A GPS aerial should be high, horizontal and uncovered (ie not in a pocket or bag) for best reception. Putting the aerial in a hat would allow it unobstructed access to the sky and would allow the aerial to be larger than it otherwise would be in a handheld unit. You'd have to remember to unplug your hat before you took it off, though.-- st3f, Jun 01 2005 And take it off in thunderstorms...-- hippo, Jun 01 2005 random, halfbakery