A miniaturized monopole transmit antenna for power transfer shaft load test wireless communication

Abstract

The application relates to a miniaturized monopole transmitting antenna for power transmission shaft load test wireless communication. The application comprises a dielectric plate, a serpentine radiation plate arranged on the upper surface of the dielectric plate, a ground plate arranged on the lower surface of the dielectric plate and a feed terminal; the feed terminal is electrically connected with the serpentine radiation plate and the ground plate respectively, so that radio frequency signals from the feed terminal excite an electromagnetic field between the serpentine radiation plate and the ground plate, and the electromagnetic field is radiated outward to space through the serpentine radiation plate; wherein the serpentine radiation plate comprises a feed transition part electrically connected with the feed terminal, a serpentine branch connected with the feed transition part, and a first parasitic patch and a second parasitic patch which are respectively connected to the serpentine branch and are arranged at intervals; the miniaturized monopole transmitting antenna is arranged inside a power transmission shaft and is arranged close to the power transmission shaft body. The application can significantly improve the communication quality in the shaft and improve the communication stability.

Description

Technical Field

[0001] This invention relates to the field of novel antenna technology, and in particular to a miniaturized monopole transmitting antenna for wireless communication used in power transmission axis load testing. Background Technology

[0002] In traditional power transmission shaft load testing systems, signal transmission between rotating and stationary components typically relies on wired connections such as slip rings or wiring harnesses. However, under complex operating conditions including high-frequency vibration, lubricant immersion, and limited installation space, this physical contact communication method often suffers from severe wear, decreased reliability, and high maintenance costs. With the development of electrification and intelligence, wireless communication technology has been gradually introduced into power transmission shaft load testing systems. By establishing a reliable short-range wireless data link, the wireless communication system on the power transmission shaft can achieve real-time monitoring of the operating status of rotating components and contactless bidirectional transmission of control commands. This effectively solves the bottlenecks of traditional wired methods and greatly improves the intelligence level and operational reliability of the power output system.

[0003] For the special application environment of power transmission axis wireless communication systems, the core antenna technology needs to meet extremely stringent physical space constraints and electromagnetic requirements. To achieve this goal, current technology focuses on developing microstrip antenna technology based on miniaturized design. By optimizing the antenna geometry and using high dielectric constant substrate materials, electromagnetic wave radiation can be effectively achieved on the limited surface of the metal axis or within a compact housing. At the same time, in order to overcome the signal fading problem caused by the rotation axis movement, antennas generally adopt polarization diversity technology. By designing antenna elements with multiple polarization characteristics at the transmitting and receiving ends, it is ensured that the system can always maintain a stable communication link in at least one polarization direction, regardless of the rotation angle of the axis or the direction of interference reflection, thereby significantly improving the reliability and anti-interference capability of data transmission.

[0004] Patent document CN205211931U discloses a planar monopole omnidirectional antenna, wherein the antenna element includes a dielectric, a planar monopole section, a serpentine monopole section, and a short-circuit section. While this patent document enables the design of a miniaturized planar monopole antenna, it is not suitable for the operating environment of a power transmission axis load test communication transmitter, and it fails to meet the stringent requirements for miniaturization and multi-polarization characteristics of the transmitting antenna in power transmission axis load test wireless communication. Summary of the Invention

[0005] Therefore, the present invention provides a miniaturized monopole transmitting antenna for wireless communication in power transmission shaft load testing, which can significantly improve the quality of in-axis communication and enhance communication stability.

[0006] To solve the above-mentioned technical problems, the present invention provides a miniaturized monopole transmitting antenna for wireless communication for power transmission shaft load testing, comprising a dielectric substrate, a serpentine radiating plate disposed on the upper surface of the dielectric substrate, a ground plate disposed on the lower surface of the dielectric substrate, and a feed terminal. The feed terminal is electrically connected to the serpentine radiating plate and the floor respectively, so that the radio frequency signal from the feed terminal excites an electromagnetic field between the serpentine radiating plate and the floor, and radiates outward into space through the serpentine radiating plate; The serpentine radiating plate includes a feed transition section electrically connected to the feed terminal, a serpentine branch connected to the feed transition section, and a first parasitic patch and a second parasitic patch respectively connected to the serpentine branch and spaced apart. The miniaturized monopole transmitting antenna is configured inside the power transmission shaft and close to the power transmission shaft body. The main extension direction of the serpentine radiating plate is parallel to the axial direction of the power transmission shaft body, so as to maintain stable wireless coupling and transmission with the receiving antenna during the rotation of the power transmission shaft body.

[0007] In one embodiment of the present invention, the power supply terminal includes an inner conductor and an outer conductor of the power supply terminal that are coaxially arranged and insulated from each other. The inner conductor of the power supply terminal is electrically connected to the serpentine radiating plate, and the outer conductor of the power supply terminal is electrically connected to the ground.

[0008] In one embodiment of the present invention, the feed transition section is a trapezoidal impedance transformation patch, which is located between the feed terminal and the serpentine stub, and is used to couple the radio frequency energy of the feed terminal to the serpentine stub.

[0009] In one embodiment of the present invention, both the first parasitic patch and the second parasitic patch are elliptical parasitic patches; The first parasitic patch and the second parasitic patch are arranged at 0.08 working frequency wavelengths along the length direction of the serpentine radiating plate; the short axis of the first parasitic patch and the second parasitic patch occupies 0.4 working frequency wavelengths; The first parasitic patch and the second parasitic patch are integrally formed with the serpentine radiating plate, or are separately welded or electrically bonded.

[0010] In one embodiment of the present invention, the outer contour of the serpentine radiating plate is rectangular; the serpentine branches are composed of multiple conductive lines that are bent sequentially and connected vertically.

[0011] In one embodiment of the present invention, both the medium plate and the floor have a rectangular outer contour; the length and width of the rectangular floor are both smaller than the length and width of the medium plate.

[0012] In one embodiment of the present invention, the dielectric plate, the serpentine radiating plate, and the floor all have a rectangular outer contour. The length of the serpentine radiating plate is set to any value within the range of 0.12 to 0.18 times the wavelength of the working frequency, and the width is set to any value within the range of 0.03 to 0.08 times the wavelength of the working frequency. The length of the dielectric substrate is set to any value within the range of 0.15 to 0.20 times the wavelength of the operating frequency, and the width is set to any value within the range of 0.05 to 0.10 times the wavelength of the operating frequency. The length of the floor is set to any value within the range of 0.05 to 0.10 times the wavelength of the working frequency, and the width is preferably set to any value within the range of 0.015 to 0.04 times the wavelength of the working frequency.

[0013] In one embodiment of the present invention, the dielectric substrate is a PCB board, the dielectric substrate thickness is 0.8mm~1.6mm, the dielectric constant is 4.2~4.8, and the loss tangent is 0.015~0.025.

[0014] In one embodiment of the present invention, the power supply terminal is a coaxial probe power supply structure or an SMA connector power supply structure.

[0015] In one embodiment of the present invention, the miniaturized monopole transmitting antenna operates in the frequency band of 2.4 GHz to 2.5 GHz, and the transmission coupling coefficient between the transmitting antenna and the receiving antenna in the operating frequency band is greater than -35 dB.

[0016] The technical solution of the present invention has the following advantages compared with the prior art: This invention achieves a miniaturized antenna layout, adapting to the confined installation space within the power transmission shaft. By incorporating multiple horizontal and vertical stubs through a serpentine radiating plate, it realizes a multi-polarization component design for the antenna. The multiple bends in the serpentine stubs extend the equivalent current transmission length, achieving resonance in the target operating frequency band within limited physical dimensions. This significantly reduces the overall antenna size while maintaining radiation performance, making it better suited for installation environments with limited space within the power transmission shaft and its protective casing.

[0017] To improve impedance matching performance and ensure stable operation within the target frequency band, this invention incorporates a feed transition section between the feed terminal and the serpentine stub, preferably employing a trapezoidal impedance transformation patch. This allows for a smooth transition of the feed impedance to the input impedance of the radiating structure, effectively reducing impedance abrupt changes at the feed point, suppressing signal reflection, and improving the antenna's port matching characteristics in the 2.4GHz to 2.5GHz operating frequency band, thereby enhancing the antenna's operational stability and transmission reliability.

[0018] This invention enhances radiation control capabilities and improves wireless communication quality. A first parasitic patch and a second parasitic patch are placed on the serpentine stub. Through the synergistic effect between the parasitic patch and the serpentine stub, the current distribution, resonance characteristics, and radiation characteristics of the antenna are optimized. This improves radiation efficiency and coupling transmission performance within the target frequency band, thereby enhancing wireless communication quality under power transmission axis load testing scenarios.

[0019] This invention improves communication stability under rotating conditions. It places a miniaturized monopole transmitting antenna close to the power transmission axis and aligns the main extension direction of the serpentine radiating plate with the axis of the power transmission axis. This allows the antenna to maintain a relatively stable wireless coupling with the receiving antenna even as the power transmission axis rotates, reducing the risk of communication attenuation caused by axis rotation, attitude changes, and space constraints, thereby improving data transmission stability under dynamic conditions.

[0020] Balancing mechanical reliability and engineering feasibility, the radiating structure, dielectric plate, and floor of this invention can all adopt regular shape designs, facilitating processing, manufacturing, and assembly. Simultaneously, the parasitic patch and serpentine radiating plate can be implemented using methods such as integral molding, separate welding, or conductive bonding. This not only helps ensure the consistency of the high-frequency structure but also meets the practical needs of different manufacturing processes and application scenarios, thereby enhancing the structural reliability and engineering application value of this invention under complex conditions such as vibration and rotation.

[0021] The miniaturized monopole transmitting antenna of this invention meets the link transmission requirements of the power transmission shaft load testing system. Operating in the 2.4GHz to 2.5GHz frequency band, it achieves good wireless coupling transmission with the receiving antenna, with a transmission coupling coefficient greater than -35dB. This demonstrates that this invention can meet the requirements for continuity, accuracy, and stability of wireless data transmission during power transmission shaft load testing. Attached Figure Description

[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0023] Figure 1 This is an exploded view of the miniaturized monopole transmitting antenna of the present invention.

[0024] Figure 2 This is a plan view of the serpentine radiating plate of the miniaturized monopole transmitting antenna of the present invention.

[0025] Figure 3 This is a plan view of the rectangular floor of the miniaturized monopole transmitting antenna of the present invention.

[0026] Figure 4 This is a side view of the miniaturized monopole transmitting antenna of the present invention.

[0027] Figure 5 This is a schematic diagram of the miniaturized monopole transmitting antenna of the present invention in the power transmission axis.

[0028] Figure 6 This is a schematic diagram of the reflection coefficient of the miniaturized monopole transmitting antenna of the present invention in the power transmission axis.

[0029] Figure 7 This is a schematic diagram showing the coupling coefficient between the miniaturized monopole transmitting antenna of the present invention and the receiving antenna under different angles of rotation of the inner shell in the power transmission axis.

[0030] Explanation of reference numerals in the instruction manual: 1. Feed terminal; 11. Inner conductor of feed terminal; 12. Outer conductor of feed terminal; 2. Flooring; 3. Medium plate; 4. Serpentine radiating plate; 41. Power supply transition section; 421. First parasitic patch; 422. Second parasitic patch; 43. Serpentine branch; 5. Power transmission shaft; 6. Power transmission shaft protective housing. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0032] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0033] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0034] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0035] Reference Figures 1 to 5 As shown, this embodiment provides a miniaturized monopole transmitting antenna for wireless communication for power transmission shaft load testing, including a dielectric substrate 3, a serpentine radiating plate 4 disposed on the upper surface of the dielectric substrate 3, a ground plate 2 disposed on the lower surface of the dielectric substrate 3, and a feed terminal 1. The power supply terminal 1 is electrically connected to the serpentine radiating plate 4 and the floor 2 respectively, so that the radio frequency signal from the power supply terminal 1 excites an electromagnetic field between the serpentine radiating plate 4 and the floor 2, and radiates outward into space through the serpentine radiating plate 4; The serpentine radiating plate 4 includes a power supply transition section 41 electrically connected to the power supply terminal 1, a serpentine branch 43 connected to the power supply transition section 41, and a first parasitic patch 421 and a second parasitic patch 422 respectively connected to the serpentine branch 43 and spaced apart. The miniaturized monopole transmitting antenna is configured inside the power transmission shaft and positioned close to the power transmission shaft body 5. The transmitting antenna is mounted on a circuit module that rotates with the power transmission shaft, and is used to transmit test data from the power transmission shaft to a stationary module on the protective shell. Due to the limited space between the power transmission shaft and the protective shell, the transmitting module on the shaft and the receiving module on the protective shell are arranged axially separately. The main extension direction of the serpentine radiating plate 4 is parallel to the axial direction of the power transmission shaft body 5, ensuring stable wireless coupling and transmission with the receiving antenna during the rotation of the power transmission shaft body 5.

[0036] By employing a structural design combining a serpentine radiating plate 4, a feed transition section 41, and a first parasitic patch 421 and a second parasitic patch 422, miniaturized antenna arrangement is achieved within a limited installation space, effectively improving impedance matching characteristics, radiation characteristics, and coupling transmission performance in the target frequency band. Simultaneously, by placing the antenna close to the power transmission axis 5 and ensuring that the main extension direction of the serpentine radiating plate 4 is parallel to the axis of the power transmission axis 5, a stable wireless coupling relationship between the antenna and the receiving antenna is maintained under axis rotation conditions, significantly improving the stability and reliability of wireless communication during power transmission axis load testing.

[0037] In one embodiment, the power supply terminal 1 includes an inner conductor 11 and an outer conductor 12 that are coaxially arranged and insulated from each other. The inner conductor 11 is electrically connected to the serpentine radiating plate 4, and the outer conductor 12 is electrically connected to the floor 2.

[0038] In one embodiment, the feed transition section 41 is a trapezoidal impedance transformation patch located between the feed terminal 1 and the serpentine stub 43. This patch couples the radio frequency energy from the feed terminal 1 to the serpentine stub 43. Due to the miniaturization constraints of the antenna in this embodiment, the input impedance of the serpentine stub 43 exhibits strong reactance characteristics. Direct feeding with a rectangular patch would result in a drastic impedance change and a narrower antenna operating bandwidth. This embodiment utilizes the characteristic of the trapezoidal patch's width gradually changing along its extension direction to form an impedance-gradient transmission line. This smoothly transitions the characteristic impedance at the feed terminal 1 to the input impedance of the serpentine stub 43, effectively suppressing current reflection at the feed point. Compared to conventional rectangular transition patches, the trapezoidal impedance transformation patch 41 significantly improves the antenna's port matching characteristics within the operating frequency band while maintaining a compact lateral dimension, ensuring the bandwidth requirements under miniaturized design.

[0039] In one embodiment, both the first parasitic patch 421 and the second parasitic patch 422 are elliptical parasitic patches. The elliptical structure design has the following technical considerations: First, the right-angled edges of rectangular parasitic patches are prone to abrupt edge field changes during current feeding, thereby exciting unnecessary higher-order modes and causing impedance mismatch spikes within the antenna's operating bandwidth. Elliptical edges, on the other hand, possess continuous curvature variation characteristics, allowing surface current to propagate smoothly along the elliptical arc, effectively suppressing abnormal splitting of in-band resonant points and resulting in a smoother reflection coefficient curve for the antenna within the operating frequency band. Second, in the dynamic condition of high-speed rotation of the power transmission shaft 5, the smooth edges of the elliptical structure make the surface current distribution of the patch significantly less sensitive to changes in rotation angle than that of a rectangular patch. This, to some extent, compensates for the polarization mismatch effect caused by rotation, maintaining a high transmission coupling coefficient stability with the receiving antenna.

[0040] In one embodiment, the first parasitic patch 421 and the second parasitic patch 422 are spaced 0.08 wavelengths apart along the length of the serpentine radiating plate 4. This spacing facilitates resonant current transmission, ensuring normal radiation of the miniaturized monopole transmitting antenna along the power transmission axis. The minor axis of the first parasitic patch 421 and the second parasitic patch 422 occupies 0.4 wavelengths of the operating frequency, contributing to good antenna resonance.

[0041] In one embodiment, the first parasitic patch 421, the second parasitic patch 422, and the serpentine radiating plate 4 are integrally formed. Considering the small size and operating frequency characteristics of the miniaturized monopole transmitting antenna, integral forming is the optimal processing method. This avoids the generation of high-frequency parasitic parameters from frequent welding. Furthermore, the antenna operates at high speed and withstands vibration during the high-speed rotation of the power transmission shaft 5; integral forming effectively ensures mechanical reliability. It is understood that the integral structure between the first parasitic patch 421, the second parasitic patch 422, and the serpentine radiating plate 4 is only a preferred embodiment of this invention. In other embodiments, depending on the actual processing technology or application scenario requirements, the parasitic patch can also be disposed on the serpentine branch 43 in the following alternative ways: Split-type soldering: The parasitic patch is an independent metal sheet, which is fixed to the corresponding position of the serpentine branch by low-temperature soldering. It is suitable for sample debugging stage and facilitates the replacement of patches of different sizes. Conductive adhesive bonding: The parasitic patch is bonded and fixed using conductive silver paste or conductive epoxy resin, which is suitable for flexible dielectric boards that cannot withstand high-temperature welding; regardless of the connection method used, as long as effective electrical conduction is ensured between the parasitic patch and the serpentine branch and the preset relative positional relationship is maintained, it falls within the scope of the equivalent settings covered by the claims of this invention.

[0042] In one embodiment, the outer contour of the serpentine radiating plate 4 is rectangular. This rectangular contour is not merely for manufacturing convenience, but is one of the key structural features of the invention for achieving adaptability within the confined space of the power transmission axis. Because the radial gap between the power transmission axis 5 and the protective shell 6 is much smaller than the available axial space, the lateral dimensions of the antenna are extremely limited. Designing the serpentine radiating plate 4 as rectangular allows the projected area required to accommodate the serpentine stubs 43 and their parasitic patches to extend axially and narrow radially. This ensures that the total bending length of the serpentine stubs 43 is sufficient to resonate in the 2.4GHz to 2.5GHz operating frequency band, while compressing the overall antenna width to 0.05 wavelengths of the operating frequency. This ensures that the antenna can be completely embedded in the surface of the circuit module without mechanical interference with the rotating axis or the stationary protective shell. Meanwhile, the long side of the rectangle coincides with the main extension direction of the serpentine branch 43, which helps to enhance the polarization purity of the antenna along the axis and improve the polarization matching stability with the receiving antenna under the dynamic rotation of the axis. Compared with square or circular outline layouts, this rectangular configuration achieves synergistic optimization of electrical performance and space utilization within the limited installation boundary.

[0043] The serpentine branch 43 is composed of multiple conductive segments that are bent sequentially and connected vertically. This multi-segment bending configuration has the following synergistic advantages: Firstly, within the extremely limited radial space between the power transmission shaft 5 and the protective shell 6, the 90° bending path can obtain the maximum surface current equivalent path within a unit projected length. This ensures that the antenna resonant frequency drops to the 2.4GHz-2.5GHz operating frequency band while compressing the overall lateral width of the antenna to only 0.05 operating frequency wavelengths, which is the core mechanism for achieving miniaturization.

[0044] Secondly, the capacitive loading effect formed by the optimized spacing between adjacent reverse parallel line segments effectively compensates for the input reactance offset introduced by the size reduction and broadens the impedance bandwidth.

[0045] Third, the right-angle bending nodes form a periodic reinforcing array in terms of structural mechanics, improving the fatigue strength of the serpentine radiating plate 4 under high-speed rotation and vibration conditions of the power transmission shaft 5. Fourth, the electromagnetic response of this vertical segmented topology is less sensitive to manufacturing tolerances; only the length dimensions of each segment need to be controlled to ensure the consistency of the resonant frequency of batch products, resulting in a high yield rate. Therefore, this serpentine branch 43 configuration meets the special application requirements of power transmission shaft load testing wireless communication in terms of electrical performance, mechanical reliability, and manufacturability.

[0046] In one embodiment, both the medium plate 3 and the floor 2 have a rectangular outer contour; the length and width of the rectangular floor 2 are both smaller than the length and width of the medium plate 3.

[0047] In one embodiment, the dielectric plate 3, the serpentine radiating plate 4, and the floor 2 all have a rectangular outer contour. The length of the serpentine radiating plate 4 is set to any value within the range of 0.12 to 0.18 times the wavelength of the working frequency, and the width is set to any value within the range of 0.03 to 0.08 times the wavelength of the working frequency. The optimal combination is a length of 0.15 wavelengths of the working frequency and a width of 0.05 wavelengths of the working frequency.

[0048] The above-mentioned size range is set based on the following: For length, the lower limit of 0.12 operating frequency wavelengths is the minimum physical length that ensures the equivalent electrical length of the serpentine stub 43 is still sufficient to make the antenna resonate in the 2.4GHz~2.5GHz operating frequency band after multiple bends. If it is lower than this value, even if the bending density is maximized, the antenna resonant frequency will be difficult to drop to the target frequency band, and the radiation resistance will decrease sharply, resulting in impedance mismatch. The upper limit of length of 0.18 operating frequency wavelengths is the maximum allowable size determined based on the available space along the power transmission axis 5 and the compactness of the circuit module layout. At the same time, it avoids exciting higher-order resonant modes and interfering with in-band performance. The preferred value of 0.15 operating frequency wavelengths has been verified by electromagnetic simulation, which shows that the optimal comprehensive performance of antenna gain, bandwidth and radiation pattern directivity can be achieved at this length.

[0049] Regarding the width, its upper limit of 0.08 operating frequency wavelengths is limited by the small radial gap between the power transmission shaft 5 and the protective shell 6. The antenna width must be smaller than this gap and a vibration safety margin must be reserved to ensure that the antenna will not mechanically interfere with the stationary protective shell 6 under high-speed rotation and vibration conditions of the power transmission shaft 5. The lower limit of the width of 0.03 operating frequency wavelengths is the critical value to ensure that the antenna has sufficient radiation resistance and impedance bandwidth. When the width is less than 0.03 operating frequency wavelengths, the antenna impedance bandwidth is extremely small. The preferred value of 0.05 operating frequency wavelengths provides sufficient lateral space for the bending density design of the serpentine branch 43 under the premise of satisfying the radial space safety constraint, which can accommodate several effective bends and extend the equivalent current path. At the same time, it ensures the reasonable layout gap between the first parasitic patch 421 and the second parasitic patch 422 and suppresses the disturbance of the resonant frequency by the edge parasitic capacitance. When the length and width are selected within the above range, it can be ensured that the transmission coupling coefficient between the antenna and the receiving antenna is greater than -35dB in the 2.4GHz~2.5GHz operating frequency band, which meets the link reliability requirements of the power transmission axis load test wireless communication system.

[0050] In one embodiment, the length of the dielectric substrate 3 is set to any value within the range of 0.15 to 0.20 times the wavelength of the operating frequency, and the width is set to any value within the range of 0.05 to 0.10 times the wavelength of the operating frequency. The optimal combination is a length of 0.17 wavelengths of the operating frequency and a width of 0.07 wavelengths of the operating frequency.

[0051] The above-mentioned size range is set based on the following: In terms of length, the dielectric substrate 3, as the physical carrier of the serpentine radiating plate 4 and the ground plane 2, must be longer than the length of the serpentine radiating plate 4, preferably by 0.1 operating frequency wavelengths, to provide necessary edge gaps at both ends of the serpentine radiating plate 4. This gap has a dual electromagnetic function: on the one hand, it prevents the electric field at the end of the serpentine radiating plate 4 from becoming excessively concentrated and exciting the surface wave mode; on the other hand, it provides a smooth dielectric transition for the edge field at the end of the radiating aperture, avoiding reflection loss caused by impedance abrupt changes. Electromagnetic simulation verification shows that when the length of the dielectric substrate 3 exceeds the length of the serpentine radiating plate 4 by 0.02λ to 0.05λ, the antenna has the best return loss and radiation pattern stability in the 2.4GHz~2.5GHz frequency band. The upper limit of 0.20 operating frequency wavelengths is based on the consideration of the axial space of the power transmission shaft 5 and the compact integration of the circuit module, avoiding the violation of the miniaturization design intention due to the redundancy of the dielectric substrate 3 size.

[0052] Regarding the width, the width of dielectric substrate 3 should also be greater than the width of serpentine radiating plate 4, preferably by 0.05 operating frequency wavelengths, to form symmetrical edge gaps on both sides of serpentine radiating plate 4. This gap can effectively suppress the coupling effect between the side electric field of serpentine radiating plate 4 and the edge of dielectric substrate, reduce the surface wave excitation intensity, thereby reducing unnecessary lateral radiation and cross-polarization components, and improving the purity of the antenna's main polarization. In addition, this gap also provides tolerance space for PCB cutting process tolerances, avoiding the serpentine radiating plate 4 being exposed outside the edge of dielectric substrate due to processing offset, which would affect radiation performance. The upper limit of width, 0.10 operating frequency wavelengths, is mainly limited by the small radial gap between power transmission shaft 5 and protective shell 6. When the width of dielectric substrate 3 is 0.07 operating frequency wavelengths, a safe gap can still be maintained between it and protective shell 6 under maximum vibration displacement conditions after the circuit module is embedded, eliminating the risk of rotational scratching. The lower limit of width, 0.05 operating frequency wavelengths, is the minimum possible value for accommodating serpentine radiating plate 4. At this point, there is no edge gap protection, and the electrical performance and mechanical reliability are not preferred. When the length and width of the dielectric substrate 3 are selected within the above range, it can be ensured that the transmission coupling coefficient between the antenna and the receiving antenna is greater than -35dB in the 2.4GHz~2.5GHz operating frequency band, and the impedance bandwidth and radiation pattern directivity of the antenna meet the link index requirements of the power transmission axis load test wireless communication system.

[0053] In one embodiment, the length of the floor 2 is set to any value in the range of 0.05 to 0.10 times the wavelength of the working frequency, and the width is preferably set to any value in the range of 0.015 to 0.04 times the wavelength of the working frequency. The optimal combination is a length of 0.07 wavelengths of the working frequency and a width of 0.02 wavelengths of the working frequency.

[0054] The above size range is based on the following criteria: Regarding length, this embodiment adopts a partial ground plane monopole antenna configuration. The ground plane 2 only covers a portion of the lower surface of the dielectric substrate 3 near the feed terminal 1. The length of the ground plane 2 directly determines the size of the ground plane at the feed point, thereby controlling the real and imaginary parts of the antenna input impedance. When the length is in the range of 0.05λ to 0.10λ, the antenna can achieve good impedance matching and high radiation efficiency in the 2.4GHz~2.5GHz operating frequency band, with a preferred value of 0.07 operating frequencies. The wavelength was verified by electromagnetic simulation, which ensured that the edge of the ground plane 2 was located near the end of the trapezoidal impedance transformation patch 41, so that the impedance transformation section was completely within the effective reference ground plane area of ​​the ground plane 2, guaranteeing the stability and consistency of the impedance gradient. If the length is less than 0.05 operating frequency wavelengths, the mirror current provided by the ground plane 2 is insufficient, the radiation resistance decreases, and the mismatch with the 50-ohm feed system is aggravated. If the length is greater than 0.10 operating frequency wavelengths, the ground plane 2 will extend excessively below the serpentine radiating plate 4, shielding the effective radiation aperture, resulting in reduced radiation efficiency, and contradicting the miniaturization design principle of the dielectric substrate 3. Regarding the width, the width of the ground plane 2 must first meet the requirements of reliable welding and grounding continuity of the outer conductor 12 of the feed terminal. At the same time, as a partial ground plane structure, its width is significantly smaller than that of the serpentine radiating plate 4, which is a key design feature for achieving effective radiation. The narrower ground plane 2 allows the electromagnetic fields on both sides of the serpentine radiating plate 4 to bypass the edge of the ground plane 2 and form a sufficient radiation aperture, rather than being completely shielded. When the width is 0.02 wavelengths of the operating frequency, it provides sufficient feed grounding reference and uniform surface current distribution space, while retaining sufficient radiation window and avoiding degradation into a weak radiation microstrip line structure. The lower limit of the width, 0.015 wavelengths of the operating frequency, is the minimum allowable value to ensure the welding reliability and grounding continuity of the feed terminal 1. The upper limit of the width, 0.04 wavelengths of the operating frequency, is the critical value to avoid the ground plane 2 from being excessively widened and blocking the lateral radiation path of the serpentine radiating plate 4, resulting in a significant decrease in antenna directivity. When the length and width of the floor 2 are selected within the above range, it can be ensured that the transmission coupling coefficient between the antenna and the receiving antenna is greater than -35dB in the 2.4GHz~2.5GHz operating frequency band, and the impedance bandwidth and directivity of the antenna meet the link index requirements of the power transmission axis load test wireless communication system.

[0055] In one embodiment, the dielectric substrate 3 is a PCB board, and the thickness of the dielectric substrate 3 is preferably set to any value within the range of 0.8mm to 1.6mm, with 1mm being the optimal implementation value. The setting of this thickness range takes into account the following factors: Firstly, within the extremely limited radial space between the power transmission shaft 5 and the protective shell 6, this thickness ensures that the antenna has sufficient radiation efficiency and impedance bandwidth, while also minimizing the profile height to ensure that it does not mechanically interfere with stationary parts when rotating with the shaft. Secondly, 1mm thick FR4 board is a standard specification in the PCB industry. The processing technology is mature, the mass production consistency is good, the dielectric layer thickness tolerance is usually ±10%, and the actual thickness can be controlled within the range of 0.9mm~1.1mm. The impact on the antenna resonant frequency is within an acceptable range. Third, a thickness of 0.8 mm or more can ensure that the dielectric plate 3 has sufficient bending stiffness under high-speed rotation and vibration conditions of the power transmission shaft 5, and avoid frequency drift caused by deformation. If the thickness is less than 0.8 mm, the radiation efficiency will be significantly reduced and the mechanical strength will be insufficient. If the thickness is greater than 1.6 mm, it will excite significant surface wave modes, leading to deterioration of cross-polarization performance and possibly exceeding the size limit of the narrow installation space.

[0056] Furthermore, the relative permittivity of the dielectric substrate 3 is set to any value within the range of 4.2 to 4.8, preferably 4.4. This range is determined based on the actual physical characteristics of the FR4 epoxy glass cloth laminate in the 2.4GHz to 2.5GHz operating frequency band. The permittivity of FR4 material fluctuates with frequency and temperature, and its maximum variation can reach 20% within the temperature range of 0 to 70℃. Setting the parameter range of 4.2 to 4.8 can cover the parameter drift caused by temperature changes and batch differences, ensuring the stable performance of the antenna under actual operating conditions. Qualitatively, when the dielectric constant is preferably 4.4, the optimal balance between antenna size reduction and impedance bandwidth can be achieved. Compared with materials with lower dielectric constants, this preferred value effectively reduces the overall size of the antenna, which meets the purpose of miniaturization. Compared with materials with higher dielectric constants, this preferred value also ensures that the antenna has sufficient impedance bandwidth in the 2.4GHz~2.5GHz frequency band. If the dielectric constant is lower than 4.2, the antenna size will increase significantly, making it difficult to meet the installation constraints in a small space. If the dielectric constant is higher than 4.8, the impedance bandwidth will be significantly narrowed, affecting the reliability of system communication.

[0057] Furthermore, the loss tangent of the dielectric substrate 3 is set to any value within the range of 0.015 to 0.025, preferably less than 0.02. This range is set based on the fact that the dielectric loss tangent directly determines the antenna's radiation efficiency. In the 2.4GHz to 2.5GHz operating frequency band, the loss tangent of FR4 material is typically between 0.018 and 0.025. Controlling the loss tangent below 0.02 ensures that the antenna radiation efficiency meets the system link budget requirements and that the transmission coupling coefficient between the transmitting antenna and the receiving antenna is greater than -35dB. If the loss tangent exceeds 0.025, the dielectric loss will increase significantly, leading to a sharp decrease in antenna radiation efficiency, which in turn affects the reliability of wireless transmission of power transmission axis load test data. This loss range ensures electrical performance while remaining compatible with the lower-cost FR4 substrate, eliminating the need to force the use of expensive high-frequency specialized substrates such as Rogers, thus achieving a good balance between performance and cost.

[0058] In one embodiment, the power supply terminal 1 is a coaxial probe power supply structure or an SMA connector power supply structure.

[0059] In one embodiment, the miniaturized monopole transmitting antenna operates in the frequency band of 2.4 GHz to 2.5 GHz, and the transmission coupling coefficient between the transmitting antenna and the receiving antenna is greater than -35 dB within the operating frequency band.

[0060] The miniaturized monopole transmitting antenna is positioned along the power transmission axis as follows: Figure 5 As shown. The reflection coefficient of the miniaturized monopole transmitting antenna in the power transmission axis is as follows. Figure 6 As shown, it resonates well and operates normally within the 2.4-2.5GHz range.

[0061] The coupling coefficient between this miniaturized monopole transmitting antenna and the receiving antenna at different angles as the inner shell rotates along the power transmission axis is as follows: Figure 7 As shown, the coupling coefficient between ports is greater than -35dB within the 2.4-2.5GHz range, achieving good signal transmission and demonstrating excellent transmission characteristics.

[0062] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A miniaturized monopole transmitting antenna for wireless communication in power transmission shaft load testing, characterized in that, It includes a dielectric plate (3), a serpentine radiating plate (4) disposed on the upper surface of the dielectric plate (3), a floor (2) disposed on the lower surface of the dielectric plate (3), and a power supply terminal (1); The power supply terminal (1) is electrically connected to the serpentine radiating plate (4) and the floor (2) respectively, so that the radio frequency signal from the power supply terminal (1) excites an electromagnetic field between the serpentine radiating plate (4) and the floor (2), and radiates outward into space through the serpentine radiating plate (4); The serpentine radiating plate (4) includes a power supply transition section (41) electrically connected to the power supply terminal (1), a serpentine branch (43) connected to the power supply transition section (41), and a first parasitic patch (421) and a second parasitic patch (422) respectively connected to the serpentine branch (43) and spaced apart. The miniaturized monopole transmitting antenna is configured inside the power transmission shaft and close to the power transmission shaft body (5). The main extension direction of the serpentine radiating plate (4) is parallel to the axial direction of the power transmission shaft body (5) so as to maintain stable wireless coupling and transmission with the receiving antenna during the rotation of the power transmission shaft body (5).

2. The miniaturized monopole transmitting antenna for power transmission shaft load testing wireless communication according to claim 1, characterized in that, The power supply terminal (1) includes an inner conductor (11) and an outer conductor (12) that are coaxially arranged and insulated from each other. The inner conductor (11) is electrically connected to the serpentine radiating plate (4), and the outer conductor (12) is electrically connected to the floor (2).

3. A miniaturized monopole transmitting antenna for power transmission axis load testing wireless communication according to claim 1, characterized in that, The feed transition section (41) is a trapezoidal impedance transformation patch. The trapezoidal impedance transformation patch (41) is located between the feed terminal (1) and the serpentine stub (43) and is used to couple the radio frequency energy of the feed terminal (1) to the serpentine stub (43).

4. A miniaturized monopole transmitting antenna for power transmission shaft load testing wireless communication according to claim 1, characterized in that, Both the first parasitic patch (421) and the second parasitic patch (422) are elliptical parasitic patches; The first parasitic patch (421) and the second parasitic patch (422) are arranged at 0.08 working frequency wavelengths along the length direction of the serpentine radiating plate (4); the short axis of the first parasitic patch (421) and the second parasitic patch (422) occupies 0.4 working frequency wavelengths; The first parasitic patch (421), the second parasitic patch (422), and the serpentine radiating plate (4) are integrally formed or separately welded or electrically bonded.

5. A miniaturized monopole transmitting antenna for wireless communication in power transmission axis load testing according to claim 1, characterized in that, The outer contour of the serpentine radiating plate (4) is rectangular; the serpentine branch (43) is composed of multiple conductive line segments that are bent sequentially and connected vertically.

6. A miniaturized monopole transmitting antenna for wireless communication in power transmission axis load testing according to claim 1, characterized in that, Both the medium plate (3) and the floor (2) have rectangular outer contours; the length and width of the rectangular floor (2) are smaller than the length and width of the medium plate (3).

7. A miniaturized monopole transmitting antenna for wireless communication in power transmission axis load testing according to claim 1, characterized in that, The dielectric plate (3), the serpentine radiating plate (4) and the floor (2) all have a rectangular outer contour. The length of the serpentine radiating plate (4) is set to any value in the range of 0.12 to 0.18 times the wavelength of the working frequency, and the width is set to any value in the range of 0.03 to 0.08 times the wavelength of the working frequency. The length of the dielectric substrate (3) is set to any value within the range of 0.15 to 0.20 times the wavelength of the working frequency, and the width is set to any value within the range of 0.05 to 0.10 times the wavelength of the working frequency. The length of the floor (2) is set to any value within the range of 0.05 to 0.10 times the wavelength of the working frequency, and the width is preferably set to any value within the range of 0.015 to 0.04 times the wavelength of the working frequency.

8. A miniaturized monopole transmitting antenna for wireless communication in power transmission axis load testing according to claim 1, characterized in that, The dielectric board (3) is a PCB board with a thickness of 0.8mm to 1.6mm, a dielectric constant of 4.2 to 4.8, and a loss tangent of 0.015 to 0.

025.

9. A miniaturized monopole transmitting antenna for wireless communication in power transmission axis load testing according to claim 1, characterized in that, The power supply terminal (1) is a coaxial probe power supply structure or an SMA connector power supply structure.

10. A miniaturized monopole transmitting antenna for power transmission axis load testing wireless communication according to claim 1, characterized in that, The miniaturized monopole transmitting antenna operates in the frequency band of 2.4 GHz to 2.5 GHz, and the transmission coupling coefficient between it and the receiving antenna is greater than -35 dB within the operating frequency band.

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