How Increase EV-DO Signal Strength

I took EVDO 2 months before. i din't get that much signal strength. one bar or maximum of two during night with two (usb) extensions. after few days, my friend old me you can boost using strength using a CD, ie, placing a cd on the EVDO wtih antenna at the right center. This worked, i got 2 bars. there was no fluctuations in the signal. then i searched for many antenna booster,for 450MHZ. but it was not that practical, self building of buying. recently i saw a video clip, for boosting signal strength for mobile phones. I calculated how much antenna length will it require to make the same thing for EVDO.
This technique did work. now i 'm getting 3 bars. The material used is a thing copper wire. Take wire about 20cm. bend at 5cm. make 5 turns of the wire on a screw or any thing that make the winding looks good. Ok then stretch the turns about 3mm wide. now make few turns on the other end.Place it on your EVDO antenna as shown in the figure. see the difference in Signal strength.