Wireless LAN Antennas

How Far Does Wifi Go?

• Defcon Las Vegas
• 2005
• Wifi Shoot-out
  • Yearly contest
• 300mw PCMCIA
• 10 & 12 ft antennas
• No amplifiers
• 125 miles
  • Regular 802.11 b wifi
  • From Utah mountain top to Las Vegas

Omni Directional

• Very common
• Even coverage in al directions
• Keep attenuation in mind
  • Gets weaker as you go

Parabolic Dish

• Instead of having 360 coverage you focus it all on a specific point.

• Imagine having gigant ears and hearing from all your neighbors

• Directional Coverage

• High Gain

• Reduced interference

• Line of sight critical

• Size of dish varies by frequency

Yagi Antenna

• Directional similar to parabolic

  • Not really big, more discrete

• Smaller footprint

• High gain

• Very focused

• Lightweight

• High wind tolerance

• Like taking a flashlight instead of a lantern

• You can point the yagi to wherever you want to go, for example an access point

  • Less interference from anything.

Whip vs. Patch antennas

• Patch antenna: a type of radio antenna with a low profile, which can be mounted on a flat surface.
  • A patch antenna is typically mounted to a wall or a mast and provides coverage in a limited angle pattern.
  • Patch antennas can be directional or omnidirectional, but a directional antenna should be used for a connection between two buildings within line of sight of each other.
• Whip antenna: a vertical omnidirectional antenna that is usually utilized in indoor environments.
  • A whip antenna is omnidirectional and cannot be used for directional use cases.