CN104332710A - Method for designing high-performance antenna of RFID reader - Google Patents

Abstract

The invention discloses a method for designing a high-performance antenna of an RFID reader. The method comprises the steps of forming an individual resonance circuit by use of an inductor and a capacitor for the inductance coil principle in the RFID reader, obtaining a total resistance value in the resonance circuit based on the equivalent resistance principle of inductance coil loss, obtaining resonance conditions in the resonance circuit and obtaining the resonant frequency of the resonance circuit when the resonance circuit vibrates, obtaining the quality factor of the whole resonance circuit based on the resonant frequency, and obtaining the inductance value of a circular antenna in the whole RFID reader based on the quality factor of the resonance circuit. According to the method for designing the high-performance antenna of the RFID reader, an ideal RFID antenna can be manufactured, and the antenna manufacturing method simple and the noise interference on the antenna is low; besides, the antenna can be encapsulated in the RFID reader easily.

Description

A kind of method of RFID reader high performance antenna design

Technical field

The present invention relates to technical field of RFID, be specifically related to the method for a kind of RFID reader high performance antenna design.

Background technology

Radio-frequency (RF) identification (RadfoFrequencyIdentification is called for short RFID) technology is a kind of contactless automatic identification technology, and it is by electromagnetic wave or inductance misfortune conjunction mode transmission of signal, to complete the automatic identification to destination object.Compared with other automatic identification technology such as bar code, magnetic card, Contact Type Ic Card, namely RFID technique have identifying need not manual intervention, can identify that multiple target, information storage are large, can work in the advantages such as various adverse circumstances simultaneously.Therefore, RFID technique has been widely used in the fields such as fixed capital management, production line automation, animal and vehicle identification, highway toll, gate control system, storage, commodity counterfeit prevention, airline baggage management, container management.Typical radio-frequency recognition system can be divided into label, reader and Back end data treatment system three parts.

Because the information transmission between reader and card is by radio-frequency antenna wireless transmission, when design, the effect of antenna is also very huge, directly affects the performance of card and reader.The reader antenna of the current overwhelming majority is all the antenna being used in pcb board making, and this antenna is subject to a large amount of noise jamming of pcb board, affect the performance of antenna, and cost is also high.

Summary of the invention

For deficiency of the prior art, poor for antenna performance in prior art, cost is high, the invention provides a kind of method that reader high performance antenna makes, thus reduces noise jamming, reduces costs.

The invention provides the method for a kind of RFID reader high performance antenna design, comprise the steps:

For the inductance coil principle in RFID reader, form single resonant tank by inductance and electric capacity;

Based on the equivalent resistance principle of inductance coil loss, obtain the total resistance value in resonant tank;

Obtain the condition of resonance in resonant tank, and when obtaining resonant tank generation concussion, resonant tank produces resonance frequency;

The quality factor of whole resonant tank are obtained based on resonance frequency;

Quality factor based on resonant tank obtain the circular antenna inductance value in whole RFID reader.

Total resistance value in described acquisition resonant tank comprises:

The equivalent resistance of inductance coil loss, the internal resistance of signal source, load resistance sum.

Described resonant tank produces resonance frequency:

$f_0=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}.$

The described quality factor obtaining whole resonant tank based on resonance frequency are:

$Q=\frac{{\mathrm{\ω}}_{0}L}{R}=\frac{1}{{\mathrm{\ω}}_0\mathrm{CR}}=\frac{1}{R}\sqrt{\frac{L}{C}}=\frac{1}{R}\mathrm{\ρ}.$

The circular antenna inductance value that the described quality factor based on resonant tank obtain in whole RFID reader is:

$L=N^2{\mathrm{\μ}}_{0}R1n\left(\frac{2R}{d}\right);$

Wherein, wherein N is the antenna number of turns, and u0 is permeability of vacuum, and R is coil radius, and d is diameter of wire.

The present invention is directed to actual RFID circuit, for the inductance coil principle in RFID reader, form single resonant tank by inductance and electric capacity; Based on the equivalent resistance principle of inductance coil loss, obtain the total resistance value in resonant tank; Obtain the condition of resonance in resonant tank, and when obtaining resonant tank generation concussion, resonant tank produces resonance frequency; The quality factor of whole resonant tank are obtained based on resonance frequency; Quality factor based on resonant tank obtain the circular antenna inductance value in whole RFID reader.Can produce desirable RFID antenna in this way, and this antenna manufacturing method is simple, the noise jamming caused antenna is little, is also easily encapsulated in RFID reader.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is rfid interrogator in the embodiment of the present invention and tag circuit structural representation;

Fig. 2 is the method flow diagram of the RFID reader high performance antenna design in the embodiment of the present invention;

Fig. 3 is that inductance in the embodiment of the present invention and capacitor form single resonant tank principle schematic.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making other embodiments all obtained under creative work prerequisite, belong to the scope of protection of the invention.

Rfid interrogator in the embodiment of the present invention and tag circuit structural representation are as shown in fig. 1.Wherein, MP1, MN1 are the power MOS pipe of read write line transmitting terminal, MP1 and MN1 is managed by multiple P and N pipe composes in parallel, and the number of paralleling MOS pipe determines that transmitting terminal sends the modulation depth of data.13.56M clock signal is received on the grid of power tube, produces the sinusoidal carrier signal of 13.56M after EMC filtering, impedance matching and antenna on antenna.Comprise abundant harmonic components in 13.56M clock signal, need low-pass filtering to be filtered, the EMC filter be made up of L_emc and C_emc plays the effect of filtering 13.56M harmonic components just; Cs_reader and Cp_reader forms impedance matching network, and on the one hand coupling antenna and the impedance from EMC filter and transmitting terminal, make antenna resonance on a carrier frequency on the other hand; R1, for adjusting the Q value of antenna, makes the bandwidth of antenna meet the requirement transmitting data.

Show the method flow diagram of the RFID reader high performance antenna design in the embodiment of the present invention for Fig. 1, Fig. 2, comprise the steps:

S201, for the inductance coil principle in RFID reader, form single resonant tank by inductance and electric capacity;

For the L_reader coil winding in RFID reader in Fig. 1, the coil winding principle in the embodiment of the present invention is as follows:

In whole process, form single resonant tank by inductance and capacitor, be called single resonance loop, as shown in 3.

S202, equivalent resistance principle based on inductance coil loss, obtain the total resistance value in resonant tank;

In Fig. 3, resistance R1 is the internal resistance of the equivalent resistance of inductance coil L loss, Rs signal source Vs, and RL is load resistance, the total resistance R=R1+Rs+RL in its whole loop.

S203, the condition of resonance obtained in resonant tank, and when obtaining resonant tank generation concussion, resonant tank produces resonance frequency;

When meeting a characteristic frequency in whole resonant tank, the condition of resonance of whole series loop is:

$X=\mathrm{\ωL}-\frac{1}{\mathrm{\ωC}}=0;$

This time whole resonant tank can shake, thus can know, the frequency that whole resonant tank produces resonance is:

$f_0=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}.$

S204, obtain the quality factor of whole resonant tank based on resonance frequency;

By in step S203, can obtain the quality factor of whole resonant tank in this step, this quality factor is obtained by formula below:

$Q=\frac{{\mathrm{\ω}}_{0}L}{R}=\frac{1}{{\mathrm{\ω}}_0\mathrm{CR}}=\frac{1}{R}\sqrt{\frac{L}{C}}=\frac{1}{R}\mathrm{\ρ}.$

S205, the circular antenna inductance value obtained based on the quality factor of resonant tank in whole RFID reader.

By above step, whole quality factor can be obtained, thus can obtain wherein: N is the antenna number of turns, and u0 is permeability of vacuum, R is coil radius, and d is diameter of wire.Soly just can obtain the RFID reader antenna number of turns, coil radius, diameter of wire, permeability of vacuum.

To sum up, the embodiment of the present invention, for the RFID circuit of reality, for the inductance coil principle in RFID reader, forms single resonant tank by inductance and electric capacity; Based on the equivalent resistance principle of inductance coil loss, obtain the total resistance value in resonant tank; Obtain the condition of resonance in resonant tank, and when obtaining resonant tank generation concussion, resonant tank produces resonance frequency; The quality factor of whole resonant tank are obtained based on resonance frequency; Quality factor based on resonant tank obtain the circular antenna inductance value in whole RFID reader.Can produce desirable RFID antenna in this way, and this antenna manufacturing method is simple, the noise jamming caused antenna is little, is also easily encapsulated in RFID reader.

One of ordinary skill in the art will appreciate that all or part of step in the various methods of above-described embodiment is that the hardware that can carry out instruction relevant by program has come, this program can be stored in a computer-readable recording medium, storage medium can comprise: read-only memory (ROM, Read Only Memory), random access memory (RAM, Random Access Memory), disk or CD etc.

Above the method realizing RFID field intensity simulation model that the embodiment of the present invention provides is described in detail, apply specific case herein to set forth principle of the present invention and execution mode, the explanation of above embodiment just understands method of the present invention and core concept thereof for helping; Meanwhile, for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (5)

1. a method for RFID reader high performance antenna design, is characterized in that, comprise the steps:

For the inductance coil principle in RFID reader, form single resonant tank by inductance and electric capacity;

Based on the equivalent resistance principle of inductance coil loss, obtain the total resistance value in resonant tank;

Obtain the condition of resonance in resonant tank, and when obtaining resonant tank generation concussion, resonant tank produces resonance frequency;

The quality factor of whole resonant tank are obtained based on resonance frequency;

Quality factor based on resonant tank obtain the circular antenna inductance value in whole RFID reader.

2. the method for RFID reader high performance antenna design as claimed in claim 1, it is characterized in that, the total resistance value in described acquisition resonant tank comprises:

The equivalent resistance of inductance coil loss, the internal resistance of signal source, load resistance sum.

3. the method for RFID reader high performance antenna design as claimed in claim 2, is characterized in that, described resonant tank produces resonance frequency and is:

$f_0=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}.$

4. the method for RFID reader high performance antenna design as claimed in claim 3, is characterized in that, the described quality factor obtaining whole resonant tank based on resonance frequency are:

$Q=\frac{{\mathrm{\ω}}_{0}L}{R}=\frac{1}{{\mathrm{\ω}}_0\mathrm{CR}}=\frac{1}{R}\sqrt{\frac{L}{C}}=\frac{1}{R}\mathrm{\ρ}$

5. the method for RFID reader high performance antenna design as claimed in claim 4, it is characterized in that, the circular antenna inductance value that the described quality factor based on resonant tank obtain in whole RFID reader is:

$L=N^2{\mathrm{\μ}}_{0}R\ln \left(\frac{2R}{d}\right);$

Wherein, wherein N is the antenna number of turns, and u0 is permeability of vacuum, and R is coil radius, and d is diameter of wire.