Ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment

Abstract

The invention provides an ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment. The ultra-wideband monopole antenna comprises a first dielectric plate, a second dielectric plate, a third dielectric plate, a fourth dielectric plate, a metal reflecting plate, a radiator, a square metal ring, a metal sleeve, a metal cap and a coaxial cable, the metal reflecting plate is printed on the lower surface of the first dielectric plate; the radiator is printed on one side surface of the second dielectric plate; the radiating body is a stepped monopole; the square metal ring is printed on one side surface of the third dielectric plate; the metal sleeve is printed on the outer surface of the fourth dielectric plate; and the fourth dielectric plate is sleeved outside the second dielectric plate and the third dielectric plate, so that the metal sleeve surrounds the radiator and the square metal ring. The ultra-wideband monopole antenna provided by the invention has a simple and compact structure, can well realize omnidirectional coverage without forming a complex array or adding a complex feed network, and is more beneficial to the development of ultrahigh frequency partial discharge detection.

Description

Technical Field

[0001] The invention relates to the field of local discharge detection of high-voltage electrical equipment, and in particular to an ultra-wideband monopole antenna used for local discharge detection of high-voltage electrical equipment. Background Art

[0002] The insulation system is the cornerstone of the safe operation of the power system. It ensures the smooth transmission of current while effectively isolating the live parts from the surrounding environment to prevent current leakage. However, when the insulation system fails, its protective barrier function will be lost, causing the power equipment to face extremely high risks. Failures such as aging or defects in the insulation system may manifest as partial discharges, which may cause electrical arcs, arc explosions and even fires if not controlled. These phenomena will not only cause devastating damage to the equipment itself, but may also release large amounts of heat energy and harmful gases, posing a serious threat to the surrounding environment. Therefore, it is crucial to detect partial discharges in the early stages, which is a convenient way to discover failures in high-voltage power equipment and make preventive replacements or repairs as early as possible.

[0003] At present, there are many partial discharge detection methods, including optical sensor detection method, current coupling method, ultrasonic method, chemical method and UHF antenna detection method. However, these detection methods have limitations in frequency range, sensitivity and accuracy. Although the capacitive coupler has high sensitivity, it is not very suitable for field testing and online monitoring. The ultrasonic method can be used for field and online monitoring, but its sensitivity is low and it is easily interfered by surrounding noise signals. The chemical detection method provides accurate measurement in laboratory tests, but it does not provide standard values ​​of dissolved gas concentration in oil and its correlation with transformer defects. The optical detection method has high sensitivity, but requires manual operation to locate the partial discharge source. The UHF antenna detection method has received widespread attention due to its advantages such as strong anti-interference, high sensitivity and non-contact. Among them, the antenna used to receive the UHF electromagnetic signal generated by partial discharge is a key component in UHF detection technology, and its performance directly affects the accuracy and sensitivity of the partial discharge detection system.

[0004] Compared with antennas used for wireless communications, antennas used to detect partial discharge signals are more difficult to design because of their lower operating frequency band and wider coverage range (0.3–3GHz). At present, a large number of different types of antennas have been studied and applied to various electrical equipment to detect partial discharge spectra. For example: spiral antennas, slot antennas, printed monopoles, broadband conical monopoles, loop antennas, open waveguides, etc. Other types of UHF antennas, such as fourth-order Hilbert antennas, fractal antennas, circular microstrip patch antennas, and printed rectangular microstrip patch antennas, have also been designed for partial discharge detection of power transformers. However, due to shortcomings such as narrow bandwidth and low gain, these UHF antennas still face the challenge of insufficient sensitivity.

[0005] The Chinese invention patent with publication number CN113422200A proposes a back-reflecting multi-frequency hollow built-in antenna for direct coupling of partial discharge ultra-high frequency electromagnetic waves, but its operating frequency interval is large and it cannot achieve omnidirectional coverage, which is not conducive to detecting the spectrum of electromagnetic waves generated by partial discharge. The Chinese invention patent with publication number CN102721910A proposes an ultra-high frequency antenna built into the switch cabinet, but the antenna has a large voltage standing wave and a narrow bandwidth, resulting in a limited spectrum of partial discharge signals detected by it, which may result in a large loss of information.

[0006] It can be seen that the UHF antenna in the prior art still needs to be further improved and perfected in terms of bandwidth, gain and other performance when applied to partial discharge detection of high-voltage electrical equipment. Summary of the invention

[0007] The purpose of the present invention is to provide an ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment to address the defects in the prior art, improve the impedance matching and gain characteristics of the antenna through a simple structure, and provide a more optimized solution for the design of partial discharge detection antennas.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] An ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment, comprising a first dielectric plate, a second dielectric plate, a third dielectric plate, a fourth dielectric plate, a metal reflector, a radiator, a square metal ring, a metal sleeve, a metal cap and a coaxial cable;

[0010] The first dielectric plate is arranged along the XOY plane, and the metal reflective plate is printed on the lower surface of the first dielectric plate;

[0011] The second dielectric plate is arranged along the XOZ plane and vertically connected to the top of the first dielectric plate, and the radiator is printed on one side of the second dielectric plate; the radiator is a step-type monopole, including a first microstrip, a second microstrip and a third microstrip arranged in sequence from bottom to top and connected in an integral manner along the Z-axis direction; the width of the second microstrip is greater than that of the first microstrip and the third microstrip, so that a step protruding outward is formed in the middle of the step-type monopole; the second microstrip and the middle of the second dielectric plate have a gap penetrating along the Y-axis direction and extending along the Z-axis direction;

[0012] The third dielectric plate is arranged along the YOZ plane, passes through the gap in the middle of the second microstrip and the second dielectric plate, and is vertically cross-connected with the second dielectric plate; the square metal ring is printed on one side of the third dielectric plate, and the center line of the square metal ring is located at the gap, so that the square metal ring crosses the radiator vertically;

[0013] The fourth dielectric plate is in the shape of a hollow cylinder, with its axis arranged along the Z axis, and the metal sleeve is printed on the outer surface of the fourth dielectric plate; the fourth dielectric plate is sleeved outside the second dielectric plate and the third dielectric plate, so that the metal sleeve surrounds the radiator and the square metal ring;

[0014] The metal cap is sleeved on the upper end of the fourth dielectric plate, so that a closed space is formed inside the fourth dielectric plate to enclose the radiator and the square metal ring;

[0015] The outer conductor of the coaxial cable is fixed to the metal reflector by welding, and the inner conductor of the coaxial cable passes through the metal reflector and the first dielectric plate in sequence and is electrically connected to the middle of the lower end of the first microstrip.

[0016] Furthermore, the first dielectric plate, the second dielectric plate, the third dielectric plate and the fourth dielectric plate are FR4 dielectric plates; the thickness of the first dielectric plate, the second dielectric plate and the third dielectric plate is 1.6 mm, and the thickness of the fourth dielectric plate is 0.2 mm.

[0017] Furthermore, the characteristic impedance of the coaxial cable is 50Ω.

[0018] Furthermore, an annular groove is formed on the metal reflector plate, the center of the annular groove is located below the radiator, and the diameter of the annular groove is greater than the diameter of the metal sleeve;

[0019] The welding point between the outer conductor of the coaxial cable and the metal reflector is located at the center of the annular groove. The inner conductor of the coaxial cable passes through the metal reflector and the first dielectric plate in sequence from the center of the annular groove and is electrically connected to the middle of the lower end of the first microstrip.

[0020] Furthermore, the metal sleeve is provided with a first annular partition groove and a second annular partition groove, and the first annular partition groove and the second annular partition groove extend in parallel with each other along the circumferential direction to divide the metal sleeve into three sections that do not contact each other.

[0021] Furthermore, the inner diameter of the metal cap is larger than the diameter of the metal sleeve, and a margin is left between the upper edge of the metal sleeve and the upper edge of the fourth dielectric plate, so that the metal sleeve and the metal cap do not contact each other; a margin is also left between the lower edge of the metal sleeve and the lower edge of the fourth dielectric plate, so that the metal sleeve and the first dielectric plate do not contact each other.

[0022] Furthermore, the lower end of the second dielectric plate has protruding connecting parts on both sides in the X-axis direction, and the lower end of the connecting part is provided with a connecting protrusion protruding downward; the first dielectric plate is provided with a connecting socket matching the connecting protrusion, and the second dielectric plate is inserted into the connecting socket through the connecting protrusion to achieve connection and fixation with the first dielectric plate.

[0023] Furthermore, the upper end of the connecting portion is provided with a connecting slot with an opening facing upward, and the lower end of the fourth dielectric plate is provided with a connecting slot with a lower opening facing downward; the lower end of the fourth dielectric plate is plugged and fixed to the second dielectric plate through the connecting slot, and the lower end of the fourth dielectric plate is also welded and fixed to the first dielectric plate through a plurality of welding pads.

[0024] Furthermore, both sides of the middle and upper end of the second dielectric plate in the X-axis direction have protruding connecting parts, and the ends of the connecting parts are provided with welding pads for welding and fixing with the side surfaces of the fourth dielectric plate.

[0025] Furthermore, the third dielectric plate has protruding connecting parts on both sides of the Y-axis direction, and the ends of the connecting parts are provided with soldering pads for welding and fixing with the side surfaces of the fourth dielectric plate; the third dielectric plate has protruding limiting parts in the middle of both sides of the Z-axis direction for limiting the position of the third dielectric plate in the gap.

[0026] The present invention provides an ultra-wideband monopole antenna suitable for partial discharge detection of high-voltage electrical equipment. By loading a metal sleeve on the basis of a traditional monopole antenna, the effects of improving impedance matching and increasing gain are achieved, and the added metal cap can reduce the height of the antenna and reduce the volume of the antenna. The present invention also achieves the effect of improving antenna impedance matching by changing the monopole radiator into a stepped radiator, connecting a square metal ring in the middle of the radiator, and etching an annular groove on the metal reflector. The ultra-wideband monopole antenna of the present invention has a simple and compact structure, and can well achieve omnidirectional coverage without forming a complex array or adding a complex feeding network, which is more conducive to the development of ultra-high frequency partial discharge detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention provides an overall structural diagram of an ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment.

[0028] Figure 2 4 is a schematic diagram of the side structure of the second dielectric plate in the embodiment of the present invention.

[0029] Figure 3 It is a schematic diagram of the side structure of the third dielectric plate in the embodiment of the present invention.

[0030] Figure 4 The present invention is a schematic diagram of the side structure of an ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment provided by an embodiment of the present invention.

[0031] Figure 5 Schematic diagram of the bottom structure of the first dielectric plate in an embodiment of the present invention.

[0032] Figure 6 1 is an S parameter diagram obtained by simulation according to an embodiment of the present invention.

[0033] Figure 7 It is the radiation pattern obtained by simulation at the center frequency according to the embodiment of the present invention.

[0034] Figure 8 4 is a gain characteristic diagram obtained by simulation according to an embodiment of the present invention.

[0035] Fig. 9 It is a comparison diagram of S parameters of the embodiment of the present invention and the traditional monopole antenna.

[0036] Fig.10 It is a comparison diagram of S parameters when radiators of different shapes are used in the embodiments of the present invention.

[0037] Fig.11 3 is a comparison diagram of S parameters in the embodiment of the present invention with and without the annular groove. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] like Figures 1 to 5 As shown, an ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment provided by the present invention comprises a first dielectric plate 11, a second dielectric plate 12, a third dielectric plate 13, a fourth dielectric plate 14, a metal reflector 2, a radiator 3, a square metal ring 4, a metal sleeve 5, a metal cap 6 and a coaxial cable 7. In this embodiment, the first dielectric plate, the second dielectric plate, the third dielectric plate and the fourth dielectric plate are FR4 dielectric plates; the thickness of the first dielectric plate, the second dielectric plate and the third dielectric plate is 1.6 mm, and the thickness of the fourth dielectric plate is 0.2 mm.

[0040] Specifically, the first dielectric plate 11 is disposed along the XOY plane, and the metal reflective plate 2 is printed on the lower surface of the first dielectric plate 11 .

[0041] The second dielectric plate 12 is arranged along the XOZ plane and vertically connected to the top of the first dielectric plate 11, and the radiator 3 is printed on one side of the second dielectric plate 12. Figure 2 As shown, in order to improve the impedance matching of the antenna at high frequencies, the radiator 3 in this embodiment is a stepped monopole, which includes a first microstrip 31, a second microstrip 32 and a third microstrip 33 arranged in sequence from bottom to top along the Z-axis direction and connected as a whole; the width of the second microstrip 32 is greater than that of the first microstrip 31 and the third microstrip 33, so that a step protruding outward is formed in the middle of the stepped monopole; the second microstrip 32 and the middle of the second dielectric plate 12 have a gap that penetrates along the Y-axis direction and extends along the Z-axis direction, which is used to install and fix the third dielectric plate.

[0042] Combination Figure 3 As shown, the third dielectric plate 13 is arranged along the YOZ plane, and the third dielectric plate 13 passes through the gap between the second microstrip 32 and the middle part of the second dielectric plate 12, and is vertically cross-connected with the second dielectric plate 12; the square metal ring 4 is printed on one side of the third dielectric plate 13, and the center line of the square metal ring 4 is located at the gap, so that the square metal ring 4 is vertically cross-connected with the radiator 3. The third dielectric plate 13 has a protruding limiting portion 130 in the middle of both sides in the Z-axis direction, which is used to limit the position of the third dielectric plate 13 in the gap.

[0043] Combination Figure 4 As shown, the fourth dielectric plate 14 is in the shape of a hollow cylinder with its axis arranged along the Z axis, and the metal sleeve 5 is printed on the outer surface of the fourth dielectric plate 14; the fourth dielectric plate 14 is sleeved on the outside of the second dielectric plate 12 and the third dielectric plate 13, so that the metal sleeve 5 surrounds the radiator 3 and the square metal ring 4.

[0044] The metal cap 6 is sleeved on the upper end of the fourth dielectric plate 14 , so that a closed space is formed inside the fourth dielectric plate 14 to enclose the radiator 3 and the square metal ring 4 therein.

[0045] The characteristic impedance of the coaxial cable 7 is 50Ω. The outer conductor of the coaxial cable 7 is welded and fixed to the metal reflector 2 , and the inner conductor of the coaxial cable 7 passes through the metal reflector 2 and the first dielectric plate 11 in sequence and is electrically connected to the middle of the lower end of the first microstrip 31 .

[0046] Furthermore, if Figure 4As shown, the metal sleeve 5 is provided with a first annular partition groove 51 and a second annular partition groove 52, and the first annular partition groove 51 and the second annular partition groove 52 extend in parallel with each other along the circumferential direction to divide the metal sleeve 5 into three sections that do not contact each other.

[0047] The inner diameter of the metal cap 6 is larger than the diameter of the metal sleeve 5. A margin 53 is left between the upper edge of the metal sleeve 5 and the upper edge of the fourth dielectric plate 14, so that the metal sleeve 5 and the metal cap 6 do not contact each other. A margin 54 is also left between the lower edge of the metal sleeve 5 and the lower edge of the fourth dielectric plate 14, so that the metal sleeve 5 and the first dielectric plate 11 do not contact each other.

[0048] Combination Figure 5 As shown, the metal reflector 2 is provided with an annular groove 20 for further improving the impedance matching of the antenna at low frequencies. The center of the annular groove 20 is located below the radiator 3, and the diameter of the annular groove 20 is greater than the diameter of the metal sleeve 5. The welding point between the outer conductor of the coaxial cable 7 and the metal reflector 2 is located at the center of the annular groove 20, and the inner conductor of the coaxial cable 7 passes through the metal reflector 2 and the first dielectric plate 11 in sequence from the center of the annular groove 20 and is electrically connected to the middle of the lower end of the first microstrip 31 to achieve feeding.

[0049] Combination Figure 2 and Figure 5 As shown, the second dielectric plate 12 has protruding connecting parts on both sides of the lower end in the X-axis direction, and the lower end of the connecting part is provided with a connecting protrusion 120 protruding downward; the first dielectric plate 11 is provided with a connecting socket 110 matching the connecting protrusion 120, and the second dielectric plate 12 is inserted into the connecting socket 110 through the connecting protrusion 120 to achieve connection and fixation with the first dielectric plate 11.

[0050] The upper end of the connecting portion is provided with a connecting slot with an opening facing upward, and the lower end of the fourth dielectric plate 14 is provided with a connecting slot with a lower opening facing downward; the lower end of the fourth dielectric plate 14 is plugged and fixed to the second dielectric plate 12 through the connecting slot, and the lower end of the fourth dielectric plate 14 is also welded and fixed to the first dielectric plate 11 through a plurality of welding pads.

[0051] Furthermore, both sides of the middle and upper end of the second dielectric plate 12 in the X-axis direction have protruding connection parts, and the ends of the connection parts are provided with welding pads for welding and fixing with the side surfaces of the fourth dielectric plate 14 .

[0052] Furthermore, combined with Figure 3 As shown, in order to reinforce the antenna structure, the third dielectric plate 13 has protruding connecting parts on both sides of the Y-axis direction, and the ends of the connecting parts are provided with pads for welding and fixing with the side surfaces of the fourth dielectric plate 14 .

[0053] Figure 6 The S parameter diagram obtained by simulating the ultra-wideband monopole antenna of the embodiment of the present invention is shown in the figure. As can be seen from the figure, in this embodiment, the frequency band in which the reflection coefficient of the ultra-wideband monopole antenna is less than -10dB can cover 0.3-1.0GHz, achieving a wider coverage range.

[0054] Figure 7 The radiation pattern obtained by simulating the embodiment of the present invention at the center frequency. The results show that the ultra-wideband monopole antenna of this embodiment has good omnidirectional radiation characteristics, which is conducive to detecting electromagnetic wave signals generated by partial discharge from 360 degrees in the horizontal plane.

[0055] Figure 8 This is a gain characteristic diagram obtained by simulation of an embodiment of the present invention. It can be seen from the figure that in the entire working frequency band, the gain of the ultra-wideband monopole antenna of this embodiment is about 0.8-5.0dBi, which is significantly higher than the prior art.

[0056] Fig. 9 The S parameter comparison diagram of the embodiment of the present invention and the traditional monopole antenna is shown in FIG. The result shows that compared with the prior art, the bandwidth of the ultra-wideband monopole antenna of the embodiment of the present invention is significantly broadened.

[0057] Fig.10 This is a comparison diagram of S parameters when different shapes of radiators are used in the embodiment of the present invention. The dotted line is the S parameter when the traditional shape of the radiator is used, and the solid line is the S parameter when the stepped radiator (i.e., stepped monopole) in this embodiment is used. The results show that compared with the prior art, this embodiment improves the impedance matching of the antenna at low and high frequencies by using the stepped radiator.

[0058] Fig.11 The S parameter comparison diagram of the embodiment of the present invention with and without the annular groove is shown in FIG. The result shows that the annular groove in the embodiment can significantly improve the impedance matching of the antenna at low frequency.

[0059] In summary, the ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment provided by the present invention achieves good vertical polarization omnidirectional radiation performance by feeding the monopole with a 50Ω coaxial cable, and the return loss in the 0.3-1.0GHz frequency band is reduced to below -10dB. The test results show that the ultra-wideband monopole antenna of the present invention has an operating bandwidth of 107.69%, a gain of 0.8-5.0dBi and good omnidirectional radiation performance, providing a better solution for the design of partial discharge detection antennas.

[0060] The present invention provides an ultra-wideband monopole antenna suitable for partial discharge detection of high-voltage electrical equipment. By loading a metal sleeve on the basis of a traditional monopole antenna, the effects of improving impedance matching and increasing gain are achieved, and the added metal cap can reduce the height of the antenna and reduce the volume of the antenna. The present invention also achieves the effect of improving antenna impedance matching by changing the monopole radiator into a stepped radiator, connecting a square metal ring in the middle of the radiator, and etching an annular groove on the metal reflector. The ultra-wideband monopole antenna of the present invention has a simple and compact structure, and can well achieve omnidirectional coverage without forming a complex array or adding a complex feeding network, which is more conducive to the development of ultra-high frequency partial discharge detection.

[0061] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment, characterized in that: It includes a first dielectric plate, a second dielectric plate, a third dielectric plate, a fourth dielectric plate, a metal reflector, a radiator, a square metal ring, a metal sleeve, a metal cap and a coaxial cable; The first dielectric plate is arranged along the XOY plane, and the metal reflective plate is printed on the lower surface of the first dielectric plate; The second dielectric plate is arranged along the XOZ plane and vertically connected to the top of the first dielectric plate, and the radiator is printed on one side of the second dielectric plate; the radiator is a step-type monopole, including a first microstrip, a second microstrip and a third microstrip arranged in sequence from bottom to top and connected in an integral manner along the Z-axis direction; the width of the second microstrip is greater than that of the first microstrip and the third microstrip, so that a step protruding outward is formed in the middle of the step-type monopole; the second microstrip and the middle of the second dielectric plate have a gap penetrating along the Y-axis direction and extending along the Z-axis direction; The third dielectric plate is arranged along the YOZ plane, passes through the gap in the middle of the second microstrip and the second dielectric plate, and is vertically cross-connected with the second dielectric plate; the square metal ring is printed on one side of the third dielectric plate, and the center line of the square metal ring is located at the gap, so that the square metal ring crosses the radiator vertically; The fourth dielectric plate is in the shape of a hollow cylinder, with its axis arranged along the Z axis, and the metal sleeve is printed on the outer surface of the fourth dielectric plate; the fourth dielectric plate is sleeved outside the second dielectric plate and the third dielectric plate, so that the metal sleeve surrounds the radiator and the square metal ring; The metal cap is sleeved on the upper end of the fourth dielectric plate, so that a closed space is formed inside the fourth dielectric plate to enclose the radiator and the square metal ring; The outer conductor of the coaxial cable is fixed to the metal reflector by welding, and the inner conductor of the coaxial cable passes through the metal reflector and the first dielectric plate in sequence and is electrically connected to the middle of the lower end of the first microstrip.

2. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 1, characterized in that: The first dielectric plate, the second dielectric plate, the third dielectric plate and the fourth dielectric plate are FR4 dielectric plates; the thickness of the first dielectric plate, the second dielectric plate and the third dielectric plate is 1.6 mm, and the thickness of the fourth dielectric plate is 0.2 mm.

3. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 1, characterized in that: The characteristic impedance of the coaxial cable is 50Ω.

4. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 1, characterized in that: The metal reflector plate is provided with an annular groove, the center of which is located below the radiator, and the diameter of the annular groove is greater than the diameter of the metal sleeve; The welding point between the outer conductor of the coaxial cable and the metal reflector is located at the center of the annular groove. The inner conductor of the coaxial cable passes through the metal reflector and the first dielectric plate in sequence from the center of the annular groove and is electrically connected to the middle of the lower end of the first microstrip.

5. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 1, characterized in that: The metal sleeve is provided with a first annular partition groove and a second annular partition groove, and the first annular partition groove and the second annular partition groove extend in parallel with each other along the circumferential direction to divide the metal sleeve into three sections that do not contact each other.

6. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 5, characterized in that: The inner diameter of the metal cap is larger than the diameter of the metal sleeve, and a margin is left between the upper edge of the metal sleeve and the upper edge of the fourth dielectric plate, so that the metal sleeve and the metal cap do not contact each other; a margin is also left between the lower edge of the metal sleeve and the lower edge of the fourth dielectric plate, so that the metal sleeve and the first dielectric plate do not contact each other.

7. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 1, characterized in that: The lower end of the second dielectric plate has protruding connecting parts on both sides of the X-axis direction, and the lower end of the connecting part is provided with a connecting protrusion protruding downward; the first dielectric plate is provided with a connecting socket matching the connecting protrusion, and the second dielectric plate is inserted into the connecting socket through the connecting protrusion to achieve connection and fixation with the first dielectric plate.

8. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 1, characterized in that: The upper end of the connecting part is provided with a connecting slot with an opening facing upward, and the lower end of the fourth dielectric plate is provided with a connecting slot with a lower opening facing downward; the lower end of the fourth dielectric plate is plugged and fixed to the second dielectric plate through the connecting slot, and the lower end of the fourth dielectric plate is also welded and fixed to the first dielectric plate through a plurality of welding pads.

9. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 8, characterized in that: Both sides of the middle and upper end of the second dielectric plate in the X-axis direction have protruding connecting parts, and the ends of the connecting parts are provided with welding pads for welding and fixing with the side surfaces of the fourth dielectric plate.

10. The ultra-wideband monopole antenna for partial discharge detection of high-voltage electrical equipment according to claim 9, characterized in that: The third dielectric plate has protruding connecting parts on both sides in the Y-axis direction, and soldering pads are provided at the ends of the connecting parts for welding and fixing with the side surfaces of the fourth dielectric plate; the third dielectric plate has protruding limiting parts in the middle of both sides in the Z-axis direction for limiting the position of the third dielectric plate in the gap.

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