I've got a Vodafone mobile internet dongle that I use when I'm away from home. Staying in a Travelodge in the East End of London, I'm surrounded by high buildings, and even though I get a nice blue 3G signal, it seems to drop out if the dongle is moved an inch or if the wind blows or if anything moves anywhere in England.
I've solved the problem as per the attached photo. Basically you put a dongle in an empty coffee mug. This is bizarre enough, but it seems to work even better if you leave the spoon in the cup too.
Sometimes you solve problems with science - sometimes you just need to stick your dongle in a mug.