Testing of Wi-Fi antennas

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Testing of Wi-Fi antennas

• By
• Nayla Hamadeh
• Jean Ghanem

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Outline

• Constructing an antenna using a Pringles can
• Theory behind Wi-Fi antenna
• Testing Results
• Conclusion

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Constructing the antenna

• Needed Parts
• Pringles can
• Washers
• Nuts
• All-thread rod
• Aluminum Tubing
• Female Connector
• Microwave Cable with SMA-RP

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Constructing the Antenna (contd)

• Construct pipe

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Constructing the Antenna (contd)

• Attach the connector to the Pringles can

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Theory behind Wi-Fi

• Pringles antenna is based on the quarter-wave
  monopole.
• The copper wire is the monopole
• The can wall is the conducting ground (mirror).

Radiation pattern a half-wave dipole
Radiation pattern of quarter-wave monopole (same
as the pringles antenna)
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Theory behind Wi-Fi

• all-thread rod and the washers act like receptive
  fields.
• Washers amplify the signal
• Adding more washers separated by ?/4 will
  increase the performance but make the antenna
  bigger.
• The rod transmit the signal

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Gain and performance

• The gain is based on the quarter-monople formulas
  with some modifications.
• Gp (4?Umax)/Pi
• Umax (20/?)I2
• Gain is 11.75dB (12 dB)
• Expected range is 5Km

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Why the antenna may not work as described in the
theory?

• Measurements must be exact (High frequency)
• No high precision tools were used.
• Small adjustments will make a difference.
• Copper wire must be vertical and must be close to
  the can wall.
• Small space due to the connector.
• A good conductor must be used for the mirror.
• Aluminum inside pringles can is not designed for
  antennas

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Testing the Antenna

• Pringles can antenna connected to Access Point
  (the D-Link Access Point DWL-900AP ), in turn
  connected to the server
• On other side, laptop with wireless card (LinkSys
  Instant Wireless USB Network Adapter)

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Testing the Antenna

• Requirement for antenna
• Have a clear line of sight
• Maximum Line of sight distance we could achieve
  was 450 meters

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Testing the Antenna

• 2 types of testing performed
• Indoors on the same floor as multimedia lab
• Outdoors around the EECE Bldg up to 450 meters

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Indoors Testing

• Testing based on 3 parameters
• ping command
• Playing a movie over the link
• Signal Strength

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Indoors Testing (contd)

• Signal Strength varied between 10-100 depending
  on location
• ping performed generally well but at times the
  packet loss rate was 50
• Video played generally well except at specific
  spots

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Indoors Testing (contd)

• Observations
• Signal provided by antenna was most of the time
  satisfying
• The spots where the signal was weak was separated
  from the server by several walls

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Outdoors Testing

• Testing based on 4 Parameters
• Signal strength
• Signal Quality
• Bandwidth
• Quality of Video played over the link

Provided by the LinkSys wireless card adapter
Calculated by downloading file using ftp
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Outdoors Testing (contd)
Distance (m) Signal strength Signal quality Bandwidth (Mbps) Quality of Video
5 100 100 8.8 excellent
20 100 100 8.4 excellent
50 100 98 7.7 Very good
100 92 98 6.9 Very good
150 95 98 6.1 good
200 89 95 5.7 good
250 91 83 5.1 good
300 85 75 4.4 acceptable
350 85 70 3.9 acceptable
400 78 70 3.4 poor
450 73 62 2.9 poor
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Outdoors Testing (contd)
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Outdoors testing (contd)

• Observations
• Bandwidth very sensitive to distance.
• Bandwidth depends on signal quality
• Effect of weather
• Sunny days relatively better signal due to less
  interference

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Thank you