CN103872429A - Miniaturized UHF RFID (Ultra High Frequency Radio Frequency Identification) tag antenna - Google Patents

Miniaturized UHF RFID (Ultra High Frequency Radio Frequency Identification) tag antenna Download PDF

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Publication number
CN103872429A
CN103872429A CN201410083422.XA CN201410083422A CN103872429A CN 103872429 A CN103872429 A CN 103872429A CN 201410083422 A CN201410083422 A CN 201410083422A CN 103872429 A CN103872429 A CN 103872429A
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CN
China
Prior art keywords
antenna
impedance
inductance element
label
chip
Prior art date
Application number
CN201410083422.XA
Other languages
Chinese (zh)
Inventor
章伟
田果成
张义强
韩德克
邱运邦
徐虎
Original Assignee
爱康普科技(大连)有限公司
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Application filed by 爱康普科技(大连)有限公司 filed Critical 爱康普科技(大连)有限公司
Priority to CN201410083422.XA priority Critical patent/CN103872429A/en
Publication of CN103872429A publication Critical patent/CN103872429A/en

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Abstract

The invention provides a miniaturized UHF RFID (Ultra High Frequency Radio Frequency Identification) tag antenna. An inductance element which is matched with equivalent capacitance in a chip is arranged on an antenna, the capacitive reactance of the equivalent capacitance is equal to the inductive reactance of the inductance element, and the equivalent capacitance in the chip and the matched inductance element are of a parallel or serial structure. The miniaturized UHF RFID tag antenna provided by the utility model has the advantages that since the inductance element replaces a short-circuit ring, the area occupied by the short-circuit ring is saved, the effective area of the antenna is increased and the gain of the antenna is improved; the antenna can be matched with tag chips with different impedance characteristics as long as different inductance is adjusted, the inductance element is only required to be replaced, the tag antenna design layout is not required to be replaced, tag design can be performed aiming at different chips, the best impedance conjugate matching is realized and the best tag performance is realized.

Description

A kind of miniaturization UHF RFID label antenna

Technical field

The present invention relates to RFID label technique field, relate in particular to a kind of small-sized UHF RFID label field.

Background technology

In the utilization of UHF RFID label, often encounter label sizes, pliability are had to harsh situation about requiring: be for example embedded into the label in rubber for tire, flexible anti-miniaturization anti-metal tag etc. and use; But designer is being perplexed in the design of label antenna being carried out to miniaturization always, conventional miniaturization scheme is exactly that the dielectric constant that improves antenna substrate carries out Miniaturization Design to label antenna--because the operation wavelength of antenna and the dielectric constant of antenna substrate are inversely proportional to, in theory, antenna substrate dielectric constant is higher, and the size of antenna is just less.But the selection of the base material of high-k is very limited, generally adopt the ceramic base material of high-k to carry out the Miniaturization Design of label, but this scheme has a series of problem and drawback:

(1) adopt the PCB base material of high-k or the pottery of the high-k label as base material, size possesses certain miniaturization feature, but often do not possess again flexible characteristic, cannot be embedded in some special environments for use and go, it is bending for example showing labelled body surface.

(2) its electrical quantity of the base material of high-k is often difficult to do stable, and the instability of its dielectric constant even reaches 30%, and this is great threat to the consistency of performance that ensures label antenna;

(3) prints labels antenna on the base material of high-k, antenna cabling is very easy to come off, thereby label was lost efficacy;

(4) base material of high-k is often very expensive, makes to adopt the label cost of this base material significantly to increase, and this is very disadvantageous to the utilization of promoting label;

Based on current technical situation, the utmost point needs a kind of stable, easy, scheme of label miniaturization cheaply, can be applied to easily in multi-form label antenna.

As shown in Figure 1, UHF RFID label is made up of two parts the chip structure of general UHF RFID label, and a part is label chip, and a part is label antenna in addition.As shown in Figure 1, the equivalent electric circuit that right side is label chip, the equivalent electric circuit that left side is label antenna; When antenna and the each self-impedance conjugate pair of label seasonable, UHF RFID label is realized best impedance matching;

Label antenna and label chip impedance conjugate relation are as follows:

It is 1500 that the value that can get the parallel resistance Ri of chip Alien-Technology-Higgs-3 equals , the value of shunt capacitance Ci equals 0.85pF, adopt ADS software to label chip impedance calculate, calculate gained chip impedance real part with histogram as shown in Figure 2, according to the requirement of impedance conjugation, antenna impedance real part should equate with chip impedance real part, is just best impedance matching.Calculate gained chip impedance imaginary part with histogram as shown in Figure 3, according to the requirement of impedance conjugation, antenna impedance imaginary part should with chip impedance imaginary part opposite number (conjugation) each other, be just best impedance matching.

But in the prior art, label antenna emotional resistance imaginary part is provided by coupling ring (short-circuited conducting sleeve), coupling ring size is larger, and emotional resistance imaginary part is just larger; Conventional tags as shown in Figure 4, is on label, to design a short-circuited conducting sleeve, on label, forms an annulus with metal wire.Therefore, adopt the antenna of the label that such method designs to comprise two parts: radiating doublet 1 and short-circuited conducting sleeve 3.According to the design theory of label antenna and practice, short-circuited conducting sleeve is larger than radiating doublet to the performance role of label, and within the specific limits, the dimensions length of short-circuited conducting sleeve is directly proportional to the emotional resistance of label antenna; Therefore label antenna will be realized and the effect of label chip conjugate impedance match, and short-circuited conducting sleeve just must reach certain size, can not arbitrarily reduce or remove.And this annulus need to account for certain area, on the unrestricted label of area, this is inessential, but for small-sized, miniature label, this planar inductor area occupied is too large, cannot realize the miniaturization of label.

This antenna can be analyzed by the circuit model of a simplification, as shown in Figure 5, obtains the input impedance of seeing into from antenna feed mouth based on circuit model:

Wherein be the mutual inductance between antenna radiator and electric feedback ring, characterize the stiffness of coupling between them; be the resistance value of electric feedback ring itself, its value depends on the inductance value of electric feedback ring itself , can be expressed as

Wherein inductance value area and track lengths by coupling ring determine, in quarter-wave, track lengths and inductive impedance value are proportional, as the emotional resistance imaginary part of nearly 200 ohm need to be provided, the area that needs coupling ring more than 15mm*15mm, is difficult to carry out the design of miniaturization.

As shown in Figure 9 and Figure 10, as shown in figure 11, wherein Rc Cc is chip equivalent series resistance, equivalent series electric capacity to its Mathematical Modeling to conventional anti-metal tag antenna; Wherein Ra La is label antenna equivalent series resistance, equivalent series inductance; Only have in the time that the condensance value of equivalent series capacitor C c and equivalent series inductance La equates with inductive impedance value, whole label is realized conjugate impedance match, reaches best effect.

Its chips equivalent series capacitor C c is fixing, and value and the antenna length of label antenna equivalent series inductance La are proportional, reach the condensance value target equal with inductive impedance value of equivalent series capacitor C c and equivalent series inductance La, the length that needs 6cm left and right, label cannot carry out the design of miniaturization.

Summary of the invention

The problem that is difficult to carry out miniaturization in order to overcome the antenna of traditional UHF RFID label, the invention provides a kind of miniaturization UHF RFID label antenna.

The technical scheme that the present invention adopted is for achieving the above object: a kind of miniaturization UHF RFID label antenna, antenna be provided with chip in the inductance element that matches of equivalent capacity, the induction reactance of the capacitive reactance of equivalent capacity and coupling inductance element equates.

Scheme one, in described chip, equivalent capacity is parallel-connection structure with the inductance element matching.

Described antenna impedance real part equates with chip impedance real part, antenna impedance imaginary part and chip impedance imaginary part conjugation.

Scheme two, in described chip, equivalent capacity is cascaded structure with the inductance element matching.

In scheme one and scheme two, described inductance element is wire-wound inductor.

Miniaturization UHF RFID label antenna of the present invention, has replaced short-circuited conducting sleeve with inductance element, has economized out short-circuited conducting sleeve area occupied, increases the effective area of antenna, thereby improves the gain of antenna; And only need to adjust different induction, can mate from the label chip with different impedance operators, so just only need to substitute inductance element, do not need to substitute label antenna design layout, can carry out label design for different chips, to reach best impedance conjugate impedance match, thereby reach best tag performance.

Brief description of the drawings

Fig. 1 is UHF RFID tag antenna structure schematic diagram.

Fig. 2 is that UHF RFID label chip impedance real part is with histogram.

Fig. 3 is that UHF RFID label chip imaginary impedance is with histogram.

Fig. 4 is conventional UHF RFID label antenna schematic diagram.

Fig. 5 is conventional UHF RFID label antenna equivalent-circuit model figure.

Fig. 6 is the embodiment of the present invention one miniaturization UHF RFID tag antenna structure schematic diagram.

Fig. 7 is the impedance real part value change profile figure under the different stress states of the embodiment of the present invention one miniaturization UHF RFID label antenna.

Fig. 8 is the imaginary impedance value change profile figure under the different stress states of the embodiment of the present invention one miniaturization UHF RFID label antenna.

Fig. 9 is conventional anti-metal tag antenna schematic top plan view.

Figure 10 is that conventional anti-metal tag antenna master looks schematic diagram.

Figure 11 is conventional anti-metal tag equivalent-circuit model figure.

Figure 12 is the embodiment of the present invention two miniaturization UHF RFID anti-metal tag antenna plan structure schematic diagrams.

Figure 13 is the main TV structure schematic diagram of the embodiment of the present invention two miniaturization UHF RFID anti-metal tag antenna.

Figure 14 is the embodiment of the present invention two miniaturization UHF RFID anti-metal tag equivalent-circuit model figure.

In figure: 1, radiating doublet, 2, chip, 3, short-circuited conducting sleeve, 4, inductance element, 5, via hole.

Embodiment

Embodiment mono-, a kind of miniaturization UHF RFID tag antenna structure of the present invention and principle are as shown in Figure 6, antenna is provided with the inductance element 4 matching with the interior equivalent capacity of chip 2, the induction reactance of the capacitive reactance of equivalent capacity and coupling inductance element 4 equates, antenna comprises radiating doublet 1 and inductance element 4, and the interior equivalent capacity of chip 2 is parallel-connection structure with the inductance element 4 matching.

Principle is as follows:

The equivalent input capacitance of chip is C, and its capacitive reactance is: XC=1/ (2 π f C);

The inductance value of coupling inductance element is L, and its induction reactance is: XL=2 π f L;

For realizing the coupling of impedance, must meet: XL=XC;

Therefore, the inductance value of coupling inductance element should be: f) 2C of L=1/[(2 π]

Fig. 7 is under different stress states, impedance real part value variation diagram.In impedance real part test comparison diagram under different stress states, the value of real part that loads the label antenna impedance of wire-wound inductor is greater than without loading the anti-value of real part of simple match loop resistance, more approach chip impedance real part, be more conducive to the conjugate impedance match of label antenna impedance and label chip impedance.

In Fig. 8, in imaginary impedance test comparison diagram under different stress states, the imaginary values that loads the label antenna impedance of wire-wound inductor loads the anti-imaginary values of simple match loop resistance much larger than nothing, the label antenna imaginary impedance value that loads simple match ring is between 0.8GHz to 1GHz in scope, all be less than 50 ohm, and the label antenna imaginary impedance value that loads wire-wound inductor 22nH is in the time of 920MHz frequency, imaginary impedance value approaches 200 ohm, with label chip imaginary impedance opposite number each other, there is better label antenna impedance and the conjugate impedance match degree of chip impedance, therefore, load wire-wound inductor and have more superior performance with respect to the label that loads simple match ring.

In the electronic tag of certain space volume, by loading wire-wound inductor design, the real part of inductance and imaginary part are increased, impedance conjugate impedance match is better, and the reading/writing distance of label is just larger; Therefore, obtain the electronic tag of same impedance magnitude, can greatly reduce volume, be convenient to the application that miniaturization embeds.

Meanwhile, in Fig. 8, by loading the wire-wound inductor of different value, can adjust label antenna imaginary impedance value; The wire-wound inductor value loading is larger, and its emotional resistance is just larger; Otherwise side is less; Only need to adjust different induction, can mate from the label chip with different impedance operators.So just only need to substitute inductance element, do not need to substitute label antenna design layout.Therefore can carry out label design for different chips, to reach best impedance conjugate impedance match, thereby reach best tag performance.By the method, the impedance conjugate impedance match degree of abstract factory antenna and label chip easily, the requirement that realizes difference and read distance;

In existing label antenna design, label antenna emotional resistance imaginary part is provided by coupling ring, and coupling ring size is larger, and emotional resistance imaginary part is just larger; As the emotional resistance imaginary part of nearly 200 ohm need to be provided, need the area of coupling ring more than 15mm*15mm, be difficult to carry out the design of miniaturization.Load the scheme of wire-wound inductor by employing, only need the space of 0402 package size just can realize mate good with chip.

Embodiment bis-, UHF RFID anti-metal tag structure and principle, as shown in Figure 12-14, adopt the mode of loaded in series wire-wound inductor, the inductive impedance value that can supplement by wire-wound inductor La, thus reduce the requirement of conjugate impedance match to label antenna size.

In anti-metal tag, by loading wire-wound inductor L, under the limited size of electronic tag, significantly improve the emotional resistance of antenna, and the level of impedance match of antenna and chip, greatly promote the reading/writing distance of label, substitute the structural design of existing coupling ring, dwindle the volume of anti-metal tag, greatly widened the miniaturization of label and used.

By loading the scheme of wire-wound inductor, under finite size, significantly improve the emotional resistance of anti-metal tag antenna, significantly improve the level of impedance match of label antenna and label chip, make in conventional design, the size of label antenna coupling ring has obtained significantly dwindling, and has greatly widened the miniaturization of label and has used scene.

By loading the wire-wound inductor of different value, can adjust anti-metal tag antenna imaginary impedance value; The wire-wound inductor value loading is larger, and its emotional resistance is just larger; Otherwise side is less; By the method, the impedance conjugate impedance match degree of abstract factory antenna and label chip easily, the requirement that realizes difference and read distance.

The present invention is described by embodiment, and those skilled in the art know, without departing from the spirit and scope of the present invention, can carry out various changes or equivalence replacement to these features and embodiment.In addition, under instruction of the present invention, can modify to adapt to concrete situation and material and can not depart from the spirit and scope of the present invention these features and embodiment.Therefore, the present invention is not subject to the restriction of specific embodiment disclosed herein, and the embodiment within the scope of all the application's of falling into claim belongs to protection scope of the present invention.

Claims (5)

1. a miniaturization UHF RFID label antenna, is characterized in that: antenna is provided with the inductance element (4) matching with the interior equivalent capacity of chip (2), and the induction reactance of the capacitive reactance of equivalent capacity and coupling inductance element (4) equates.
2. a kind of miniaturization UHF RFID label antenna according to claim 1, is characterized in that: the interior equivalent capacity of described chip (2) is parallel-connection structure with the inductance element (4) matching.
3. a kind of miniaturization UHF RFID label antenna according to claim 2, is characterized in that: described antenna impedance real part equates with chip (2) impedance real part, antenna impedance imaginary part and chip (2) imaginary impedance conjugation.
4. a kind of miniaturization UHF RFID label antenna according to claim 1, is characterized in that: the interior equivalent capacity of described chip (2) is cascaded structure with the inductance element (4) matching.
5. according to a kind of miniaturization UHF RFID label antenna described in claim 3 or 4, it is characterized in that: described inductance element (4) is wire-wound inductor.
CN201410083422.XA 2014-03-07 2014-03-07 Miniaturized UHF RFID (Ultra High Frequency Radio Frequency Identification) tag antenna CN103872429A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105279550A (en) * 2015-11-30 2016-01-27 爱康普科技(大连)有限公司 RFID tag for cigarette case identification

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101013771A (en) * 2006-01-31 2007-08-08 富士通株式会社 Folding dipole antenna and tag using the same
KR20080013213A (en) * 2006-08-07 2008-02-13 전자부품연구원 Rfid tag
US20110132988A1 (en) * 2008-07-31 2011-06-09 Renesas Electronics Corporation Non-contact electronic device
CN203119091U (en) * 2012-01-02 2013-08-07 耀登电通科技(昆山)有限公司 Passive radio frequency identification tag antenna applicable to metal surfaces

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101013771A (en) * 2006-01-31 2007-08-08 富士通株式会社 Folding dipole antenna and tag using the same
KR20080013213A (en) * 2006-08-07 2008-02-13 전자부품연구원 Rfid tag
US20110132988A1 (en) * 2008-07-31 2011-06-09 Renesas Electronics Corporation Non-contact electronic device
CN203119091U (en) * 2012-01-02 2013-08-07 耀登电通科技(昆山)有限公司 Passive radio frequency identification tag antenna applicable to metal surfaces

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105279550A (en) * 2015-11-30 2016-01-27 爱康普科技(大连)有限公司 RFID tag for cigarette case identification

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Application publication date: 20140618