Just to add to this don't forget that by lifting your antenna up higher you will be probably "gaining" more than your lost 2db by being able to get a better signal.
Hey Speedcom, I'm no radio expert but LOS on these Omni high gain antennas seems a little less important hence I think it's a bit of a balancing act with height against cable length/loss, especially when you push up to 4G 1800 because the dB loss nearly doubles. My particular antenna drops back to 3dB gain on the current Telstra 4G which is pretty much equal to the expected loss, therefore the only real benefit I get is the elevation and getting the signal from outside the structure of the camper. I assume if I made the cable longer signal would degrade.
I think if you wanted to get some serious height you might be better running a wireless repeater system, I've toyed with the idea of making one of these, I was thinking with a slingshot and some fishing line I could install a repeater high in a tree but still within wifi range. I've worked out how I would do it but I just haven't got the motivation yet.
