Absorbers - Flexible Absorbent Material (FAM)
(4) FAQ (RFID/NFC)
Flexible Absorbent Material
FAM is a thin and flexible material, include soft rubber type and flexible sintered ferrite sheet with higher permeability. It can be cut any shape easily, freely arranged in space and provide effective EMI suppression in a wide frequency range (1MHz to 18GHz). Also can be a solution for RFID (Radio Frequency Identification) system on metal. It suitable for LF(125/134.2KHz) and HF(13.56MHz) bands on metal environment. It also works well in NFC (Near Field Communication) technology application and Wireless Charger (WPC/Qi).
FAQ for RFID/NFC applications :
Q1 : Why FAM applicable frequency is GHz but can be used for for LF (125/134.2KHz) and HF (13.56MHz) ?
A1 : FAM is a kind of high electrical resistivity and low magnetic loss material. It works well for suppression near-field electromagnetic coupling effects (RFID/NFC/Wirelss Power) because it’s power loss is low when frequency is under 10MHz.
Q2 : How RFID/NFC affect by metal?
A2 : The magnetic flux from RFID/NFC tag or reader/writer will induce eddy current on metal surface and generate a reverse magnetic field to offset the magnetic flux to cancel the communication.
Q3 : How to use FAM for a RFID/NFC tag?
A3 : Attach FAM with antenna / inlay tightly and embed into any shape as you need. When the tag attached on metal surface, please use FAM side, not antenna side.
Q4 : How to use FAM for a RFID/NFC reader/writer?
A4 : Insert FAM between reader’s antenna area and circuit board tightly to get a compact design. When use the reader/writer, please don’t use antenna side to attach the metal surface.
Q5 : Can I use FAM for a UHF RFID tag?
A5 : FAM is not suitable for UHF RFID tags.
Q6 : How to choose FAM thickness?
A6 : FAM has standard thickness as page 8. You can test different thickness with your RFID/NFC device directly to compare which thickness can get the best distance. It's a fast and easy function to evaluate FAM.
Q7 : Why I can’t get a good read distance after using FAM?
A7 : When FAM close RFID/NFC device, the inductance in LC circuit will increase and the response frequency will become lower. If your tag’s frequency is far away reader’s frequency, the read range will become shorter than before. In such a case, re-design the antenna to adjust L and C to get a reasonable response frequency will be the best function. (please see page 5)
Q8 : Is there any factors can change RFID/NFC tag read range?
A8 : Many diverse factors will cause read range different, for example : operation frequency, reader output power, tag antenna size, reader antenna size, active tag or passive tag, reader position, objects interference, others RF device interference, metal material/size, FAM material/size and etc.
Q9 : What FAM dimension should I use?
A9 : When FAM cover the whole RFID/NFC antenna area can get the best performance.
(please see page 6)
Q10 : How is the performance if I assemble small piece FAM to cover the whole RFID/NFC antenna?
A10 : The performance will the same the whole piece FAM.
Q11 : Is there any different for FAM two sides?
A11 : FAM is a well mixed material with one single layer design so the two sides are the same.
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