CN103886363B - Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag and implementation method - Google Patents

Abstract

The invention belongs to microstrip antenna technical field, it is provided that double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag and implementation method, including: substrate, surface silver slurry carries out silk-screen, has 2 merit parallel circuit ends, feeder duct, the patterns of chip slot after silk-screen；Electrode layer, the silver slurry layer of the substrate surface for being coated in addition to area of the pattern after silk-screen；Chip, is placed in chip slot, has 2 contacts, is respectively used to connect electrode layer and feeder line；Feeder line, is placed in feeder duct, is connected with ground plane conducting；Ground plane, for being coated in the silver slurry layer of monoblock substrate back；And draw feeder line input impedance Za(L by the curve chart of return loss)=27+j200 and the input impedance Z of chip_LMate most during=27.5 j201.The present invention has the own bandwidth improving microstrip antenna, and all can normally can work in various metallic reflection environment, the advantage that the suitability is strong.

Description

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag and implementation method

Technical field

The invention belongs to microstrip antenna technical field, high particularly to a kind of own bandwidth, can be in various metallic reflections The double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag that all can normally work in environment and implementation method.

Background technology

In logistics, asset management, production operation management, be attached to by the bar code of printing in product or its packaging is this Mode has been commonly used.But, this barcode technology exist read away near, can not group reads, reading efficiency is low, its information can not The problem such as update, can not use under many special environments.

For the various types of RFID label tag existed on market, the first type is to be fabricated to dipole antenna, When it is installed on non-conductor face, it is thus achieved that the reading/writing distance needed for signal communication；But when it being pasted or being installed on metal watch During face, metal weakens the communication performance of RFID label tag greatly, causes reading away from significantly reducing, causes the reason of this phenomenon to exist Can produce electric current rightabout with dipole antenna surface current in metal surface, it can offset dipole antenna surface current The electromagnetic field produced.The second type is when making dipole antenna, increases its distance to metal surface to reduce gold Belong to the object impact on it, this mode, the impact of the reverse current on metal object surface can be reduced, can suitably increase its communication away from From, but reduce when its communication distance is the most less attached in metal object, and its bandwidth will narrow, when having reading away from wanting Asking or during bandwidth requirement, this type of label has the biggest application limitation.The third type is to be fabricated to unipole antenna, this antenna When being affixed on metal surface, still having preferable bandwidth and gain, this antenna is usually and uses erosion on dielectric material Carving or silver slurry typography processes, its cost is of a relatively high.

Therefore, microstrip antenna technical field be badly in need of a kind of own bandwidth high, can in various metallic reflection environment equal energy The double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of normal work and its implementation.

Summary of the invention

The invention provides a kind of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag and its implementation, technical scheme As follows:

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag, wherein, including: substrate, electrode layer, chip, feeder line, ground connection Layer；

Substrate, surface silver slurry carries out silk-screen, has 2 merit parallel circuit ends, feeder duct, the patterns of chip slot after silk-screen；

Electrode layer, for being coated in the substrate in addition to 2 merit parallel circuit ends, feeder duct, chip slot area of the pattern after silk-screen The silver slurry layer on surface；

Chip, is placed in chip slot, has 2 contacts, is respectively used to connect electrode layer and feeder line；

Feeder line, is placed in feeder duct, is connected with ground plane conducting；

Ground plane, for being coated in the silver slurry layer of monoblock substrate back.

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, substrate is ceramic substrate.

A kind of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, substrate is macromolecule material Substrate or wooden substrate or glass material substrate.

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, chip is active or passive RFID chip.

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, chip is band hyperfrequency function Other chip.

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, 2 merit parallel circuit ends become central shaft Symmetrical form silk-screen is on substrate.

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, substrate is aluminium oxide ceramic substrate.

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, the silver powder particles degree of silver slurry layer is 300 mesh, overall silver content is 82%.

The implementation method of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag, wherein, comprises the steps:

Step one: make the double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of plurality of specifications；

First design the pattern of substrate, specially substrate surface and there is 2 merit parallel circuit ends, feeder duct, chip slot Pattern, the position of chip slot is different along with the length difference of feeder duct；

Further, by silver slurry, substrate surface is carried out silk-screen according to pre-designed substrate pattern；

Further, the silk screen of size equal with substrate pattern is covered the pattern position after substrate surface silk-screen, then Substrate is carried out silver slurry coating；

Further, the substrate after silver slurry coating is carried out 300 ° of middle temperature to dry；

Further, the substrate after drying is put in 850 ° of high temperature roasters and is sintered；

Further, feeder line and chip are separately mounted in feeder duct and chip slot, and by the 1 of chip contact and electricity Pole layer is connected, and another 1 contact is connected with one end of feeder line, and the other end of feeder line is connected with ground plane, i.e. obtains multiple The double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of specification；

Step 2: will put into according to the multiple double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag sintered out in step one Instrument carries out return loss measurement, according further to frequency f_rDraw out the multiple double resonance anti-gold of high bandwidth RFIDnt ultra-high frequency Belong to the curve chart of the return loss of label；And the curve chart of return loss is analyzed；The least according to return loss, chip energy The widest principle of bandwidth of work, it is known that: when frequency is 915MHz, return loss value is minimum；

Step 3: calculate conduction band width according to the electrical property value that conduction band parameter is fixing；

Concrete formula is as follows:

$W=\frac{c}{2f_r}{\left(\frac{{\mathrm{\ϵ}}_r+1}{2}\right)}^{-1/2},$

Wherein, W represents conduction band width, unit m；C represents the light velocity, unit 3 × 10⁸Meter per second；f_rRepresent frequency, unit Hz； ε_rRepresent relative dielectric constant；

Step 4: the conduction band width W calculated according to step 3, calculates the equivalent elongation of wavelength；

Concrete formula is as follows:

$\mathrm{\ΔL}=0.412h\frac{({\mathrm{\ϵ}}_e+0.3)(w/h+0.264)}{({\mathrm{\ϵ}}_e-0.258)(w/h+0.8)},$

Wherein, Δ L represents the equivalence elongation of wavelength, unit m；H represents substrate thickness, unit m；ε_eRepresent distribution capacity rate Constant, concrete numerical value is 1.45；

Step 5: according to the equivalence elongation of the wavelength that step 4 calculates, calculate feed line length；

Concrete formula is as follows:

${\mathrm{\λ}}_g=\frac{c}{f_r},$

L=0.5 λ_g-2 Δ L,

Wherein, L represents feed line length, unit m；λ g represents incidence wave length, unit m,；C represents the light velocity, unit 3 × 10⁸ Meter per second；f_rRepresent frequency, unit Hz；；

Step 6: first, calculates substrate thickness h and the relation of conduction band width W in advance, then selectes Z₀ ^αThe piecewise function being suitable for Calculating, if substrate thickness is more than or equal to conduction band width, then the span calculating independent variable W/h is less than, equal to 1, entering And the first paragraph function that substrate thickness h and conduction band width W brings into piecewise function obtains impedance Z₀ ^α；If substrate thickness is less than conduction band Width, then the span calculating independent variable W/h is greater than 1, and then substrate thickness h and conduction band width W brings piecewise function into Second segment function obtain impedance Z₀ ^α；

Concrete formula is as follows:

${Z_0}^{\mathrm{\α}}=\left\{\begin{array}{cc}59.925\ln (\frac{8h}{W}+\frac{W}{4h})& (\frac{W}{h}\≤1)\\ \frac{119.904\mathrm{\π}}{\frac{W}{h}+2.42-0.44\frac{h}{W}+{(1-\frac{h}{W})}^6}& (\frac{W}{h}>1)\end{array}\right.,$

Wherein, Z₀ ^αRepresent impedance；

Step 7: according to the impedance Z obtained in step 6₀ ^αObtain the characteristic impedance Z of feeder line₀；

$Z_0={Z_0}^{\mathrm{\α}}/\sqrt{{\mathrm{\ϵ}}_e}$

Wherein, Z₀Represent the characteristic impedance of feeder line, ε_eRepresenting distribution capacity rate constant, concrete numerical value is 1.45；

Step 8: according to the characteristic impedance Z calculated in step 7₀, calculate antenna feed impedance Z_a(L)；

Concrete formula is as follows:

$Z_a\left(L\right)=Z_0\frac{Z_L+j{Z}_0\tan \left(\mathrm{\βL}\right)}{Z_0+j{Z}_L\tan \left(\mathrm{\βL}\right)},$

Wherein, Za (L) represents antenna feed impedance, and unit is Ω；Z₀Representing the characteristic impedance of feeder line, unit is Ω；Z_LTable Showing the input impedance of chip, unit is Ω；L represents feed line length, unit m；β represents propagation coefficient, without unit；

Step 9: from the calculating of step 3 to eight, when frequency is 915MHz, return loss value is minimum, feedback now Line mates the most with chip, therefore draws the input impedance Z of feeder line input impedance Za (L)=27+j200 and chip_L=27.5- Mate most during j201.

The implementation method of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag as above, wherein, will in step one The substrate dried is put into the step being sintered in 850 ° of high temperature roasters and is: first will be filled with noble gas nitrogen in high temperature roaster Gas, then the ceramic substrate of drying is placed in baking box heating, until it reaches fall the most slowly after the highest design temperature 850 ° Low temperature, until being cooled to room temperature；Again by substrate overturning repeat the above steps, till all faces are the most burned.

Beneficial effects of the present invention:

1. on electrode surface, use bimodal design, two-wire equinoctial line merit parallel circuit is i.e. set, it is possible to increase bandwidth, exist simultaneously When frequency is 915MHz, antenna feed impedance Za (L)=27+j200 and the input impedance Z of chip_L=27.5-j201 matches Time, return loss value is minimum, and the gain effect of feeder line is the best.

2. by adjusting two-wire equinoctial line merit parallel circuit and the relation of impedance, make originally 120～100 diectric antenna product Prime factor Q-value drops to original 1/2, and bandwidth becomes original 1/2 immediately, is equivalent to the bandwidth with 2 times.

3. present invention reduces the difficulty of processing, allow chip can work in broader bandwidth simultaneously, and then various All can normally work in the reflection environment of metal, the suitability is strong.

Accompanying drawing explanation

The present invention is described below in conjunction with the accompanying drawings in detail with detailed description of the invention:

Fig. 1 is the structural representation of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of the present invention.

Fig. 2 is the curve chart of the return loss of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of the present invention.

Detailed description of the invention

For the measure making the technology of the present invention realize, creation characteristic, reach purpose and be easy to understand with effect, below knot Conjunction is specifically illustrating, and the present invention is expanded on further.

Fig. 1 is the structural representation of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of the present invention.

Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag, wherein, including: substrate 2, electrode layer 1, chip, feeder line, connect Stratum 3；

As it is shown in figure 1, substrate 2 surface silver slurry carry out silk-screen, have after silk-screen 2 merit parallel circuit ends 21, feeder duct 22, The pattern of chip slot 23；

Electrode layer 1, for 2 merit parallel circuit ends 21, feeder duct 22, chip slot 23 and area of the pattern after being coated in except silk-screen The silver slurry layer on outer substrate 2 surface；2 merit parallel circuit ends 21 become form silk-screen substantially symmetrical about its central axis on substrate.

Chip, is placed in chip slot 23, has 2 contacts, is respectively used to connect electrode layer and feeder line；

Feeder line, is placed in feeder duct 22, is connected with ground plane 3 conducting；

Ground plane 3, for being coated in the silver slurry layer at monoblock substrate 2 back side.

In the present embodiment, substrate 2 uses aluminium oxide ceramic substrate, and substrate 2 can also be other ceramic substrate or macromolecule material Matter substrate or wooden substrate or glass material substrate.

Being placed on the chip in chip slot 23 is active or passive RFID chip or other chip of band hyperfrequency function.

The silver powder particles degree of the silver slurry layer of substrate 2 surface and monoblock substrate 2 backside coating is all 300 mesh, overall silver content It is 82%.

The implementation method of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag, wherein, comprises the steps:

Step one: make the double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of plurality of specifications；

First design the pattern of substrate, specially substrate surface and there are 2 merit parallel circuit ends 21, feeder duct 22, chips The pattern of groove 23 sum, the position of chip slot 23 is different along with the length difference of feeder duct 22；

Further, by silver slurry, substrate 2 surface is carried out silk-screen according to the pattern of pre-designed substrate 2；

Further, the silk screen with the substrate 2 equal size of pattern is covered the pattern position after substrate surface silk-screen, then Substrate 2 is carried out silver slurry coating；

Further, the substrate 2 after silver slurry coating is carried out 300 ° of middle temperature to dry；

Further, the substrate 2 after drying is put in 850 ° of high temperature roasters and is sintered；

First high temperature roaster will be filled with inert nitrogen gas, then the substrate 2 of drying is placed in baking box heating, until Reach reduction temperature the most slowly after the highest design temperature 850 °, until being cooled to room temperature；Again substrate 2 turn-over is repeated above-mentioned Step, till all faces are the most burned；

Further, feeder line and chip are separately mounted in feeder duct 22 and chip slot 23, and by the 1 of chip contact Being connected with electrode layer 1, another 1 contact is connected with one end of feeder line, and the other end of feeder line is connected with ground plane 3, to obtain final product Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag to plurality of specifications；

Step 2: will put into according to the multiple double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag sintered out in step one Instrument carries out return loss measurement, according further to frequency f_rDraw out multiple double resonance high bandwidth as shown in Figure 2 The curve chart of the return loss of RFIDnt ultra-high frequency anti-metal tag, Fig. 2 is the double resonance anti-gold of high bandwidth RFIDnt ultra-high frequency of the present invention Belong to the curve chart of the return loss of label；And the curve chart of return loss is analyzed；The least according to return loss, chip energy The widest principle of bandwidth of work, it is known that: when frequency is 915MHz, return loss value is minimum；

Step 3: calculate conduction band width according to the electrical property value that conduction band parameter is fixing；

Concrete formula is as follows:

$W=\frac{c}{2f_r}{\left(\frac{{\mathrm{\ϵ}}_r+1}{2}\right)}^{-1/2},$

Wherein, W represents conduction band width, unit m；C represents the light velocity, unit 3 × 10⁸Meter per second；f_rRepresent frequency, unit Hz； ε_rRepresent relative dielectric constant；

Step 4: the conduction band width W calculated according to step 3, calculates the equivalent elongation of wavelength；

Concrete formula is as follows:

$\mathrm{\ΔL}=0.412h\frac{({\mathrm{\ϵ}}_e+0.3)(w/h+0.264)}{({\mathrm{\ϵ}}_e-0.258)(w/h+0.8)},$

Wherein, Δ L represents the equivalence elongation of wavelength, unit m；H represents substrate thickness, unit m；ε_eRepresent distribution capacity rate Constant, concrete numerical value is 1.45；

Step 5: according to the equivalence elongation of the wavelength that step 4 calculates, calculate feed line length；

Concrete formula is as follows:

${\mathrm{\λ}}_g=\frac{c}{f_r},$

L=0.5 λ_g-2 Δ L,

Wherein, L represents feed line length, unit m；λ g represents incidence wave length, unit m,；C represents the light velocity, unit 3 × 10⁸ Meter per second；f_rRepresent frequency, unit Hz；；

Step 6: first, calculates substrate thickness h and the relation of conduction band width W in advance, then selectes Z₀ ^αThe piecewise function being suitable for Calculating, if substrate thickness is more than or equal to conduction band width, then the span calculating independent variable W/h is less than, equal to 1, entering And the first paragraph function that substrate 2 thickness h and conduction band width W are brought into piecewise function obtains impedance Z₀ ^α；If substrate 2 thickness is less than leading Bandwidth, then the span calculating independent variable W/h is greater than 1, and then substrate thickness h and conduction band width W brings segmentation letter into The second segment function of number obtains impedance Z₀ ^α；

Concrete formula is as follows:

${Z_0}^{\mathrm{\α}}=\left\{\begin{array}{cc}59.925\ln (\frac{8h}{W}+\frac{W}{4h})& (\frac{W}{h}\≤1)\\ \frac{119.904\mathrm{\π}}{\frac{W}{h}+2.42-0.44\frac{h}{W}+{(1-\frac{h}{W})}^6}& (\frac{W}{h}>1)\end{array}\right.,$

Wherein, Z₀ ^αRepresent impedance；

Step 7: according to the impedance Z obtained in step 6₀ ^αObtain the characteristic impedance Z of feeder line₀；

$Z_0={Z_0}^{\mathrm{\α}}/\sqrt{{\mathrm{\ϵ}}_e}$

Wherein, Z₀Represent the characteristic impedance of feeder line, ε_eRepresenting distribution capacity rate constant, concrete numerical value is 1.45；

Step 8: according to the characteristic impedance Z calculated in step 7₀, calculate antenna feed impedance Z_a(L)；

Concrete formula is as follows:

$Z_a\left(L\right)=Z_0\frac{Z_L+j{Z}_0\tan \left(\mathrm{\βL}\right)}{Z_0+j{Z}_L\tan \left(\mathrm{\βL}\right)},$

Wherein, Za (L) represents antenna feed impedance, and unit is Ω；Z₀Representing the characteristic impedance of feeder line, unit is Ω；Z_LTable Showing the input impedance of chip, unit is Ω；L represents feed line length, unit m；β represents propagation coefficient, without unit；

Step 9: from the calculating of step 3 to eight, when frequency is 915MHz, return loss value is minimum, feedback now Line mates the most with chip, therefore draws the input impedance Z of feeder line input impedance Za (L)=27+j200 and chip_L=27.5- Mate most during j201.

The present invention uses bimodal design on electrode surface, i.e. arranges two-wire equinoctial line merit parallel circuit, it is possible to increase bandwidth, with Time when frequency is 915MHz, the input impedance Z of antenna feed impedance Za (L)=27+j200 and chip_L=27.5-j201 phase During coupling, return loss value is minimum, and the gain effect of feeder line is the best.

The present invention by adjusting two-wire equinoctial line merit parallel circuit and the relation of impedance, make originally 120～100 medium sky Line quality factor q value drops to original 1/2, and bandwidth becomes original 1/2 immediately, is equivalent to the bandwidth with 2 times.

Present invention reduces the difficulty of processing, allow chip can work in broader bandwidth simultaneously, and then at various gold All can normally work in the reflection environment belonged to, the suitability is strong.

The ultimate principle of the present invention, principal character and advantages of the present invention have more than been shown and described.The technology of the industry Personnel, it should be appreciated that the present invention is not restricted to the described embodiments, simply illustrating this described in above-described embodiment and description The principle of invention, the present invention also has various changes and modifications without departing from the spirit and scope of the present invention, and these become Change and improvement both falls within scope of the claimed invention.Claimed scope by appending claims and Equivalent defines.

Claims (2)

1. the implementation method of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag, it is characterised in that comprise the steps:

Step one: make the double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag of plurality of specifications；

First design the pattern of substrate, specially substrate surface and there are 2 merit parallel circuit ends, feeder duct, the patterns of chip slot, The position of chip slot is different along with the length difference of feeder duct；

Further, by silver slurry, substrate surface is carried out silk-screen according to pre-designed substrate pattern；

Further, the silk screen of size equal with substrate pattern is covered the pattern position after substrate surface silk-screen, then to base Plate carries out silver slurry coating；

Further, the substrate after silver slurry coating is carried out 300 ° of middle temperature to dry；

Further, the substrate after drying is put in 850 ° of high temperature roasters and is sintered；

Further, feeder line and chip are separately mounted in feeder duct and chip slot, and by the 1 of chip contact and electrode layer Being connected, another 1 contact is connected with one end of feeder line, and the other end of feeder line is connected with ground plane, i.e. obtains plurality of specifications Double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag；

Step 2: instrument will be put into according to the multiple double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag sintered out in this step one Device carries out return loss measurement, according further to frequency f_rDraw out multiple double resonance high bandwidth RFIDnt ultra-high frequency anti-metal The curve chart of the return loss of label；And the curve chart of return loss is analyzed；The least according to return loss, chip energy work The widest principle of bandwidth made, it is known that: when frequency is 915MHz, return loss value is minimum；

Step 3: calculate conduction band width according to the electrical property value that conduction band parameter is fixing；

Concrete formula is as follows:

$W=\frac{c}{2f_r}{\left(\frac{{\mathrm{\ϵ}}_r+1}{2}\right)}^{-1/2},$

Wherein, W represents conduction band width, unit m；C represents the light velocity, unit 3 × 10⁸Meter per second；f_rRepresent frequency, unit Hz；ε_rTable Show relative dielectric constant；

Step 4: the conduction band width W calculated according to this step 3, calculates the equivalent elongation of wavelength；

Concrete formula is as follows:

$\mathrm{\Δ}L=0.412h\frac{({\mathrm{\ϵ}}_e+0.3)(W/h+0.264)}{({\mathrm{\ϵ}}_e-0.258)(W/h+0.8)},$

Wherein, Δ L represents the equivalence elongation of wavelength, unit m；H represents substrate thickness, unit m；ε_eRepresent distribution capacity rate constant, Concrete numerical value is 1.45；

Step 5: according to the equivalence elongation of the wavelength that this step 4 calculates, calculate feed line length；

Concrete formula is as follows:

${\mathrm{\λ}}_g=\frac{c}{f_r}$

L=0.5 λ_g-2ΔL

Wherein, L represents feed line length, unit m；λ g represents incidence wave length, unit m；C represents the light velocity, unit 3 × 10⁸Meter per second； f_rRepresent frequency, unit Hz；

Step 6: first, calculates substrate thickness h and the relation of conduction band width W in advance, then selectes Z₀ ^αThe piecewise function being suitable for is carried out Calculating, if substrate thickness is more than or equal to conduction band width, then the span calculating independent variable W/h is less than equal to 1, and then will Substrate thickness h and conduction band width W brings the first paragraph function of piecewise function into and obtains impedance Z₀ ^α；If substrate thickness is less than conduction band width Degree, then the span calculating independent variable W/h is greater than 1, and then substrate thickness h and conduction band width W brings piecewise function into Second segment function obtains impedance Z₀ ^α；

Concrete formula is as follows:

${Z_0}^{\mathrm{\α}}=\left\{\begin{array}{cc}59.952\ln (\frac{8h}{W}+\frac{W}{4h})& \left(\begin{array}{c}\frac{W}{h}\≤1\end{array}\right)\\ \frac{119.904\mathrm{\π}}{\frac{W}{h}+2.42-0.44\frac{h}{W}+{(1-\frac{h}{W})}^6}& \left(\begin{array}{c}\frac{W}{h}>1\end{array}\right)\end{array}\right.,$

Wherein, Z₀ ^αRepresent impedance；

Step 7: according to the impedance obtained in this step 6Obtain the characteristic impedance Z of feeder line₀；

$Z_0={Z_0}^{\mathrm{\α}}/\sqrt{{\mathrm{\ϵ}}_e}$

Wherein, Z₀Represent the characteristic impedance of feeder line, ε_eRepresenting distribution capacity rate constant, concrete numerical value is 1.45；

Step 8: according to the characteristic impedance Z calculated in this step 7₀, calculate antenna feed impedance Z_a(L)；

Concrete formula is as follows:

$Z_a\left(L\right)=Z_0\frac{Z_L+{\mathrm{jZ}}_{0}tan\left(\mathrm{\β}L\right)}{Z_0+{\mathrm{jZ}}_{L}tan\left(\mathrm{\β}L\right)},$

Wherein, Za (L) represents antenna feed impedance, and unit is Ω；Z₀Representing the characteristic impedance of feeder line, unit is Ω；Z_LRepresent core The input impedance of sheet, unit is Ω；L represents feed line length, unit m；β represents propagation coefficient, without unit；Step 9: by this step The calculating of rapid three to eight understands, and when frequency is 915MHz, return loss value is minimum, and feeder line now mates the most with chip, therefore Draw the input impedance Z of feeder line input impedance Za (L)=27+j200 and chip_LMate most during=27.5-j201.

The implementation method of double resonance high bandwidth RFIDnt ultra-high frequency anti-metal tag the most according to claim 1, its feature exists In, the substrate of drying is put in this step one step being sintered in 850 ° of high temperature roasters is: first by high temperature roaster It is filled with inert nitrogen gas, then the substrate of drying is placed in baking box heating, until it reaches after the highest design temperature 850 ° Reduction temperature the most slowly, until being cooled to room temperature；Again by ceramic substrate turn-over repeat the above steps, until all faces are the most burned Till.