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WiFi Antennas Reid Palmeira EE496 WiFi Specification IEEE 802.11b Uses 2.4 GHz frequency band Up to 11 Mbps Has fallback data rates to 5.5, 2 and 1 Mbps Uses only Direct Sequence Spread Spectrum Approx. 200 ft. clear line of sight range 14 total channels, 11 channels (in US) Designs

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wifi antennas

WiFi Antennas

Reid Palmeira

EE496

wifi specification
WiFi Specification
  • IEEE 802.11b
      • Uses 2.4 GHz frequency band
      • Up to 11 Mbps
      • Has fallback data rates to 5.5, 2 and 1 Mbps
      • Uses only Direct Sequence Spread Spectrum
      • Approx. 200 ft. clear line of sight range
      • 14 total channels, 11 channels (in US)
designs
Designs
  • Pringles can
    • Effective directional antenna
  • Cantenna
    • More effective
  • Parabolic dish
    • Much more effective
    • Significantly improved SNR
    • Limits the useful range of WiFi
legality disclaimer
Legality Disclaimer
  • Illegal by FCC regulations
    • You can only attach an FCC approval antenna to a WiFi card or base station
    • Only commercial antennas are approved
    • Enforcement provisions are minimal
design considerations
Design Considerations
  • Effectiveness
    • SNR improvement
    • Signal range improvement
  • Size
    • Portability
    • Storage
  • Cost and Build Time
    • Realistic use
    • Accessibility
  • Legality
    • If the FCC comes knocking, be French: run away!
design
Design
  • N-Connector and pigtail from the reflector (the can) to the AP or to the WiFi card
  • Mount the injector to the side of the reflector
  • Parts must be checked to make sure matching errors don’t occur – for example standard coax cable from something like a TV will absorb the entire signal very quickly.
  • The longer the reflector (the can) the more directional and less omni-directional the antenna becomes
benefits of can type booster antenna
Benefits of can type booster antenna
  • Improved SNR and performance
  • Increase in effective range of WiFi
  • Cost is much less than commercial antenna with similar performance
  • Build and testing times are small
design of parabolic
Design of Parabolic
  • Shaped wire mesh bent over a parabolic frame to form a miniature grid antenna
  • Mesh material should be such that
  • Attached to the AP
  • Focal length varies proportionally with the size of the mesh dish - scalability
benefits of parabolic design
Benefits of parabolic design
  • Increased security, since signal degrades behind the parabola
  • Minimal parts and build time
  • Significant reduction of interference
  • Less parts and no N-connectors, pigtails or cables means no matching problems or transmission line worries
  • No modification of any WiFi cards or modification to parts of the AP
testing with network stumbler
Testing with Network Stumbler

Green is signal

Red is noise

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