Instructables

homemade signal booster?

i was trying to figure out how to boast my signal coverage in my area, and a got an idea:


to use a UHF amplifier, to pick up the towers signal and rebroadcast it. of coarse since things like WiFi, Bluetooth, and cellular 2G/3G/4G networks use two way radio, the signal can go back to the reviving end of the UHF amp, and get broadcasting to hit whatever tower. my phone should better recognize the tower, as if i just magically made a tower 2 feet away. however this might also amplify stay noise.

if this idea doesn't work, why not? i think i am going to need at least a 20dB increase in power, but as of now i  need to do more research.
but if i can buy a product that does a similar thing for less than $40, i would.

http://en.wikipedia.org/wiki/Dead_zone_(cell_phone)#Dead_zones 
http://en.wikipedia.org/wiki/Repeater
http://en.wikipedia.org/wiki/Wireless_spectrum (cellphones use UHF spectrum)
http://en.wikipedia.org/wiki/Signal_booster

Picture of homemade signal booster?
rickharris2 years ago
Where will you get the UHF amplifier from?

How will you tap into your phones circuit to extract the Rf signal to drive the amplifier.

The cheapest option is to add an external antenna.
-max- (author)  rickharris2 years ago
\i plan on buying one, ir if i can, build one. i am sure the gain is going to have to be very high, it might be cheaper to buy a few cheap ones and hook the output of one to the input of the next one to get exponential gain, maybe 3? the last one is going to be a higher wattage to emit the signal. this i think should work.

the phones emit rf signal into the air, so i make an antenna to pick it up and re amplify. the amplified signal goes to a emitting antenna, both i might cheap out on and just use a 5 inch long coiled up wire. (helical design)

i tried to place a wire to the 1/2 inch long antenna, only to find out whatever i did i decreased my signal strength. (from 98dbm to 110dbm, from 1-2-ish bat to nothing..) i was able to get better WiFi signal however, with a 1.5 inch steel wire. :)

besides, it would be weird to carry a phone with a antenna sticking out the top of it,(especially on a galaxy s3) that is SO 90's
I have a feeling this isn't going to work - BUT your making the best effort by buying the complicated parts e.g. the UHF amp.

Let us know how you get on.
-max- (author)  rickharris2 years ago
i also have my doubts, i have no way of knowing if i built a working amplifier, and if i did, how much gain would i need, how do certain dbm gain translate to the actual gain? (3 times, 10 times, 100 times 200 times increase in gain?)

then my last problem would be, if i did get all of that to work, and everything is the right rating to work properly, then what if all i end up amplifying is just as much noise as the signal? it is probably my biggest concern.