CN214313543U - Passive anti-metal RFID tag antenna - Google Patents
Passive anti-metal RFID tag antenna Download PDFInfo
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- CN214313543U CN214313543U CN202120482318.3U CN202120482318U CN214313543U CN 214313543 U CN214313543 U CN 214313543U CN 202120482318 U CN202120482318 U CN 202120482318U CN 214313543 U CN214313543 U CN 214313543U
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Abstract
The application provides a passive anti-metal RFID tag antenna. The passive anti-metal RF ID tag antenna comprises: a dielectric layer, a metal surface layer with a slot is arranged on one side of the dielectric layer, the other side opposite to one side is a metal ground, and the metal surface layer comprises: the passive chip is arranged at the interval between the first metal surface and the second metal surface, and the first metal surface and the second metal surface are symmetrically arranged along the passive chip as a central axis and/or are centrosymmetrically arranged. The metal surface comprises the deformed I-shaped groove to realize the low resistance and high inductance resistance of the antenna, and the passive anti-metal RF ID tag antenna can be conveniently stuck on the metal surface and can be well detected by a reader antenna.
Description
Technical Field
The application relates to the technical field of radio frequency, in particular to a passive anti-metal RFID (radio frequency identification) tag antenna.
Background
Radio Frequency identification (rfid) technology has the advantages of being fast, plastic, durable in anti-fouling, changeable, and the like, and is widely applied to various fields in recent years; but also presents some bottlenecks and research challenges, such as resistance to metals. The special electromagnetic property of metal can cause the phenomenon of reading failure; however, in the actual production practice process, metal environments exist in various industries at present, such as goods shelves in logistics, intelligent medical appliances and the like; therefore, the use of RFID tag antennas is very limited for industries such as logistics and steel. To study the effect of metallic environment on RFID, it is also becoming more important to design an RFID tag antenna with resistance to metallic properties.
In recent years, scholars at home and abroad propose a plurality of metal-resistant RFID tag antennas. The document [ compass courage, handsome, yeanzhong ] UHF RFID tag antenna optimization design for metal surfaces [ J ] microwave science, 2015,31(03):31-35] proposes an improved folded dipole antenna, which uses an optimization algorithm to add a short-circuit section to adjust the input impedance of the tag antenna. The structure is relatively simple, but the size is larger and the length is 90 mm; and the gain is small, and when the power reaches the limit of 4W, the reading distance is only 2.4 m. The design of a broadband anti-metal tag antenna adopting a capacitive coupling feed mode [ J ] informationized research, 2014,40(01):51-54] designs an anti-metal antenna adopting capacitive coupling feed; the antenna adopts a single-layer FR4 substrate, and a groove is formed in the circular patch, so that the size of the groove is changed to conveniently achieve impedance matching; however, the reading distance is relatively short, when the power of the reader reaches 4W, the theoretical reading distance can only reach less than 3 meters, the size is larger, 160mm x 40mm, and the installation is not beneficial to occasions with small planes. Substrates with high dielectric constants are often used to reduce the size of the tag antenna, which is equivalent to raising the distance between the tag and the metal surface; in the document [ open bridge, Zhouyonggang, Pengjiang dew, UHF frequency band anti-metal tag antenna analysis and design [ J ] electronic technology, 2016,29(08):4-6], ceramic is used as a substrate, and open-circuit branch lines and short-circuit pieces are loaded, so that the structure is simple, but the cost is too high. The literature [ Wai-Hau Ng; Eng-Hock Lim; Fwee-Leong Bong; a folding slot Antenna using foam as a substrate is provided in book-Kuan Chung.folded Page Antenna With Tunable Inductive Slots and Stubs for UHF Tag design. IEEE Transactions on Antennas and propagation.Yeast: 2018, Volume:66, Issue:6, pages: 2799 and 2806], and the folding slot Antenna uses a C-shaped groove and an L-shaped groove to adjust the resonant frequency and has the advantage of conformal characteristic; but has the disadvantages of complicated structure and difficult processing and production. Literature [ Cai-Wei Moh; Eng-Hock Lim; Fwee-Leong Bong; a foldable Coplanar feeder-powered flexible Folded antenna is designed for book-Kuan Chung, miniature Coplanar antenna-Fed Folded antenna for Metal Mountable UHF RFID tag, IEEE Transactions on Antennas and Propagation, Yeast: 2018, Volume:66, Issue:5, pages: 2245 and 2253, a C-shaped groove is added to increase the capacitance property, an etching notch is used to increase the tuning range, and a stub can be used for effectively tuning the impedance of a tag antenna; however, the thickness of the adhesive is 3mm, and the adhesive does not have the characteristic of low profile, and is not easy to be adhered to the metal surface. The documents [ y. -h.lee, p. -s.chee, e. -h.limandf. -l.bang, "Coupled-PILAs for minor On-metal RFID Tag Design,"2020IEEE Asia-Pacific Microwave Conference (APMC), Hong Kong,2020, pp.878-880, doi: 10.1109/APMC47863.2020.9331605 ] propose a Tag antenna for micro-metals, which is magnetically Coupled by two planar inverted-L antennas acting as a radiator and a coupler, respectively, to achieve miniaturization, ideally achieving a read distance of 8m at an operating frequency of 4W, but with a general gain performance and a large size.
For the application requirement of the tag adhered on the metal surface, the effectiveness of communication between the reader antenna and the tag antenna is considered, the problems of low profile and size of the tag antenna are also considered, and the wear-resistant characteristic of the tag is considered.
For this reason, improvements in existing tag antennas are needed.
SUMMERY OF THE UTILITY MODEL
In order to overcome the above-mentioned defect point, the present application aims at: the utility model provides a novel passive anti metal RFID tag antenna also called super high frequency RFID anti metal tag antenna, this tag antenna be convenient for process and paste satisfy the design demand completely when metal surface environment.
In order to achieve the purpose, the following technical scheme is adopted in the application:
a passive anti-metal RFID tag antenna, characterized in that, the tag antenna is a slot microstrip antenna, it includes:
a dielectric layer, a metal surface layer with a slot is arranged on one side surface of the dielectric layer, a metal ground is arranged on the other side opposite to one side surface,
the metal facing comprises: a first metal surface, a second metal surface and a passive chip,
the passive chip is configured at the interval between the first metal surface and the second metal surface,
the first metal surface and the second metal surface are respectively configured into a horn shape and are symmetrical and/or centrosymmetrical along the passive chip as a central axis.
In one embodiment, the passive metal-resistant RFID tag antenna further includes at least a copper foil layer, wherein the copper foil layer is adhered to the side arm of the metal surface and the end of the dielectric layer to serve as a short-circuit sensing stub, so as to reduce the size.
In one embodiment, the thickness of the metal surface layer is between 0.03mm and 0.05 mm.
In one embodiment, two sides of the first metal surface and the second metal surface are gradually tapered in a shape of a Chinese character 'ba', so as to improve the bandwidth of the antenna.
In one embodiment, the first metal face comprises: a pair of L-shaped slots, I-shaped slots and rectangular slots which are symmetrically arranged, the slots are used for expanding the bandwidth and finely adjusting the resonant frequency,
the I-shaped groove part is connected with the rectangular groove, and the I-shaped groove is symmetrically arranged along the length extending direction of the rectangular groove.
In one embodiment, a convex part is arranged in the middle of the edge of the first metal surface, first rectangular grooves are respectively arranged on two sides of the convex part, and a copper foil which is as wide as the convex part extends from the side wall of the convex part to be connected to a lower layer as a short circuit induction stub; to supplement the current path and improve the gain.
In one embodiment, the L-shaped slot comprises: a long arm and a short arm connected to one end of the long arm, the long arm being disposed parallel or substantially parallel to the space.
In one embodiment, the i-shaped groove comprises: the base and with the shoulder that base one end is connected, rectangular groove is connected to the other end of base.
In one embodiment, the base is perpendicular to the rectangular slot.
In one embodiment, the passive chip is Monza R6-P chip, the chip is placed in the center of the metal surface layer,
when the tag antenna works in the 915MHz field, the impedance of the passive chip is 12.28-j 122.03 omega.
Advantageous effects
Compared with the prior art, the passive anti-metal RFID tag antenna can be conveniently adhered to a metal surface (such as a copper surface) and can be well detected by a reader antenna, and the tag antenna has good gain and reading distance; in addition, the tag antenna has the advantages of simple structure, easy processing, low profile, wear resistance and the like, and is convenient to install.
Drawings
Fig. 1 is a schematic top view of a passive anti-metal RFID tag antenna according to an embodiment of the present application.
Fig. 2 is a schematic side view of a passive anti-metal RFID tag antenna according to an embodiment of the present application.
Fig. 3 is an antenna impedance simulation diagram of a tag antenna according to an embodiment of the present application.
Fig. 4 is a schematic view of simulated return loss of an antenna of a tag antenna according to an embodiment of the present application.
Fig. 5 is an antenna far-field simulation pattern of the tag antenna according to the embodiment of the present application.
Fig. 6 is a schematic diagram of matching a tag antenna with a reader according to an embodiment of the present application.
Detailed Description
The above-described scheme is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes and are not intended to limit the scope of the present invention. The conditions employed in the examples may be further adjusted as determined by the particular manufacturer, and the conditions not specified are typically those used in routine experimentation.
The application provides a passive anti-metal RFID tag antenna. The passive anti-metal RFID tag antenna comprises: a dielectric layer, a metal surface layer with a slot is arranged on one side surface of the dielectric layer, the other side opposite to one side is a metal ground, the metal surface layer comprises: the passive chip is arranged at the interval between the first metal surface and the second metal surface, and the first metal surface and the second metal surface are symmetrically arranged along the passive chip as a central axis and/or are centrosymmetrically arranged. The metal surface comprises the deformed I-shaped groove to realize the low resistance and high inductance resistance of the antenna, and the passive anti-metal RFID tag antenna can be conveniently adhered to the metal surface and can be well detected by a reader antenna. The working principle of the tag antenna is as follows: when the anti-metal RFID tag antenna works, the reader is matched with a reader, firstly, an 'interrogation' signal is radiated by the reader to excite a passive tag antenna, and a meander is formed by slotting on the first metal surface of the tag antenna, so that the effective path of current is prolonged, and the miniaturization of the anti-metal RFID tag antenna is realized; the lateral short-circuit sensing stub has the same function. The two sides of the gradual change shape and the introduction of the L-shaped groove and the I-shaped groove are used for better completing impedance matching, and a broadband effect is formed. The short circuit induction stub line with the same width as the convex part in the middle of the two sides can compensate a current path and improve the gain.
The passive anti-metal RFID tag antenna proposed by the present application is described next with reference to fig. 1 to 6.
As shown in fig. 1 and 2, the passive anti-metal RFID tag antenna includes: a dielectric layer 13, a metal surface layer 10 with a slot is configured on one side of the dielectric layer 13, and the other side opposite to one side is a metal ground (plane), wherein the metal surface 10 with a slot includes: the first metal plane 11 and the second metal plane 12 are disposed with a gap 14 (width is G) between the first metal plane 11 and the second metal plane 12, the passive chip 13 is disposed in the gap 14 (also called gap), and the first metal plane 11 and the second metal plane 12 are disposed symmetrically along a center line of the gap 14 or the first metal plane 11 and the second metal plane 12 are disposed symmetrically along a center line of the gap 14 and a center line of the Y direction, respectively. In this embodiment, the tag antenna is a slot microstrip antenna, and is completely axisymmetric and centrosymmetric with respect to the passive chip 13. Connected to the metal surface by copper foil 16 glued to the side arms. The medium layer is made of FR4 medium plate, preferably, the thickness H1 is 1.6mm, the relative dielectric constant is 4.4, and the loss tangent is 0.02. In one embodiment, the upper/lower metal layers are each 0.035mm thick.
In this embodiment, the first metal surface 11 and the second metal surface 12 have the same structure and are horn-shaped, two sides of the horn-shaped metal surface are gradually changed, and the distance between the gaps is l7, so as to improve the bandwidth of the antenna; the first metal surface 11 is described below as an example, and includes: a pair of L-shaped grooves 111, I-shaped grooves 113, and rectangular grooves 112, which are symmetrically arranged. Preferably, the middle of the two sides of the edge of the first metal surface 11 and the second metal surface 12 has two long L5 symmetrical along the protrusion 116, a rectangular slot 116a with a width T6, a long arm 111b of the L-shaped slot 111 is disposed parallel or approximately parallel to the gap 14, and the i-shaped slots 113 are disposed on the two sides of the rectangular slot 112 and are symmetrically disposed. The base 113a of the rectangular groove 113 is connected to the rectangular groove 113, and has a width T4 in the X direction, a shoulder 113b having a width T5 and a length I6, and a length (X direction) I1 of the rectangular groove 112.
In this embodiment, the metal surface layer 10 has L-shaped grooves formed at four corners of the metal surface, the long arm 111b of the L-shaped groove has a width T3, a side length L3, a side length L4 of the short arm 111a, and a distance L9 from the edge. The four corner side walls are respectively provided with copper foils with width T1 (in X direction) as short circuit induction short stubs. Two symmetrical long l5 and T6 wide rectangular slots are formed in the middle of the two sides of the edge, the distance between the two rectangular slots 116a is T2, and the copper foil with the same width of T2 extends from the side wall of the convex portion 116 in the middle of the two slots to be connected to the lower layer (metal ground) as a short-circuit induction stub (not shown).
Symmetrical grooves are formed in the metal surfaces on the two sides of the passive chip, the grooves are formed by compounding rectangular grooves and I-shaped grooves, the center positions of the grooves are overlapped, and the long edges of the I-shaped grooves are perpendicular to the long edges of the rectangular grooves. The rectangular slot 112 has a width T4, a long side parallel to the slot, and a long side l1 spaced from the slot l 8. The total length l2 of the I-shaped groove and the width T4 of the middle part; the two ends are l6 long and T5 wide. In this embodiment, the parameters of the tag antenna structure are as follows:
L11＝40mm，l1＝25mm，l2＝6mm，l3＝8mm，l4＝4.8mm，l5＝3mm，l6＝2mm，l7＝5mm， l8＝10mm，l9＝1.2mm，T1＝5mm，T2＝0.9mm，T3＝1mm，T4＝1mm，T5＝0.5mm，T6＝0.3mm， G＝0.9mm，H1＝1.6mm。
four corners of the metal surface layer arranged on the upper layer of the tag antenna are respectively provided with an L-shaped groove, so that the bandwidth can be expanded, and meanwhile, the vibration frequency can be tuned slightly. The side wall copper foil 16 is used as a short circuit induction stub, the copper foils with the widths of T1 at the four corners are used as main current paths, the copper foils with the widths of T2 at the right middle parts of the two side edges are used as supplements of the current paths, and the gain can be improved by matching with the rectangular grooves at the corresponding positions of the metal surfaces.
This passive chip adopts the Monza R6-P chip as the feed end of antenna, and the chip is placed in the central point of metal covering, places the feed part in the middle zone, and the benefit lies in: on one hand, the miniaturization is realized, and on the other hand, the processing and welding are also convenient. The chip impedance was 12.28-j 122.03 Ω when operating at 915 MHz. In design, it is necessary to satisfy the conjugate matching of the antenna impedance and the chip impedance. In this embodiment, the antenna uses a modified i-shaped slot to achieve low resistance and high inductance characteristics of the antenna.
The simulation effect of the passive anti-metal RFID tag antenna is described next in connection with fig. 3-6.
Fig. 3 is an antenna impedance simulation diagram of a tag antenna according to an embodiment of the present application. Its input impedance at 915MHz is 15.43+ j 119.50 Ω.
Fig. 4 is a schematic view of simulated return loss of an antenna of a tag antenna according to an embodiment of the present application. As can be seen from the figure, the-10 dB impedance bandwidth is 160MHz, from 810MHz to 970 MHz.
Fig. 5 is an antenna far-field simulation pattern of the tag antenna according to the embodiment of the present application. Fig. 6 is a schematic diagram of matching a tag antenna with a reader according to an embodiment of the present application. An external reader antenna is set to be R2000, the gain is 8dB, the input power is 28dBm (about 630mW), the reader antenna is a circularly polarized antenna, and the size of the metal surface is 200 x 200 mm; the measured reading distance can reach 160cm (in the testing step, an external reader antenna working in an ultrahigh frequency band is adopted, the anti-metal RFID tag antenna is slowly moved and stuck on metal, the distance between the external antenna and the tag antenna is measured by comparing the distance with the distance calculated by a Frans formula until the reader cannot identify the anti-metal tag antenna, and the average value is obtained by measuring for multiple times), and the result shows that the distance required by monitoring is met when the tag antenna provided by the application is stuck on the metal surface. The reader firstly radiates an 'interrogation' signal to excite a passive electronic tag, the tag antenna receives electromagnetic energy from the reader and then drives a chip (such as a Monza R6-P chip) to work, then a 'response' signal carrying chip information is radiated back through the tag antenna, and finally the reader receives the tag signal and carries out data analysis through a data processing module.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, which cannot limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.
Claims (10)
1. A passive anti-metal RFID tag antenna, characterized in that, the tag antenna is a slot microstrip antenna, it includes:
a dielectric layer, a metal surface layer with a slot is arranged on one side surface of the dielectric layer, a metal ground is arranged on the other side opposite to one side surface,
the metal facing comprises: a first metal surface, a second metal surface and a passive chip,
the passive chip is configured at the interval between the first metal surface and the second metal surface,
the first metal surface and the second metal surface are respectively configured into a horn shape and are symmetrical and/or centrosymmetrical along the passive chip as a central axis.
2. The passive metal-resistant RFID tag antenna of claim 1, further comprising at least a copper foil layer adhered to the side arms of the first and second metal planes and the end of the dielectric layer to act as a short sensing stub for size reduction.
3. The passive metal-resistant RFID tag antenna of claim 1, wherein the thickness of the metal facing is between 0.03mm and 0.05 mm.
4. The passive anti-metal RFID tag antenna of claim 1,
the two sides of the first metal surface and the second metal surface are in splayed gradual change shapes and are used for improving the bandwidth of the antenna.
5. The passive anti-metal RFID tag antenna of claim 1,
the first metal face includes: a pair of L-shaped slots, I-shaped slots and rectangular slots which are symmetrically arranged, the slots are used for expanding the bandwidth and finely adjusting the resonant frequency,
the I-shaped groove part is connected with the rectangular groove, and the I-shaped groove is symmetrically arranged along the length extending direction of the rectangular groove.
6. The passive anti-metal RFID tag antenna of claim 5,
a convex part is arranged in the middle of the edge of the first metal surface, first rectangular grooves are respectively arranged on two sides of the convex part, and a copper foil which is as wide as the convex part can extend from the side wall of the convex part to be used as a short circuit induction stub to be connected to the lower layer; to supplement the current path and improve the gain.
7. A passive, metal-resistant RFID tag antenna according to claim 5 or 6, wherein the L-shaped slot comprises: a long arm and a short arm connected to one end of the long arm, the long arm being disposed parallel or substantially parallel to the space.
8. The passive, metal-resistant RFID tag antenna of claim 5 or 6, wherein the I-shaped slot comprises: the base and with the shoulder that base one end is connected, rectangular groove is connected to the other end of base.
9. The passive metal-resistant RFID tag antenna of claim 8, wherein the base is perpendicular to the rectangular slot.
10. The passive metal-resistant RFID tag antenna of claim 1, wherein the passive chip is a Monza R6-P chip, the chip is placed in the center of the metal facing,
when the tag antenna works in the 915MHz field, the impedance of the passive chip is 12.28-j 122.03 omega.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202120482318.3U CN214313543U (en) | 2021-03-06 | 2021-03-06 | Passive anti-metal RFID tag antenna |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120482318.3U CN214313543U (en) | 2021-03-06 | 2021-03-06 | Passive anti-metal RFID tag antenna |
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| CN214313543U true CN214313543U (en) | 2021-09-28 |
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| CN202120482318.3U Active CN214313543U (en) | 2021-03-06 | 2021-03-06 | Passive anti-metal RFID tag antenna |
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- 2021-03-06 CN CN202120482318.3U patent/CN214313543U/en active Active
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