As dchky points out the higher the frequencies are the more directional; they become and as we are talking about the 850/900/1800/1900 mhz/ghz cell phone frequencies they don't get much higher than that.

Woody is spot on when he talks about repeaters as this is the only real way of sustaining network coverage at that high in the spectrum as transmissions are very much "line of sight" and only takes a bit of metal to stop it dead in its tracks and also does not travel through thick walls too good hence why we get little or no signal inside a building especially in a built up area.

Incidentally it is a great shame that the cell network didn't win the 700mhz part of the spectrum as it would have meant much better and further signal transmission area's.

If we had vhf then there would be no problems at all but antenna size would be much bigger, oh well the joys of uhf and above.

Repeaters are the only way forward because to make a quad band dipole antenna would need very low noise in line amps and no mobile has anywhere near the space for that kind of antenna, we are stuck with a basic 0db gain antenna but would be nice to have enough space to mount better gain antenna's, a tremendous amount of work involved even for anyone who knows anything about high gain antenna's.