CN104577328A - RFID antenna and automatic matching method thereof - Google Patents
RFID antenna and automatic matching method thereof Download PDFInfo
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- CN104577328A CN104577328A CN201510032834.5A CN201510032834A CN104577328A CN 104577328 A CN104577328 A CN 104577328A CN 201510032834 A CN201510032834 A CN 201510032834A CN 104577328 A CN104577328 A CN 104577328A
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Abstract
The invention relates to an RFID antenna and an automatic matching method of the RFID antennas. The RFID antenna comprises a coaxial feeder, a balun, a load modulation triode, a load modulation resistor, a parallel match capacitor bank, a series match capacitor bank, an antenna metal pipe, a Q-valued regulating resistor, a control circuit, a micro controller, a drive circuit, a detector circuit and an analog-digital converter ADC. The automatic matching method comprises the steps that 1, the parameters of the RFID antenna of a user are measured; 2, the capacitance value Cp of a parallel match capacitor needing to be connected to a circuit and a capacitance value Cs of a series match capacitor needing to be connected to a circuit are calculated; 3, the match capacitors are controlled to be connected to the circuit; 4, match points are finely adjusted. The user can install RFID readers in different shapes without changing the circuit and the RFID readers, the RFID antennas are suitable for different application occasions and are made to basically reach the best match state, the match circuit parameters can be changed when the parameters of the RFID readers are changed, automatic matching is achieved, and therefore bandwidth and economic practicability are guaranteed.
Description
Technical field
The present invention relates to a kind of RFID antenna and automatic matching method thereof, belong to electricity field.
Background technology
Radio-frequency (RF) identification (RFID) is a kind of contactless automatic identification technology, it automatically identifies destination object by radiofrequency signal and obtains related data, identification work need not manual intervention, as the wireless version of bar code, RFID technique has waterproof not available for bar code, antimagnetic, high temperature resistant, long service life, reading distance are large, on label data can encrypt, store that data capacity is larger, the storage information change advantage such as freely, its application will bring revolutionary variation to the industry such as retail, logistics.
Rfid system, be made up of reader, electronic tag and application software three parts, its operation principle is the radio magnetic wave that a characteristic frequency launched by reader, electronic tag is driven the data of its inside to be sent, now, reader receives unscrambling data, gives application program and does corresponding process.
At present, widely used is at home rfid system based on ISO15693 agreement and ISO14443 agreement, and its operating center frequency is all 13.56MHz, with passive mode, so just require that reader transmitting antenna impedance matching is good, guarantee to launch enough power.The antenna of this rfid system that domestic market can be seen is all fixing match pattern, based on not of uniform size square, fix when match circuit is also and dispatches from the factory, user can not bend or change the shape of antenna voluntarily, otherwise antenna standing wave can be caused to increase, and decrease in efficiency is damage equipment even.In actual applications, some occasion needs user to change the form of antenna voluntarily, such as elongate in shape, circular, or other is even integrated with ornament, to support this function, just must provide a kind of method that antenna impedance automatically detects and mates.
Summary of the invention
For the deficiencies in the prior art, the invention discloses a kind of RFID antenna;
The invention also discloses the automatic matching method of above-mentioned RFID antenna;
The principle of the automatic matching method of above-mentioned RFID antenna is: first, measure intrinsic series inductance L0 and intrinsic series resistance R0, then, according to LC match circuit computing formula, obtain answering the matching capacitance value Cp in parallel of place in circuit and answering the series connection matching capacitance value Cs of place in circuit, choose immediate capacitance place in circuit by microcontroller by magnetic latching relay again, finally, finely tune.
Technical scheme of the present invention is:
A kind of RFID antenna, comprises coaxial feeder, Ba Lun, load-modulate triode, load-modulate resistance, matching capacitance group in parallel, series connection matching capacitance group, antenna metal pipe, Q value regulating resistance, control circuit, microcontroller, drive circuit, detecting circuit, analog to digital converter ADC, described matching capacitance group in parallel comprises matching capacitance in parallel and the magnetic latching relay of multiple series series connection, described series connection matching capacitance group comprises series connection matching capacitance and the magnetic latching relay of multiple series series connection, described antenna metal pipe comprises intrinsic series inductance L0 and intrinsic series resistance R0, described coaxial feeder connects described Ba Lun input, described Ba Lun output connects described matching capacitance group in parallel, described Ba Lun output also connects one end of described series connection matching capacitance group simultaneously, the other end of described series connection matching capacitance group is connected described antenna metal pipe one end, the described antenna metal pipe other end is connected described Q value regulating resistance, and described Q value regulating resistance connects described Ba Lun output, described Ba Lun output also connects the input of described detecting circuit, the output of described detecting circuit connects described analog to digital converter ADC, described analog to digital converter ADC connects described microcontroller, one tunnel of described microcontroller exports control signal and connects described drive circuit, described drive circuit connects the control end of magnetic latching relay described in each road by described control circuit, another road of described microcontroller exports the base stage that control signal is connected to described load-modulate triode, the emitter of described load-modulate triode is in parallel with the output of described Ba Lun by described load-modulate resistance with collector electrode.
Preferred according to the present invention, the ascending one-tenth of capacitance 2 times of relations of the matching capacitance multiple in parallel in described matching capacitance group in parallel, the ascending one-tenth of capacitance 2 times of relations of the multiple series connection matching capacitance in described series connection matching capacitance group.
The ascending one-tenth of capacitance 2 times of relations of matching capacitance multiple in parallel in described matching capacitance group in parallel, such as, the capacitance of seven matching capacitance in parallel in described matching capacitance group in parallel is followed successively by 25p, 50p, 100p, 200p, 400p, 800p, 1600p; The ascending one-tenth of capacitance 2 times of relations of multiple series connection matching capacitance in described series connection matching capacitance group, such as, the capacitance of ten series connection matching capacitance in described series connection matching capacitance group is followed successively by 1p, 2p, 4p, 8p, 16p, 32p, 64p, 128p, 256p, 512p.
Antenna metal pipe is bent voluntarily by user, changes, and antenna metal pipe major parameter is equivalent to intrinsic series inductance L0 and intrinsic series resistance R0.
The automatic matching method of above-mentioned RFID antenna, concrete steps comprise:
(1) user's RFID antenna parameter is measured
Power on, described microcontroller exports control signal makes all described magnetic latching relays be in open-circuit condition, matching capacitance in parallel in series connection matching capacitance in described series connection matching capacitance group and described matching capacitance group in parallel is all in off-state, now be in open-circuit condition, magnitude of voltage U0 under the open-circuit condition that analog to digital converter ADC described in described microcontroller record gathers, described microcontroller controls the magnetic latching relay of described series connection matching capacitance group further, according to the order that the capacitance of described series connection matching capacitance is ascending, described series connection matching capacitance progressively closes, the capacitance in access loop is progressively increased, in the process that capacitance progressively increases, described microcontroller obtains voltage minimum by described analog to digital converter ADC, described voltage minimum refers to the minimum value of described analog to digital converter ADC in the data obtained the continuous sampling of described Ba Lun output voltage, record the capacitance sum Cs0 of the described series connection matching capacitance being closed access loop of leading by described magnetic latching relay, recording voltage minimum U1, calculate the value of the intrinsic series inductance L0 of described antenna metal pipe, be shown below:
L0＝1/(4*pi^2*f0^2*Cs0)
In formula, pi=3.14, f0 are the centre frequency of RFID antenna, f0=13.56MHz;
Calculate the value of intrinsic series resistance R0, be shown below:
R0＝Z0*U1/(U0-U1)-Rq
In formula, Z0 is described coaxial feeder impedance, Z0=50 ohm, and Rq is Q value regulating resistance, and the span of Rq is 0-4 ohm;
(2) the capacitance Cs of the series connection matching capacitance of answering the capacitance Cp of the matching capacitance in parallel of place in circuit and answer place in circuit is calculated
Step (1) obtains the intrinsic series inductance L0 of antenna metal pipe and intrinsic series resistance R0, according to LC match circuit computing formula, obtain the capacitance Cs of the series connection matching capacitance of answering the capacitance Cp of the matching capacitance in parallel of place in circuit and answering place in circuit, be shown below:
Cp＝(Z0*Rf-Rf^2)^0.5/(2*pi*f0*Z0*Rf)
Cs＝1/(4*pi^2*f0^2*L0-2*pi*f0*(Z0*Rf-Rf^2)^0.5)
In formula, Rf=R0+Rq;
(3) matching capacitance access is controlled
Step (2) obtains the capacitance Cs of the series connection matching capacitance obtaining answering the capacitance Cp of the matching capacitance in parallel of place in circuit and answer place in circuit, the combination of matching capacitance in parallel selected by described microcontroller from described matching capacitance group in parallel, the combined electrical capacitance of described matching capacitance in parallel is Cp ', make Cp ' closest to Cp, by controlling described magnetic latching relay by place in circuit in parallel for the combination of described matching capacitance in parallel, the combination of series connection matching capacitance selected by described microcontroller from described series connection matching capacitance group, the combined electrical capacitance of described series connection matching capacitance is Cs ', make Cs ' closest to Cs, by controlling described magnetic latching relay by the combined serial place in circuit of described series connection matching capacitance, wherein, described matching capacitance refers to the combination of described matching capacitance in parallel and the combination of described series connection matching capacitance,
(4) match point is finely tuned
The combined electrical capacitance Cp ' of the matching capacitance in parallel of place in circuit is finely tuned with the combined electrical capacitance Cs ' of the matching capacitance of connecting of place in circuit, the combined electrical capacitance Cs ' of the series connection matching capacitance of described microcontroller fine setting place in circuit, when | when U-U0/2| gets minimum value, the combined electrical capacitance Cs of the series connection matching capacitance of corresponding place in circuit " be the combination optimum Match capacitance of the series connection matching capacitance of place in circuit, the combined electrical capacitance Cp ' of the matching capacitance in parallel of described microcontroller fine setting place in circuit, when | when U-U0/2| gets minimum value, the combined electrical capacitance Cp of the matching capacitance in parallel of corresponding place in circuit " be the combination optimum Match capacitance of the matching capacitance in parallel of place in circuit, fine setting terminates, wherein, U is that described microcontroller is in real time by the signal amplitude value of described analog to digital converter ADC collection.
Through step (1) to step (3), described RFID antenna is in the state of basic coupling, in order to weaken measurements and calculations error further, carries out step (4) fine setting match point.
The running of described RFID antenna is: non-equilibrium input signal enters described Ba Lun through described coaxial feeder, the 50 ohm of LC resonance impedance converting networks be made up of described matching capacitance group in parallel, described series connection matching capacitance group and described antenna metal pipe are flow through after being transformed into balanced signal, and being radiated the external space by described antenna metal pipe, described Q value regulating resistance reduces RFID antenna Q value in order to avoid bandwidth is narrow, during work, described detecting circuit is sampled described Ba Lun output end signal, be translated into voltage amplitude value, and send described microcontroller to through described analog to digital converter ADC, described microcontroller detects described Ba Lun output end signal amplitude, described microcontroller is according to automatic matching method simultaneously, the break-make of magnetic latching relay described in each road is controlled by described drive circuit, complete matching process, load-modulate triode, the circuit of load-modulate resistance composition is mainly used in described microcontroller and produces load-modulate to signal, multiplexed signals coaxial feeder sends RFID reader to.
Beneficial effect of the present invention is:
The invention provides a kind of automatic matching method of RFID antenna, user is when without the need to changing circuit and RFID reader, difform RFID reader is installed, be applicable to different application scenarios, further, the matching status making RFID antenna substantially reach best, also can change match circuit parameter when RFID reader parameter changes, realize Auto-matching, the Match circuits of simplification ensures bandwidth sum economic and practical.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of RFID antenna of the present invention;
Wherein, 1, coaxial feeder, 2, Ba Lun, 3, load-modulate resistance, 4, magnetic latching relay, 5, series connection matching capacitance, 6, load-modulate triode, 7, matching capacitance in parallel, 8, control circuit, 9, antenna metal pipe, 10, intrinsic series inductance L0,11, intrinsic series resistance R0,12, Q value regulating resistance, 13, microcontroller, 14, drive circuit, 15, analog to digital converter ADC, 16, detecting circuit.
Embodiment
Below in conjunction with Figure of description and embodiment, further restriction is done to the present invention, but be not limited thereto.
Embodiment 1
A kind of RFID antenna, comprises coaxial feeder 1, Ba Lun 2, load-modulate triode 6, load-modulate resistance 3, matching capacitance group in parallel, series connection matching capacitance group, antenna metal pipe 9, Q value regulating resistance 12, control circuit 8, microcontroller 13, drive circuit 14, detecting circuit 16, analog to digital converter ADC 15, described matching capacitance group in parallel comprises the matching capacitance in parallel 7 and magnetic latching relay 4 that seven tunnels are connected in series, described series connection matching capacitance group comprises the series connection matching capacitance 5 and magnetic latching relay 4 that ten tunnels are connected in series, described antenna metal pipe 9 comprises intrinsic series inductance L010 and intrinsic series resistance R011, described coaxial feeder 1 connects described Ba Lun 2 input, described Ba Lun 2 output connects described matching capacitance group in parallel, described Ba Lun 2 output also connects one end of described series connection matching capacitance group simultaneously, the other end of described series connection matching capacitance group is connected described antenna metal pipe 9 one end, described antenna metal pipe 9 other end is connected described Q value regulating resistance 12, and described Q value regulating resistance 12 connects described Ba Lun 2 output, described Ba Lun 2 output also connects the input of described detecting circuit 16, the output of described detecting circuit 16 connects described analog to digital converter ADC 15, described analog to digital converter ADC 15 connects described microcontroller 13, one tunnel of described microcontroller 13 exports control signal and connects described drive circuit 14, described drive circuit 14 connects the control end of magnetic latching relay 4 described in each road by described control circuit 8, described another road of microcontroller 13 exports the base stage that control signal is connected to described load-modulate triode 6, the emitter of described load-modulate triode 6 is in parallel with the output of described Ba Lun 2 by described load-modulate resistance 3 with collector electrode.
The ascending one-tenth of capacitance 2 times of relations of seven matching capacitance 7 in parallel in described matching capacitance group in parallel, the ascending one-tenth of capacitance 2 times of relations of ten series connection matching capacitance 5 in described series connection matching capacitance group.
The ascending one-tenth of capacitance 2 times of relations of seven matching capacitance 7 in parallel in described matching capacitance group in parallel, the capacitance of seven matching capacitance 7 in parallel in described matching capacitance group in parallel is followed successively by 25p, 50p, 100p, 200p, 400p, 800p, 1600p; The ascending one-tenth of capacitance 2 times of relations of ten series connection matching capacitance 5 in described series connection matching capacitance group, the capacitance of ten series connection matching capacitance 5 in described series connection matching capacitance group is followed successively by 1p, 2p, 4p, 8p, 16p, 32p, 64p, 128p, 256p, 512p.
Antenna metal pipe 9 is bent voluntarily by user, changes, and antenna metal pipe 9 major parameter is equivalent to intrinsic series inductance L010 and intrinsic series resistance R011.
Embodiment 2
The automatic matching method of RFID antenna according to embodiment 1, concrete steps comprise:
(1) user's RFID antenna parameter is measured
Power on, described microcontroller 13 exports control signal makes all described magnetic latching relays 4 be in open-circuit condition, matching capacitance in parallel 7 in series connection matching capacitance 5 in described series connection matching capacitance group and described matching capacitance group in parallel is all in off-state, now be in open-circuit condition, described microcontroller 13 records the magnitude of voltage U0 under the open-circuit condition of described analog to digital converter ADC 15 collection, described microcontroller 13 controls the magnetic latching relay 4 of described series connection matching capacitance group further, according to the order that the capacitance of described series connection matching capacitance 5 is ascending, described series connection matching capacitance 5 progressively closes, the capacitance in access loop is progressively increased, in the process that capacitance progressively increases, described microcontroller 13 obtains voltage minimum by described analog to digital converter ADC 15, described voltage minimum refers to the minimum value of described analog to digital converter ADC 15 in the data obtained the continuous sampling of described Ba Lun 2 output voltage, record by the capacitance sum Cs0 of the described series connection matching capacitance 5 in the closed access loop of leading of described magnetic latching relay 4, recording voltage minimum U1, calculate the value of the intrinsic series inductance L0 of described antenna metal pipe 9, be shown below:
L0＝1/(4*pi^2*f0^2*Cs0)
In formula, pi=3.14, f0 are the centre frequency of RFID antenna, f0=13.56MHz;
Calculate the value of intrinsic series resistance R0, be shown below:
R0＝Z0*U1/(U0-U1)-Rq
In formula, Z0 is the impedance of described coaxial feeder 1, Z0=50 ohm, and Rq is Q value regulating resistance, and the span of Rq is 0-4 ohm;
(2) the capacitance Cs of the series connection matching capacitance 5 of answering the capacitance Cp of the matching capacitance in parallel 7 of place in circuit and answer place in circuit is calculated
Step (1) obtains the intrinsic series inductance L0 of antenna metal pipe and intrinsic series resistance R0, according to LC match circuit computing formula, obtain the capacitance Cs of the series connection matching capacitance 5 of answering the capacitance Cp of the matching capacitance in parallel 7 of place in circuit and answering place in circuit, be shown below:
Cp＝(Z0*Rf-Rf^2)^0.5/(2*pi*f0*Z0*Rf)
Cs＝1/(4*pi^2*f0^2*L0-2*pi*f0*(Z0*Rf-Rf^2)^0.5)
In formula, Rf=R0+Rq;
(3) matching capacitance access is controlled
Step (2) obtains the capacitance Cs of the series connection matching capacitance 5 obtaining answering the capacitance Cp of the matching capacitance in parallel 7 of place in circuit and answer place in circuit, the combination of matching capacitance 7 in parallel selected by described microcontroller 13 from described matching capacitance group in parallel, the combined electrical capacitance of described matching capacitance in parallel 7 is Cp ', make Cp ' closest to Cp, by controlling described magnetic latching relay 4 by place in circuit in parallel for the combination of described matching capacitance 7 in parallel, the combination of series connection matching capacitance 5 selected by described microcontroller 13 from described series connection matching capacitance group, the combined electrical capacitance of described series connection matching capacitance 5 is Cs ', make Cs ' closest to Cs, by controlling described magnetic latching relay 4 by the combined serial place in circuit of described series connection matching capacitance 5, wherein, described matching capacitance refers to the combination of described matching capacitance in parallel 7 and the combination of described series connection matching capacitance 5,
(4) match point is finely tuned
The combined electrical capacitance Cp ' of the matching capacitance in parallel 7 of place in circuit is finely tuned with the combined electrical capacitance Cs ' of the matching capacitance 5 of connecting of place in circuit, the combined electrical capacitance Cs ' of the series connection matching capacitance 5 of place in circuit finely tuned by described microcontroller 13, when | when U-U0/2| gets minimum value, the combined electrical capacitance Cs of the series connection matching capacitance 5 of corresponding place in circuit " be the combination optimum Match capacitance of the series connection matching capacitance 5 of place in circuit, the combined electrical capacitance Cp ' of the matching capacitance in parallel 7 of place in circuit finely tuned by described microcontroller 13, when | when U-U0/2| gets minimum value, the combined electrical capacitance Cp of the matching capacitance in parallel 7 of corresponding place in circuit " be the combination optimum Match capacitance of the matching capacitance in parallel 7 of place in circuit, fine setting terminates, wherein, U is that described microcontroller 13 is in real time by the signal amplitude value of described analog to digital converter ADC 15 collection.
Through step (1) to step (3), described RFID antenna is in the state of basic coupling, in order to weaken measurements and calculations error further, carries out step (4) fine setting match point.
The running of described RFID antenna is: non-equilibrium input signal enters described Ba Lun 2 through described coaxial feeder 1, the 50 ohm of LC resonance impedance converting networks be made up of described matching capacitance group in parallel, described series connection matching capacitance group and described antenna metal pipe 9 are flow through after being transformed into balanced signal, and being radiated the external space by described antenna metal pipe 9, described Q value regulating resistance 12 reduces RFID antenna Q value in order to avoid bandwidth is narrow, during work, described detecting circuit 16 is sampled described Ba Lun 2 output end signal, be translated into voltage amplitude value, and send described microcontroller 13 to through described analog to digital converter ADC 15, described microcontroller 13 detects described Ba Lun 2 output end signal amplitude, described microcontroller 13 is according to automatic matching method simultaneously, the break-make of magnetic latching relay 4 described in each road is controlled by described drive circuit 14, complete matching process, load-modulate triode 6, the circuit that load-modulate resistance 3 forms is mainly used in described microcontroller 13 pairs of signals and produces load-modulate, multiplexed signals coaxial feeder 1 sends RFID reader to.
Claims (3)
1. a RFID antenna, is characterized in that, comprises coaxial feeder, Ba Lun, load-modulate triode, load-modulate resistance, matching capacitance group in parallel, series connection matching capacitance group, antenna metal pipe, Q value regulating resistance, control circuit, microcontroller, drive circuit, detecting circuit, analog to digital converter ADC, described matching capacitance group in parallel comprises matching capacitance in parallel and the magnetic latching relay of multiple series series connection, described series connection matching capacitance group comprises series connection matching capacitance and the magnetic latching relay of multiple series series connection, described antenna metal pipe comprises intrinsic series inductance L0 and intrinsic series resistance R0, described coaxial feeder connects described Ba Lun input, described Ba Lun output connects described matching capacitance group in parallel, described Ba Lun output also connects one end of described series connection matching capacitance group simultaneously, the other end of described series connection matching capacitance group is connected described antenna metal pipe one end, the described antenna metal pipe other end is connected described Q value regulating resistance, and described Q value regulating resistance connects described Ba Lun output, described Ba Lun output also connects the input of described detecting circuit, the output of described detecting circuit connects described analog to digital converter ADC, described analog to digital converter ADC connects described microcontroller, one tunnel of described microcontroller exports control signal and connects described drive circuit, described drive circuit connects the control end of magnetic latching relay described in each road by described control circuit, another road of described microcontroller exports the base stage that control signal is connected to described load-modulate triode, the emitter of described load-modulate triode is in parallel with the output of described Ba Lun by described load-modulate resistance with collector electrode.
2. RFID antenna according to claim 1, it is characterized in that, the ascending one-tenth of capacitance 2 times of relations of matching capacitance multiple in parallel in described matching capacitance group in parallel, the ascending one-tenth of capacitance 2 times of relations of the multiple series connection matching capacitance in described series connection matching capacitance group.
3. the automatic matching method of RFID antenna according to claim 1 or 2, it is characterized in that, concrete steps comprise:
(1) user's RFID antenna parameter is measured
Power on, described microcontroller exports control signal makes all described magnetic latching relays be in open-circuit condition, matching capacitance in parallel in series connection matching capacitance in described series connection matching capacitance group and described matching capacitance group in parallel is all in off-state, now be in open-circuit condition, magnitude of voltage U0 under the open-circuit condition that analog to digital converter ADC described in described microcontroller record gathers, described microcontroller controls the magnetic latching relay of described series connection matching capacitance group further, according to the order that the capacitance of described series connection matching capacitance is ascending, described series connection matching capacitance progressively closes, the capacitance in access loop is progressively increased, in the process that capacitance progressively increases, described microcontroller obtains voltage minimum by described analog to digital converter ADC, described voltage minimum refers to the minimum value of described analog to digital converter ADC in the data obtained the continuous sampling of described Ba Lun output voltage, record the capacitance sum Cs0 of the described series connection matching capacitance being closed access loop of leading by described magnetic latching relay, recording voltage minimum U1, calculate the value of the intrinsic series inductance L0 of described antenna metal pipe, be shown below:
L0＝1/(4*pi^2*f0^2*Cs0)
In formula, pi=3.14, f0 are the centre frequency of RFID antenna, f0=13.56MHz;
Calculate the value of intrinsic series resistance R0, be shown below:
R0＝Z0*U1/(U0-U1)-Rq
In formula, Z0 is described coaxial feeder impedance, Z0=50 ohm, and Rq is Q value regulating resistance, and the span of Rq is 0-4 ohm;
(2) the capacitance Cs of the series connection matching capacitance of answering the capacitance Cp of the matching capacitance in parallel of place in circuit and answer place in circuit is calculated
Step (1) obtains the intrinsic series inductance L0 of antenna metal pipe and intrinsic series resistance R0, according to LC match circuit computing formula, obtain the capacitance Cs of the series connection matching capacitance of answering the capacitance Cp of the matching capacitance in parallel of place in circuit and answering place in circuit, be shown below:
Cp＝(Z0*Rf-Rf^2)^0.5/(2*pi*f0*Z0*Rf)
Cs＝1/(4*pi^2*f0^2*L0-2*pi*f0*(Z0*Rf-Rf^2)^0.5)
In formula, Rf=R0+Rq;
(3) matching capacitance access is controlled
Step (2) obtains the capacitance Cs of the series connection matching capacitance obtaining answering the capacitance Cp of the matching capacitance in parallel of place in circuit and answer place in circuit, the combination of matching capacitance in parallel selected by described microcontroller from described matching capacitance group in parallel, the combined electrical capacitance of described matching capacitance in parallel is Cp ', make Cp ' closest to Cp, by controlling described magnetic latching relay by place in circuit in parallel for the combination of described matching capacitance in parallel, the combination of series connection matching capacitance selected by described microcontroller from described series connection matching capacitance group, the combined electrical capacitance of described series connection matching capacitance is Cs ', make Cs ' closest to Cs, by controlling described magnetic latching relay by the combined serial place in circuit of described series connection matching capacitance, wherein, described matching capacitance refers to the combination of described matching capacitance in parallel and the combination of described series connection matching capacitance,
(4) match point is finely tuned
The combined electrical capacitance Cp ' of the matching capacitance in parallel of place in circuit is finely tuned with the combined electrical capacitance Cs ' of the matching capacitance of connecting of place in circuit, the combined electrical capacitance Cs ' of the series connection matching capacitance of described microcontroller fine setting place in circuit, when | when U-U0/2| gets minimum value, the combined electrical capacitance Cs of the series connection matching capacitance of corresponding place in circuit " be the combination optimum Match capacitance of the series connection matching capacitance of place in circuit, the combined electrical capacitance Cp ' of the matching capacitance in parallel of described microcontroller fine setting place in circuit, when | when U-U0/2| gets minimum value, the combined electrical capacitance Cp of the matching capacitance in parallel of corresponding place in circuit " be the combination optimum Match capacitance of the matching capacitance in parallel of place in circuit, fine setting terminates, wherein, U is that described microcontroller is in real time by the signal amplitude value of described analog to digital converter ADC collection.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105071054A (en) * | 2015-07-22 | 2015-11-18 | 深圳中安安防科技有限公司 | Capacitor matching circuit of resonance antenna and anti-theft system |
| CN107154788A (en) * | 2017-04-21 | 2017-09-12 | 西安电子科技大学 | L-type impedance matching system and method in a kind of RF energy Acquisition Circuit |
| CN107154788B (en) * | 2017-04-21 | 2020-07-07 | 西安电子科技大学 | L-shaped impedance matching system and method in radio frequency energy acquisition circuit |
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| CN115079069A (en) * | 2022-07-25 | 2022-09-20 | 国仪量子(合肥)技术有限公司 | Frequency-variable modulation field system, control method thereof and EPR spectrometer |
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