There are some other things to consider regarding boonie commo.  A nice
multi-element beam antenna in the proper bandwidth will allow the patient to
ferret out a distant tower using a phototripod and pan head.  Even smaller,
a log-periodic with a similar pointing method will do nicely.  That's the
way the big boys do it.  USDA remote monitoring systems and so on.  Now the
trick is to slowly sweep a likely azimuth using your phone as the signal
detector.  SLOWLY.  When you find one, there you are connected to some
farmers funkeefone.  You can use a parabolic dish but they're a little
tougher to point.  Remember, this is only for boonie commo where the closest
Starbux Wi-fi is terribly far away.   You can use a 2.4 GHz system phased
antenna to get a reasonable 15 mile range on your wifi but there is a
scarcity of targets where larry and the nutria hang out.  Especially in the
2.4GHz domain.  This stuff is definitely point and shoot.  You will need
visible contact with the target.  In the 900mhz arena you can be less
discriminating.  Or if you have a willing partner 30 miles of high grade
fishing line a couple of cans...

Check out Ken at W5VJB for details on the log-periodic.