Uhf rfid omni-directional antenna adaptation method for hybrid topology and related device

Abstract

The application relates to the technical field of UHF RFID, in particular to a UHF RFID omnidirectional antenna adaptation method of a mixed topology structure and related devices. The UHF RFID omnidirectional antenna adaptation method of the mixed topology structure is provided, and the steps include: constructing a mixed topology radiation structure, the mixed topology radiation structure comprises a first radiation unit arranged on a PCB substrate and a cable type second radiation unit connected to the PCB substrate, the first radiation unit is used for realizing basic signal radiation, and the cable type second radiation unit is used for expanding the radiation range. The mixed topology radiation structure of the first radiation unit of the PCB substrate and the cable type second radiation unit is constructed, and the contradiction between miniaturization, reading distance and omnidirectional radiation in the prior art is solved. The first radiation unit on the PCB substrate utilizes the miniaturization characteristics of the PCB, realizes efficient radiation of the basic signal, and guarantees the compactness of the antenna.

Description

Technical Field

[0001] This invention relates to the field of UHF RFID technology, specifically to a method and related apparatus for adapting a hybrid topology UHF RFID omnidirectional antenna. Background Technology

[0002] Ultra-high frequency radio frequency identification (UHF RFID) has driven the extension of IoT applications to more refined and miniaturized scenarios due to its long-range identification, simultaneous reading of multiple tags, and high-speed data transmission characteristics, such as equipment identification inside industrial cabinets and identification of irregularly shaped smart terminals. This has placed more stringent requirements on the performance of UHF RFID antennas. They must be able to adapt to the installation constraints of confined spaces, such as the limited three-dimensional space inside a cabinet, while ensuring sufficient reading distance to cover the tag distribution area. At the same time, they must have true 360-degree omnidirectional radiation characteristics to ensure that tags can be effectively identified no matter where they are located around the antenna.

[0003] However, the design of existing UHF RFID omnidirectional antennas often falls into a dilemma between size and performance: in order to achieve miniaturization, existing antennas mostly adopt a single microstrip patch or short dipole structure. Although this can reduce the size, the limited size of the radiating element leads to a decrease in radiated power density, and the reading distance is difficult to meet the needs of practical applications. For example, the distance between the tag and the antenna inside the cabinet often exceeds 2 meters. If the antenna size is increased in order to improve the reading distance, it cannot meet the installation requirements of a small space.

[0004] Furthermore, even though some antennas attempt to extend their radiation range by increasing the number of radiating elements, the radiation pattern still exhibits significant directional deviations due to limitations in the radiating structure topology design. For example, the actual radiation angle is often less than 120 degrees, failing to achieve 360-degree omnidirectional coverage. This results in tags being unidentifiable in certain locations, severely restricting the performance of UHF RFID systems. Therefore, how to achieve synergistic optimization of miniaturization, sufficient reading distance, and 360-degree omnidirectional radiation characteristics for UHF RFID omnidirectional antennas in confined space installation scenarios has become a current technical challenge for UHF RFID antennas. Summary of the Invention

[0005] This disclosure proposes a method and related apparatus for adapting a UHF RFID omnidirectional antenna with a hybrid topology, aiming to overcome at least one of the defects existing in the prior art.

[0006] To achieve the above objectives, the technical solution disclosed in this invention is as follows:

[0007] According to one aspect of this disclosure, a method for adapting a hybrid topology UHF RFID omnidirectional antenna is provided, comprising the steps of:

[0008] A hybrid topology radiation structure is constructed, comprising a first radiation unit disposed on a PCB substrate and a cable-type second radiation unit connected to the PCB substrate. The first radiation unit is used to realize basic signal radiation, and the cable-type second radiation unit is used to extend the radiation range.

[0009] Impedance matching is performed on the hybrid topology radiation structure by adjusting the matching circuit parameters on the PCB substrate to match the input impedance of the hybrid topology radiation structure with the output impedance of the power supply system, thereby improving signal transmission efficiency.

[0010] Adjust the length of the cable-type second radiating unit, and calculate the electrical length of the cable-type second radiating unit according to the UHF RFID operating frequency, until the hybrid topology radiating structure forms a 360-degree omnidirectional radiating characteristic;

[0011] The adaptation effect of the hybrid topology radiation structure was verified, and its reading distance and omnidirectional radiation angle when installed in a confined space were tested to meet the application requirements of UHF RFID.

[0012] Furthermore, the first radiating unit is a microstrip patch radiating unit, which is disposed on the front side of the PCB substrate. The microstrip patch radiating unit is rectangular in shape, and its size is set according to the UHF RFID operating frequency to achieve miniaturized basic signal radiation.

[0013] Furthermore, one end of the cable-type second radiation unit is connected to the reverse side of the PCB substrate via a power supply point, which is electrically connected to the first radiation unit. The other end of the cable-type second radiation unit is a free end, which is used to extend the radiation range by adjusting the position of the free end.

[0014] Furthermore, the impedance matching step for the hybrid topology radiation structure includes: the matching circuit is an L-shaped matching network disposed on the reverse side of the PCB substrate. The L-shaped matching network includes an inductor and a capacitor connected in series, one end of which is connected to the feed point and the other end is connected to the first radiation unit, for matching the input impedance with the output impedance of the feed system by adjusting the inductance and capacitance values.

[0015] Furthermore, the electrical length of the cable-type second radiating unit is λ / 4, where λ is the wavelength corresponding to the UHF RFID operating frequency. The electrical length is achieved by adjusting the physical length of the cable-type second radiating unit, so that the radiation pattern of the hybrid topology radiation structure exhibits 360-degree omnidirectional characteristics.

[0016] Furthermore, the step of verifying the adaptation effect of the hybrid topology radiation structure includes: installing the hybrid topology radiation structure inside a cabinet in a confined space and detecting the reading distance of the UHF RFID tag; obtaining the radiation pattern of the hybrid topology radiation structure through an anechoic chamber test and detecting whether its omnidirectional radiation angle is not less than 360 degrees.

[0017] Furthermore, impedance matching of the hybrid topology radiation structure also includes: acquiring the ambient temperature through a temperature sensor installed on the PCB substrate, and adjusting the parameters of the matching circuit according to the ambient temperature to maintain the input impedance of the hybrid topology radiation structure and the output impedance of the power supply system at different temperatures.

[0018] Furthermore, adjusting the length of the cable-type second radiating unit also includes: detecting the antenna vibration state by using an accelerometer installed on the PCB substrate; when the vibration amplitude exceeds a preset threshold, adjusting the length of the cable-type second radiating unit to stabilize the omnidirectional radiation characteristics of the hybrid topology radiation structure under vibration conditions.

[0019] Furthermore, after verifying the adaptation effect of the hybrid topology radiation structure, the method further includes: real-time monitoring of the reading distance and omnidirectional radiation angle; when the reading distance is less than a preset value or the omnidirectional radiation angle deviates from 360 degrees, automatically adjusting the length of the cable-type second radiation unit and the parameters of the matching circuit to achieve dynamic adaptation.

[0020] According to another aspect of this disclosure, a hybrid topology UHF RFID omnidirectional antenna adaptation system is provided for implementing the hybrid topology UHF RFID omnidirectional antenna adaptation method as described above, comprising:

[0021] A hybrid topology radiation structure construction module is used to construct a hybrid topology radiation structure, which includes a first radiation unit disposed on a PCB substrate and a cable-type second radiation unit connected to the PCB substrate. The first radiation unit is used to realize basic signal radiation, and the cable-type second radiation unit is used to extend the radiation range.

[0022] Impedance matching module is used to perform impedance matching on the hybrid topology radiation structure. By adjusting the matching circuit parameters on the PCB substrate, the input impedance of the hybrid topology radiation structure is matched with the output impedance of the power supply system, thereby improving signal transmission efficiency.

[0023] The radiation characteristic optimization module is used to adjust the length of the cable-type second radiation unit and calculate the electrical length of the cable-type second radiation unit according to the UHF RFID operating frequency, so that the hybrid topology radiation structure forms a 360-degree omnidirectional radiation characteristic.

[0024] The adaptation effect verification module is used to verify the adaptation effect of the hybrid topology radiation structure, and to detect its reading distance and omnidirectional radiation angle when installed in a confined space, so as to meet the application requirements of UHF RFID.

[0025] According to another aspect of this disclosure, a UHF RFID omnidirectional antenna is provided, comprising:

[0026] The PCB substrate is made of a high dielectric constant material to reduce the size of the antenna;

[0027] The first radiating unit is a microstrip patch radiating unit, which is disposed on the front side of the PCB substrate and is used to realize basic signal radiation.

[0028] The second radiation unit is a coaxial cable, one end of which is connected to the reverse side of the PCB substrate through a feed point, and the other end is a free end used to extend the radiation range.

[0029] The matching circuit, which is an L-shaped matching network, is located on the reverse side of the PCB substrate and connected between the feed point and the first radiating unit. It is used to adjust the input impedance of the hybrid topology radiating structure.

[0030] The hybrid topology UHF RFID omnidirectional antenna adapter system described above is integrated into the PCB substrate;

[0031] A snap-fit ​​structure is provided on the edge of the PCB substrate to fix the PCB substrate in a narrow installation position.

[0032] A length adjustment mechanism is provided on the cable-type second radiating unit for adjusting the length of the cable-type second radiating unit.

[0033] According to another aspect of this disclosure, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the UHF RFID omnidirectional antenna adaptation method with a hybrid topology as described above.

[0034] The beneficial effects of this invention are:

[0035] This invention resolves the contradiction between miniaturization and readout distance and omnidirectional radiation in existing technologies by constructing a hybrid topology radiation structure consisting of a first radiating unit on a PCB substrate and a second radiating unit on a cable. The first radiating unit on the PCB substrate utilizes the miniaturization characteristics of the PCB to achieve efficient radiation of the basic signal, ensuring the antenna's compactness and perfectly adapting to the installation requirements of confined spaces such as server racks and irregularly shaped equipment.

[0036] Furthermore, the cable-type second radiating unit, by adjusting its length, extends the radiation range, effectively compensating for the insufficient reading distance of the miniaturized radiating unit and ensuring the effectiveness of tag identification. Simultaneously, through impedance matching design of the hybrid topology radiating structure, the matching degree between the input impedance and the power supply system is optimized, improving signal transmission efficiency and further guaranteeing the stability of the reading distance.

[0037] Furthermore, by calculating the electrical length of the cable-type second radiating unit corresponding to the UHF RFID operating frequency, the hybrid topology radiating structure forms a true 360-degree omnidirectional radiation characteristic, completely solving the problem of directional deviation of existing antennas and ensuring that the tag can be effectively identified no matter where it is located around the antenna.

[0038] Furthermore, by verifying the adaptation effect, the performance stability of the antenna when installed in a confined space was ensured. This achieved coordinated optimization of miniaturization, sufficient reading distance, and 360-degree omnidirectional radiation, significantly improving the reliability and adaptability of the UHF RFID system in confined space scenarios and providing technical support for the extension of IoT applications to the fields of refinement and miniaturization.

[0039] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0040] Figure 1 This is a flowchart of a UHF RFID omnidirectional antenna adaptation method with a hybrid topology in one embodiment of the present invention;

[0041] Figure 2 This is a 3D model diagram of a hybrid topology structure in one embodiment of the present invention;

[0042] Figure 3 This is an omnidirectional radiation pattern of a UHF RFID antenna in one embodiment of the present invention;

[0043] Figure 4 This is a Smith chart showing impedance matching in one embodiment of the present invention;

[0044] Figure 5 This is a broadband frequency response characteristic curve diagram in one embodiment of the present invention;

[0045] Figure 6 This is a schematic diagram of the three-dimensional electromagnetic field distribution in one embodiment of the present invention;

[0046] Figure 7 This is a diagram of an environmental adaptability system in one embodiment of the present invention;

[0047] Figure 8This is a three-dimensional schematic diagram of the system verification effect in one embodiment of the present invention. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0049] Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0050] The present invention provides the following preferred embodiments:

[0051] Example 1: To address the issues of limited radiation range, insufficient signal transmission efficiency, and difficulty in guaranteeing omnidirectional characteristics when UHF RFID antennas are installed in confined spaces, this example provides a hybrid topology UHF RFID omnidirectional antenna adaptation method. By constructing a hybrid topology radiation structure and optimizing its impedance matching and radiation characteristics, the antenna achieves efficient omnidirectional radiation and adaptability to confined spaces in the UHF band. Figure 1 As shown, the adaptation method flow is as follows:

[0052] S100: Construct a hybrid topology radiation structure, which includes a first radiation unit disposed on the PCB substrate and a cable-type second radiation unit connected to the PCB substrate. The first radiation unit is used to realize basic signal radiation, and the cable-type second radiation unit is used to extend the radiation range.

[0053] S200: Impedance matching of hybrid topology radiating structures. By adjusting the matching circuit parameters on the PCB substrate, the input impedance of the hybrid topology radiating structure is matched with the output impedance of the power supply system, thereby improving signal transmission efficiency.

[0054] S300: Adjust the length of the cable-type second radiating unit, calculate the electrical length of the cable-type second radiating unit according to the UHF RFID operating frequency, until the hybrid topology radiating structure forms a 360-degree omnidirectional radiating characteristic.

[0055] S400: Verify the adaptation effect of the hybrid topology radiation structure, and test its reading distance and omnidirectional radiation angle when installed in a confined space to meet the application requirements of UHF RFID.

[0056] When constructing a hybrid topology radiating structure, a PCB substrate is used as the basic carrier of the antenna. The PCB substrate has a rectangular structure, such as... Figure 2The PCB substrate in the hybrid topology 3D model shown has a first radiating unit and a cable-type second radiating unit connected to the PCB substrate. The first radiating unit is a microstrip patch structure, such as... Figure 2 The blue area refers to a rectangular patch on the PCB substrate, extending from 10 mm to 50 mm along the X-axis and from 15 mm to 35 mm along the Y-axis. This patch is used to achieve basic signal radiation in the UHF band, ensuring signal strength of the antenna in the core frequency band. The cable-type second radiating element has a spiral structure, such as... Figure 2 The red curve in the middle extends from 3 mm to 28 mm along the Z-axis. Its X-coordinate is 30 mm plus 8 mm multiplied by a sine function, i.e., 2π × 0.3 × z. cable， Where z cable This represents the length of the second radiating unit of the cable type in the Z-axis direction; the Y-coordinate is 25 mm plus 6 mm multiplied by the cosine function, i.e.: 2π × 0.25 × z cable By extending the spatial range of the antenna through the spiral structure, the antenna radiation field can cover a wider spatial area, thus compensating for the limited radiation range of the microstrip patch.

[0057] Furthermore, when performing impedance matching on the hybrid topology radiating structure, the input impedance is matched to the output impedance of the power supply system by adjusting the matching circuit parameters on the PCB substrate. The matching circuit adopts an L-shaped structure, such as... Figure 2 The "L-shaped matching network" marked near the feed point is located at the feed point on the PCB substrate. By changing the inductance and capacitance values ​​in the L-shaped circuit, the input impedance of the hybrid topology radiation structure is adjusted, such as... Figure 4 As shown, the Smith chart is used to monitor the changes in input impedance in real time until the input impedance point falls within the 50-ohm output impedance matching region of the power supply system, thereby reducing the reflection loss of the signal from the power supply system to the radiation structure and improving the signal transmission efficiency.

[0058] Furthermore, when adjusting the length of the cable-type second radiating unit, its electrical length is calculated based on the UHF RFID operating frequency. The electrical length is the physical length of the cable multiplied by the ratio of the dielectric wavelength to the free space wavelength, where the dielectric wavelength is the free space wavelength divided by the square root of the relative permittivity of the dielectric. This is achieved by changing the helix length of the cable-type second radiating unit, such as adjusting z... cable The range was adjusted from 3 mm to 28 mm to 3 mm to 30 mm, so that the electrical length of the cable-type second radiating unit was equal to 1 / 2 wavelength or 1 / 4 wavelength of the UHF band, until the radiation pattern of the hybrid topology radiating structure exhibited 360-degree omnidirectional characteristics, such as... Figure 3As shown, the radiation field is circularly distributed on the horizontal plane, and the difference in radiation intensity in each direction is less than 1 dB, ensuring that the antenna can achieve uniform radiation in all directions on the horizontal plane, meeting the requirements of the UHF RFID system for omnidirectional coverage.

[0059] Furthermore, when verifying the adaptation effect of the hybrid topology radiation structure, the antenna is installed in a confined space, such as inside a cabinet. Figure 7 The environmental adaptability system diagram shown and Figure 8 The cabinet installation environment shown is a verification scenario where the reading distance and omnidirectional radiation angle are tested. Reading distance is tested by placing UHF RFID tags at different locations within the cabinet, such as the front, side, or top, and using a power meter and spectrum analyzer to measure the furthest distance at which the antenna can stably read the tag. Figure 8 The "2.5-meter reading range" marked on the label ensures sufficient reading distance even in confined spaces. The omnidirectional radiation angle detection involves placing tags every 10 degrees on a horizontal plane to test the tag reading success rate, ensuring that the reading success rate is greater than 95% within a 360-degree range. This verifies that the omnidirectional radiation characteristics of the antenna are not affected when installed in confined spaces, thus meeting the application requirements of UHF RFID in confined spaces such as cabinets, warehouse shelves, and medical equipment.

[0060] This embodiment achieves efficient omnidirectional radiation of a UHF RFID antenna in the UHF band by constructing a hybrid topology radiation structure combined with impedance matching and radiation characteristic optimization. At the same time, by verifying its installation adaptability in confined spaces, it ensures that the antenna can meet the reading distance and omnidirectional characteristics requirements in practical applications, providing technical support for the deployment of UHF RFID systems in confined spaces.

[0061] Example 2: To address the issue that the basic radiation performance of UHF RFID antennas is easily limited by size in miniaturized designs, this example further refines the first radiating unit in the hybrid topology radiation structure, setting it as a rectangular microstrip patch adapted to the UHF frequency band. By optimizing its structural parameters and integration method with the PCB substrate, the miniaturized basic signal radiation and the hybrid topology structure are synergistically adapted.

[0062] Specifically, when constructing the hybrid topology radiating structure, the first radiating unit adopts a microstrip patch form and is directly disposed on the front side of the PCB substrate, such as... Figure 2In the 3D model of the hybrid topology shown, the blue area represents the microstrip patch, which completely covers the core area of ​​the PCB substrate's upper surface. This microstrip patch has a rectangular structure, extending from 10 mm to 50 mm along the X-axis and from 15 mm to 35 mm along the Y-axis of the PCB substrate. Its length and width are strictly based on the operating frequency of UHF RFID. The choice of a rectangular shape is based on the classic design logic of microstrip patch antennas, ensuring stable radiation characteristics and high compatibility with PCB processes. This guarantees structural consistency in mass production while avoiding interference from complex shapes on the radiation field.

[0063] Furthermore, the size of the microstrip patch needs to consider the dielectric properties of the PCB substrate and the resonance requirements of the UHF band. The PCB substrate uses FR4 material with a relative permittivity of 4.4 and a thickness of 1.6 mm. During the design process, the effective permittivity of the microstrip patch is first calculated based on the operating frequency. Then, edge effect correction is applied to compensate for the resonant frequency shift caused by the capacitance effect at the edges of the microstrip patch, ultimately determining the length and width of the rectangular microstrip patch. For example, for a center frequency of 915 MHz, the length of the microstrip patch is approximately 40 mm, corresponding to a resonant length of 1 / 2 wavelength in the dielectric, and the width is approximately 20 mm to ensure the coordination of the input impedance and matching circuit. This size satisfies the resonance requirements of the UHF band while maintaining the miniaturization characteristics of the antenna. Figure 2 The PCB substrate measures 60 mm × 50 mm, with microstrip patches occupying the main surface area but not extending beyond the substrate boundary.

[0064] Furthermore, as the basic radiating unit of the hybrid topology radiating structure, the main function of the rectangular microstrip patch is to achieve basic signal radiation in the UHF band, ensuring the signal strength of the antenna in the core frequency band. Its planar structure is fully integrated with the PCB substrate, avoiding additional volume occupation, making it ideal for installation in confined spaces, such as... Figure 8 The rack installation environment is shown. Meanwhile, the radiation direction of the microstrip patch is mainly concentrated in the normal direction of the PCB substrate (Z-axis direction), complementing the cable-type second radiating element (spiral structure, radiation direction concentrated in the horizontal direction, i.e., the XY plane). The normal direction radiation of the microstrip patch ensures the antenna's signal coverage in the vertical direction, while the horizontal direction radiation of the cable-type second radiating element extends the antenna's lateral coverage. The superposition of their radiation fields achieves the antenna's 360-degree omnidirectional radiation characteristics, such as... Figure 3 The omnidirectional radiation pattern shown has a radiation intensity difference of less than 1 dB on the horizontal plane.

[0065] Furthermore, the size setting of the rectangular microstrip patch also needs to be coordinated with the matching circuit. For example, Figure 2The L-shaped matching network near the feed point requires adjustments to its inductance and capacitance values ​​in conjunction with the microstrip patch's input impedance. This impedance is primarily determined by the microstrip patch's width; a wider patch results in a lower input impedance. Therefore, the design must balance the microstrip patch's width with its input impedance to ensure the matching circuit effectively adjusts the input impedance of the hybrid topology to match the feed system's 50-ohm output impedance. Figure 4 As shown in the Smith chart, the input impedance point falls within the matching region. This cooperative design ensures efficient signal transmission from the feed system to the radiating structure, avoiding signal reflection loss caused by input impedance mismatch.

[0066] Furthermore, through Figure 5 The frequency response curves shown indicate that within the UHF RFID band, the return loss (S11) is consistently below -10 dB, with -35 dB at 915 MHz and -28 dB at 875 MHz. This demonstrates the good basic radiation performance of the rectangular microstrip patch, and its size conforms to the resonance requirements of the UHF band. Simultaneously, the voltage standing wave ratio (VSWR) is consistently less than 2 within this band. Figure 5 As shown by the red dashed line, the synergistic effect of the microstrip patch and the matching circuit is further verified, ensuring signal transmission efficiency.

[0067] This embodiment achieves a balance between antenna miniaturization and basic radiation performance by refining the first radiating element into a rectangular microstrip patch and setting its size according to the UHF frequency. This provides fundamental support for the omnidirectional radiation and adaptability to confined spaces in the hybrid topology structure. The planar structure of the rectangular microstrip patch is compatible with PCB manufacturing processes, and its size setting meets the resonance requirements of the UHF band. Its basic radiation characteristics complement the extended radiation characteristics of the cable-type second radiating element, jointly achieving efficient omnidirectional radiation of the UHF RFID antenna.

[0068] Example 3: In order to solve the problems of electrical connection coordination between the second radiation unit and the first radiation unit and the adaptation of radiation range expansion in the hybrid topology radiation structure, this example further optimizes the integration method of the cable-type second radiation unit, clarifies its electrical connection relationship with the PCB substrate and the first radiation unit, and realizes flexible expansion of radiation range through the structural design of free end.

[0069] When constructing a hybrid topology radiating structure, the cable-type second radiating unit adopts a spiral structure, such as... Figure 2The red curve shown has one end fixedly connected to the reverse side of the PCB substrate, specifically through a feed point located at the edge of the reverse side of the PCB. This feed point penetrates the PCB substrate through a metallized via and is directly electrically connected to the feed area of ​​the microstrip patch of the first radiating unit on the front side, forming a direct electrical coupling between the first and second radiating units. This connection method ensures that the signal is transmitted from the first radiating unit to the second radiating unit through the feed point, and the current distribution of both produces a synergistic effect, jointly forming a mixed radiation field, such as... Figure 6 The three-dimensional electromagnetic field distribution shown is as follows: the red area represents the radiation field of the cable unit, and the blue area represents the radiation field of the microstrip patch. The two are superimposed in space to form a continuous electromagnetic field coverage.

[0070] Furthermore, the other end of the cable-type second radiating unit is a free end, not fixed to any structure, such as... Figure 2 The end of the spiral structure extends above the PCB substrate without connecting to other components. This free-end design allows for flexible optimization of the radiation characteristics of the cable-type unit by adjusting the position of the free end. For example, changing the extension length of the free end along the Z-axis or the horizontal offset along the X and Y axes can adjust the effective length and spatial distribution of the spiral structure, thereby changing the main lobe direction and side lobe level of its radiation pattern. Figure 3 As shown in the omnidirectional radiation pattern, the difference in radiation intensity on the horizontal plane is less than 1 dB. This result is directly related to the adjustment of the free end of the cable unit. By optimizing the position of the free end, the horizontal radiation field of the cable unit and the normal radiation field of the microstrip patch are more uniformly superimposed, thereby expanding the omnidirectional coverage of the antenna.

[0071] It is important to understand that the spiral structure parameters of the cable-type second radiating unit and the adjustment of the free end position need to be designed in a coordinated manner. For example... Figure 2 The spiral structure has an X-axis offset of 8 mm and a Y-axis offset of 6 mm. This design allows the radiation field of the cable-type unit to form a wider horizontal coverage, while the height of the free end is set to 28 mm to ensure that its radiation field effectively superimposes with the radiation field of the microstrip patch in space. Figure 6 As shown, the electromagnetic fields of the two are most significantly superimposed in the region 10 to 30 millimeters above the PCB substrate. This collaborative design not only ensures the miniaturization characteristics of the hybrid topology, such as... Figure 8 The rack installation environment shown has an overall antenna height of no more than 30 millimeters, and it also allows for flexible expansion of the radiation range.

[0072] Furthermore, the design of the free end of the cable-type second radiating unit needs to consider electrical isolation from the PCB substrate. For example, using surface-insulated enameled wire as the cable material can prevent short circuits caused by contact between the free end and the PCB substrate or other metal components, ensuring the stability of its radiation characteristics. Simultaneously, the adjustment range of the free end must be limited within the size range of the PCB substrate, such as... Figure 2 The X-axis should not exceed 0 to 60 mm and the Y-axis should not exceed 0 to 50 mm to avoid affecting the overall miniaturization design of the antenna due to excessive extension of the free end.

[0073] The advantage of this embodiment is that by clearly defining the electrical connection relationship between the cable-type second radiating unit, the PCB substrate, and the first radiating unit, the electrical synergy of the hybrid topology structure is ensured. At the same time, the structural design of the free end enables flexible expansion of the radiation range, providing an adjustable expansion path for the omnidirectional coverage of the hybrid topology radiation structure.

[0074] Example 4: In order to solve the matching problem between the input impedance of the hybrid topology radiating structure and the output impedance of the power supply system, this example further refines the matching circuit design in the impedance matching step, adopts an L-shaped matching network and optimizes its integration with the radiating structure, and achieves efficient impedance matching by adjusting the inductor and capacitor values.

[0075] Specifically, the impedance matching circuit adopts an L-shaped network structure and is directly set on the reverse side of the PCB substrate, such as... Figure 2 The "L-shaped matching network" marked area is located at the center of the reverse side of the PCB substrate. This arrangement avoids the matching circuit occupying space on the front side of the PCB and does not obstruct the radiation area of ​​the microstrip patch of the first radiating unit. Figure 2 The micro-strip surface mount is located on the front of the PCB, covering the core area, and the matching network on the back does not block its radiation field. The L-shaped matching network consists of an inductor and a capacitor connected in series. The inductor is a surface mount wire-wound inductor, and the capacitor is a surface mount multilayer ceramic capacitor. The two are connected in series through copper foil traces on the back of the PCB to form a complete matching path.

[0076] Furthermore, one end of the L-shaped matching network is connected to the feed point on the reverse side of the PCB, such as... Figure 2 Feed point 1 in the circuit has a metallized via penetrating the PCB substrate and connecting to the feed point of the microstrip patch on the front side. The other end is directly connected to the edge area of ​​the microstrip patch in the first radiating unit, achieving electrical connection through copper foil traces inside the PCB. This connection method allows the matching network to be connected in series between the feeding system and the hybrid topology radiating structure. The signal is transmitted from the feeding system to the matching network, undergoes impedance adjustment by inductors and capacitors, and then is transmitted to the first radiating unit and the cable-type second radiating unit. This ensures that the input impedance of the entire radiating structure matches the 50-ohm output impedance of the feeding system. Figure 4The Smith chart shown indicates that the input impedance point is located within the 50-ohm matching circle, which means the matching effect meets the requirements.

[0077] Furthermore, the inductance and capacitance values ​​of the L-shaped matching network are adjusted to achieve impedance matching. During the design process, the input impedance of the hybrid topology radiating structure is first measured using a network analyzer, along with the impedance without the matching network, to obtain its real and imaginary parts in the UHF RFID band. Then, based on the impedance transformation principle of the L-shaped network, the required inductance and capacitance values ​​are calculated. For example, when the input impedance of the radiating structure is inductive, a capacitor is chosen to cancel the inductive reactance; when it is capacitive, an inductor is chosen to cancel the capacitive reactance, ultimately ensuring that the adjusted input impedance has a real part of 50 ohms and an imaginary part of zero. The values ​​of inductance and capacitance are repeatedly adjusted, for example, the inductance value is adjusted between 1 and 10 microhenries, and the capacitance value is adjusted between 1 and 10 picofarads. The adjustment effect is verified using simulation software until the input impedance enters the matching region. Figure 4 The Smith chart simulation shown is shown.

[0078] It is important to understand that the inductance and capacitance values ​​of the L-type matching network need to be designed in conjunction with the input impedance characteristics of the hybrid topology radial structure. For example... Figure 5 The broadband frequency response curves shown indicate that the return loss is below -10 dB in the UHF RFID band. This result is directly related to the adjustment of the inductance and capacitance values ​​of the L-shaped network. By optimizing the inductance and capacitance values, the matching network effectively cancels out the reactive component of the radiating structure, minimizing the reflection loss during signal transmission. Simultaneously, the series structure of the L-shaped network results in low insertion loss and does not significantly affect the gain of the radiating structure. Figure 3 The omnidirectional radiation pattern shown has a gain of around 2 dB, which meets the requirements of a UHF RFID antenna.

[0079] Furthermore, the integration method of the L-shaped matching network needs to consider its coordination with the cable-type second radiating unit. For example, the matching network is set at the center of the reverse side of the PCB, and the connection feed point with the cable-type unit is as follows: Figure 2 The feed point 2 in the system is kept at a certain distance to avoid mutual interference between the electromagnetic fields of the two. At the same time, the copper foil line of the matching network adopts the form of microstrip line, and its width and length are designed according to the impedance matching requirements to ensure that the impedance of the line itself will not affect the matching effect. For example, the microstrip line width is set to 2 mm and the length is set to 5 mm, so that its characteristic impedance is equal to 50 ohms.

[0080] The advantage of this embodiment is that, through the structural design and integration of the L-shaped matching network, it achieves efficient matching between the input impedance of the hybrid topology radiation structure and the power supply system, ensuring the stability of signal transmission and providing a basis for impedance adaptation for the radiation performance of the hybrid topology.

[0081] Example 5: In order to solve the stability problem of the omnidirectional radiation characteristics of the hybrid topology radiation structure, this example further optimizes the electrical length design of the cable-type second radiation unit, clarifies its coordination relationship with the UHF RFID operating frequency, and achieves an electrical length of λ / 4 by adjusting the physical length, so as to ensure that the hybrid topology structure presents 360-degree omnidirectional radiation characteristics.

[0082] When constructing a hybrid topology radiating structure, the cable-type second radiating unit adopts a spiral structure, such as... Figure 2 The red curve shown extends along the Z-axis, and its electrical length is designed to be λ / 4 of the UHF RFID operating frequency. This design is based on transmission line theory; the λ / 4 electrical length allows the cable-type unit to resonate at the operating frequency, maximizing the current distribution and significantly enhancing the radiation field intensity. Figure 6 The three-dimensional electromagnetic field distribution shown is illustrated, with the red area representing the radiation field of the cable-type unit. Its intensity is directly related to the electrical length design. To achieve an electrical length of λ / 4, the physical parameters of the helical structure need to be adjusted, such as the number of turns, pitch, and central shaft length. For example... Figure 2 The spiral structure has 5 turns, a pitch of 6 mm, and a central shaft length of 30 mm. This design ensures that the effective physical length of the spiral structure, i.e., the total length along the spiral, is exactly equal to λ / 4 after adjusting the spiral factor. For example, the λ / 4 electrical length corresponding to 915 MHz is approximately 82 mm. With a spiral factor of 0.8, the physical length is approximately 102.5 mm. At this point, the total length of the spiral with 5 turns and a pitch of 6 mm is approximately 102 mm, which meets the requirements.

[0083] It is important to understand that the electrical length design of the cable-type second radiating unit must be strictly coordinated with the UHF RFID operating frequency. For example, when the operating frequency is 860MHz, the corresponding λ / 4 electrical length is approximately 87 mm. In this case, the number of turns of the spiral structure needs to be adjusted to 6 turns or the pitch to 7 mm to ensure that its electrical length equals 87 mm. This coordinated design ensures that the radiation characteristics of the cable-type unit match the operating frequency, and its radiation field forms a uniform distribution in the horizontal direction, such as... Figure 3 The horizontal radiation pattern shown exhibits radiation intensity differences of less than 1 dB at various angles. This uniformly distributed radiation field, when superimposed with the normal radiation field of the microstrip patch, forms a continuous 360-degree omnidirectional coverage, as... Figure 3 The omnidirectional radiation pattern shown has a coverage angle of 360 degrees on the horizontal plane.

[0084] Furthermore, the adjustment of the physical length of the cable-type second radiating unit needs to take into account its structural symmetry. For example... Figure 2The central axis of the spiral structure perfectly coincides with the normal direction (Z-axis) of the PCB substrate. This design ensures good symmetry of the spiral structure's radiation field in the horizontal direction, avoiding differences in radiation intensity caused by central axis misalignment. Furthermore, enameled wire with a diameter of 1 mm is used as the cable material, and its surface insulation layer prevents short circuits with the PCB substrate or other metal components, ensuring the stability of physical length adjustment. In addition, the free end of the spiral structure is not fixed to any structure; this design allows for unrestricted physical length adjustment, facilitating optimization based on changes in operating frequency.

[0085] Furthermore, combined Figure 3 As shown in the omnidirectional radiation pattern, the difference in horizontal radiation intensity of the hybrid topology is less than 1 dB. This result is directly related to the λ / 4 electrical length design of the cable cell. The λ / 4 electrical length ensures that the radiation field of the cable cell is uniformly distributed in the horizontal direction, while the radiation field of the microstrip patch is stronger in the normal direction (Z-axis). After the two are superimposed, the horizontal radiation intensity is compensated, forming 360-degree omnidirectional coverage. It is important to understand that this superposition effect requires precise design of the electrical length. If the electrical length deviates from λ / 4, the radiation field of the cable cell will exhibit a directional shift, leading to an increase in the difference in horizontal radiation intensity and failing to achieve omnidirectional characteristics.

[0086] The advantage of this embodiment is that by optimizing the electrical length of the cable-type second radiating unit to λ / 4, a 360-degree omnidirectional radiation characteristic of the hybrid topology radiation structure is achieved, ensuring uniform coverage in UHF RFID applications and providing a basis for the radiation characteristics of the hybrid topology adaptation performance.

[0087] Example 6: In order to solve the problem of verifying the adaptability of the hybrid topology radiation structure in a real environment, this example further refines the steps for verifying the adaptability effect, clarifies the specific implementation methods for cabinet installation testing in a confined space and radiation pattern testing in an anechoic chamber, and ensures the omnidirectional radiation performance of the hybrid topology structure and its adaptability in practical applications.

[0088] The first step in verifying the adaptation effect was to conduct rack installation tests in a confined space. The hybrid topology radiating structure was installed in a corner inside the rack using magnetic attachment. Magnetic tabs were placed at the bottom of the antenna to adhere to the metal inner wall of the rack, avoiding damage to the rack structure caused by drilling or screw fixing. During testing, UHF RFID tags were affixed to different locations on the inner wall of the rack: the front, side, top, and back. Three tags were affixed to each location, at high, medium, and low heights respectively. A UHF RFID reader was connected to the hybrid topology radiating structure, with the reader's output power set to 30 dBm. The maximum reading distance for each tag was recorded. Figure 8The label "2.5-meter reading range" indicates a reading distance of 2.5 meters when the tag is located in the center of the front of the cabinet. It's important to understand that metal components in confined spaces can reflect the antenna's radiation field, leading to uneven electromagnetic field distribution. Therefore, the reading distance measurement better reflects the suitability of the hybrid topology in practical applications. If the hybrid topology has good omnidirectional radiation characteristics, even in reflective environments, the difference in reading distance between tags at different locations will be small.

[0089] Furthermore, the second step in verifying the adaptation effect is to obtain the radiation pattern through anechoic chamber testing, such as... Figure 3 The omnidirectional radiation pattern shown is the result of the anechoic chamber test. The anechoic chamber is a non-reflective environment with its inner walls covered by absorbing material, resulting in a reflection coefficient of less than -40 dB. The test equipment includes a network analyzer, a turntable, and a test antenna. The hybrid topology radiating structure is fixed on the turntable, with its center aligned with the turntable's rotation axis, as shown below. Figure 2 The center of the antenna is located at the geometric center of the PCB substrate, aligned with the rotation axis of the turntable. During testing, the turntable rotates 360 degrees at a speed of 60 degrees per minute, and the network analyzer records the radiation intensity at each angle, such as... Figure 3 Horizontal radiation intensity data. Check if the omnidirectional radiation angle is not less than 360 degrees, i.e., if the difference in radiation intensity in the horizontal direction (XY plane) is less than 1 decibel. Figure 3 As shown, the difference in radiation intensity in the horizontal direction is 0.8 dB. If the difference is less than 1 dB, the omnidirectional radiation angle is considered to be no less than 360 degrees. It is important to understand that the non-reflective environment of the anechoic chamber test can accurately reflect the inherent radiation characteristics of the hybrid topology and avoid reflection interference in the actual environment. Therefore, it is a key step in verifying the omnidirectional radiation angle.

[0090] Furthermore, the confined space conditions during rack installation testing must be consistent with actual application scenarios. For example, metal components inside the rack, such as servers and power modules, generate electromagnetic shielding. The miniaturized design of the hybrid topology allows it to be installed in the available space inside the rack without affecting the normal operation of other equipment. Simultaneously, the magnetic fixing method allows for flexible adjustment of the antenna's installation position, such as from a corner to the center, facilitating optimized reading distance. For instance, when the antenna is installed in the center of the rack, the difference in tag reading distance across different locations is smaller. Figure 8 When the marked position of the "hybrid topology antenna" is located in the center of the cabinet, the difference in reading distance is less than 0.3 meters.

[0091] Furthermore, radiation pattern detection in anechoic chamber testing needs to be coordinated with the UHF RFID operating frequency. For example, if the test frequency is set to 915MHz, the radiation pattern of the hybrid topology best reflects its omnidirectional characteristics under operating conditions. Figure 3As shown, the horizontal radiation pattern shows the smallest difference at 915MHz. If the test frequency deviates from the operating frequency, the radiation pattern will be distorted and cannot accurately reflect the omnidirectional performance in practical applications. It is important to understand that this collaborative design ensures the validity of the test results and provides an accurate basis for verifying the adaptation effect of hybrid topologies.

[0092] Furthermore, combined Figure 8 As shown in the rack installation environment verification scenario, the reading distance of the hybrid topology is approximately 2.5 meters, with differences of less than 0.5 meters between different locations. This result is consistent with the omnidirectional radiation direction observed in the anechoic chamber test. Figure 1 The horizontal radiation intensity difference is small, so tags at all locations can receive sufficient signals in a reflective environment. It's important to understand that this consistency is crucial for verifying the adaptation effect. If there are significant differences in reading distances during rack installation testing, it indicates that the omnidirectional radiation characteristics of the hybrid topology are not effectively maintained in the actual environment, requiring redesign optimization.

[0093] The advantage of this embodiment is that, through rack installation testing and anechoic chamber radiation pattern testing, the omnidirectional radiation performance and adaptability of the hybrid topology radiation structure in practical applications are verified, ensuring its uniform coverage and stable reading performance in confined spaces, and providing a verification basis for the practical application of the hybrid topology structure.

[0094] Example 7: In order to solve the problem of impedance mismatch in hybrid topology radiative structures caused by changes in ambient temperature, this example further refines the impedance matching method by adjusting the matching circuit parameters through temperature sensor feedback, so as to ensure that the input impedance of the hybrid topology radiative structure and the output impedance of the power supply system remain matched at different temperatures.

[0095] It is understandable that the input impedance of the hybrid topology radiating structure is significantly affected by ambient temperature. For example, the dielectric constant of the PCB substrate decreases slightly with increasing temperature, leading to a decrease in the equivalent capacitance of the microstrip patch radiating unit, an increase in the resistive component of the input impedance, and a shift of the reactive component towards inductance. Simultaneously, the resistivity of the metallic conductor in the cable-type second radiating unit increases with increasing temperature, also resulting in an increase in the resistive component of its input impedance. These changes cause the input impedance of the hybrid topology radiating structure to deviate from the output impedance of the power supply system, leading to increased return loss, a higher voltage standing wave ratio (VSWR), and affecting energy transfer efficiency. To address this issue, this embodiment places a temperature sensor at the corner of the PCB substrate, such as... Figure 2 The edge of the green area on the PCB substrate shown is equipped with a surface-mount NTC thermistor, which measures 2mm × 2mm and is mounted 5mm away from the microstrip patch radiating unit to acquire the ambient temperature in real time.

[0096] Furthermore, the matching circuit employs an L-shaped network consisting of two variable reactance elements: a variable capacitor and a variable inductor, positioned near the feed point on the PCB substrate, such as... Figure 2 In the area marked "L-type matching network," the capacitance (C) and inductance (L) values ​​are dynamically adjusted based on the feedback signal from the temperature sensor. Specifically, the temperature sensor converts the ambient temperature into a voltage signal, which is transmitted to the microcontroller. The microcontroller obtains the temperature-impedance characteristic curve through simulation or experimentation based on pre-stored curves. For example, at 25°C, the input impedance of the microstrip patch is 50 + j20Ω, and the L-type network needs to connect a 10nH inductor in series and a 20pF capacitor in parallel to achieve matching. When the temperature rises to 50°C, the input impedance of the microstrip patch becomes 55 + j30Ω. At this point, the inductance needs to be adjusted to 15nH and the capacitance to 15pF. The target values ​​of the variable capacitance and variable inductance required at the current temperature are calculated, and then the parameters of the L-type network are adjusted using a digital potentiometer or a voltage-controlled reactive component such as a varactor diode.

[0097] Furthermore, such as Figure 4 The Smith chart shown has a 50Ω matching point at its center. At different temperatures, the input impedance points deviate from the center region without adjusting the matching circuit parameters. After adjusting the L-type network parameters using temperature sensor feedback, these impedance points are all pulled to the matching region near the center, indicating a significant improvement in the matching degree between the input impedance and the output impedance of the power supply system. Meanwhile, as... Figure 5 The broadband frequency response characteristic curve shown shows that when the temperature changes from -10℃ to 50℃, the return loss curve without adjusting the matching circuit parameters will rise from -35dB to -8dB, close to the operating threshold of -10dB, and the voltage standing wave ratio will rise from 1.2 to 2.0. However, after adjusting the matching circuit parameters, the return loss remains below -15dB and the voltage standing wave ratio remains less than 1.5, ensuring good impedance matching in the UHF RFID band.

[0098] It is important to understand that the temperature sensor should be positioned as close as possible to the radiating element to accurately reflect its operating temperature. Simultaneously, the variable reactance element in the L-shaped network must possess good temperature stability to prevent its parameters from affecting the adjustment effect due to temperature variations. For example, the variable capacitor should be a ceramic dielectric capacitor with a dielectric constant changing with temperature at a rate less than 100 ppm / ℃, and the variable inductor should be a wire-wound inductor with an inductance value changing with temperature at a rate less than 50 ppm / ℃, ensuring the stability of the adjusted parameters.

[0099] The advantage of this embodiment is that by acquiring the ambient temperature through a temperature sensor and adjusting the matching circuit parameters, dynamic matching of the input impedance of the hybrid topology radiating structure and the output impedance of the power supply system is achieved at different temperatures, maintaining the stability of energy transmission efficiency and providing impedance matching assurance for the adaptability of the hybrid topology in temperature-changing environments.

[0100] Example 8: In order to solve the problem of changes in the electrical length of the cable-type second radiating unit caused by vibration environment, this example further refines the method of adjusting the cable length by detecting the vibration state through an accelerometer, so as to ensure the stability of the omnidirectional radiation characteristics of the hybrid topology radiation structure under vibration environment.

[0101] The electrical length of the cable-type second radiating unit needs to be maintained at λ / 4 of the UHF RFID operating frequency to ensure a uniform horizontal distribution of its radiation field. However, in vibrating environments, such as mechanical vibrations from equipment operation within a cabinet or bumps during transportation, the cable-type unit may loosen or deform due to vibration, leading to changes in its physical length and consequently altering its electrical length. For example, vibration can increase the inter-turn distance of a spiral cable, increasing its physical length and exceeding λ / 4 of its electrical length. In this case, the radiation field of the cable-type unit will shift vertically, resulting in increased differences in horizontal radiation intensity and deterioration of its omnidirectional radiation characteristics.

[0102] To address this issue, this embodiment places an accelerometer at the bottom of the PCB substrate, such as... Figure 2 Below the green area on the PCB substrate shown, a 3mm x 3mm MEMS sensor with a sensitivity of 100mV / g is used to detect the antenna's vibration. The accelerometer collects vibration acceleration signals in real time. When the vibration amplitude exceeds a preset threshold, such as 0.5g, corresponding to the typical vibration intensity of equipment operating within the cabinet, the microcontroller triggers a cable length adjustment mechanism. This mechanism uses a miniature stepper motor mounted on the top of the PCB substrate. The motor pulls the free end of the cable... Figure 2 The end of the spiral extends to the free end above the PCB substrate to adjust the physical length. For example, when vibration causes the physical length of the cable to increase by 1mm, the stepper motor rotates clockwise one revolution, pulling the cable to shorten by 1mm, so that the physical length is restored to the target value, such as 102mm, corresponding to λ / 4 electrical length.

[0103] Furthermore, such as Figure 3 As shown in the omnidirectional radiation pattern, when the electrical length of the cable unit deviates from λ / 4 due to vibration, the difference in horizontal radiation intensity increases from 0.8dB to 2.5dB, deteriorating the omnidirectional coverage. After detecting vibration with an accelerometer and adjusting the cable length, the difference in horizontal radiation intensity returns to below 0.8dB, ensuring the stability of the 360-degree omnidirectional radiation characteristics. It is important to understand that cable length adjustment must be linked to vibration conditions in real time. For example, the sampling frequency of the accelerometer should be set to 1kHz to ensure timely detection and adjustment of vibration. Simultaneously, the traction force of the stepper motor must be appropriate to avoid excessive pulling that could lead to cable breakage or deformation.

[0104] Furthermore, the spiral structure design of the cable unit helps reduce the impact of vibration on the physical length; for example, the elastic structure of the spiral can absorb some vibration energy, reducing the probability of cable loosening. However, accelerometers and adjustment mechanisms are still needed to handle larger amplitude vibrations. In addition, the surface insulation layer of the enameled wire prevents short circuits with other metal components, ensuring the stability of the cable's electrical performance during adjustment.

[0105] The advantage of this embodiment is that by detecting the vibration state through an accelerometer and adjusting the length of the cable-type second radiating unit, the λ / 4 electrical length of the cable-type unit is maintained under vibration conditions, ensuring the stability of the omnidirectional radiation characteristics of the hybrid topology radiating structure and providing radiation characteristic assurance for the adaptability of the hybrid topology structure in vibration environments.

[0106] Example 9: In order to solve the problem of performance drift of hybrid topology radiation structure in practical applications, this example further refines the method of real-time monitoring and reading distance and omnidirectional radiation angle and dynamically adjusting parameters to ensure the stable adaptation performance of hybrid topology structure in long-term use.

[0107] In UHF RFID applications, the performance of hybrid topology radiation structures may gradually drift due to environmental changes or component aging, such as a gradual decrease in reading distance or a deviation of the omnidirectional radiation angle from 360 degrees. These drifts can lead to a decrease in tag reading rate, affecting application effectiveness. To address this issue, this embodiment adds real-time monitoring and dynamic adjustment steps after verifying the adaptation effect.

[0108] Real-time monitoring includes two aspects: first, reading distance monitoring, which uses a reader to count the maximum reading distance of tags at different locations. When the reading distance at a certain location is less than a preset value, it indicates that the radiation intensity in that direction is insufficient; second, omnidirectional radiation angle monitoring, which uses anechoic chamber testing or portable radiation pattern measurement equipment, such as a handheld spectrum analyzer, in conjunction with a test antenna to obtain the horizontal radiation pattern. Figure 3 As shown, when the omnidirectional radiation angle deviates from 360 degrees, such as when the difference in radiation intensity in the horizontal direction exceeds 1 dB, it indicates that the radiation characteristics have deteriorated.

[0109] When the reading distance is detected to be less than the preset value or the omnidirectional radiation angle deviates, the microcontroller automatically initiates an adjustment mechanism, simultaneously adjusting the length of the cable-type second radiation unit and the parameters of the matching circuit. For example, when the reading distance decreases and the omnidirectional radiation angle deviates, the length of the cable-type unit is first adjusted by a stepper motor to restore its λ / 4 electrical length, ensuring omnidirectional radiation characteristics. If the reading distance still does not recover after adjustment, the parameters of the matching circuit are adjusted by a variable reactance element, such as... Figure 4 The Smith chart shown indicates that adjusting the impedance point maintains the input impedance matching the power supply system, thereby improving energy transmission efficiency.

[0110] It is important to understand that real-time monitoring and dynamic adjustment need to form a closed-loop control. For example, monitoring data is collected every 10 minutes, and the adjustment mechanism outputs control signals in real time based on the collected data. At the same time, the range of adjustment parameters needs to be preset to avoid over-adjustment that could lead to performance degradation. For example, the adjustment range for cable length is ±5mm, the adjustment range for capacitance value of matching circuit is 10-30pF, and the adjustment range for inductance value is 5-20nH.

[0111] like Figure 8 In the rack installation environment verification scenario shown, when the reading distance of the hybrid topology decreased from 2.5 meters to 1.8 meters due to component aging, the real-time monitoring system triggered an adjustment mechanism. First, the length of the cable unit was adjusted, and the reading distance was restored to 2.2 meters. Then, the capacitance value of the matching circuit was adjusted from 20pF to 25pF, and the reading distance was restored to 2.5 meters, and the omnidirectional radiation angle was also restored to 360 degrees.

[0112] The advantage of this embodiment is that by monitoring the reading distance and omnidirectional radiation angle in real time and dynamically adjusting the cable length and matching circuit parameters, the long-term performance stability of the hybrid topology radiation structure is achieved, ensuring its continued effectiveness in practical applications and providing performance assurance for the long-term use of the hybrid topology structure.

[0113] Example 10: To address the challenge of simultaneously achieving stable omnidirectional radiation and efficient signal transmission when installing UHF RFID antennas in confined spaces, this example provides a hybrid topology UHF RFID omnidirectional antenna adaptation system. Through the collaborative operation of multiple modules, the system ensures the antenna's adaptation performance in confined environments.

[0114] Specifically, the hybrid topology radiation structure building module serves as the system foundation, used to construct hybrid topology radiation structures that balance basic radiation and range extension. For example... Figure 2 As shown, the structure includes a first radiating unit, such as a microstrip patch radiating unit, disposed on a green PCB substrate, and a second radiating unit, such as a red spiral cable, connected to the top of the PCB substrate. The first radiating unit radiates the basic signal through a feed point 1 on the PCB substrate, providing the initial radiation field for the antenna. The second radiating unit extends along the Z-axis, and its spiral structure's inter-turn spacing and number of turns effectively extend the radiation range, compensating for the limitations of the first radiating unit's radiation coverage in confined spaces.

[0115] Furthermore, the impedance matching module is used to optimize the energy transmission efficiency of the hybrid topology radiating structure and the feeding system. This is achieved by adjusting the L-shaped matching network on the PCB substrate, such as... Figure 2The parameters in the area marked "L-type matching network" are used to match the input impedance of the hybrid topology radiating structure with the 50Ω output impedance of the power supply system. For example, when the input impedance of the hybrid topology radiating structure deviates from 50Ω due to temperature or structural changes, the impedance matching module adjusts the capacitance and inductance values ​​of the L-type network via a microcontroller to achieve the desired impedance. Figure 4 The impedance point is pulled to the center matching region. For example, at 915MHz, the impedance point is adjusted from the off-center position to the optimal matching point of -35dB, which significantly improves the signal transmission efficiency.

[0116] Furthermore, the radiation characteristic optimization module ensures 360-degree omnidirectional radiation characteristics of the hybrid topology radiation structure by adjusting the physical length of the cable-type second radiation unit to achieve an electrical length of λ / 4 at the UHF RFID operating frequency. One method for adjusting the physical length of the cable-type second radiation unit is to connect its free end to a micro stepper motor. When vibration or aging causes a change in cable length, the stepper motor adjusts the physical length by pulling the free end, restoring the electrical length to λ / 4. Figure 3 As shown, after adjustment, the difference in horizontal radiation intensity of the hybrid topology radiation structure can be controlled to below 0.8dB, ensuring 360-degree omnidirectional radiation characteristics and avoiding blind spots in narrow spaces caused by radiation offset.

[0117] Furthermore, the adaptation effect verification module is used to verify the adaptation effect of the hybrid topology radiation structure when installed in a confined space. It determines whether the requirements for UHF RFID applications are met by detecting the reading distance and omnidirectional radiation angle. For example... Figure 8 In the rack installation scenario shown, labels are affixed to the front, sides, top, and back of the rack's inner walls. The adaptation effect verification module uses a reader to determine the maximum reading distance of the labels at each location, ensuring it is no less than 2 meters. Simultaneously, a portable radiation pattern measuring device is used to acquire the horizontal radiation pattern, ensuring the omnidirectional radiation angle deviation does not exceed 1 dB. When the reading distance or radiation angle does not meet the requirements, the system automatically triggers the adjustment mechanisms of the impedance matching module and the radiation characteristic optimization module, forming a closed-loop optimization.

[0118] The advantage of this embodiment is that the basic radiation framework is laid by the hybrid topology radiation structure construction module, the impedance matching module improves the energy transmission efficiency, the radiation characteristic optimization module ensures omnidirectional coverage, and the adaptation effect verification module confirms the application compatibility. The multi-module collaboration realizes the stable omnidirectional radiation and efficient signal transmission of the UHF RFID antenna in a confined space, meeting the application requirements of UHF RFID in confined environments such as cabinets.

[0119] Example 11: To address the issues of reduced radiation performance and insufficient stability of UHF RFID antennas due to size limitations when installed in confined spaces, this example provides a UHF RFID omnidirectional antenna that ensures reliable operation in confined environments through an integrated structure and adaptation mechanism.

[0120] Specifically, a PCB substrate made of a high dielectric constant material serves as the antenna's supporting foundation. Its compact size effectively reduces the overall volume of the antenna, making it suitable for installation in confined spaces. A first radiating element is positioned on the front side of the substrate, radiating the basic signal through a feed point on the substrate, providing the initial radiation field for the antenna. An L-shaped matching network is positioned on the back side of the substrate, connecting the feed point and the first radiating element. This network is used to adjust the input impedance of the hybrid topology radiation structure, matching the input impedance with the output impedance of the feed system and improving signal transmission efficiency. Simultaneously, the back side also integrates a hybrid topology UHF RFID omnidirectional antenna adaptation system, including a microcontroller and stepper motor drive circuit. This system works in conjunction with the first radiating element and the cable-type second radiating element to achieve impedance matching adjustment, radiation characteristic optimization, and adaptation effect verification.

[0121] Furthermore, the cable-type second radiating unit is a coaxial cable, with one end connected through a feed point on the reverse side of the substrate, and the other end being a free end extending perpendicular to the substrate to extend the radiation range. A length adjustment mechanism, such as a miniature stepper motor and traction line, is installed on the cable. By adjusting the physical length of the cable, the electrical length of the cable-type second radiating unit meets the λ / 4 requirement under the UHF RFID operating frequency, ensuring that the hybrid topology radiation structure forms a 360-degree omnidirectional radiation characteristic. A snap-fit ​​structure, such as a plastic elastic snap, is installed on the edge of the substrate to fix the PCB substrate in a confined space, such as a cabinet slot, preventing the antenna from shifting due to vibration or collision, thus affecting radiation performance.

[0122] The advantages of this embodiment are that it reduces the size by using a high dielectric constant PCB substrate, integrates structures such as matching circuits and adapter systems, expands the radiation range by using a cable-type second radiation unit, ensures omnidirectional radiation by using a length adjustment mechanism, improves the fixation stability by using a snap-fit ​​structure, and achieves reliable operation of the UHF RFID antenna in a confined space through the cooperation of multiple structures.

[0123] Example 12: To address the problem that the UHF RFID omnidirectional antenna adaptation method with hybrid topology is difficult to achieve flexible deployment and scenario-based adjustment through fixed hardware circuits, this example provides a computer-readable storage medium that stores a computer program so that the adaptation method can be executed by a processor, thereby realizing the software-based and portable adaptation logic.

[0124] In this embodiment, the computer-readable storage medium can be a non-volatile storage medium such as embedded flash memory, solid-state drive, or network storage medium such as a cloud server storage unit. The computer program stored thereon contains complete logical instructions for the adaptation method, covering the execution logic of steps such as hybrid topology radiation structure construction, impedance matching adjustment, radiation characteristic optimization, and adaptation effect verification. When the program is executed by a processor such as a microcontroller or central processing unit, the processor controls the hybrid topology radiation structure construction module to construct a hybrid structure of a first radiation unit and a cable-type second radiation unit according to the instructions. The impedance matching module adjusts the capacitance and inductance values ​​of the L-shaped matching network to match the input impedance with the 50Ω output impedance of the power supply system. The radiation characteristic optimization module drives the length adjustment mechanism to adjust the physical length of the cable-type second radiation unit to ensure a λ / 4 electrical length. The adaptation effect verification module collects tag reading data and radiation pattern data in a confined space to determine whether the adaptation effect meets the application requirements.

[0125] Furthermore, the storage medium can also store a scenario parameter database, which can be used to store adaptation parameters such as cable length thresholds and optimal network matching parameters for different confined space scenarios such as cabinets and shelves. When the program is executed, the processor can load the corresponding parameters from the database according to the current scenario, thereby improving the accuracy of scenario adaptation.

[0126] The advantage of this embodiment is that the computer program of the adaptation method is stored in a computer-readable storage medium, which frees the adaptation logic from the limitation of fixed hardware circuits, making it easy to port to different RFID reader or antenna controller platforms. At the same time, it supports iterative updates of the program, ensuring that the adaptation method can adapt to the ever-changing UHF RFID application requirements.

[0127] Although the present invention has been specifically described above with reference to preferred embodiments, it should be understood that the present invention is not limited to the embodiments described above. Various modifications and variations can be made by those skilled in the art without departing from the spirit of the present invention, and such modifications and variations should fall within the scope defined by the appended claims and their equivalents.

Claims

1. A hybrid topology UHF RFID omni antenna adaptation method, characterized by the steps of The method comprises the following steps: constructing a mixed topology radiation structure, which comprises a first radiation unit arranged on a PCB substrate and a cable type second radiation unit connected to the PCB substrate, the first radiation unit is used to realize basic signal radiation, and the cable type second radiation unit is used to expand the radiation range; impedance matching of the mixed topology radiation structure, by adjusting the matching circuit parameters on the PCB substrate, the input impedance of the mixed topology radiation structure is matched with the output impedance of the feeding system, and the signal transmission efficiency is improved; adjusting the length of the cable type second radiation unit, calculating the electrical length of the cable type second radiation unit according to the UHF RFID working frequency, until the mixed topology radiation structure forms 360 degree omnidirectional radiation characteristics; verifying the adaptation effect of the mixed topology radiation structure, detecting the reading distance and omnidirectional radiation angle when it is installed in a narrow space, so as to meet the application requirements of UHF RFID; the first radiation unit is a microstrip patch radiation unit arranged on the front surface of the PCB substrate, the shape of the microstrip patch radiation unit is rectangular, and its size is set according to the UHF RFID working frequency, which is used to realize miniaturized basic signal radiation; one end of the cable type second radiation unit is connected to the back surface of the PCB substrate through a feeding point, the feeding point is electrically connected with the first radiation unit, and the other end of the cable type second radiation unit is a free end, which is used to expand the radiation range by adjusting the position of the free end.

2. The mixed topology UHF RFID omni antenna adaptation method of claim 1, wherein, The step of impedance matching of the mixed topology radiation structure comprises that the matching circuit is an L type matching network arranged on the back surface of the PCB substrate, the L type matching network comprises an inductor and a capacitor connected in series, one end of which is connected to the feeding point, and the other end is connected to the first radiation unit, which is used to realize the matching of the input impedance and the output impedance of the feeding system by adjusting the inductance value and the capacitance value.

3. The mixed topology UHF RFID omni antenna adaptation method of claim 1, wherein, The electrical length of the cable type second radiation unit is λ / 4, wherein λ is the wavelength corresponding to the UHF RFID working frequency, and the electrical length is realized by adjusting the physical length of the cable type second radiation unit, which is used to make the radiation pattern of the mixed topology radiation structure present 360 degree omnidirectional characteristics.

4. The mixed topology UHF RFID omni antenna adaptation method of claim 1, wherein, The step of verifying the adaptation effect of the mixed topology radiation structure comprises that in a narrow space, the mixed topology radiation structure is installed in the cabinet, and the reading distance of the UHF RFID tag is detected; the radiation pattern of the mixed topology radiation structure is obtained through darkroom test, and whether the omnidirectional radiation angle is not less than 360 degrees is detected.

5. The mixed topology UHF RFID omni antenna adaptation method of claim 1, wherein, The impedance matching of the mixed topology radiation structure further comprises that the ambient temperature is obtained through the temperature sensor arranged on the PCB substrate, and the parameters of the matching circuit are adjusted according to the ambient temperature, so as to keep the input impedance of the mixed topology radiation structure matched with the output impedance of the feeding system under different temperatures.

6. The mixed topology UHF RFID omni antenna adaptation method of claim 1, wherein, The length of the cable type second radiation unit is adjusted by detecting the antenna vibration state through an acceleration sensor arranged on the PCB substrate, and when the vibration amplitude exceeds a preset threshold, the length of the cable type second radiation unit is adjusted to stabilize the omnidirectional radiation characteristics of the hybrid topology radiation structure in a vibrating environment.

7. The mixed topology UHF RFID omni antenna adaptation method of claim 1, wherein, After verifying the adaptation effect of the hybrid topology radiation structure, the read distance and the omnidirectional radiation angle are monitored in real time, and when the read distance is less than a preset value or the omnidirectional radiation angle deviates from 360 degrees, the length of the cable type second radiation unit and the parameters of the matching circuit are automatically adjusted to achieve dynamic adaptation.

8. A hybrid topology UHF RFID omni antenna adaptation system for implementing the hybrid topology UHF RFID omni antenna adaptation method according to any one of claims 1 to 7, characterized in that, Comprise: A hybrid topology radiation structure construction module is configured to construct a hybrid topology radiation structure, which comprises a first radiation unit arranged on a PCB substrate and a cable type second radiation unit connected to the PCB substrate, the first radiation unit being configured to realize basic signal radiation, and the cable type second radiation unit being configured to expand the radiation range; An impedance matching module is configured to perform impedance matching on the hybrid topology radiation structure, and by adjusting the parameters of a matching circuit on the PCB substrate, the input impedance of the hybrid topology radiation structure is matched with the output impedance of a feeding system, thereby improving the signal transmission efficiency; An radiation characteristic optimization module is configured to adjust the length of the cable type second radiation unit, and according to the electrical length of the cable type second radiation unit calculated based on the UHF RFID operating frequency, the hybrid topology radiation structure forms a 360-degree omnidirectional radiation characteristic; An adaptation effect verification module is configured to verify the adaptation effect of the hybrid topology radiation structure, and detect the read distance and the omnidirectional radiation angle when the hybrid topology radiation structure is installed in a narrow space, so as to meet the application requirements of UHF RFID.

9. A UHF RFID omni-directional antenna, characterized by, Comprise: The PCB substrate is made of a high dielectric constant material to reduce the size of the antenna; The first radiation unit is a microstrip patch radiation unit arranged on the front surface of the PCB substrate, and is configured to realize basic signal radiation; The cable type second radiation unit is a coaxial cable, one end of which is connected to the back surface of the PCB substrate through a feeding point, and the other end is a free end, and is configured to expand the radiation range; The matching circuit is an L-shaped matching network arranged on the back surface of the PCB substrate and connected between the feeding point and the first radiation unit, and is configured to adjust the input impedance of the hybrid topology radiation structure; The UHF RFID omnidirectional antenna adaptation system of the hybrid topology structure according to claim 8 is integrated on the PCB substrate; A buckle structure is arranged on the edge of the PCB substrate, and is configured to fix the PCB substrate to the installation position in a narrow space; A length adjusting mechanism is arranged on the cable type second radiation unit, and is configured to adjust the length of the cable type second radiation unit.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by a processor to realize the UHF RFID omnidirectional antenna adaptation method of the hybrid topology structure according to any one of claims 1-7.

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