A broadband RFID reader antenna

Abstract

The present invention discloses a wide-band RFID reader antenna, comprising a dielectric support cone: a radiation unit; the radiation unit is attached to the surface of the dielectric support cone; a feeding balun; the feeding balun is installed in the middle of the dielectric support cone; the radiation unit comprises two metal strips, the metal strips are wound around the surface of the dielectric support cone to form a spiral line. The present invention solves the technical problem in the prior art of sacrificing the bandwidth of the antenna in order to reduce the size of the antenna.

Description

Technical Field

[0001] The present invention relates to the technical field of radio communications, and in particular to a wide-band RFID reader / writer antenna. Background Art

[0002] With the development of modern wireless communication technology and antenna technology, antenna design is moving towards miniaturization and broadband. The bandwidth of traditional microstrip antennas is only about 5%, which is not wide enough. At present, both military and civilian fields have high requirements for the working frequency range of antennas. Too narrow bandwidth causes many antennas to fail to meet technical requirements and are abandoned. Wideband circularly polarized antennas have many broadband characteristics, and have the advantages of fast transmission rate, high efficiency, and strong anti-interference ability. They are widely used in the field of radio communications.

[0003] Existing wide-band circularly polarized antennas such as Archimedean antennas and planar equiangular spiral antennas are relatively simple in structure. When the frequency band is determined, it is difficult to further reduce the size. The bandwidth of the antenna is often sacrificed in order to reduce the size.

[0004] The invention patent with the authorization number: CN 104112898 B discloses a new type of miniaturized ultra-wideband circularly polarized antenna, including a planar equiangular spiral antenna part, a spherical spiral antenna part, an antenna feeding balun and an antenna reflection cavity; the antenna feeding balun passes through the antenna reflection cavity from the bottom of the antenna and is connected to the starting ends of the spiral arms near the center of the planar spiral antenna part; the patent achieves its miniaturization purpose in the form of a combination of a planar equiangular spiral antenna and a spherical spiral antenna, but this antenna is not conducive to processing. Summary of the invention

[0005] The purpose of the present invention is to provide a wide-band RFID reader / writer antenna, which solves the technical problem in the prior art of sacrificing the bandwidth of the antenna in order to reduce the size of the antenna.

[0006] A broadband RFID reader / writer antenna includes a dielectric support cone:

[0007] A radiation unit; the radiation unit is attached to the surface of the dielectric support frustum;

[0008] A feeding balun; the feeding balun is installed in the middle of the dielectric support cone;

[0009] The radiation unit includes two metal strips, which are wound around the surface of the dielectric support cone to form a spiral line.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows:

[0011] Furthermore, two side edges of the front projection of the medium-supporting frustum are parabolas.

[0012] Furthermore, the inner side surface of the spiral line contacts the outer surface of the medium supporting cone.

[0013] Furthermore, the horizontal projection of the helix is ​​a planar equiangular helix.

[0014] Furthermore, the feeding balun structure is a PCB board with copper patches on both sides.

[0015] Furthermore, the width of the copper patch gradually increases from top to bottom, the upper end of the copper patch is connected to the upper ends of the two metal strips, and the lower end of the copper patch is located at the bottom of the dielectric support cone for connecting the input of the microwave signal.

[0016] Beneficial effects of the present invention:

[0017] The invention provides a wide-band RFID reader antenna, which uses a traditional planar equiangular spiral antenna in a tapered form to further reduce the size of the antenna while ensuring the wide band; the antenna of the invention has a wide-band characteristic, a bandwidth of 200 MHz, an antenna gain better than 6.3 dB within the working bandwidth, an antenna efficiency better than 80%, an axial ratio better than 2 dB, and a compact structure and good directivity; the projection of the spiral line in the invention is a parabola with a smoother appearance and a more compact structure, and from the simulation results, the antenna prepared under the same size has better antenna performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A top view of a wide-band RFID reader / writer antenna according to a specific embodiment of the present invention;

[0020] Figure 2 A front view of a spiral line of a wide-band RFID reader / writer antenna according to a specific embodiment of the present invention;

[0021] Figure 3 It is a front projection diagram of a dielectric support cone of a wide-band RFID reader / writer antenna according to a specific embodiment of the present invention;

[0022] Figure 4 It is a horizontal projection diagram of a dielectric support cone of a wide-band RFID reader / writer antenna according to a specific embodiment of the present invention;

[0023] Figure 5 A front view of a feeding balun structure of a wide-band RFID reader / writer antenna according to a specific embodiment of the present invention;

[0024] Figure 6 It is the simulation and measured standing wave diagram of the present invention;

[0025] Figure 7 is the simulated radiation pattern of the antenna;

[0026] Reference numerals:

[0027] 1- dielectric support cone; 2- radiation unit; 3- feeding balun;

[0028] 201-metal belt; 202-spiral wire;

[0029] 301-Copper patch; 302-PCB board. DETAILED DESCRIPTION

[0030] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0031] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0032] In the description of the present application, it should be understood that the terms "center", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0033] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Example

[0035] like Figure 1-4As shown, a broadband RFID reader / writer antenna provided by the present invention includes a dielectric support cone 1:

[0036] A radiation unit 2; the radiation unit 2 is attached to the surface of the dielectric support cone 1;

[0037] A feeding balun 3; the feeding balun 3 is installed in the middle of the dielectric support cone 1;

[0038] The radiation unit 2 includes two metal strips 201 , and the metal strips 201 are wound around the surface of the dielectric support cone 1 to form a spiral line 202 .

[0039] The structure of the present invention is as follows Figure 1 As shown, the broadband RFID reader antenna consists of three parts: a radiation unit 2, a dielectric support cone 1, and a feeding balun unit 3. The radiation unit is formed by a plane equiangular spiral structure through a cone, and the cone contour is a parabola. The material is a metal conductive material such as copper; the dielectric substrate plays a supporting and insulating role in the entire antenna, and can be made of dielectric insulating materials such as polytetrafluoroethylene; the feeding part is a balun structure with a gradient structure, which plays an impedance matching role in the entire antenna;

[0040] Wherein, both sides of the front projection of the medium-supporting frustum 1 are parabolas, and the inner side surface of the spiral line is in contact with the outer surface of the medium-supporting frustum.

[0041] The horizontal projection of the helix 202 is a plane equiangular helix.

[0042] The feeding balun structure 3 is a PCB board 302 with copper patches 301 on both sides.

[0043] Among them, the width of the copper patch 301 gradually increases from top to bottom, the upper end of the copper patch 301 is connected to the upper ends of the two metal strips 201, and the lower end of the copper patch 301 is located at the bottom of the dielectric support cone 1 for connecting the input of the microwave signal.

[0044] During production, metal conductive materials are first processed into Figure 2 The antenna radiation unit structure shown in the figure is composed of two metal strips forming a cone-shaped equiangular spiral structure, and then the antenna radiation unit is attached to Figure 3 The feed balun structure is a double-sided copper-clad PCB structure, and the upper and lower surfaces have the same structure, both of which are formed by a gradient copper patch structure to form the antenna feed structure. In actual use, a rectangular groove needs to be dug out in the middle of the antenna dielectric substrate. Figure 3As shown, the feeding balun is then installed in the dielectric substrate, wherein the bottom end of the feeding balun is placed at the bottom of the substrate truncated cone for connecting the input of the microwave signal, and the upper and lower surfaces of the upper end are respectively connected to two metal strips of equiangular spirals;

[0045] Compared with existing products, the greatest advantage of the present invention is its more compact size and better antenna performance; the antenna efficiency is 5% higher than similar antennas, the gain is about 0.5dB higher, and the axial ratio characteristic is flatter.

[0046] Figure 6 The simulation and measured standing wave diagrams of the antenna, the dotted line is the simulation result, and the solid line is the test result. Figure 6 It can be seen that the bandwidth of the antenna is 800-1000MHz, which can fully meet the current RFID applications in the UHF frequency band;

[0047] Figure 7 (a) is the directional diagram of the 900MHz antenna in the xz plane (shown by the solid line) and the yz plane (shown by the dotted line) obtained by simulating the antenna of the embodiment. The directional diagram represents the distribution of the radiation energy of the antenna in space within the working frequency band. It can be seen from the figure that the antenna has good directivity in the two main radiation planes (-90 degrees -90 degrees), which can meet the directivity requirements of RFID in certain applications;

[0048] Figure 7 (b) is the right-hand circular polarization (solid line) and left-hand circular polarization (dotted line) radiation patterns obtained by simulating the antenna of the embodiment, and the radiation pattern of 900MHz is given. The radiation pattern characterizes the distribution of the radiation energy of the antenna in space within the working frequency band. From the results, it can be seen that the antenna of the present invention has good directivity within the working frequency band. The 0-degree direction corresponds to the right-hand circular polarization wave, and the 180-degree direction corresponds to the left-hand circular polarization wave, and the radiation in the 0-degree direction is significantly stronger than that in the 180-degree direction. In addition, within the range of ±80°, the left-hand circular polarization wave is significantly smaller than the right-hand circular polarization wave, indicating that the axial ratio index of the antenna in the forward area is relatively high, which can well meet the demand for circularly polarized waves in RFID applications.

[0049] In the description of the present invention, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A broadband RFID reader / writer antenna, comprising a dielectric support cone: A radiation unit; the radiation unit is attached to the surface of the dielectric support frustum; A feeding balun; the feeding balun is installed in the middle of the dielectric support cone; It is characterized in that The two sides of the front projection of the dielectric support frustum are parabolas, a rectangular groove is hollowed out in the middle of the dielectric support frustum, and the feed balun is installed in the rectangular groove; The radiation unit includes two metal strips, which are wound around the surface of the dielectric support cone to form a spiral line, and the horizontal projection of the spiral line is a plane equiangular spiral line; the radiation unit is firstly obtained by processing a metal conductive material, and then attached to the dielectric support cone; The feed balun is a PCB board with copper patches on both sides, and the structures of the upper and lower surfaces are consistent; the width of the copper patch gradually increases from top to bottom, the upper end of the copper patch is connected to the upper ends of the two metal strips, and the lower end of the copper patch is located at the bottom of the dielectric support cone for connecting the input of the microwave signal.

2. A broadband RFID reader / writer antenna according to claim 1, It is characterized in that The inner side surface of the spiral line contacts the outer surface of the medium supporting cone.

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