Using a Directional Antenna to Improve GSM/UMTS Reception

It’s 2006 but sad to say, thre are still some places where you get dead spots on your mobile phone. It’s either you’re too far away from the cell site, or you’re in an area too densely situated with infrastructure (in other words, a concrete jungle).

Graeme blogs about using a homemade biquad WiFi antenna to boost reception, or more accurately to get a signal where there was none at all.

I realised that there really isn’t much difference in operating frequency between WiFi (around 2.4Ghz) and UMTS (2.1Ghz). And there are loads of different clandestine WiFi antenna ideas floating around the Internet. If I could find an easy-to-build directional WiFi antenna, perhaps I could reverse-engineer its dimensions and adapt it for 2100Mhz use.

So I set about the task. I decided on the biquad antenna type, as it’s fairly compact and easy to build, yet provides decent (10-14dB) gain and is quite directional. My primary sources of information were the many WiFi biquad and double bi-quad antenna tutorials and blog entries, such as: Engadget’s; Trevor Marshall’s tutorials. More can be found on my del.icio.us page for the tag ‘antenna’.

This is an interesting hack, and I’d say it’s a hit-or-miss proposition, especially considering that running a cable from a transceiver (in this case, your mobile) to an antenna does produce some signal loss. But if the gain (increased signal) compensates for the loss, then you’ve hit the sweet spot in modifying your system. Still, this is good for stationary cases, and wouldn’t give you much benefit when in a mobile setup, such as in your car. Directional antennae are very sensitive to movement, precisely because they’re directional, and should be pointed straight to the other signal source, in this case at the cell site.

Great use of Google Earth to estimate distance and positioning, though!

July 30th, 2006 Posted by J. Angelo Racoma in Hacks at 6:59 pm Comment Now! »
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