การวัดการทำงานของความถี่ RFID โดยใช้ Hioki Impedance Analyzer IM758x Series
What is RFID?
RFID refers to Radio-frequency identification and uses radio frequency electromagnetic fields to transfer digital information. Because of it’s non-contact method of wireless information collection, the technology has been recently in the spotlight during the pandemic, especially in the healthcare industry and supply chain.
There is a huge potential in RFID technology lately as it helps to reduce physical contact and can be used in the fight of against COVID-19.
Some hospitals are even using RFID technology to track how often healthcare workers are washing their hands.
Other industries/applications that use RFID technology include:
– Supply chain management
-Passport
– ID cards
-Wireless Payments
-Food Industry
-Healthcare Industry
-Automotive Industry …and more.
Operating Frequencies of RFIDs:
The operating frequencies of RFIDs, which are also known as IC tags or contactless IC cards, are defined by standards. When performing L measurement of a board used by a contactless IC card, the measurement must be made near the operating frequency of 13.56 MHz.
Setting example of measurement conditions
|
Measurement Mode |
ANALYZER |
|
Parameters |
Z-θ frequency characteristics analysis(L-Q、R evaluation available) |
|
Sweep parameter |
FREQ |
|
Sweep frequency |
Sweep measurement close to the operating frequency (See the table below) |
|
Signal level |
V mode 1V (350x, IM35xx series) or 1dBm (IM758x series) |
*The above settings apply to an example measurement. Since optimal conditions vary with the measurement target, specific settings should be determined by the instrument operator.
RFID standards
|
Category |
Frequency |
Effective distance |
Standard |
|
ID cards |
13.56MHz |
Up to 10cm (Proximity applications) |
ISO14443 |
|
Automatic recognition |
125kHz |
Up to 70cm (Vicinity applications) |
ISO14443 |
|
13.56MHz |
ISO15693 |
Structure of RFID tag
RFIDs generally consist of an antenna and IC. Signal transmission is accomplished by a resonant circuit formed by the antenna inductor (Ls) and the IC chip’s built-in input capacitance (Cp).
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Inductor |
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Circuit model |
Frequency characteristics of defective and non-defective components
As shown in the following figures, the Z-θ frequency characteristics of defective and non-defective components differ. The non-defective component exhibits a resonance point near the operating frequency.
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Frequency Characteristics of Impedance |
Frequency Characteristics of Phase |
Products Used
Production line and R&D applications
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Model |
Measurement frequency |
RFID |
|
 |
100k to 1.3GHz * |
Mainly for high-frequency RFID |
|
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4Hz to 5MHz |
Mainly for low-frequency to medium frequency RFID |
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*For more information, please see the product catalog . |
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Pass/Fail Judgments Using Analyzer Mode
Either of two methods can be used to generate pass/fail judgments when using analyzer mode: peak judgment and area judgment.
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Judgment method: Whether the resonance points fall inside a judgment area. |
Judgment method: Whether all measured values fall inside a judgment area. |
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Peak Judgement |
Area judgment |
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Judgment areas can be set as follows.
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Ascertaining Electrical Constants By Means Of Equivalent Circuit Analysis
The instrument’s equivalent circuit analysis function can be used to calculate the constants in a three-terminal circuit model such as an RFID antenna.
*Model A should be used for coils with a large core loss (R) in order to facilitate more accurate analysis.
