with dB / dt spectrum characteristics has better pulse richness. Therefore, the lightning location system using this type of antenna can identify more locatable pulse radiation sources in the same time window, thereby obtaining more radiation source location results, making its detection of the entire lightning process more accurate.

[0055] In this embodiment, the diameter of the first groove 11 is 248 mm, the number of winding turns of the single-layer enameled wire is 32, and the diameter of the enameled wire is 0.41 mm. The diameter of the second groove 21 is 248 mm, the number of winding turns of the single-layer enameled wire is 32, and the diameter of the enameled wire is 0.41 mm.

[0056] Therefore, in this embodiment , Substituting the above parameters into the above formula (1), the measurement sensitivity of the magnetic ring of this embodiment to the magnetic field change rate is obtained as follows:

[0057] .

[0058] Reference Figure 7 Through this antenna design, the gain difference between the low-frequency end and the high-frequency band is 100 times, so the amplification factor of the high-frequency end signal is significantly improved, so that the high-frequency end components that have a greater effect on positioning accuracy and quantity, the measurement system obtains more high-frequency components.

Claims

1. A lightning broadband magnetic field signal detection antenna system, characterized in that: The invention comprises a magnetic antenna and an amplifying circuit connected to the magnetic antenna; the magnetic antenna comprises two vertically cross-distributed magnetic rings, the magnetic rings are cross-arranged with the center line of the plane as the axis; the magnetic rings are composed of multiple turns of single-layer enameled wire; the magnetic antenna comprises two vertically cross-arranged annular frames, each of which is wound with multiple turns of single-layer enameled wire; a groove is arranged on the annular frame, and the multiple turns of single-layer enameled wire are wound in the groove; the annular frame adopts a circular frame, and a groove concentrically arranged with the circular frame is arranged on the outer circumference of the circular frame, and the two circular frames constitute a spherical frame; the spherical frame comprises an upper hemisphere and a lower hemisphere, and the lower hemisphere and the upper hemisphere are fixed by a supporting connecting frame; the diameters of the two magnetic rings are both 248 mm, and each magnetic ring is provided with 32 turns of single-layer enameled wire tightly arranged on the magnetic ring in each direction, and the diameter of the enameled wire is 0.41 mm.

2. The lightning broadband magnetic field signal detection antenna system according to any one of claim 1, characterized in that: The amplifier circuit comprises a first amplifier circuit and a second amplifier circuit, wherein the signal input end of the first amplifier circuit is connected to one of the magnetic ring signals, and the signal input end of the second amplifier circuit is connected to the other magnetic ring signal; the first amplifier circuit comprises a chopper resonance adjustment circuit (6), a high-pass filter amplifier circuit (7), a low-pass filter amplifier circuit (8), a matching circuit (9) and a power supply circuit (10); the signal of the magnetic ring is connected to the chopper resonance adjustment circuit (6), the output end of the chopper resonance adjustment circuit (6) is connected to the input end of the high-pass filter amplifier circuit (7), the output end of the high-pass filter amplifier circuit (7) is connected to the input end of the low-pass filter amplifier circuit (8), and the output end of the low-pass filter amplifier circuit (8) is connected to the input end of the matching circuit (9); the power supply circuit (10) supplies power to the chopper resonance adjustment circuit (6), the high-pass filter amplifier circuit (7), the low-pass filter amplifier circuit (8) and the matching circuit (9); the second amplifier circuit has the same structure as the first amplifier circuit.

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