CN102456946A - Method for accurately adjusting center frequency of radio frequency identification antenna - Google Patents
Method for accurately adjusting center frequency of radio frequency identification antenna Download PDFInfo
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- CN102456946A CN102456946A CN2010105149461A CN201010514946A CN102456946A CN 102456946 A CN102456946 A CN 102456946A CN 2010105149461 A CN2010105149461 A CN 2010105149461A CN 201010514946 A CN201010514946 A CN 201010514946A CN 102456946 A CN102456946 A CN 102456946A
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Abstract
The invention discloses a method for accurately adjusting a center frequency of a radio frequency identification antenna. By adding a series resistor, a series capacitor and a parallel capacitor into the radio frequency identification antenna, the natural inductance and natural capacitance of the radio frequency identification antenna can be accurately measured and calculated. By adoption of a design method of the radio frequency identification antenna and a method for quantitatively and accurately measuring and calculating equivalent capacitance and inductance, the problems of inaccuracy in judgment of the center frequency and blindness in test of inductance and capacitance parameters by a radio frequency identification product development engineer during antenna design are effectively solved, and a radio frequency identification antenna can be applied to various kinds of using occasions.
Description
Technical field
The present invention relates to method for designing and the equivalent inductance thereof of RFID antenna, the method for measurement of equivalent capacity, and the method that how to realize adjusting the RFID antenna center frequency point, relate in particular to a kind of accurate method of adjustment of RFID antenna centre frequency.
Background technology
Along with REID extensively adopts, the antenna performance of rfid device has been designed to the major issue that the engineer pays close attention to.And the centre frequency of antenna is very big to performance impact, the measurement of centre frequency has been become a necessary Consideration of Antenna Design.At present a lot of engineers be the parameter of coming electric capacity and inductance in the decision circuitry with sensation and experience, design RFID antenna, and measurement is not only not accurate enough like this, also need spend the plenty of time to test.The present invention provides a kind of simple antenna design method and the method for quantitatively calculating RFID antenna equivalent capacity inductance to solve this problem, has effectively solved radio frequency identification PRODUCT DEVELOPMENT ENGINEER and in Antenna Design, centre frequency has been judged problem inaccurate and that blindly debug inductance and capacitance parameter.
Summary of the invention
The problem that is difficult to accurately allocate the center of antenna frequency in the process to existing RFID antenna developing and debugging; The object of the invention is: adopt simple RFID antenna method for designing; Method with quick estimation circuit equivalent inductance and equivalent capacity; Realize accurately allocating the RFID antenna centre frequency, solve RFID antenna Developmental Engineer's practical challenges.
A kind of accurate method of adjustment of RFID antenna centre frequency; Described the present invention is employed in increases a series resistance, a series capacitance and a shunt capacitance on the RFID antenna, realize the inherent inductance of antenna and the accurate measuring and calculating of natural capacity; Concrete method of adjustment is following:
The computing formula of antenna resonant frequency:
----formula 1
According to this formula, it is solid that we are called L to the inherent inductance L of antenna own, and it is solid to be called C to the natural capacity C of antenna own; Resistance is got 0 ohm in Fig. 2, and series connection or parallel connection can obtain following formula a resistance time again:
L is total=L is solid----formula 2
----formula 3
C is total=and C is solid+C----formula 4 also
Thereby can calculate the inherent inductance and the natural capacity of antenna, mix a suitable series capacitance or shunt capacitance according to these two parameters again, so just can obtain the centre frequency that we hope that antenna has.Summing up rule is that shunt capacitance appearance value is big more, and centre frequency is more little; Series capacitance appearance value is big more, and centre frequency is big more.
Calculate electric capacity and the inductance value that satisfies the RFID antenna centre frequency according to mathematical formulae.By this method, the RFID antenna Developmental Engineer can quick and precisely measure the equivalent capacity and the equivalent inductance of tested antenna, and then obtains the capacitance of actual needs.That this method realizes is simple, fast, cost is low, can effectively realize coil antenna centre frequency measuring and calculating and the allotment fast to RFID antenna, solves the problem that RFID antenna is difficult for adjustment.The developer who gives RFID antenna brings accurately reference data and makes things convenient for environment for use in design and debugging radio frequency identification aerial.
Description of drawings
Fig. 1 is the work structuring sketch map of conventional radio frequency identification aerial;
Fig. 2 is the work structuring sketch map of RFID antenna of the present invention.
Embodiment
How further specify the present invention below in conjunction with accompanying drawing realizes:
As shown in Figure 1, traditional RFID antenna be on printed circuit board (PCB) with the Copper Foil loop aerial that connects up out, the number of turns, shape and the size of antenna are different usually, the intrinsic centre frequency that obtains antenna like this has difference.
As shown in Figure 2, the present invention is employed on traditional RFID antenna, increases the method for a series resistance, a series capacitance and a shunt capacitance, and the parameters such as intrinsic centre frequency that obtain antenna like this can be adjusted through these three components and parts.Concrete method of adjustment is following:
The computing formula of antenna resonant frequency:
----formula 1
According to this formula, it is solid that we are called L to the inherent inductance L of antenna own, and it is solid to be called C to the natural capacity C of antenna own; Resistance is got 0 ohm in Fig. 2, and series connection or parallel connection can obtain following formula a resistance time again:
L is total=L is solid----formula 2
C is total=and C is solid+C----formula 4 also
Thereby can calculate the inherent inductance and the natural capacity of antenna, mix a suitable series capacitance or shunt capacitance according to these two parameters again, so just can obtain the centre frequency that we hope that antenna has.Summing up rule is that shunt capacitance appearance value is big more, and centre frequency is more little; Series capacitance appearance value is big more, and centre frequency is big more.
Illustrate as follows for the method
To an improved RFID RFID antenna of the present invention, we do following experiment:
(1) one 0 Ohmic resistance of elder generation's series connection, the 82PF electric capacity of connecting again is 10.09MHz through actual measurement center of antenna frequency;
(2) changing the electric capacity of series connection into 39PF again, is 11.488MHz through actual measurement center of antenna frequency; By above two experiments, send into formula 1, formula 2, formula 3, formula 4 to two groups of data respectively, carry out linear equation in two unknowns, can obtain L and be 196UH admittedly, C is 31PF admittedly.Solid and the solid parameter value of L according to the C that calculates, by the 13.56MHz of RFID code requirement, according to the antenna resonant frequency computing formula, the appearance value that can calculate the actual series connection that should use or shunt capacitance gets final product again.Usually when the natural frequency of RFID antenna during greater than 13.56MHz, we adopt the method for shunt capacitance to adjust the centre frequency of RFID antenna.0 ohm that connects in the circuit is to reserve device, for the Q quality factor value that prevents circuit is too high, and usually need be less than 50.
This RFID antenna centre frequency method of adjustment is easy to use, quick; Obtain data accurately and reliably; RFID antenna centre frequency measuring method is easy to learn, can make the method for same antenna through adjustment resistance capacitance parameter, satisfies the demand of different occasions.
Claims (3)
1. the accurate method of adjustment of a RFID antenna centre frequency; It is characterized in that: being employed in increases a series resistance, a series capacitance and a shunt capacitance on the RFID antenna, realize the inherent inductance of antenna and the accurate Calculation of natural capacity: concrete method of adjustment is following:
The computing formula of antenna resonant frequency:
----formula 1
According to this formula, it is solid to be called L to the inherent inductance L of antenna own, and it is solid to be called C to the natural capacity C of antenna own; Resistance is got 0 ohm in figure (2), series connection or parallelly connected resistance the time, can obtain following formula again:
L is total=L is solid----formula 2
C is total=and C is solid+C----formula 4 also
2. according to the accurate method of adjustment of a kind of RFID antenna centre frequency under the claim 1, it is characterized in that: describedly accurately calculate electric capacity, the inductance of actual needs, the parameter value of resistance through computational methods.
3. according to the accurate method of adjustment of a kind of RFID antenna centre frequency under the claim 1, it is characterized in that: described shunt capacitance appearance value is big more, and centre frequency is more little; Series capacitance appearance value is big more, and centre frequency is big more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010105149461A CN102456946A (en) | 2010-10-21 | 2010-10-21 | Method for accurately adjusting center frequency of radio frequency identification antenna |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010105149461A CN102456946A (en) | 2010-10-21 | 2010-10-21 | Method for accurately adjusting center frequency of radio frequency identification antenna |
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| CN102456946A true CN102456946A (en) | 2012-05-16 |
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| CN2010105149461A Pending CN102456946A (en) | 2010-10-21 | 2010-10-21 | Method for accurately adjusting center frequency of radio frequency identification antenna |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104112912A (en) * | 2013-04-18 | 2014-10-22 | 航天信息股份有限公司 | Parameter adjustment method for high-frequency reader-writer antenna applied in metal environment |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001185939A (en) * | 1999-12-24 | 2001-07-06 | Mitsubishi Electric Corp | Antenna coil and electromagnetic induction type contactless data carrier system |
| JP2001326526A (en) * | 2000-05-16 | 2001-11-22 | Mitsubishi Electric Corp | Shield antenna coil |
| EP1160915A2 (en) * | 2000-05-30 | 2001-12-05 | Mitsubishi Materials Corporation | Antenna device of interrogator |
| JP2006140842A (en) * | 2004-11-12 | 2006-06-01 | Matsushita Electric Ind Co Ltd | Contactless ic card reader/writer |
| CN101501991A (en) * | 2006-06-27 | 2009-08-05 | 传感电子公司 | Resonant circuit tuning system with dynamic impedance matching |
-
2010
- 2010-10-21 CN CN2010105149461A patent/CN102456946A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001185939A (en) * | 1999-12-24 | 2001-07-06 | Mitsubishi Electric Corp | Antenna coil and electromagnetic induction type contactless data carrier system |
| JP2001326526A (en) * | 2000-05-16 | 2001-11-22 | Mitsubishi Electric Corp | Shield antenna coil |
| EP1160915A2 (en) * | 2000-05-30 | 2001-12-05 | Mitsubishi Materials Corporation | Antenna device of interrogator |
| JP2006140842A (en) * | 2004-11-12 | 2006-06-01 | Matsushita Electric Ind Co Ltd | Contactless ic card reader/writer |
| CN101501991A (en) * | 2006-06-27 | 2009-08-05 | 传感电子公司 | Resonant circuit tuning system with dynamic impedance matching |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104112912A (en) * | 2013-04-18 | 2014-10-22 | 航天信息股份有限公司 | Parameter adjustment method for high-frequency reader-writer antenna applied in metal environment |
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Application publication date: 20120516 |