Circularly polarized high gain uhf rfid reader antenna

Abstract

The application provides a circularly polarized high-gain super-high-frequency RFID reader antenna, which comprises a first dielectric plate, a second dielectric plate, a first metal patch, a second metal patch, four square metal patches, a coaxial line, four metal sheets, eight metal probes and a plurality of insulating columns; the first metal patch and the four square metal patches are attached above the first dielectric plate; the second metal patch is attached below the second dielectric plate; the four metal sheets are connected around the second metal patch and vertically stand around the second dielectric plate; the coaxial line is connected with the first metal patch and the second metal patch through the first dielectric plate and the second dielectric plate at both ends; the lower ends of the metal probes are connected with the second metal patch, wherein the upper ends of four metal probes are connected with the first metal patch, the upper ends of the other four metal probes are connected with the four square metal patches, and the upper and lower ends of the insulating columns are connected with the first dielectric plate and the second dielectric plate respectively; the antenna has small size, low cost and good performance.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to circularly polarized high-gain ultra-high frequency RFID reader antennas. Background Technology

[0002] Radio Frequency Identification (RFID) technology mainly consists of three parts: The first part is the transponder, generally a tag, which is designed specifically for different usage scenarios. The second part is the reader, a device used to read and write information to the tag. The third part is the application software system, which further processes the collected data for use by people, depending on the specific scenario. To date, RFID systems have been widely used in many fields, such as logistics management, manufacturing, library management, identification, and automatic road toll collection.

[0003] There are many types of antennas, and different applications require different antennas. The development of RFID readers is increasingly trending towards miniaturization and portability. Ultra-high frequency (UHF) RFID systems operate at around 915 MHz, and traditional antennas are too large for handheld RFID systems. The reader antenna is taking up an increasingly large proportion of the reader's size. Reducing the size of the reader antenna while maintaining performance is far more difficult than reducing the size of the reader circuitry. Therefore, miniaturization of the antenna has become a current trend in RFID reader antenna research.

[0004] A wider operating bandwidth means that it can operate in a wider range of frequency bands, which means that the reader antenna can be used in UHF RFID systems in more countries.

[0005] High gain means a longer transmission distance under otherwise equal conditions. Therefore, in recent years, more and more scholars have devoted themselves to the research of high-gain RFID reader antennas, which may use expensive materials with low loss or be very large in size. However, in low-power, short-range RFID systems, a small and low-cost antenna is needed. Summary of the Invention

[0006] This invention proposes a circularly polarized high-gain UHF RFID reader antenna, whose operating frequency is covered by the application frequency bands of UHF RFID tag antennas in all countries. The antenna has high gain, good directivity, small size, and low cost.

[0007] The present invention adopts the following technical solution.

[0008] A circularly polarized high-gain ultra-high frequency RFID reader antenna, the antenna comprising a first dielectric plate (7) and a second dielectric plate (8) arranged in parallel and connected by insulating pillars; the top surface of the first dielectric plate is covered with a first metal patch (1) with a hollow structure; the hollow structure contains square metal patches A (3), B (4), C (5), and D (6) attached to the top surface of the first dielectric plate. The bottom surface of the second dielectric substrate is covered with a rectangular second metal patch (2); the four sides of the second metal patch are respectively provided with metal pieces A (17), B (18), C (19), and D (20) standing vertically at the periphery of the second dielectric substrate; the surface of the second metal patch is provided with metal probes A (9), B (10), C (11), and D (12) respectively connected to square metal patches A, B, C, and D, and metal probes E (12), F (13), G (14), and H (15) connected to the first metal patch are also provided vertically; the second metal patch is connected to the first metal patch by a coaxial line (25).

[0009] The hollow structure of the first metal patch is a planar structure formed by subtracting two rectangles, four squares, and one dumbbell shape from a rectangular piece adapted to the size of the first dielectric plate. It includes left rectangular notches and right rectangular notches on both sides, as well as four square hollow positions and one dumbbell-shaped hollow position in the middle. Square metal patches A, B, C, and D are respectively disposed in the four square hollow positions. The insulating pillars include insulating pillar A (21) and insulating pillar B (22) located in the left rectangular notch, and insulating pillar C (23) and insulating pillar D (24) located in the right rectangular notch.

[0010] The second metal patch is a metal surface with a regular shape.

[0011] The second metal patch is a rectangle that matches the size of the second dielectric substrate.

[0012] The square metal patches A, B, C, and D are located on the same plane as the first metal patch, and the four square metal patches are symmetrically arranged in pairs on the first dielectric substrate with the antenna center as the center of symmetry.

[0013] Metal sheets A, B, C, and D are all rectangular sheets of the same thickness and material, and their length is half the length of the first dielectric plate.

[0014] The antenna is fed by a coaxial line, which includes an outer core and an inner core. The outer core is sleeved outside the inner core. The upper end of the inner core passes upward through the first dielectric plate and is connected to the first metal patch. The lower end of the outer core passes downward through the second dielectric plate and is connected to the second metal patch.

[0015] An air layer of predetermined height is provided between the first dielectric plate and the second dielectric plate, and the first dielectric plate and the second dielectric plate are fixed by a plurality of insulating posts distributed between them.

[0016] During the forming process of the first metal patch hollow structure, the left rectangular notch and the right rectangular notch are symmetrical about the center of the first metal patch.

[0017] The part where the inner core of the coaxial line is connected to the first metal patch is located at the vertical axis of symmetry of the first metal patch at the dumbbell-shaped cutout position.

[0018] The overall dimensions of the antenna are 120mm × 120mm × 19.6mm.

[0019] The antenna is a directional antenna with a frequency band of 864MHz-955MHz at -10dBi, a frequency band of 901MHz-925MHz with an axial ratio below 3dB, and an actual gain of 7dBi.

[0020] Compared with existing technologies, this invention has the following advantages: a circularly polarized high-gain UHF RFID reader antenna with a wide bandwidth, applicable to UHF RFID systems worldwide, high gain, excellent directivity, reasonable design, and small size. The antenna has a simple structure and uses common dielectric substrates, resulting in low manufacturing costs and making it suitable for use in IoT intelligent identification systems. Attached Figure Description

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Appendix Figure 1 This is a three-dimensional schematic diagram of the antenna structure according to an embodiment of the present invention; Appendix Figure 2 This is a top view of the antenna structure according to an embodiment of the present invention; Appendix Figure 3 This is a front view schematic diagram of the antenna structure according to an embodiment of the present invention; Appendix Figure 4 This is a schematic diagram of the simulation results of the antenna reflection coefficient in an embodiment of the present invention; Appendix Figure 5 This is a schematic diagram of the antenna axis ratio simulation results in an embodiment of the present invention; Appendix Figure 6 This is a schematic diagram of the actual antenna gain simulation results in an embodiment of the present invention; Appendix Figure 7This is an example of an antenna radiation pattern according to an embodiment of the present invention; In the diagram: 1-First metal patch; 2-Second metal patch; 3-Square metal patch A; 4-Square metal patch B; 5-Square metal patch C; 6-Square metal patch D; 7-First dielectric substrate; 8-Second dielectric substrate; 9-Metal probe A; 10-Metal probe B; 11-Metal probe C; 12-Metal probe D; 13-Metal probe E; 14-Metal probe F; 15-Metal probe G; 16-Metal probe H; 17-Metal sheet A; 18-Metal sheet B; 19-Metal sheet C; 20-Metal sheet D; 21-Insulating post A; 22-Insulating post B; 23-Insulating post C; 24-Insulating post D; 25-Coaxial line. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, 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 application pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] As shown in the figure, a circularly polarized high-gain ultra-high frequency RFID reader antenna includes a first dielectric plate 7 and a second dielectric plate 8 arranged vertically and connected by insulating pillars; the top surface of the first dielectric plate is covered with a first metal patch 1 with a hollow structure; the hollow structure contains square metal patches A3, B4, C5, and D6 attached to the top surface of the first dielectric plate. The bottom surface of the second dielectric substrate is covered with a rectangular second metal patch 2; the four sides of the second metal patch are respectively provided with metal pieces A17, B18, C19 and D20 standing vertically at the periphery of the second dielectric substrate; the surface of the second metal patch is provided with metal probes A9, B10, C11 and D12 respectively connected to square metal patches A, B, C and D, and metal probes E12, F13, G14 and H15 are also vertically provided connected to the first metal patch; the second metal patch is connected to the first metal patch by a coaxial line 25.

[0026] The hollow structure of the first metal patch is a planar structure formed by subtracting two rectangles, four squares, and one dumbbell shape from a rectangular piece adapted to the size of the first dielectric plate. It includes left rectangular notches and right rectangular notches on both sides, as well as four square hollow positions and one dumbbell-shaped hollow position in the middle. Square metal patches A, B, C, and D are respectively disposed in the four square hollow positions. The insulating pillars include insulating pillars A21 and B22 located in the left rectangular notch, and insulating pillars C23 and D24 located in the right rectangular notch.

[0027] The second metal patch is a metal surface with a regular shape.

[0028] The second metal patch is a rectangle that matches the size of the second dielectric substrate.

[0029] The square metal patches A, B, C, and D are located on the same plane as the first metal patch, and the four square metal patches are symmetrically arranged in pairs on the first dielectric substrate with the antenna center as the center of symmetry.

[0030] Metal sheets A, B, C, and D are all rectangular sheets of the same thickness and material, and their length is half the length of the first dielectric plate.

[0031] The antenna is fed by a coaxial line, which includes an outer core and an inner core. The outer core is sleeved outside the inner core. The upper end of the inner core passes upward through the first dielectric plate and is connected to the first metal patch. The lower end of the outer core passes downward through the second dielectric plate and is connected to the second metal patch.

[0032] An air layer of predetermined height is provided between the first dielectric plate and the second dielectric plate, and the first dielectric plate and the second dielectric plate are fixed by a plurality of insulating posts distributed between them.

[0033] During the forming process of the first metal patch hollow structure, the left rectangular notch and the right rectangular notch are symmetrical about the center of the first metal patch.

[0034] The part where the inner core of the coaxial line is connected to the first metal patch is located at the vertical axis of symmetry of the first metal patch at the dumbbell-shaped cutout position.

[0035] The overall dimensions of the antenna are 120mm × 120mm × 19.6mm.

[0036] The antenna is a directional antenna with a frequency band of 864MHz-955MHz at -10dBi, a frequency band of 901MHz-925MHz with an axial ratio below 3dB, and an actual gain of 7dBi.

[0037] This antenna exhibits excellent directional radiation. It is covered by the frequency bands used in global UHF RFID reader antennas and can be applied in complex IoT intelligent identification systems.

[0038] The above description is merely the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology and essence demonstrated in the present invention should be included within the protection scope of the present invention.

Claims

1. A circularly polarized high-gain ultra-high frequency RFID reader antenna, characterized in that: The antenna includes a first dielectric plate (7) and a second dielectric plate (8) arranged in parallel and connected by insulating pillars; the top surface of the first dielectric plate is covered with a first metal patch (1) with a hollow structure; the hollow structure contains square metal patches A (3), B (4), C (5), and D (6) attached to the top surface of the first dielectric plate. The bottom surface of the second dielectric substrate is covered with a rectangular second metal patch (2); the four sides of the second metal patch are respectively provided with metal pieces A (17), B (18), C (19), and D (20) standing vertically at the periphery of the second dielectric substrate; the surface of the second metal patch is provided with metal probes A (9), B (10), C (11), and D (12) respectively connected to square metal pieces A, B, C, and D, and metal probes E (13), F (14), G (15), and H (16) connected to the first metal patch are also provided vertically; the second metal patch is connected to the first metal patch by a coaxial line (25); The hollow structure of the first metal patch is a planar structure formed by subtracting two rectangles, four squares, and one dumbbell shape from a rectangular patch. It includes left rectangular notches and right rectangular notches on both sides, as well as four square hollow positions and one dumbbell-shaped hollow position in the middle. Square metal patches A, B, C, and D are respectively set in the four square hollow positions. The insulating pillars include insulating pillar A (21) and insulating pillar B (22) located in the left rectangular notch, and insulating pillar C (23) and insulating pillar D (24) located in the right rectangular notch. The second metal patch is a metal surface with a regular shape; The square metal patches A, B, C, and D are disposed on the same plane as the first metal patch, and the four square metal patches are symmetrically arranged in pairs on the first dielectric substrate with the antenna center as the center of symmetry. Metal sheets A, B, C, and D are all rectangular sheets of the same thickness and material, and their length is half the length of the first dielectric plate. The antenna is fed by a coaxial line, which includes an outer core and an inner core. The outer core is sleeved outside the inner core. The upper end of the inner core passes upward through the first dielectric plate and is connected to the first metal patch. The lower end of the outer core passes downward through the second dielectric plate and is connected to the second metal patch. An air layer of predetermined height is provided between the first dielectric plate and the second dielectric plate, and the first dielectric plate and the second dielectric plate are fixed by a plurality of insulating pillars distributed between them; During the forming process of the first metal patch hollow structure, the left rectangular notch and the right rectangular notch are symmetrical about the center of the first metal patch; The part where the inner core of the coaxial line is connected to the first metal patch is located at the vertical axis of symmetry of the first metal patch at the dumbbell-shaped hollow position. The antenna is a directional antenna.

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