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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.
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.
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