I live in an urban area over a 1000 miles (1600 km) from the nearest atomic time radio tower, so I usually have great difficulty in receiving the signal. For months my AWGM100 was unable to receive the signal. Until one night I left it inside a metal wire cube shelf (see below), and "magically" it was able to sync that night. I repeated the same experiment by putting the watch on the same shelf, it was able to sync for at least 2 more nights within a week. It has to be a clear night though, for that to happen, as I discovered. But I think the metal shelving definitely improved the reception, probably by acting as an antenna. The most interesting thing is the shelf is not even close to a window, it's inside a closet!
Obviously with only 1 watch, it is not enough of a sample size to prove my theory. I would like someone else to try this experiment. Pretty simple, just put your watch inside a similar metal shelving and see if it improves your time signal reception. Make sure you post back here for your results, thanks!