CN111310879A - Testing device and method for online adjustment of antenna parameters of RFID system - Google Patents

Abstract

The invention discloses a testing device and a method for online adjusting antenna parameters of an RFID system, wherein an RFID read-write chip, an LC resonance circuit, an impedance matching network and a buckle plate connector are arranged on a bottom plate; the PCB antenna is arranged on the antenna buckle plate; the impedance matching network is electrically connected with the PCB antenna through the buckle plate connector; the RFID read-write chip, the LC resonance circuit, the impedance matching network and the buckle plate connector are connected in sequence; the impedance matching network is composed of a plurality of adjustable capacitors, so that the integral output impedance formed by the internal circuit of the RFID read-write chip and the LC resonance circuit is equal to the characteristic impedance of the PCB antenna. The invention forms an impedance matching network through the adjustable capacitor, realizes the online adjustment of the antenna parameters of the RFID system, and greatly saves the workload and the adjusting and measuring time.

Description

A test device and method for online adjustment of RFID system antenna parameters

technical field

The invention belongs to the field of short-range wireless communication, and in particular relates to a testing device and method for online adjustment of antenna parameters of an RFID system.

Background technique

For the RFID system, the most critical part is the antenna circuit design. The antenna circuit mainly includes several parts as shown in Figure 1, the RFID read-write chip (11), the LC resonant circuit (12), the matching circuit (3) and the PCB antenna (31), The LC resonance circuit (12) amplifies the signal energy of the required frequency and suppresses the EMC radiation outside the required frequency band. When the RFID system selects the operating frequency, the parameter value of L1 C1 can be determined according to the following formula (L2 C8 is also applicable),

For example, for a 13.56MHZ high-frequency RFID system, you can set L1=L2=680NH, C1=C8=200PF, at this time the resonant frequency

The matching network (3) realizes maximum power transmission. The greater the transmission power, the greater the effective reading and writing distance of the RFID. It is necessary to make the internal circuit of the RFID reading and writing chip (11) + the output impedance of the LC resonant circuit (12) = PCB antenna (31) Characteristic impedance, in order to achieve this effect, a matching network (3) needs to be added, and the matching network (3) is the key to the adjustment of the antenna parameters; the PCB antenna (31) radiates energy into free space.

For the RFID system, after the working frequency is selected, the parameters of the LC resonant circuit (12) can be determined, but in different application scenarios, PCB antennas (31) of different specifications are generally designed, including the antenna area, the number of coils, the Therefore, it is necessary to adjust the parameters of the matching network (31) to ensure impedance matching, that is, to adjust the capacitance values of C2-C7 in Fig. 1 .

The existing method for adjusting the parameters of the matching network (3) includes the following steps:

STEP1: Solder C2-C7 capacitors on the PCB board. The capacitance value is generally determined based on experience. Use an oscilloscope to test the amplitude of the electrical signal at the PCB antenna, or directly test the RFID reading and writing distance. The higher the impedance matching degree, the effective reading and writing distance of RFID. bigger;

STEP2: Modify the capacitance value of C2-C7, and test the amplitude of the electrical signal or the effective reading and writing distance of RFID;

Repeat STEP 1 and STEP 2 until the electrical signal amplitude or RFID effective reading and writing distance meets the design requirements.

The disadvantage of this offline debugging method is that every time the capacitance value of C2-C7 is modified, it is necessary to remove the C2-C7 capacitor from the PCB board, then solder a new capacitor, and then re-power on the test, which requires a lot of work. And it is not possible to observe the test results in real time. It often takes several days to adjust the 6 capacitance parameters of C2-C7 to the optimum.

SUMMARY OF THE INVENTION

In view of the above existing technical problems, the present invention provides a test device for online adjustment of RFID system antenna parameters, which can adjust C2-C7 adjustable capacitance parameters in real time, and observe the corresponding test results, using the following technical solutions:

Including RFID read-write chip, LC resonant circuit, impedance matching network, gusset connector, PCB antenna, bottom plate and antenna gusset, among which,

The RFID read-write chip, the LC resonant circuit, the impedance matching network and the pin board connector are arranged on the bottom plate; the PCB antenna is arranged on the antenna pin board; the electrical connection between the impedance matching network and the PCB antenna is realized through the pin board connector ;

The RFID read-write chip, the LC resonant circuit, the impedance matching network and the gusset connector are connected in sequence; the impedance matching network is composed of several adjustable capacitors, so that the internal circuit of the RFID read-write chip and the LC resonant circuit form an integral whole. The output impedance is equal to the characteristic impedance of the PCB antenna.

Preferably, the bottom plate is buckled with the antenna plate.

Preferably, the LC resonant circuit is a dual-antenna type.

Preferably, it also includes a test rack, which fixes the bottom plate and is connected in an adjustable manner.

Based on the above purpose, the present invention also provides a method for a test device for online adjustment of antenna parameters of an RFID system, comprising the following steps:

S10, fasten the antenna plate to be tested on the bottom plate;

S20, lead out the test wire from the electrical signal test point and connect it to the oscilloscope, and place the RFID terminal under the antenna gusset;

S30, adjust the adjustable capacitor in the impedance matching network, and observe the real-time changing waveform of the signal amplitude on the oscilloscope; repeat S30 until the electrical signal amplitude or the RFID effective reading and writing distance meets the preset requirements;

S40, turn off the power supply of the base plate, remove the adjustable capacitor, and test its capacitance as the final impedance matching network parameter;

S50, on the base plate of the RFID system in practical application, set each capacitor of the impedance matching network to the capacitor with the capacitance value determined in S40.

Preferably, the base plate is adjustably connected to the test stand.

Preferably, the height of the test stand can also be adjusted at the same time to directly test the effective distance of RFID reading and writing in real time.

Preferably, the test point is set after the impedance matching network and before the PCB antenna.

Preferably, the RFID terminal includes an electronic tag or an IC card.

Preferably, in the S40, the capacitance value of each adjustable capacitor can be directly tested on the base plate by an online capacitance tester.

The present invention has at least the following beneficial effects:

1. Set up RFID read/write chip, LC resonant circuit, impedance matching network and gusset connector on the bottom plate, completely simulating the practical application of RFID system;

2. Replace the matching network with fixed capacitance in the prior art with an impedance matching network with adjustable capacitance, adjust the capacitance online, and observe the electrical signal through an oscilloscope to determine the most suitable capacitance;

3. The test stand can be set up to test the effective distance of RFID reading and writing, so that one device can be used for multiple purposes.

Description of drawings

Fig. 1 is the structural schematic diagram of the testing device of the antenna parameter of RFID system in the prior art;

2 is a schematic diagram of a PCB antenna structure of a test device for online adjustment of RFID system antenna parameters according to an embodiment of the present invention;

3 is a schematic structural diagram of a testing device for online adjustment of antenna parameters of an RFID system according to an embodiment of the present invention;

4 is a bottom view of the structure of a test device for online adjustment of antenna parameters of an RFID system according to an embodiment of the present invention;

5 is a schematic side view of the structure of a test device for online adjustment of antenna parameters of an RFID system according to a specific embodiment of the present invention;

Fig. 6 is the PCB layout of the bottom plate of the test device for online adjusting the antenna parameters of the RFID system according to the specific embodiment of the present invention;

7 is a schematic structural diagram of a testing device for online adjustment of antenna parameters of an RFID system according to another specific embodiment of the present invention;

FIG. 8 is a flow chart of steps of a test method for online adjustment of antenna parameters of an RFID system according to a specific embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Device Example 1

2-6, the present invention discloses a test device for online adjustment of RFID system antenna parameters, including RFID read-write chip 11, LC resonant circuit 12, impedance matching network 13, gusset connector 14, PCB antenna, base plate 10 and the antenna pinch plate 30, wherein,

The RFID read-write chip 11, the LC resonant circuit 12, the impedance matching network 13 and the pin board connector 14 are arranged on the bottom plate 10; the PCB antenna is arranged on the antenna pin board 30; the impedance matching network 13 and the PCB are realized through the pin board connector 14 the electrical connection of the antenna;

The RFID read-write chip 11, the LC resonant circuit 12, the impedance matching network 13 and the gusset connector 14 are connected in sequence; the impedance matching network 13 is composed of several adjustable capacitors, so that the internal circuit of the RFID read-write chip and the LC resonant circuit form a whole The output impedance is equal to the characteristic impedance of the PCB antenna.

The bottom plate 10 is fastened to the antenna plate 30, and the PCB antenna is arranged on the antenna plate 30. The antenna plate 30 can be replaced to realize online adjustment and matching of PCB antennas of different specifications. The LC resonance circuit 12 is of a dual antenna type.

A control circuit 15 is also provided on the base plate 10 .

Device Example 2

On the basis of Embodiment 1, referring to FIG. 7 , the test device for online adjustment of the antenna parameters of the RFID system provided by the embodiment of the present invention further includes a test frame 20 , a fixed base plate 10 , an adjustable connection, and an adjustable connection between the base plate 10 and the RFID terminal 50 . Distance, test the effective distance of RFID reading and writing, the higher the impedance matching degree, the greater the effective reading and writing distance of RFID; the test line drawn from the base plate 10 is connected to the oscilloscope 40, and the test point of the lead out test line is after the impedance matching network 13, the PCB antenna Previously, the higher the impedance matching, the greater the amplitude of the electrical signal detected by the oscilloscope 40 .

Method Example 1

Referring to FIG. 8 , a method for a test device for online adjustment of RFID system antenna parameters applicable to the above test device for online adjustment of RFID system antenna parameters includes the following steps:

S10, fasten the antenna plate to be tested on the bottom plate;

S20, lead out the test wire from the electrical signal test point and connect it to the oscilloscope, and place the RFID terminal under the antenna gusset;

S30, adjust the adjustable capacitor in the impedance matching network, and observe the real-time changing waveform of the signal amplitude on the oscilloscope; repeat S30 until the electrical signal amplitude or the RFID effective reading and writing distance meets the preset requirements;

S40, turn off the power supply of the base plate, remove the adjustable capacitor, and test its capacitance as the final impedance matching network parameter;

S50, on the base plate of the RFID system in practical application, set each capacitor of the impedance matching network to the capacitor with the capacitance value determined in S40.

In a specific embodiment, the bottom plate and the test frame are connected in an adjustable manner, and the height of the test frame can also be adjusted at the same time, so as to directly test the effective distance of RFID reading and writing in real time.

The test point is set after the impedance matching network and before the PCB antenna.

RFID terminals include electronic tags or IC cards.

In the S40, the capacitance value of each adjustable capacitor can be directly tested on the base plate through an online capacitance tester.

It should be understood that the exemplary embodiments described herein are illustrative and not restrictive. Although one or more embodiments of the invention have been described in conjunction with the accompanying drawings, those of ordinary skill in the art will appreciate that various changes can be made without departing from the spirit and scope of the invention as defined by the appended claims. Changes in form and detail.

Claims (10)

1. A test device for online adjustment of antenna parameters of an RFID system is characterized by comprising an RFID read-write chip, an LC resonance circuit, an impedance matching network, a buckle plate connector, a PCB antenna, a bottom plate and an antenna buckle plate, wherein,

the RFID read-write chip, the LC resonance circuit, the impedance matching network and the buckle plate connector are arranged on the bottom plate; the PCB antenna is arranged on the antenna buckle plate; the impedance matching network is electrically connected with the PCB antenna through the buckle plate connector;

the RFID read-write chip, the LC resonance circuit, the impedance matching network and the buckle plate connector are sequentially connected; the impedance matching network is composed of a plurality of adjustable capacitors, so that the integral output impedance formed by the internal circuit of the RFID read-write chip and the LC resonance circuit is equal to the characteristic impedance of the PCB antenna.

2. The device as claimed in claim 1, wherein the base plate is fastened to the antenna clip.

3. The device for testing the on-line adjustment of the antenna parameters of the RFID system according to claim 1, wherein the LC resonant circuit is a dual antenna type or a single antenna type.

4. The device as claimed in claim 1, further comprising a testing jig for fixing the base plate and adjustably connecting the base plate.

5. A method for using the test device for online adjustment of antenna parameters of an RFID system according to one of claims 1 to 4, characterized in that it comprises the following steps:

s10, buckling the antenna buckle plate to be tested on the bottom plate;

s20, leading out a test line from the electric signal test point to be connected to an oscilloscope, and placing the RFID terminal below the antenna buckle plate;

s30, adjusting an adjustable capacitor in the impedance matching network, and observing real-time change waveform of signal amplitude on an oscilloscope; repeating S30 until the amplitude of the electric signal or the effective reading and writing distance of the RFID meets the preset requirement;

s40, closing the power supply of the bottom plate, taking down the adjustable capacitor, and testing the capacitance value of the adjustable capacitor to be used as a final impedance matching network parameter;

s50, on the chassis of the RFID system in practical use, the respective capacitances of the impedance matching network are set to the capacitances of the capacitance values determined in S40.

6. The method of claim 5, wherein the base plate is adjustably connected to the test rack.

7. The method of claim 6, wherein the height of the test rack can be adjusted simultaneously to directly test the effective distance between the RFID reader and the RFID reader in real time.

8. The method of claim 5, wherein the test point is disposed after the impedance matching network and before the PCB antenna.

9. The method of claim 5, wherein the RFID terminal comprises an electronic tag or an IC card.

10. The method of claim 5, wherein in S40, the capacitance value of each tunable capacitor can be directly tested on the backplane by an in-line capacitance tester.

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