Preparation for RFID Certification Exam

Cheat Sheet – RFID Solution Design

MAIN OBJECTIVES

  • Know the components of an RFID system
  • Know what are the configuration factors that impact overall system effectiveness

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COMPONENTS OF AN RFID SYSTEM

  • A Reader – fixed, handheld, sled, embedded, module
  • A Cable – various lengths and thicknesses
  • Connectors – cable connectors to reader and antenna, power connectors, network connectors
  • An Antenna
    • Circular polarization
    • Linear polarization
  • A Hub or a multiplexer (not always present) – allows to connect more antennas to a reader than there are available ports.
  • Peripherals (not always present) – RFID printer/encoder, barcode scanner, lights, sensors

CONFIGURATION FACTORS THAT IMPACT OVERALL SYSTEM EFFECTIVENESS

  • Reader port impedance – must match the antenna impedance (loss resistance, voltage to current, standard is 50 ohm, tuned at manufacturing) for proper performance and to avoid component damage.
  • Antenna should have minimum VSWR (voltage standing wave ratio/return loss) for best impedance and most efficient operation.
  • Antenna polarization
    • Circular polarization – shorter read range, but orientation insensitivity
    • Linear polarization – longer read range, more focused, orientation sensitive
  • Antenna gain
    • The higher the gain, the narrower the beam but the longer read range.
    • The lower the gain, the wider the beam but the shorter the read range.
    • Gain together with reader power output have to produce certain total transmitted power that complies with regulations.
  • Cable connector type/materials
  • Cable type & signal loss – The thicker the cable, the lower the loss, the more expensive the cable.
  • Cable length – The longer the cable, the higher the loss, the worse system performance
  • Tag antenna size and type – the larger the antenna, the more power it can harvest from reader signal, the longer the read range. But may not be practical for small items.
    • Single dipole tag antenna – may be orientation sensitive with linearly polarized reader antennas
    • Dual dipole tag antenna – less orientation sensitive
  • Material tag is placed on or near
    • Water, moist materials, aqueous liquids – can detune the tag, must tune specifically and create offset from the surface
    • Metal – detunes the tag, must tune specifically and create offset
  • Tag processor type (“chip”) – chips differ by manufacturer, by processing speed, sensitivity, memory size and attachment to the antenna.
  • Tag antenna impedance has to match the impedance of the integrated circuit (IC) over a desired bandwidth for best performance. It is tuned at manufacturing.

What is required is knowledge of what factors must be taken into account in configuring a RFID system rather than detailed knowledge of how to do so