Topband: [Bulk] Best wire antenna for roof top location

[Tom W8JI]

> And remember -- the roof of this building is 110m, so a horizontal antenna 
> is high enough to have pretty good low angle radiation!  See
>

Large buildings are not towers or poles. Buildings have a significant amount 
of large conductive metallic things and noise generating junk inside.

A simple vertical antenna has elevation pattern mostly determined by ground 
several wavelengths from the antenna.

A simple horizontal antenna generally has elevation pattern mostly 
determined by ground immediately below the antenna up to a few wavelengths 
out.

If the building has wiring and large connected metallic things under the 
horizontal antenna, it will act like a reflector. If the antenna is somewhat 
low to the roof (less than 1/4 wave or more above the roof), the elevation 
pattern won't be much different than a low dipole over flat earth. Most of 
the radiation will be beamed straight up.

A vertical also will have a null below the antenna, nulling building 
coupling for RF.   A horizontal has maximum possible signal into and out of 
the building. Even with a 400 ft high building, a horizontal antenna a 
fraction of wave over the roof can be very disappointing.

73 Tom