Radio frequency identification miniaturized narrow-beam antenna based on edge inductive loading
By co-designing the edge-inductive loading structure with the multilayer dielectric substrate and the feeding network, the problem of miniaturization of narrow-beam antennas in space-constrained environments is solved, achieving significant size reduction and high-performance radiation characteristics, making it suitable for large-scale applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-20
- Publication Date
- 2026-04-14
AI Technical Summary
Existing narrow-beam antennas are too large in physical size for applications such as remote directional access control and area fixed-point monitoring, making them difficult to adapt to space-constrained environments. Furthermore, traditional designs cannot achieve miniaturization while ensuring good radiation performance.
An edge-inductive loading-based miniaturized narrow-beam RFID antenna design is adopted. By setting rhomboid metal patches and triangular parasitic patches on the top dielectric substrate and connecting them to the reflective copper ground plane with short-circuit screws, an edge-inductive loading structure is formed. Combined with a multilayer dielectric substrate and a feeding network, the antenna achieves miniaturization and directional radiation characteristics.
While maintaining the same operating frequency band, the physical size of the antenna is significantly reduced, breaking through the limitation of the operating wavelength on the physical size. This achieves good narrow beam performance and stable radiation performance, reduces manufacturing complexity and cost, and facilitates integration with conventional RFID readers.
Smart Images
Figure CN121863048A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of antenna technology, and more specifically to a miniaturized narrow-beam antenna for radio frequency identification based on edge-sensitive loading. Background Technology
[0002] As one of the core technologies of the Internet of Things (IoT), Radio Frequency Identification (RFID) technology is increasingly widely used in scenarios such as electronic toll collection (ETC) on highways, remote directional access control, and regional fixed-point monitoring. These application scenarios place stringent requirements on the radiation characteristics of antennas: not only do they need to have narrow beam characteristics to achieve accurate directional identification and area coverage control, avoiding signal interference and misreading, but they also need to be miniaturized to adapt to the layout requirements of compact devices with limited installation space or specific application scenarios.
[0003] Narrow-beam antennas, by concentrating radiated energy, can effectively improve read / write distance and reliability in a specific direction while reducing multipath interference. However, traditional narrow-beam antenna designs, such as those employing large reflectors, waveguide slot arrays, or parasitic patch arrays, typically rely on large electrical dimensions or complex feed networks to achieve high gain and narrow beamwidth. This results in generally large antenna physical sizes, making integration into space-sensitive platforms or devices difficult and limiting their deployment in many modern applications. Especially in the UHF RFID band, achieving both miniaturization and high performance is even more challenging due to the longer operating wavelength. Therefore, how to achieve antenna miniaturization while ensuring good radiation performance (especially circularly polarized narrow-beam characteristics) has become a key technical problem urgently needing to be solved in the field of RFID antenna design. Summary of the Invention
[0004] This invention provides a miniaturized narrow-beam RFID antenna based on edge-sensitive loading, aiming to solve the problems of excessive physical size and difficulty in adapting to space-constrained environments faced by existing narrow-beam antennas in applications such as remote directional access control and area fixed-point monitoring. The specific technical solution adopted is as follows:
[0005] A miniaturized narrow-beam RFID antenna based on edge-sensitive loading, the antenna comprising: a top dielectric substrate and a bottom dielectric substrate;
[0006] The lower surface of the bottom dielectric substrate is provided with a reflective copper ground plane for the grounding plane of the antenna, and the upper surface is provided with a feed network.
[0007] The upper surface of the top dielectric substrate is provided with a rhombus-shaped metal patch with two power feeding points, and the four corners of the rhombus-shaped metal patch are respectively located at the midpoint of the four sides of the top dielectric substrate.
[0008] Each of the four corners of the top dielectric substrate is provided with a triangular parasitic patch. Each triangular parasitic patch is connected to the reflective copper ground plane on the lower surface of the bottom dielectric substrate by a short-circuit screw required for inductive loading. The short-circuit screw located between the top dielectric substrate and the bottom dielectric substrate maintains a specific height gap between the top dielectric substrate and the bottom dielectric substrate, thereby forming the required air layer.
[0009] The two feed points of the rhomboid metal patch are respectively connected to the feed network on the upper surface of the bottom dielectric substrate through metal probes that penetrate the air layer.
[0010] Preferably, the triangular parasitic patch and the short-circuit screw constitute an edge-sensitive loading structure.
[0011] Preferably, the hypotenuse of the triangular parasitic patch is parallel to the side of the corresponding rhombic metal patch, and a certain gap is maintained between the triangular parasitic patch and the rhombic metal patch.
[0012] Preferably, the top dielectric substrate consists of two pieces, which are symmetrically arranged on the upper surface of the bottom dielectric substrate.
[0013] Furthermore, the bottom dielectric substrate is also provided with metal vias, and the power supply network is connected to the reflective copper ground plane on the lower surface of the bottom dielectric substrate through the metal vias; the upper surface of the bottom dielectric substrate is fed to the power supply network through the power supply port of the power supply network for coplanar power supply.
[0014] Preferably, the power distribution network employs a 1-to-4 Wilkinson power divider network that distributes the power of the input radio frequency signal and generates the required phase relationship to provide circular polarization excitation for the top dielectric substrate.
[0015] Furthermore, the 1-to-4 Wilkinson power divider network includes a 1-to-2 first-stage power divider and two 1-to-2 second-stage power dividers;
[0016] The first-stage power divider is cascaded with two second-stage power dividers. The first-stage power divider divides the input signal into two in-phase signals, and the two second-stage power dividers further divide the two in-phase signals into two in-phase signals.
[0017] Furthermore, a λ / 4 microstrip delay line of a specific length is provided in one branch of the second-stage power divider to cause the signal of that branch to have a 90-degree phase shift, so that output signals with equal amplitude and a 90-degree phase difference are obtained at the two feed points of the same radiating unit.
[0018] Furthermore, isolation resistors are integrated at the power distribution nodes of both the first-stage power divider and the second-stage power divider.
[0019] Preferably, each triangular parasitic patch is connected to the reflective copper ground plane on the lower surface of the underlying dielectric substrate by a plurality of shorting screws; the plurality of shorting screws are equally spaced on the two right-angled sides of the triangular parasitic patch and form an "L" shape.
[0020] The present invention has the following beneficial effects:
[0021] The top dielectric substrate based on an edge-inductive loading structure provided by this invention has a diamond-shaped metal patch with two feed points on its upper surface, and a triangular parasitic patch at each of the four corners of the top dielectric substrate. The triangular parasitic patch is connected to the reflective copper ground plane on the lower surface of the bottom dielectric substrate through short-circuit screws required for inductive loading, thereby forming an effective magnetic wall boundary condition, introducing additional inductance and extending the current path, and reducing the antenna operating frequency. While maintaining the same operating frequency band, a significant reduction in physical size is achieved, breaking through the limitation of operating wavelength on physical size in traditional antenna design.
[0022] Using an edge-inductively loaded top dielectric substrate as the radiating unit, the edge-inductively loaded structure is integrated with the multilayer dielectric substrate, the feed network, and the reflective copper ground plane. This allows the triangular parasitic patch and shorting screw to be miniaturized while working together with the reflective ground plane to form directional radiation characteristics, thereby maintaining good narrow beam performance while reducing antenna size.
[0023] This invention employs a combination of radiating units and edge-sensitive loading technology. Miniaturization can be achieved simply by adding an edge-sensitive loading structure around the original traditional patch radiating unit. It has the advantages of simple processing and low cost. It can be processed using a full PCB process, reducing manufacturing complexity and production costs. At the same time, it is easy to integrate with conventional RFID readers, making it more suitable for large-scale applications.
[0024] This invention achieves miniaturization while maintaining good impedance matching characteristics, appropriate gain, and narrow beam radiation performance through the synergistic design of an edge-sensitive loading structure and a multilayer dielectric substrate, ensuring stable operation of the antenna in the UHF RFID band. Attached Figure Description
[0025] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1This is a schematic diagram of the overall structure of a miniaturized narrow-beam antenna for radio frequency identification based on edge-sensitive loading, provided in one embodiment of the present invention.
[0027] Figure 2 This is a top view of a radiating element provided in one embodiment of the present invention.
[0028] Figure 3 This is a schematic diagram of a 1-to-4 Wilkinson power divider network provided in an embodiment of the present invention.
[0029] Figure 4 The reflection coefficient S11 and gain curve of a miniaturized narrow-beam RFID antenna provided in one embodiment of the present invention are shown.
[0030] Figure 5 The antenna radiation angle response diagram of a miniaturized narrow-beam antenna for radio frequency identification provided in one embodiment of the present invention is shown.
[0031] Figure 6 The antenna radiation pattern of a miniaturized narrow-beam antenna for radio frequency identification provided in one embodiment of the present invention.
[0032] In the figure, 1-top dielectric substrate, 2-bottom dielectric substrate, 3-diamond-shaped metal patch, 4-triangular parasitic patch, 5-short-circuit screw, 6-metal probe, 7-feed network, 7a-isolation resistor, 7b-microstrip delay line, 701-first stage power divider, 702-second stage power divider, 8-feed port, 9-metal via, 10-reflective copper-clad ground plane. Detailed Implementation
[0033] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a miniaturized narrow-beam RFID antenna based on edge-sensitive loading proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.
[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0035] The following description, in conjunction with the accompanying drawings, details a specific solution for a miniaturized narrow-beam RFID antenna based on edge-sensitive loading provided by the present invention.
[0036] Please see Figure 1The diagram shows a schematic of the structure of a miniaturized narrow beam antenna for radio frequency identification based on edge-sensitive loading according to an embodiment of the present invention. The present invention provides a miniaturized narrow beam antenna for radio frequency identification based on edge-sensitive loading, the antenna comprising: a top dielectric substrate 1 and a bottom dielectric substrate 2.
[0037] The lower surface of the bottom dielectric substrate 2 is provided with a reflective copper ground plane 10 for the grounding plane of the antenna, and the upper surface is provided with a feed network 7.
[0038] The upper surface of the top dielectric substrate 1 is provided with a rhombus-shaped metal patch 3 with two power feeding points, and the four corners of the rhombus-shaped metal patch 3 are respectively located at the midpoint of the four sides of the top dielectric substrate 1.
[0039] Each of the four corners of the top dielectric substrate 1 is provided with a triangular parasitic patch 4. Each triangular parasitic patch 4 is connected to the reflective copper ground plane 10 on the lower surface of the bottom dielectric substrate by a short-circuit screw 5 required for inductive loading. The short-circuit screw 5 located between the top dielectric substrate 1 and the bottom dielectric substrate keeps the top dielectric substrate 1 and the bottom dielectric substrate at a specific height distance, thereby forming the required air layer.
[0040] The two feed points of the rhomboid metal patch 3 are respectively connected to the feed network 7 on the upper surface of the bottom dielectric substrate through a metal probe 6 that penetrates the air layer vertically.
[0041] The top dielectric substrate 1 based on the edge inductive loading structure provided by the present invention has a diamond-shaped metal patch 3 with two feed points on its upper surface, and a triangular parasitic patch 4 is provided at each of the four corners of the top dielectric substrate 1. The triangular parasitic patch 4 is connected to the reflective copper ground plane 10 on the lower surface of the bottom dielectric substrate through the short-circuit screw 5 required for inductive loading, thereby forming an effective magnetic wall boundary condition, introducing additional inductance and extending the current path, thereby reducing the antenna operating frequency; while maintaining the same operating frequency band, a significant reduction in physical size is achieved, breaking through the limitation of operating wavelength on physical size in traditional antenna design.
[0042] Using the top dielectric substrate 1 with edge-sensitive loading as the radiating unit, the edge-sensitive loading structure is integrated with the multilayer dielectric substrate, the feed network 7 and the reflective copper ground plane 10. This allows the triangular parasitic patch 4 and the short-circuit screw 5 to be miniaturized while working together with the reflective ground plane to form directional radiation characteristics, thereby maintaining good narrow beam performance while reducing the antenna size.
[0043] This invention employs a combination of radiating units and edge-sensitive loading technology. Miniaturization can be achieved simply by adding an edge-sensitive loading structure around the original traditional patch radiating unit. It has the advantages of simple processing and low cost. It can be processed using a full PCB process, reducing manufacturing complexity and production costs. At the same time, it is easy to integrate with conventional RFID readers, making it more suitable for large-scale applications.
[0044] This invention achieves miniaturization while maintaining good impedance matching characteristics, appropriate gain, and narrow beam radiation performance through the synergistic design of an edge-sensitive loading structure and a multilayer dielectric substrate, ensuring stable operation of the antenna in the UHF RFID band.
[0045] In this embodiment, the top dielectric substrate 1 serves as the substrate for the radiating element, and the bottom dielectric substrate serves as the substrate for the reflective ground plane and the feed network 7. The top dielectric substrate 1 is fixedly mounted on the bottom dielectric substrate by short-circuit screws 5 required for inductive loading, and maintains a specific height distance from the bottom dielectric substrate to form the required air layer. The upper surface of the bottom dielectric substrate is provided with a feed network 7, which is responsible for distributing the power of the input radio frequency signal and generating the required phase relationship to provide accurate circular polarization excitation for the radiating element in the top dielectric substrate 1. The lower surface of the bottom dielectric substrate is a complete reflective copper-clad ground plane 10, which serves as the ground plane of the antenna, effectively reflecting electromagnetic waves, enhancing the directivity of the antenna, suppressing back radiation and unnecessary sidelobes, thereby contributing to the improvement of forward gain.
[0046] In this embodiment, as Figure 2 As shown, the radiating unit includes a rhomboid metal patch 3 with two feed points on the upper surface of the top dielectric substrate 1, and triangular parasitic patches 4 disposed at the four corners of the top dielectric substrate 1; each of the triangular parasitic patches 4 is connected to the reflective copper ground plane 10 on the lower surface of the bottom dielectric substrate by a short-circuit screw 5.
[0047] In this invention, the triangular parasitic patch 4 and the short-circuit screw 5 constitute an edge-inductive loading structure. The two feed points of the rhomboid metal patch 3 are respectively connected to the feed network 7 on the upper surface of the underlying dielectric substrate through two metal probes 6 that perpendicularly penetrate the air layer. The synergistic effect of the triangular parasitic patch 4 and the short-circuit screw 5 in the edge-inductive loading structure forms an effective magnetic wall boundary condition around the radiating element, introducing not only additional inductive components but also significantly extending the effective path of the surface current, thereby achieving a reduction in resonant frequency while reducing physical size. This edge-inductive loading structure allows the antenna to maintain its radiation performance while reducing the size of its radiating element by approximately 30% compared to traditional patch antennas, effectively overcoming the constraint between antenna operating frequency and physical size, and realizing miniaturized antenna design.
[0048] In this embodiment, as Figure 2 As shown, the hypotenuse of the triangular parasitic patch 4 is parallel to the side of the corresponding rhombic metal patch 3, and a certain gap is maintained between the triangular parasitic patch 4 and the rhombic metal patch 3. In other words, the triangular parasitic patch 4 is located in the corner of the triangle formed by the side of the rhombic metal patch 3 and the two adjacent sides of the top dielectric substrate 1. The triangular parasitic patch 4 is not directly connected to the rhombic metal patch 3, and a certain gap is maintained between the triangular parasitic patch 4 and the rhombic metal patch 3; the rhombic metal patch 3 serves as the main radiating unit.
[0049] In this embodiment, as Figure 1 As shown, the top dielectric substrate 1 has two parts, which are symmetrically arranged on the upper surface of the bottom dielectric substrate 2. The bottom dielectric substrate 2 is also provided with metal vias 9, and the power supply network 7 is connected to the reflective copper ground plane 10 on the lower surface of the bottom dielectric substrate 2 through the metal vias 9; the upper surface of the bottom dielectric substrate 2 is coplanarly fed to the power supply network 7 through the power supply port 8 of the power supply network 7.
[0050] The metal via 9 and the power supply port 8 of the power supply network 7 are located on the axis of symmetry of the two top layer dielectric substrates 1.
[0051] In this embodiment, as Figure 3 As shown, the power distribution network 7 is a Wilkinson power divider network that distributes the power of the input radio frequency signal and generates the required phase relationship to provide circular polarization excitation for the top dielectric substrate 1.
[0052] In this embodiment, the 1-to-4 Wilkinson power divider network includes a 1-to-2 first-stage power divider 701 and two 1-to-2 second-stage power dividers 702.
[0053] The first-stage power divider 701 and two second-stage power dividers 702 are cascaded. The first-stage power divider 701 divides the input signal into two in-phase signals, and the two second-stage power dividers 702 further divide the two in-phase signals into two in-phase signals.
[0054] Furthermore, a λ / 4 microstrip delay line 7b of a specific length is provided in one branch of the second-stage power divider 702 to cause the signal of that branch to have a 90-degree phase shift, so that output signals with equal amplitude and a 90-degree phase difference are obtained at the two feed points of the same radiating unit.
[0055] Furthermore, isolation resistors 7a are integrated at the power distribution nodes of both the first-stage power divider 701 and the second-stage power divider 702. The isolation resistors 7a integrated at the power distribution nodes of each stage of the power divider are used to absorb reflected energy, ensuring the isolation and amplitude-phase stability between each port, thereby providing a stable feed excitation to the radiating unit that meets the requirements of circular polarization.
[0056] In this embodiment, the 1-to-4 Wilkinson power divider feed network uses metal vias 9 to bring the reflective copper ground plane 10 on the lower surface of the bottom dielectric substrate to the upper surface, and then feeds the power dividers of each stage to the upper surface of the bottom dielectric substrate through the feed port 8 for coplanar feeding.
[0057] like Figure 1 , 2 As shown, each triangular parasitic patch 4 is connected to the reflective copper ground plane 10 on the lower surface of the underlying dielectric substrate by a plurality of shorting screws 5; the plurality of shorting screws 5 are equally spaced on the two right-angled sides of the triangular parasitic patch 4, forming an "L" shape. This can be understood as the plurality of shorting screws 5 being equally spaced along the edges of the two right-angled sides of the triangular parasitic patch 4, forming an "L" shape.
[0058] In this embodiment, the hypotenuse of the triangular parasitic patch 4 is parallel to the side of the rhomboid metal patch 3, forming the main coupling and radiation edges. The two right-angled sides of the triangular parasitic patch are crucial for shaping the magnetic wall boundary. The closely spaced "L"-shaped short-circuit screw array ensures simultaneous control of the current distribution from two vertical directions (x and y directions), making the boundary conditions of the entire structure symmetrical and stable, thus ensuring the uniformity of the inductive load. If the spacing of the short-circuit screws is uneven, it will lead to uneven inductance along the current path, with some points having high inductive reactance and others having low inductive reactance, thereby causing distortion in the current distribution. The "L"-shaped and equally spaced design ensures the symmetry and uniformity of the load, which is beneficial for maintaining good circular polarization characteristics and a regular radiation pattern.
[0059] The miniaturized narrow-beam RFID antenna with edge-sensitive loading provided in this embodiment operates in the UHF band, and the side length of a single top-layer dielectric substrate 1 is 75mm, which is about 30% smaller than that of a traditional patch antenna. Figure 4 As shown in the diagram, the reflection coefficient S11 and gain curves indicate that the antenna's reflection coefficient S11 is within the 860-960MHz range. 11 All values are below -10dB, demonstrating good wideband impedance matching characteristics, with a peak gain of 7dBi. Figure 5 The antenna radiation angle response diagram shown is consistent with... Figure 6 The antenna radiation pattern shown in the figure indicates that the antenna has a half-power beamwidth (HPBW) of 100° in the E-plane and 56° in the H-plane, exhibiting good narrow-beam radiation characteristics.
[0060] In summary, this invention achieves miniaturization while also ensuring good impedance matching, stable radiation gain, and significant narrow beam characteristics.
[0061] Because most narrow-beam antennas are designed to achieve high directional gain and narrow beam characteristics, they typically employ large radiating apertures or complex array structures, such as the Vivaldi antenna array. This directly results in a large overall antenna size, inconvenient installation, and difficulty in integrating into space-sensitive platforms or devices. In contrast, this invention, through innovative edge-sensitive loading technology, significantly reduces the physical size of the antenna while maintaining good circularly polarized narrow-beam performance, effectively resolving the contradiction between miniaturization and high performance in existing narrow-beam antennas.
[0062] Compared to existing miniaturized narrow-beam antenna technologies, such as designs based on multi-element PIFA arrays or traditional dual-element structures, although optimized layouts reduce space requirements to some extent, their physical size is still constrained by the operating wavelength, making it difficult to meet the needs of applications with strict space limitations. Furthermore, multi-element designs require complex feeding networks 7, resulting in relatively high manufacturing costs and debugging difficulties, limiting their potential for further miniaturization and cost reduction. This invention, through a diamond-shaped metal patch 3 with two feeding points and an integrated feeding network 7, allows the antenna structure to be directly fabricated using standard PCB processes while maintaining circularly polarized narrow-beam performance, greatly simplifying the manufacturing process and reducing costs.
[0063] Compared to some narrow-beam antenna solutions, such as waveguide-slot-based structures, while achieving high gain and low sidelobes, their waveguide structures are bulky, complex to manufacture, and expensive in the UHF band, and are difficult to integrate with conventional RFID readers, failing to meet the urgent needs of RFID applications for low cost, lightweight design, and miniaturization. This invention provides a planar antenna structure based on PCB technology. Utilizing mature printed circuit board technology, it achieves high-performance narrow-beam circularly polarized radiation while maintaining lightweight and low cost, facilitating integration with existing RFID systems.
[0064] Compared to existing technologies, many antenna designs, in pursuit of miniaturization, often sacrifice key performance indicators such as gain, beamwidth, or impedance bandwidth. For example, some compact antenna designs reduce size through strong resonance or high-dielectric-constant substrates, but this may lead to decreased radiation efficiency and narrower operating bandwidth. This invention, through the synergistic design of an edge-sensitive loading structure and a multilayer air dielectric structure, achieves significant miniaturization while maintaining good impedance matching, appropriate gain, and narrow beam characteristics, ensuring stable and comprehensive antenna performance in the UHF RFID band.
[0065] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
[0066] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.
Claims
1. A miniaturized narrow-beam antenna for radio frequency identification based on edge-sensitive loading, characterized in that: The antenna includes: a top dielectric substrate (1) and a bottom dielectric substrate (2). The lower surface of the bottom dielectric substrate (2) is provided with a reflective copper ground plane (10) for the ground plane of the antenna, and the upper surface is provided with a feed network (7). The upper surface of the top dielectric substrate (1) is provided with a rhombus-shaped metal patch (3) with two power feeding points, and the four corners of the rhombus-shaped metal patch (3) are respectively located at the midpoint of the four sides of the top dielectric substrate (1). The top dielectric substrate (1) has a triangular parasitic patch (4) at each of its four corners. Each triangular parasitic patch (4) is connected to the reflective copper ground plane (10) on the lower surface of the bottom dielectric substrate by a short-circuit screw (5) required for inductive loading. The short-circuit screw (5) located between the top dielectric substrate (1) and the bottom dielectric substrate keeps the top dielectric substrate (1) and the bottom dielectric substrate at a specific height distance, thereby forming the required air layer. The two feed points of the rhomboid metal patch (3) are respectively connected to the feed network (7) on the upper surface of the bottom dielectric substrate through a metal probe (6) that penetrates the air layer vertically.
2. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 1, characterized in that: The triangular parasitic patch (4) and the short-circuit screw (5) constitute an edge-sensitive loading structure.
3. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 1, characterized in that: The hypotenuse of the triangular parasitic patch (4) is parallel to the side of the corresponding rhomboid metal patch (3), and a certain gap is maintained between the triangular parasitic patch (4) and the rhomboid metal patch (3).
4. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 1, characterized in that: The top dielectric substrate (1) consists of two pieces, which are symmetrically arranged on the upper surface of the bottom dielectric substrate (2).
5. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 4, characterized in that: The bottom dielectric substrate (2) is also provided with a metal via (9), and the power supply network (7) is connected to the reflective copper ground plane (10) on the lower surface of the bottom dielectric substrate (2) through the metal via (9); the upper surface of the bottom dielectric substrate (2) is fed to the power supply network (7) through the power supply port (8) of the power supply network (7) for coplanar power supply.
6. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 1, characterized in that: The power distribution network (7) is a Wilkinson power divider network that distributes the power of the input radio frequency signal and generates the required phase relationship to provide circular polarization excitation to the top dielectric substrate (1).
7. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 6, characterized in that: The 1-to-4 Wilkinson power divider feeder network includes a 1-to-2 first-stage power divider 701 and two 1-to-2 second-stage power dividers 702. The first-stage power divider 701 and two second-stage power dividers 702 are cascaded. The first-stage power divider 701 divides the input signal into two in-phase signals, and the two second-stage power dividers 702 further divide the two in-phase signals into two in-phase signals.
8. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 7, characterized in that: A λ / 4 microstrip delay line (7b) of a specific length is provided in one branch of the second-stage power divider 702 to cause the signal of that branch to have a 90-degree phase shift, so that output signals with equal amplitude and a 90-degree phase difference are obtained at two feed points of the same radiating unit.
9. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to any one of claims 7 or 8, characterized in that: Isolation resistors (7A) are integrated at the power distribution nodes of both the first-stage power divider and the second-stage power divider.
10. The miniaturized narrow-beam RFID antenna based on edge-sensitive loading according to claim 1, characterized in that: Each of the triangular parasitic patches (4) is connected to the reflective copper ground plane (10) on the lower surface of the underlying dielectric substrate by a number of shorting screws (5); the number of shorting screws (5) are equally spaced on the two right-angled sides of the triangular parasitic patch (4) and form an "L" shape.