- Realtime Analyzing
      - Harmonic Distortion
        Reduction Feedback
      - Adaptive Filtering
      - Chat Program with

      - DIY Speakers
      - Amplifier
      - Preamplifier
      - Wireless Access
      - Wireless Antennas


Wireless Antennas

I became interested in extending the range of my WiFi 802.11b network card in high school.  The ability to create a wireless network with a friend blocks away was intriguing.  I began my search by reading and learning about antenna types.

The first antenna I made was a dipole, approximately 2 ft tall.  I enclosed it in a pvc pipe and glued the BNC connector for connecting to my laptop wireless card into the end of the pvc.  The antenna showed decent results but nothing like the promises I had been reading on the Internet.

Reading more into directional antennas such as waveguides and yagis, I decided to build the "pringes yagi" that had recently emerged on DIY articles on the Internet.  Even though it technically isn't a yagi, the antenna worked well.  I convinced and helped my friend build one as well and we went out to a long stretch of road.  With the two pringles can antennas we were able to keep a link to about 7/10ths of a mile. Impressive for a primitive antenna.

Discovering the transmission loss for 2.4GHz is very high for normal coax, I decided to find some low-loss coax.  Having done so, the gain of both antennas built went up noticeably.

A few other antenna build attempts were made that were unsuccessful because of difficulty in fabrication.  Eventually a new antenna using a cookie tin and a heating duct coupler proved to work very well.  It is effectively a waveguide with a horn.  The heating duct functions as a horn that helps to minimize the response of the antenna to unwanted signals not in the favored direction of radiation, raising the SNR (Signal-to-Noise-Ratio).  This antenna measured approximately 16dB of gain.

Information and content Copyright © David Swiston
Images released under GPL