Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 325 views

    CST Application Note Rfid

    Uploaded by

    Abohicham Abh
    tyghj

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    CST Application Note Rfid

    Uploaded by

    Abohicham Abh
    325 views15 pages
    tyghj

    Original Title

    Cst Application Note Rfid

    Copyright

    © © All Rights Reserved

    Available Formats

    PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    tyghj

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    325 views15 pages

    CST Application Note Rfid

    Uploaded by

    Abohicham Abh
    tyghj

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 15
    At a glance
    Powered by AI
    RFID technology can be used for various applications such as identification, access control, and payment. RFID tags can contain more information than barcodes and allow contactless identification.

    Some common frequency ranges used for RFID are 125/134 kHz for animal identification, 13.56 MHz for product identification, 868-928 MHz for various applications, 2.4 GHz for vehicle identification, and 5.8 GHz for electronic toll collection in Europe.

    The two main operating principles for RFID tags are inductive coupling for lower frequencies up to 15 MHz, and microwave coupling for higher frequencies from 868 MHz to 5.8 GHz.

    www.cst.

    com 1
    Overview
    Operating Principles
    Inductive Coupling
    Microwave Coupling
    Matching of RFID Tags
    Summary
    twi / v1.0 / 09. Nov 2006
    CST STUDIO SUITE2006B
    Application Note
    RFID Simulation
    www.cst.com 2
    Overview
    Fundamental tool for Automatic Identification:
    authentication, ticketing, access control, supply
    management, parking, payment, vending, surveillance
    Advantages:
    Contains more information than e.g. Barcodes
    Can be read/write
    Contactless ID (in contrast to phone or bank cards)
    May become cheap mass product (e.g. in supermarkets)
    Radio Frequency IDentification
    www.cst.com 3
    General Principle
    Typical characteristics of RFID:
    Tag is a passive device, energy is transmitted fromreader
    Distance mm to 10m (typically ~20 cm)
    Contains silicon chip, can be read only or read/write
    Responds with modulated signal
    Mostly printed (planar) structures
    Reader
    RFID tag
    Data
    Energy
    www.cst.com 4
    Frequencies
    125/134 kHz Animal identification, industrial applications, very
    robust, lowdata transmisstion (64 bit)
    7.4 - 8.8 MHz Electronic Article Surveillance (EAS)
    13.56 MHz "Smart Labels" widely used for product/article ID
    868 - 928 MHz Several applications
    2.4 GHz Vehicle identification, electronic toll collection
    5.8 GHz electronic toll collection in Europe
    www.cst.com 5
    Operating Principles
    Inductive Coupling (125 kHz 15 MHz)
    Very small dimensions compared to
    Coupling only through magnetic field
    Tag typically a planar coil
    Microwave Coupling (868 MHz 5.8 GHz)
    typically a regular antenna
    (e.g. planar folded dipole)
    Matching network important to keep
    antenna small
    www.cst.com 6
    Inductive Coupling
    RFID tags are mostly planar coils with small dimensions compared to
    Hexahedral or tetrahedral F-Solver are typically most suited.
    Example for
    13.56 MHz
    with courtesy and permissionof Legic Identsystems AG
    At 13.56 MHz Measurement: (7.15 + 398i)
    Simulation: (7.0 + 334i)
    Measurement
    CST MWS simulation
    Imaginary part
    of impedance
    Curves are overlying each other,
    excellent agreement!
    www.cst.com 7
    Microwave Coupling
    900 MHz RFID Tag Antenna
    www.alientechnology.com/products/rfid_tags.php
    Simulation of the planar structure
    with a standard 50 port
    Mesh view
    www.cst.com 8
    50
    Non-resonant simulation,
    3 min sim. time
    Wrong resonance frequency, lowcoupling
    Antenna is poorly matched
    900 MHz RFID Tag Antenna
    www.cst.com 9
    Matching Procedure
    Matching impedance: 1.55
    Lumped Capacitance for shifting the
    resonance frequency:
    Z_im= 89.5i L = 15.8 nH
    (or: L fromTemplate Based Postprocessing)
    (or: Macros -> Calculate -> Calculate L-C-fres)
    pF 96 . 1
    1
    2
    = =
    L
    C
    www.cst.com 10
    Matching in CST DESIGN STUDIO
    1.5
    Resonance frequency correct (900 MHz),
    excellent matching (-30 dB)
    Simulation run in
    CST DESIGN STUDIO
    TM
    : 5 sec.
    www.cst.com 11
    Alternative Approach
    Inclusion of lumped element in CST MWS simulation
    Resonant simulation,
    20 min sim. time
    Excellent agreement between matching in
    Design Studio and matching in CST MWS
    CST DS approach is 7 times faster
    1.5 1.96 pF
    www.cst.com 12
    Field Monitors
    Current Density
    Electric Field
    Farfield
    Dipole field
    With lumped element included in CST MWS
    all field monitors are available
    www.cst.com 13
    Test under Realistic Surroundings
    RFID tag in front
    of metal can
    RFID tag in front
    of water bottles
    www.cst.com 14
    Field Distortion by PEC-Cans
    poorer matching
    Second resonance
    Unsymmetric
    fields
    www.cst.com 15
    Summary
    RFID is a general concept using different
    technical principals
    CST complete technology approach offers
    best solution for each case
    Frequency Domain / CST EMS for coil type
    Transient Simulator for microwave type
    Tags often contain lumped elements
    Possible in both CST MWS or CST DS
    CST DS typically more efficient

    You might also like