High-sensitivity electric field sensing structure

Abstract

A high-sensitivity electric field sensing structure, comprising a regular polygonal metal microstrip patch internally tangent to a circle, wherein the regular polygon has at least eight sides, and the regular polygon has an even number of sides. A Koch curve is used to carry out second-order or higher-order fractal processing on the metal microstrip patch; complementary slotting processing of 0.4-0.8 times is carried out in the metal microstrip patch subjected to fractal processing; a complementary slot and a front feeder line form a gradient network structure; and the outer edge of the metal microstrip patch is further provided with asymmetric branches. The use of the fractal technology, the complementary slotting technology, the asymptotic technology and the asymmetric loading technology well expands the bandwidth, most or even full coverage of an electric field frequency band can be basically achieved with a relatively small size, the structure is simple, the use of the complementary slotting technology reduces the use amount of copper sheets and the use costs, and real acquisition of high-voltage electric field signals can be achieved.

Description

A highly sensitive electric field sensing structure Technical Field

[0001] The present invention relates to the technical field of electric field sensors, in particular to a high-sensitivity electric field sensing structure. Background Art

[0002] High-voltage electric fields are accompanied by complex physical processes and chemical reactions, including sound, light, and heat, providing a theoretical basis for detecting them. High-voltage electric fields within equipment are often accompanied by the neutralization of a large number of positive and negative charges. Steep currents with nanosecond rise times excite electromagnetic wave signals in the 300-3000 MHz frequency range. These signals can be collected and used to measure the magnitude of the discharge using electric field sensors. High-voltage electric field detection offers the advantages of non-destructive testing and online testing, enabling effective detection and accurate location of high-voltage electric fields in power equipment. The transmission of high-voltage electric field signals from the radiation source to the electric field sensor is a complex process, and actual operation is subject to significant interference, making it challenging to analyze the integrity of the acquired electric field signals. Even though online electric field monitoring has been in operation for decades, it still suffers from high false alarm rates, low discharge type detection accuracy, and significant difficulty. To meet the needs of both external live detection and internal online monitoring, the development of wide-bandwidth, miniaturized, high-gain sensors suitable for high-voltage electric field detection is crucial for ensuring proper equipment operation and improving power supply reliability.

[0003] High-voltage electric fields can be classified into different discharge types based on their location and mechanism. Therefore, detecting high-voltage electric field signals can provide a detailed and comprehensive analysis of fault causes, severity, and discharge locations, providing guidance for equipment troubleshooting, operational management, and risk assessment. Rapid, accurate, and convenient identification of various discharge types is a crucial component of online equipment monitoring, effectively supporting the long-term, stable, and reliable operation of equipment. The use of high-precision, wideband sensors is crucial for improving detection accuracy and reliability, ensuring stable power system operation.

[0004] Research on achieving broadband electric field sensors focuses primarily on reducing the quality factor. This can be achieved by modifying the dielectric substrate's material properties, such as the dielectric constant; modifying the substrate's structure, such as increasing its thickness; implementing additional matching networks; employing complementary structures; and employing slotting or slit technology. Antenna miniaturization currently focuses on using specialized dielectric substrates, loading microstrip antennas with shorting pins, meandering techniques, and fractal technology.

[0005] Electric field sensors come in a variety of shapes and styles. Based on their structure, they can be broadly categorized as disc sensors, spiral sensors, Vivaldi sensors, and fractal sensors. Disc sensors are external sensors whose frequency bands generally cover the electric field range and offer high fidelity. However, their large size makes them difficult to use. Spiral sensors, primarily including flat spiral antennas and Archimedean antennas, exhibit frequency-invariant characteristics within a certain range. However, these spiral antennas are too large to be practical. For example, in their 2016 paper "Research on Miniaturized Planar Spiral Antennas for Detecting Partial Discharge in GIS," published in High Voltage Technology, Wang Yongqiang, Li Jianfang, Li Changyuan, and others proposed using a novel loading technique to improve the low-frequency characteristics of the antenna, reducing the antenna size while maintaining the advantages of a wide bandwidth and exhibiting good bidirectional radiation characteristics. The Vivaldi antenna has good antenna gain, and its working frequency band can cover the electric field frequency band; for example, in 2022, Liu Shufang, Xue Yuan, Li Kunzhe and others published "High-gain circularly polarized double-slot Vivaldi antenna" in the "Journal of Radio Science", proposing a circularly polarized double-slot Vivaldi antenna. The slotted part is composed of different exponential function lines, which can achieve an in-band gain greater than 3.5dBi and a maximum gain of 12.5dBi, significantly improving the antenna gain; however, the Vivaldi antenna they designed is a three-dimensional structure. Although it achieves a standing wave ratio of less than 2 in the electric field segment, it is not suitable for actual applications of high-voltage electric field detection of equipment. The self-similarity of fractal technology gives it wide-band and multi-band characteristics, but as the fractal order increases, the processing difficulty and cost also increase. For example, in 2017, Zhou Zhong, Zhang Xiaochun, Guo Bixiang and others proposed in the "Tree-like Fractal Ultra-Wideband Antenna for GIS Partial Discharge" published in "High Voltage Electrical Appliances" that an ultra-wideband antenna was designed using a tree-like fractal structure; the return loss was less than -10dB in the range of 0.5 to 1GHz, it had good directivity, and could achieve omnidirectional reflection; in addition, the gain was large in the 0.5 to 1GHz band, and the antenna size was 200mm×160mm×1.6mm3. For example, in 2019, Yan Xin from Southwest Jiaotong University proposed in the article "Research on Electromagnetic Radiation Characteristics of Bow-Net Arc Based on Hilbert Fractal Antenna" published in "Southwest Jiaotong University" that the third-order Hilbert fractal curve was used to analyze the influence of antenna size, fractal order, feeding position, etc. on antenna performance, and designed a fractal antenna with a size of 70mm×70mm×1.6mm3, but it has the problem of large return loss.

[0006] Current electric field sensors still struggle to overcome the constraints of bandwidth and size. Existing single-bandwidth technologies aim to expand bandwidth by reducing the quality factor. However, blindly reducing the quality factor increases return loss and degrades sensor sensitivity. Current single-band miniaturization technologies sacrifice some low-frequency performance. For high-voltage electric fields in devices, the primary information resides in the lower frequency bands. Furthermore, the pursuit of a wide bandwidth while miniaturizing the sensor design results in an overly complex structure, making it difficult to manufacture and costly, making it difficult to meet the demands of mass production. Therefore, we propose a highly sensitive electric field sensing structure.

[0007] Summary of the Invention

[0008] The object of the present invention is to provide a high-sensitivity electric field sensing structure to solve the problems raised in the above background technology.

[0009] In order to solve the above technical problems, one of the objects of the present invention is to provide a high-sensitivity electric field sensing structure, comprising a metal microstrip patch of a regular polygon inscribed in a circle, wherein the number of sides of the regular polygon is at least eight and an even number, and the metal microstrip patch is subjected to fractal processing of greater than or equal to the second order using a Koch curve, and a complementary slot processing of 0.4 to 0.8 times is performed inside the metal microstrip patch after the fractal processing, and the complementary slot and the front feed line form a gradient network structure, and the outer edge of the metal microstrip patch is also provided with asymmetric branches.

[0010] A second object of the present invention is to provide a specific design and manufacturing process of a high-sensitivity electric field sensing structure, comprising the following steps:

[0011] S1. First, based on the circular patch sensor, calculate and design the patch sensor with an inscribed regular octagon;

[0012] S2. Replace the side length of the regular octagon with the Koch curve and preliminarily change the length of the back ground plane to achieve impedance matching.

[0013] S3, using complementary slotting, a slot with the same shape as the outer boundary is opened inside the Koch metal patch;

[0014] S4. Finally, the back ground plane is designed as a progressive structure, and asymmetric branches of metal patches are added.

[0015] As a further improvement of the present technical solution, in step S1, when calculating and designing the patch sensor of the inscribed regular octagon, it is necessary to first calculate the size of the circular patch sensor, specifically:

[0016] Based on the relationship between the TM mode resonant frequency and radius of the circular microstrip antenna, the size of the circular patch within the electric field frequency band is calculated. When the resonant frequency is less than 2 GHz, ignoring the influence of the fringe field, the radius is:

[0017] When the resonant frequency is greater than 2 GHz, considering the influence of the fringe field, the radius is:

[0018] Where r is the radius of the circular patch ignoring the influence of the fringe field, c is the speed of light, and f r is the resonant frequency, ε r is the relative dielectric constant, r x is the radius of the circular patch considering the influence of the fringe field, and d is the width of the feed line.

[0019] As a further improvement of the present technical solution, in step S1, when calculating and designing the patch sensor of an inscribed regular octagon, after determining the size of the circular patch sensor, it is also necessary to calculate the size of the initial dielectric substrate according to different feeding modes, specifically:

[0020] Calculate the initial size of the dielectric substrate, taking into account the reduction of production costs, the reduction of antenna size and the reduction of antenna weight; shorten the size of the dielectric substrate as much as possible while ensuring good electrical performance of the antenna; for coaxial feeding methods, there are: W g =W+0.2λ g (3) L g =L+0.2λ g (4)

[0021] Among them, W and L are the width and length of the required patch respectively, W g 、L g are the width and length of the dielectric substrate, λ g is the length of the waveguide in the medium;

[0022] For the microstrip line feeding method: W c =W+0.2λ g (5)

[0023] Among them, W c is the width of the dielectric substrate, λ g is the waveguide length in the medium, λ is the waveguide length in vacuum, c is the speed of light, f r is the resonant frequency, ε e is the effective dielectric constant, ε r is the relative dielectric constant, and d is the width of the feed line.

[0024] As a further improvement of this technical solution, in step S1, when calculating and designing the patch sensor of the inscribed regular octagon, the width of the feeder also needs to be calculated, specifically:

[0025] Where d is the width of the feeder, ε r is the relative dielectric constant, Z0 is the characteristic impedance, M and N are both intermediate transition parameters;

[0026] As a further improvement of the present technical solution, in S1, after determining the size of the patch sensor of the inscribed regular octagon, the size of the radiation space box needs to be set. The size of the radiation space box is set to be greater than λ / 4 from the boundary of the antenna.

[0027] As a further improvement of the present technical solution, in S2, the method of preliminarily changing the length of the back ground plate to achieve impedance matching adopts fractal processing of the Koch curve, which is based on the principle that fractals have self-similarity, multi-band and wide-band properties, and the fractal order directly affects the antenna performance.

[0028] As a further improvement of the present technical solution, in S3, the impact of the complementary slots on the sensor performance is as follows: when the metal microstrip patch whose side length is represented by the Koch curve is bent, the radiation boundary conditions of the sensor will change, thereby exciting higher-order modes, which in turn will lead to an increase in the sensor resonant frequency and a reduction in the lower cutoff frequency of the antenna, thereby expanding the bandwidth.

[0029] As a further improvement of the present technical solution, in S4, the back ground plane is designed as a progressive structure, that is, the radiation performance of the antenna is affected by changing the shape of the ground plane, and at the same time, asymmetric branches of the metal patch are added to change the shape of the microstrip patch, so as to greatly extend the path through which the current flows and increase the electrical scale within a certain limited range.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This high-sensitivity electric field sensor structure proposes a high-sensitivity electric field sensor structure design based on the sensor structure, achieving the goals of wide bandwidth, miniaturization, and high gain. It can obtain more accurate and richer information from the electric field sensor and overcome the shortcomings of traditional methods of increasing antenna size to expand bandwidth.

[0032] 2. This high-sensitivity electric field sensing structure utilizes a comprehensive design of a microstrip patch sensor using fractal technology, complementary slotting technology, asymmetric loading technology, and asymmetric loading technology. This significantly expands the bandwidth, achieving substantial or even complete coverage of the electric field frequency band with a relatively small size. The complementary slotting technology reduces copper material and operating costs, addressing the increased return loss caused by the actual processing process. The sensor exhibits excellent gain in the Z-axis direction, and its compact size and high sensitivity make it ideal for practical high-voltage electric field detection, demonstrating its promising application prospects.

[0033] 3. This high-sensitivity electric field sensing structure has a simple structure and only uses second-order fractals, making it fully suitable for direct printing on most machines. In addition, the use of complementary slots saves the use of copper. Using this structure, the real acquisition of high-voltage electric field signals can be achieved, providing a solid foundation for subsequent signal processing and identification. It also lays the foundation for applications such as online identification of signs of equipment insulation degradation, assessment of discharge types, and differentiation of operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is an exemplary initial model diagram of the present invention;

[0035] FIG2 is a diagram of an exemplary sensor structure optimization process according to the present invention;

[0036] FIG3 is an exemplary zero-order fractal diagram of a Koch curve constructed by HFSS in the present invention;

[0037] FIG4 is an exemplary first-order fractal diagram of a Koch curve constructed by HFSS in the present invention;

[0038] FIG5 is an exemplary second-order fractal diagram of a Koch curve constructed by HFSS in the present invention;

[0039] FIG6 is an exemplary model diagram of the present invention with complementary grooves added;

[0040] FIG7 is an exemplary model diagram of the present invention with asymmetric branches added;

[0041] FIG8 is a schematic diagram of exemplary preferred model parameters in the present invention. DETAILED DESCRIPTION

[0042] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] Example 1

[0044] As shown in Figure 7, this embodiment provides a high-sensitivity electric field sensing structure, including a metal microstrip patch inscribed in a circle in the form of a regular polygon, wherein the number of sides of the regular polygon is at least eight and is an even number, and the metal microstrip patch is subjected to fractal processing of a second order or greater using a Koch curve. Complementary slotting of 0.4 to 0.8 times is performed inside the fractal-processed metal microstrip patch, and a progressive technique is used to form a gradient network structure between the complementary slots and the front feed line. Asymmetric branches are also provided on the outer edge of the metal microstrip patch.

[0045] As shown in FIG. 1 to FIG. 8 , this embodiment also provides a specific design and manufacturing process of a high-sensitivity electric field sensing structure, which includes the following steps.

[0046] S1. First, based on the circular patch sensor, calculate and design the patch sensor with an inscribed regular octagon;

[0047] In this step, you need to first calculate the size of the circular patch sensor, specifically:

[0048] Based on the relationship between the TM mode resonant frequency and radius of the circular microstrip antenna, the size of the circular patch within the electric field frequency band is calculated. When the resonant frequency is less than 2 GHz, ignoring the influence of the fringe field, the radius is:

[0049] When the resonant frequency is greater than 2 GHz, considering the influence of the fringe field, the radius is:

[0050] Where r is the radius of the circular patch ignoring the influence of the fringe field, c is the speed of light, and f r is the resonant frequency, ε r is the relative dielectric constant, r x is the radius of the circular patch considering the influence of the fringe field, and d is the width of the feed line.

[0051] Furthermore, after determining the size of the circular patch sensor, it is also necessary to calculate the size of the initial dielectric substrate according to different feeding methods, specifically:

[0052] Calculate the initial size of the dielectric substrate, taking into account the reduction of production costs, the reduction of antenna size and the reduction of antenna weight. The size of the dielectric substrate should be shortened as much as possible while ensuring good electrical performance of the antenna; for coaxial feeding methods, there are: W g =W+0.2λ g (3) L g =L+0.2λ g (4)

[0053] Where W and L are the width and length of the required patch, respectively. For a general circular patch antenna, the actual antenna size is much larger than the theoretical radius. In this paper, W = 2 × r + 10 mm is temporarily taken; W g 、L g are the width and length of the dielectric substrate, λ g is the length of the waveguide in the medium;

[0054] For the microstrip line feeding method: W c =W+0.2λ g (5)

[0055] Among them, W c is the width of the dielectric substrate, λ g is the waveguide length in the medium, λ is the waveguide length in vacuum, c is the speed of light, f r is the resonant frequency, ε e is the effective dielectric constant, ε r is the relative dielectric constant, and d is the width of the feed line.

[0056] Furthermore, the width of the feeder needs to be calculated, specifically:

[0057] Where d is the width of the feeder, ε r is the relative dielectric constant, Z0 is the characteristic impedance, and M and N are intermediate transition parameters. Combining the above three formulas, we can obtain that when the impedance Z0 is 50Ω, the width of the microstrip line is 3mm.

[0058] Furthermore, the dimensions of the radiation box must be set. This distance must be greater than λ / 4 from the antenna boundary. For broadband antennas, the lower the frequency, the longer the wavelength. If the radiation box is not sufficiently large, significant errors will occur at low frequencies. Therefore, 0.3 GHz is used as the design guideline. Considering that subsequent optimization methods can achieve miniaturization, the preliminary design dimensions of the dielectric plate are 120 mm × 120 mm × 1.6 mm³, with a dielectric constant of 4.4, a regular octagonal side length of 31 mm, a feed line width of 3 mm, and a length of 45 mm. The radiation box measures 600 mm × 600 mm × 500 mm³.

[0059] The circular patch is embedded in a regular octagon, resulting in the initial model shown in Figure 1. At this point, the sensor's performance is insufficient to meet requirements, and the return loss is excessive. Initial optimization of the backplane length is required to meet initial impedance matching requirements. This will lead to the next step.

[0060] S2. Replace the side length of the regular octagon with the Koch curve and preliminarily change the length of the back ground plane to achieve impedance matching.

[0061] In this step, in the design of the microstrip patch antenna, slight changes in the structural shape and size will greatly affect the antenna's performance parameters, such as the outer dimensions, antenna width, feed point position, and the thickness and material of the dielectric substrate. Due to laboratory conditions and practical engineering considerations, this embodiment optimizes the Koch curve from four aspects: fractal order, complementary slots, substrate thickness, and progressive and asymmetric loading. The optimization design flow chart is shown in Figure 2.

[0062] The initial method for achieving impedance matching by varying the length of the back ground plane utilizes fractal processing of Koch curves. This is based on the self-similarity, multi-band, and broadband nature of fractals, and the principle that the fractal order directly influences antenna performance. As the fractal order increases, the structure becomes more refined and the processing difficulty increases accordingly. Figures 3-5 show Koch curves from zero to second order constructed using HFSS.

[0063] As the order of the Koch fractal antenna increases, the processing difficulty increases, the frequency reduction of the antenna medium decreases, and the processing cost and difficulty also increase. Considering the above, the second-order fractal is selected as the target in this embodiment.

[0064] S3, using complementary slotting, a slot with the same shape as the outer boundary is opened inside the Koch metal patch;

[0065] In this step, the impact of complementary slots on sensor performance is considered: when the metal microstrip patch (the side length of which is represented by the Koch curve) is bent, the sensor's radiation boundary conditions change, exciting higher-order modes. This in turn increases the sensor's resonant frequency and lowers the antenna's lower cutoff frequency, thereby expanding the bandwidth. The model after adding complementary slots is shown in Figure 6.

[0066] Furthermore, as the resonant frequency gradually decreases, it can play a role in widening the frequency band. However, the patch slot reduces the coupling with the ground plane, which will increase the return loss, and as the slot multiple increases, the gain in the Z-axis direction becomes smaller. Taking the above considerations into account, among the slot multiples of 0.4 to 0.8 times, this embodiment ultimately prefers to use 0.5 times internal slots.

[0067] S4. Finally, the back ground plane is designed as a progressive structure, and asymmetric branches of metal patches are added.

[0068] In this step, the back ground plane is designed as a progressive structure, that is, the radiation performance of the antenna is affected by changing the shape of the ground plane, and the shape of the microstrip patch is changed by adding asymmetric branches of the metal patch, which is used to greatly extend the path of current flow and increase the electrical scale within a certain limited range.

[0069] Considering the use of a progressive technique, the progressive grooves and front feeder form a gradient network structure, and changing the shape of the ground plane affects the antenna's radiation performance. Furthermore, when using asymmetric branches, changing the shape of the microstrip patch can significantly extend the current path and increase the electrical dimension within a certain limited range. The modeling using progressive and asymmetric loading is shown in Figure 7.

[0070] Finally, after modeling and simulation experiments, the preferred specifications were an asymmetric branch length of 60mm and a width of 3mm, and a progressive groove width of 3mm and a length of 5mm. The lower cutoff frequency was 731.5MHz. The final sensor size parameters are shown in Figure 8.

[0071] This invention is a sensor structure design solution based on the integrated application of fractal technology, complementary slotting, asymmetric loading, and asymmetric techniques. The key is to utilize the same Koch curve within the fractal patch for complementary slotting based on a second-order Koch fractal, and then load asymmetric branches and progressive slotting to achieve broadband, miniaturized, and high-gain performance. Based on the sensor structure, this invention proposes a highly sensitive electric field sensor structure design that achieves broadband, miniaturized, and high-gain performance. This design allows for more accurate and richer information to be obtained from the electric field sensor, overcoming the drawbacks of traditional methods that increase antenna size to expand bandwidth.

[0072] Those skilled in the art will appreciate that the process of implementing all or part of the steps of the above embodiments may be accomplished by hardware, or by instructing related hardware through a program.

[0073] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-sensitivity electric field sensing structure, characterized in that: A metal microstrip patch comprising a regular polygon inscribed in a circle, wherein the number of sides of the regular polygon is at least eight and is an even number, the metal microstrip patch is subjected to fractal processing of a magnitude greater than or equal to the second order using a Koch curve, a complementary slotting processing of 0.4 to 0.8 times is performed inside the metal microstrip patch after the fractal processing, and the complementary slotting and the front feeder are a gradient network structure, and an asymmetric branch is also provided on the outer edge of the metal microstrip patch; The specific design and production process of the high-sensitivity electric field sensing structure includes the following steps: S1. First, based on the circular patch sensor, calculate and design the patch sensor with an inscribed regular octagon; S2. Replace the side length of the regular octagon with the Koch curve and preliminarily change the length of the back ground plane to achieve impedance matching; S3, using complementary slotting, a slot with the same shape as the outer boundary is opened inside the Koch metal patch; S4. Finally, the back ground plane is designed as a progressive structure and asymmetric branches of metal patches are added.

2. The high-sensitivity electric field sensing structure according to claim 1, characterized in that: In S1, when calculating and designing the patch sensor of the inscribed regular octagon, it is necessary to first calculate the size of the circular patch sensor, specifically: According to the relationship between the TM mode resonant frequency and radius of the circular microstrip antenna, the size of the circular patch in the electric field frequency band is calculated. When the resonant frequency is less than 2 GHz, the influence of the fringe field is ignored, and the radius is: When the resonant frequency is greater than 2 GHz, considering the influence of the edge field, the radius is: Where r is the radius of the circular patch ignoring the effect of the edge field, c is the speed of light, and f r is the resonant frequency, ε r is the relative dielectric constant, r x is the radius of the circular patch considering the influence of the fringe field, and d is the width of the feed line.

3. The high-sensitivity electric field sensing structure according to claim 2, characterized in that: In S1, when calculating and designing the patch sensor of the inscribed regular octagon, after determining the size of the circular patch sensor, it is also necessary to calculate the size of the initial dielectric substrate according to different feeding methods, specifically: The size of the dielectric substrate should be shortened as much as possible while ensuring good electrical performance of the antenna; the coaxial feeding methods are: W g =W+0.2λ g (3) L g =L+0.2λ g (4) Among them, W and L are the width and length of the required patch respectively, W g , L g are the width and length of the dielectric substrate, λ g is the length of the waveguide in the medium; For the microstrip line feeding method: W c =W+0.2λ g (5) Among them, W c is the width of the dielectric substrate, λ g is the waveguide length in the medium, λ is the waveguide length in vacuum, c is the speed of light, f r is the resonant frequency, ε e is the effective dielectric constant, ε r is the relative dielectric constant and d is the width of the feed line.

4. The high-sensitivity electric field sensing structure according to claim 3, characterized in that: In S1, when calculating and designing the patch sensor of the inscribed regular octagon, the width of the feed line needs to be calculated at the end, specifically: Where d is the width of the feeder, ε r is the relative dielectric constant, Z0 is the characteristic impedance, and M and N are intermediate transition parameters.

5. The high-sensitivity electric field sensing structure according to claim 4, characterized in that: In S1, after determining the size of the patch sensor of the inscribed regular octagon, the size of the radiation space box needs to be set. The size of the radiation space box is set to be greater than λ / 4 from the boundary of the antenna.

6. The high-sensitivity electric field sensing structure according to claim 1, characterized in that: In S2, the method of preliminarily changing the length of the back ground plate to achieve impedance matching adopts fractal processing of the Koch curve, which is based on the principle that fractals have self-similarity, multi-band and wide-band properties, and the fractal order directly affects the antenna performance.

7. The high-sensitivity electric field sensing structure according to claim 1, characterized in that: In S3, the influence of the complementary slots on the sensor performance is as follows: when the metal microstrip patch whose side length is represented by the Koch curve is bent, the radiation boundary conditions of the sensor will change, thereby exciting higher-order modes, which will lead to an increase in the sensor resonant frequency and reduce the lower cutoff frequency of the antenna, thereby expanding the bandwidth.

8. The high-sensitivity electric field sensing structure according to claim 1, characterized in that: In S4, the back ground plane is designed as a progressive structure, that is, the radiation performance of the antenna is affected by changing the shape of the ground plane, and at the same time, asymmetric branches of the metal patch are added to change the shape of the microstrip patch, so as to greatly extend the path of the current flow and increase the electrical dimension within a certain limited range.

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