CN103022649A - Impedance-adjustable tag antenna applied to UHF (ultrahigh frequency) RFID (radio-frequency identification) system - Google Patents
Impedance-adjustable tag antenna applied to UHF (ultrahigh frequency) RFID (radio-frequency identification) system Download PDFInfo
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- CN103022649A CN103022649A CN2013100114652A CN201310011465A CN103022649A CN 103022649 A CN103022649 A CN 103022649A CN 2013100114652 A CN2013100114652 A CN 2013100114652A CN 201310011465 A CN201310011465 A CN 201310011465A CN 103022649 A CN103022649 A CN 103022649A
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Abstract
The invention relates to the field of RFID (radio-frequency identification) electronic tags, in particular to an impedance-adjustable broadband tag antenna applied to UHF (ultrahigh frequency). The tag structure has the advantages of UHF RFID function, tunable impedance, dual-frequency resonance, high gain and the like and comprises an antenna radiation body 1, a dielectric board 2 and a target chip 3. The antenna radiation body 1 comprises two dipoles close to each other and an n-type matching network. The chip with impedance varying from (5-j50) to (80-j400) is matched by regulating the height and width of the n-type matching network, so that the antenna radiation body is fine in conjugated matching in the range of UHF in China.
Description
Technical field
The present invention relates to the radio frequency recognizing electronic label field, be specifically related to a kind of uhf band, the adjustable broadband of impedance label antenna of being applied to.
Background technology
Radio-frequency (RF) identification (Radio Frequency Identification, be called for short RFID) is a kind ofly to carry out contactless bidirectional data communication by wireless radio frequency mode, thus the technology that target is identified.Radio-frequency recognition system generally is comprised of reader (Reader) and electronic tag (Tag).Electronic tag is comprised of on-chip antenna and chip, carries out exchanges data by electromagnetic wave and reader, has intelligent read and encrypted communication function.Antenna is vital device in the rfid system, and rfid system is realized emission, received electromagnetic wave by radio-frequency antenna, thereby realizes that reader is to the identification of electronic tag.
Radio-frequency recognition system operates mainly in low frequency, high frequency, hyperfrequency and microwave frequency band.Low frequency and high-frequency radio frequency system finish identification by the mode of inductance coupling high, read near distance.And hyperfrequency and Microwave radio frequency system are finished identification by the mode of electromagnetic wave transmission, read distant.At present, the frequency of utilization of international standard recommendation hyperfrequency (Ultra High Frequency is called for short UHF) band RFID equipment is 860MHz～960MHz.Wherein, the frequency range that use the North America is 902MHz～928MHz, and the frequency range that use in Europe is 865MHz～868MHz, and the frequency range that Japan uses is 952MHz～954MHz.China's Ministry of Information Industry has issued uhf band rfid system application specifies in April, 2007, China adopts 840MHz～845MHz and 920MHz～925MHz to use frequency range as the uhf band rfid system, and the power of wireless transmitting device is defined as 2W ERP.Electronic tag is divided into active label and passive label, and the self-contained battery of active label provides energy for itself and reader communication, and passive label then receives the electromagnetic wave that sends from reader by label antenna and obtains energy activated chip.The present invention is based on the design theory of passive label, below analyzes technical background of the present invention and necessity thereof:
At first, the scope of Chinese uhf band is 840MHz～845MHz and 920MHz～925MHz, and the centre differs 75MHz, and this has just brought very large problem to Antenna Design and the practical application of rfid system.For example, when one when 840MHz～ideal label antenna of 845MHz scope interior resonance runs into the application background of the read write line of working in a 920MHz～925MHz frequency range or 920MHz～925MHz scope, reading apart from reducing rapidly of label, even can not read, this is because both application bands are not in the same effective range.The designed antenna of the present invention is to cover 840MHz～845MHz and two frequency ranges of 920MHz～925MHz, has very strong frequency range adaptability.
Secondly, present existing Antenna Design technology, can not take into account the tunable characteristic of wide bandwidth characteristic and impedance, for example the design of some antenna has very desirable bandwidth performance, but the tunable scope of impedance is very limited, and this label antenna that has just limited same structure is for the tuning value in the multiple different application environment.Therefore, how to solve this design challenges and just become research emphasis of the present invention.
Again, because plane antenna structure forming label cost is low, be more suitable for large-scale mass production, be worth so the double frequency-band label antenna of studying plane structure has very high practical commercial.
Summary of the invention
The objective of the invention is to overcome existing antenna and taking into account bandwidth, gain and the impedance deficiency aspect adjustable, propose the tunable label antenna of hyperfrequency impedance of a kind of wide bandwidth, high-gain for concrete practical application.This impedance tunable antenna has the characteristics such as wide bandwidth, high-gain, and plane sizes is 101.8mm*22.3mm.For example, this antenna is when coupling NXP super high frequency radio frequency chip, and the resonance double frequency of formation-10dB bandwidth is 834MHz～978MHz, and the reflection coefficient at the 915MHz place is-14dB that gain reaches 2.55dBi.
The present invention is applied to the tunable label antenna of impedance of uhf band rfid system, comprises dielectric-slab and antenna structure.Antenna structure is at the dielectric-slab upper surface, feeder line is added in the centre position of internal dipole, make the structural parameters of internal dipole compare to the structural parameters of outside dipole, the resonance double frequency-band is produced larger impact, the structural parameters of being convenient in the concrete applied environment are regulated.
Compare with existing antenna structure, the present invention has following advantage and beneficial effect:
(1) the tunable label antenna of impedance of the present invention comprises two in-plant dipoles and a ∏ type matching network, in radiosymmetric mode, so that current path is symmetrical, stable and reliable for performance;
(2) inside and outside two dipoles of the tunable label of impedance of the present invention form two resonant elements arranged side by side, and the resonance double frequency is transferred near the centre frequency, with the bandwidth of extended antenna, thereby make antenna present good broadband character;
(3) contain adjustable opening ∏ type matching network in the tunable label construction of impedance of the present invention, regulate width and the height of ∏ type matching network, the chip that antenna and impedance from (5-j50) to (80-j400) are changed reaches conjugate impedance match;
(4) the tunable label of impedance of the present invention connect inside and outside two dipoles matching network on the basis of ∏ type structure, the improvement of various shape (X-type, ellipse, circular etc.) can be arranged according to application demand.
(5) the outside dipole of the tunable label of impedance of the present invention has tunability, can be bent into arbitrary shape according to different application backgrounds, makes simultaneously the area of label antenna have tunability.
Description of drawings
Fig. 1 is the tunable label antenna vertical view of uhf band RFID impedance;
Fig. 2 is the tunable label antenna end view of uhf band RFID impedance;
Fig. 3 is the equivalent circuit diagram of the tunable label of uhf band RFID impedance;
Reflection coefficient chart when Fig. 4 is the tunable label antenna of uhf band RFID impedance and respective impedance chip coupling;
Fig. 5 is the tunable label antenna of uhf band RFID impedance in matched impedance during for the chip in (14.8-j*128) Europe, and gain is with frequency variation curve figure;
Embodiment
(840MHz～845MHz and 920MHz～925MHz) identify, impedance is tunable, the high-gain label antenna of double frequency-band resonance by the super high frequency radio frequency of rfid system use in order to cover Chinese uhf band for this programme.∏ type matching network is realized hyperfrequency to label antenna of the present invention, impedance is adjustable, the design of high-gain label antenna by adopting, and label chip adopts NXP super high frequency radio frequency chip, and the impedance of chip when 915MHz is (14.8-j*128) Ohm.The below also is elaborated by reference to the accompanying drawings for label antenna of the present invention.
The tunable label antenna of uhf band RFID of the present invention impedance, label construction comprises: 1, antenna radiator 2, dielectric-slab 3, label chip.Uhf band RFID impedance is tunable, and label antenna vertical view and end view are distinguished as depicted in figs. 1 and 2, and the equivalent circuit diagram of the tunable label of uhf band RFID impedance as shown in Figure 3.The tunable label antenna of uhf band RFID of the present invention impedance, medium substrate adopts the hydrocarbon ceramic base material, and relative dielectric constant is 3.38, and loss angle tangent is 0.0021, and dielectric-slab thickness is 0.51mm.
For super high frequency radio frequency identification label, its chip impedance generally is plural number.In order to realize the ceiling capacity transmission between antenna and the chip, need input impedance and the chip impedance conjugate impedance match of antenna, namely real part is equal, imaginary part is opposite.For the antenna that makes certain structure can with the chip conjugate impedance match of multiple market main flow, just require the real part of label antenna input impedance and imaginary part that certain regulating power is arranged.For the double frequency-band label antenna of this invention, it belongs to the microband paste structure, by radio circuit knowledge as can be known, by regulating the width of ∏ type matching network, can change the size of inside and outside two dipole shunt inductances, thereby regulate the reactive component in the impedance.The circuit length of the circuit width of internal dipole and outside dipole has considerable influence to the impedance of this antenna simultaneously, so can realize by regulating above structure the coupling of antenna and chip.Regulate height and the width (size of T1 and T3 value in the accompanying drawing 1) of matching network in the tunable label antenna of uhf band RFID impedance, can make the impedance of antenna and corresponding chip impedance in Chinese uhf band scope, reach good coupling.
The total length of the radiating surface of uhf band rfid system double frequency-band label antenna of the present invention is 101.8mm, and width is 22.3mm.By the HFSS Electromagnetic Simulation, the reflection coefficient curve of antenna and the gain with frequency variation curve respectively such as Fig. 4 and Fig. 5.As can be seen from Figure 4, antenna has formed the resonance double frequency near 915MHz; As can be seen from Figure 5, antenna has larger gain, can read distance by Effective Raise.
Such scheme is a kind of embodiment of the present invention, and those of ordinary skills can determine multiple implementation structure and implementation thereof according to actual conditions, and therefore, scope of the present invention should not described to limit by this.It should be appreciated by those skilled in the art, do not breaking away from any structural modification or the local deformation of the scope of the invention, all belong to claim restricted portion of the present invention.
Claims (6)
1. a impedance tunable label antenna that is applied to the uhf band rfid system, it is characterized in that: label antenna comprises two in-plant dipoles and a ∏ type matching network.
2. the impedance tunable label antenna that is applied to the uhf band rfid system according to claim 1, it is characterized in that: inside and outside two dipoles form two resonant elements arranged side by side, the resonance double frequency is transferred near the centre frequency, with the bandwidth of extended antenna, thereby make antenna present good broadband character.
3. the impedance tunable label antenna that is applied to the uhf band rfid system according to claim 1, it is characterized in that: contain adjustable opening ∏ type matching network in the tag antenna structure, regulate width and the height of ∏ type matching network, the chip that antenna and impedance from (50-j50) to (80-j400) are changed reaches conjugate impedance match.
4. the impedance tunable label antenna that is applied to the uhf band rfid system according to claim 1, it is characterized in that: connect the matching network of inside and outside two dipoles on the basis of ∏ type structure, the improvement of various shape (X-type, ellipse, circle etc.) can be arranged according to application demand.
5. the impedance tunable label antenna that is applied to the uhf band rfid system according to claim 1, it is characterized in that: outside dipole has tunability, can be bent into arbitrary shape according to different application backgrounds, make simultaneously the area of label antenna have tunability.
6. the impedance tunable label antenna that is applied to the uhf band rfid system according to claim 1, it is characterized in that: the centre position at internal dipole connects feeder line, make the structural parameters of internal dipole compare to the structural parameters of outside dipole, the resonance double frequency-band is produced larger impact.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013100114652A CN103022649A (en) | 2013-01-14 | 2013-01-14 | Impedance-adjustable tag antenna applied to UHF (ultrahigh frequency) RFID (radio-frequency identification) system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013100114652A CN103022649A (en) | 2013-01-14 | 2013-01-14 | Impedance-adjustable tag antenna applied to UHF (ultrahigh frequency) RFID (radio-frequency identification) system |
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| CN103022649A true CN103022649A (en) | 2013-04-03 |
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| CN2013100114652A Pending CN103022649A (en) | 2013-01-14 | 2013-01-14 | Impedance-adjustable tag antenna applied to UHF (ultrahigh frequency) RFID (radio-frequency identification) system |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104966897A (en) * | 2015-07-07 | 2015-10-07 | 深圳市共进电子股份有限公司 | T type dipole antenna |
| CN106785491A (en) * | 2016-12-30 | 2017-05-31 | 歌尔科技有限公司 | A kind of dipole dual-band antenna and electronic product |
| CN107092955A (en) * | 2017-06-12 | 2017-08-25 | 北京智芯微电子科技有限公司 | A kind of impedance regulation label antenna and electronic tag |
| CN109409156A (en) * | 2018-10-31 | 2019-03-01 | 华大半导体有限公司 | A kind of antenna impedance method of adjustment of UHF RFID label tag |
| CN111931893A (en) * | 2020-07-10 | 2020-11-13 | 菜鸟智能物流控股有限公司 | Radio frequency label |
| CN112909526A (en) * | 2021-01-22 | 2021-06-04 | 宁波大学 | Dual-frequency point ultrahigh-frequency bandwidth tagged antenna |
-
2013
- 2013-01-14 CN CN2013100114652A patent/CN103022649A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 谭娟娟等: ""新型双U-T结构宽频带RFID标签天线设计"", 《电子器件》 * |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104966897A (en) * | 2015-07-07 | 2015-10-07 | 深圳市共进电子股份有限公司 | T type dipole antenna |
| CN104966897B (en) * | 2015-07-07 | 2018-07-13 | 深圳市共进电子股份有限公司 | T-type dipole antenna |
| CN106785491A (en) * | 2016-12-30 | 2017-05-31 | 歌尔科技有限公司 | A kind of dipole dual-band antenna and electronic product |
| CN106785491B (en) * | 2016-12-30 | 2023-07-21 | 歌尔科技有限公司 | Dipole dual-frequency antenna and electronic product |
| CN107092955A (en) * | 2017-06-12 | 2017-08-25 | 北京智芯微电子科技有限公司 | A kind of impedance regulation label antenna and electronic tag |
| CN109409156A (en) * | 2018-10-31 | 2019-03-01 | 华大半导体有限公司 | A kind of antenna impedance method of adjustment of UHF RFID label tag |
| CN109409156B (en) * | 2018-10-31 | 2021-10-26 | 华大恒芯科技有限公司 | Antenna impedance adjusting method for UHF RFID tag |
| CN111931893A (en) * | 2020-07-10 | 2020-11-13 | 菜鸟智能物流控股有限公司 | Radio frequency label |
| CN111931893B (en) * | 2020-07-10 | 2023-12-26 | 菜鸟智能物流控股有限公司 | Radio frequency tag |
| CN112909526A (en) * | 2021-01-22 | 2021-06-04 | 宁波大学 | Dual-frequency point ultrahigh-frequency bandwidth tagged antenna |
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