Cell Phone Reception Hack 142
New Breeze writes "Has this ever happened to you? Just when you need to make a phone call, the bars of reception are scant to none. But Graeme, who writes a blog called 'Earth: Mostly Harmless,' gives us hope. Succeeding where most would quit, he chronicled his ingenuity in a post titled 'How I got mobile phone reception where there was no signal.'" Update: 08/01 14:31 GMT by T : Note: Credit for this story belongs to Mike Yamamoto, who wrote it for CNET's News.com.
site down? (Score:1, Informative)
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Article text (Score:1, Informative)
Posted at 20:30 by Graeme
Categories: Uncategorized
(Or, to be more accurate, where 20ft of solid stone was blocking line-of-sight to the nearest transmitter.)
I just got a Nokia E61 on T-Mobile. When I signed up, I knew that the signal was really weak in the back of our house - the building forms a large square, and my bedroom faces into the centre of the square. I could get a signal in the living room (just), but wouldn't it be great, I thought, not to have to go through there every time the phone rings. Although outside my house full-strength UMTS signals are readily available, the building's construction prevents them diffracting into the internal 'courtyard'.
All I needed was enough reception to receive and send SMS messages. I have home WiFi for data access, and I can potentially make calls over that too. I planned to aim for UMTS reception rather than GSM since: a) I didn't know which GSM frequency to aim for and b) E series Nokia phones maintain their batteries better if they have UMTS signals (otherwise they constantly search for a UMTS signal).
I tried two car-type external antennas that I got via eBay - but unfortunately the gain on both of these was just too low (barely even compensating for the losses in the cable running to the phone). Also, neither were sufficiently directional to catch enough of the reflected signal to give me anything to work with.
The first step was the figure out what the extent of the problem was. I located my nearest T-Mobile base station using the government's Sitefinder service. This also confirmed the frequency that the transmitter used - 2100Mhz. This is the standard frequency for UMTS (i.e. 3G) services in Europe.
By drawing a line between the transmitter's location and my building in Google Earth, I was able to confirm the approximate distance and angle of the signal I needed to catch.
Buying a directional antenna wasn't really an option - for a start, they are expensive - and anyway I couldn't be sure that such an antenna would actually help. If it didn't, I'd have wasted £60-£100.
However, in an incredibly geeky flash of inspiration, 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'.
Both WiFi and UMTS operate in microwave frequencies - however, there's a substantial difference between the middle WiFi channel (around 2.4Ghz - what people usually tune their WiFi antennas to in order to give a good amplification factor across the channel range) and UMTS' 2.1Ghz. To my knowledge no-one has built a homebrew biquad UMTS antenna before, so there wasn't much to go on. What also didn't help was that most WiFi biquad tutorials just give you the measurements verbatim - not the calculations of formulae.
Having done no physics since school, my expertise in antenna building is poor to say the least. Still I did realise a few things about most of the designs floating around the Web: all of the dimensions were multiples of the wavelength at 2.44Ghz (122mm or 0.122m). So then, I just needed to figure out the multiplication factors in each case and I was sorted.
My list is as follows: ( = wavelength)
* Emitter wire total length: 2
* Emitter 'square' side length: 0.25
Big deal,it is obvious! (Score:5, Informative)
A " Cell Phone Reception Hack" - whatever (Score:5, Informative)
Cool. I'll check that one out.
I pull up the list of comments and I click on the link to the article. I read the article from start to finish and having consumed the literary words on the page, let me be the first to post...
ARE YOU FUCKING KIDDING ME?
Read my lips: Antenna != hack
This is in no way, shape, or form a hack. It is a guy building an antenna. It's only been done by thousands of other ppl over the last 50 years. But yea, let's run the story anyway and call it a 'hack'.
Well, it's not.
Re:Bars (Score:3, Informative)
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Use an external antenna. A lot of phones still have connectors for those, so no hacks required there.
Obligatory karma whoring: Here's a good place to buy one. [wilsonelectronics.com]
For CAN$50 I got myself a mag mount 5 dBi external antenna. [wilsonelectronics.com]
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RG-58 is 50 ohm cable (Score:3, Informative)
Re:Sitefinder (Score:4, Informative)
Then I found out that someone has a google maps interface [cellreception.com] to the same data. Screw that FCC site! :-)
Re:Getting Gain in the US for Home or Car (Score:3, Informative)
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Of course, I hope the French are pissed. :-)
Reinventing the wheel. (Score:4, Informative)
Yeah, pretty much.
I don't want to be too hard on the guy, because it sounds like this was his first antenna project, but the whole article just makes me a little sad. What he did isn't even all that hard, and if he had done a little more searching around he would have found literally thousands of pages and hundreds of articles, complete with formulae and schematics, on how to build antennas of this type.
There's an amateur radio band located just above (and IIRC overlapping slightly with) the 2.4GHz ISM band. There's tons of antenna construction resources; the American Radio Relay League has two volumes written about the topic [arrl.org]. (Although it covers a lot more than just antennas, admittedly.) Although I don't own the book, I'd bet that most of those articles probably have equations for scaling the dimensions to particular frequencies, so it would be trivial to do what he was attempting. (And a quite likely a violation of FCC rules, but that's another story.)
On a more general note, it's a little sad to see how little of a connection there is between the radio "hacking" community and the computer one. Perhaps it's due to there being a generational gap in there, but I've never met two groups of people that have as much in common, philosophically, as computer hackers and ham radio tinkerers. When I read articles like TFA, where the author says "To my knowledge no-one has built a homebrew biquad UMTS antenna before..." it just really underscores how poor a job the amateur radio community has done in connecting with computer geeks. The topic at hand here isn't something breathless and new, it's well-understood to the point of probably being boring. But because of the lack of connection between the two interest groups (even though, as in this case, they have a lot of common interests even if they don't realize it), we have computer geeks painfully reinventing the basics of antenna design, and we have ham radio operators who haven't in some cases even figured the Web out completely, much less how to use it to collaborate.
That's not to say that there aren't computer geeks who are into ham radio and vice versa -- the number of radio-related software projects is testament to that (as am I, and others here on