HI all,

A few questions have arisen in my mind since some guy came around to
install a wi-fi system at my girlfriend's apartment. This system uses
a dish and the signal frequency is 5Ghz. I asked the installer what
type of fancy, low-loss coax he was going to route the down feed with
and he told me "CAT 5" which I've never heard of. Anyway, it turns out
this stuff is essentially just telephone wire!
There must be some serious gaps in my understanding about transmission
lines, because on further enquriy it transpires the loss with this
wire is pretty low and the installer told me he can have a run of 100
meters before he has to worry about signal loss.
What's the deal here? How come I have to have some fancy, military
grad coax that costs a fortune and must be as short as possible just
for the 23cm band when this guy can use what is basically just phone
wire at 5Ghz and slop the stuff over half the building without a worry?