Sick Harware Modz!
Thanks for all your ideas and comments guys! I had a crack at this GPS antenna mod and also the Battery mod (using a HTC EVO 3D Battery). If you want to check out the battery mod thread my post & pics are on page 26, here's the link for that page:
http://xdaforums.com/showthread.php?t=1344761&page=26#post66099295. Through testing and checking the numbers/stats I was able to confirm a great improvement for both mods!
I am getting the same amazing results like this user Joe Baliu on page 35 (SNR levels in the 40's) using my homemade GPS antenna but I should add that I only get the absolute best results with both the silicone phone cover off and the GPS antenna bent out slightly from the metal phone housing. It should also be noted that the phone in portrait mode (vertical) has a slightly better SNR numbers than in horizontal. (It seems true the rumours that there is probably some issue with the aluminium phone housing dampening/interferring with the signal which is why you get better reception as soon as the home made antenna is bent even slightly away from the case.) Thankfully in the worst conditions weather condition I just do this to get a quick lock then throw the silicone cover back on. Since there are issues of both f*ck around factor of removing and replacing the silicone cover and bending & re-bending GPS antenna (which might possibly snap it eventually, requiring a resolder, I only do this on overcast days when I'm running late and need a GPS lock quicker and am waiting to drive my car somewhere in a hurry. Normally I only use the phone with the silicone case still on (which is still a great improvement IMHO from stock), or to improve GPS lock time just a moderate amount without bending the antenna I simply remove the silicone case, get a lock then put it back on, before hitting the roads.
It was a few months ago when I did this build and I didn't write down my measurements (so I forget) but for the antenna measurement, going off what it says on (
http://www.antenna-theory.com/design/gps.php), I'm pretty sure I used the measurements of a half-wavelength at GPS frequency (1.575 GHz) which is a piece of wire about 9.5 cm or 3.75 inches. I used a piece of solder as the entire antenna wire and a piece of heat shrink that fit it perfectly. I then "tacked" it on by only soldering on very quickly with the soldering iron (too long and the length of solder wire will shrink/break). I found that the properties of using a piece of solder wire for the entire antenna is that it stays very flexible and so it can take more bending before it is likley to snap at the solder connection such as with most common metal wires people have tried here. As you can see in my photos I've folded the homemade antenna in half. I soldered one end to one of the contacts and the other end to the other contact. I used the soldering iron to carefully melt hole in the plastic panel (the panel for the LEDs and GPS Antenna) so that I could fit the wire though it as seen in my photos. As I hope you can see in my photos the silicone cover nicely keeps the antenna and EVO 3D battery all safe from bumps & knocks. It doesn't make the silicone case bow/stick out much more on the back but it is noticable in the sides of the silicone case from the front of the phone (as shown in my photo). No biggie IMO.
