I own a Ulefone P6+ now, which has a moderate GPS antenna.
I managed to enhance the GPS signal by 25% by just a little simple fix. No need for soldering!
All you need is some adhesive copper tape. You can buy it at the garden store, it's used to stop snails from eating your plants.
I created a video of the mod. Look how I did it, and how it improved the signal!
Looks good, but how is GPS able to use the strip to increase signal? It's not touching GPS antenna.
To rule out placebo effect, go ahead and remove back of phone and run test again, don't move, don't take one step. just remove the back of phone and rerun test, I want to see those numbers, with back on and back off.
I've shown the signals without the copper strip (in the beginning of the video) and with the copper strip (on the end of the video), on the same place. So no placebo.
Here's someone demonstrating that just holding some conductor near the antenna increases the signal:
Somehow the foil is acting as a shield of some kind.
Even in my bedroom I get a lock now, I didn't get that before
Just a sidenote, you can try aluminium kitchen foil, but that doesn't work as good as copper foil.
For those who are still sceptical here's another video of someone proving it:
I've made the copper strip a little wider and the signal is even better now.
I opened my Note 3 clone and added an aluminium foil strip from the GPS connector and I'm getting great signal, even indoor, but as soon as I close the phone again (with the foil taped at the back) the signal dies..
I will try this mod but directly connect the copper tape to the connectors inside the phone instead and report back.
Tried it on my htm M1 and seemed to improve the signal to the point that I can still get one indoors. Tried it on my T200 no effect, but that has a GPS anyway so the difference is probably too small to notice.