Presentation on theme: "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."— Presentation transcript:
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 Pringles can Effective directional antenna Cantenna More effective Parabolic dish Much more effective Significantly improved SNR Limits the useful range of WiFi
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 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 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 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 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 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 Green is signal Red is noise
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