On Jul 19, 1:58*pm, Gsat wrote:
On the yard around my house I have two possible spots where to erect a
multiband vertical, an HF6V.
On the first spot it is possible to lay down a symmetrical net of
radials as long as the antenna is tall, but the antenna will be close
to buildings on tree sides, at a distance about two to four times the
antenna height. Buildings in Italy are built by rinforced concrete
with a lot of steel inside, so I expect there will be some effect to
the antenna efficiency and radiation pattern.
On the second spot, the antenna can be more clear of buildings, but
the radials pattern is not symmetrical because il is limited to a
strip of land wide half the antenna height.
So now is my question: if a tradeoff must be made, what is more
important, to have an antenna on the clear or to have the best ground
radials system ?
A second question: is it possible to estimate the effect of ground
symmetry and of buildings presence on the antenna radiation pattern
using antenna simulation software like eznec ?

Thanks to all
Giovanni
IZ0SQZ

I think I'd rather have the one in the clear. What you can do is
use shorter radials in the directions with less room along
with the longer ones in the better directions. Most of the
ground loss with a monopole is at the immediate base of
the radiator. So the shorter radials should help more than
one might think. But I think it would be worth it to get away
from the wire laden buildings.
Actually, I would prefer to elevate the antenna on a mast,
but I don't know if that is an option.
Elevating gives a much better line of sight, but also greatly
reduces the number of radials needed to reduce ground loss.
If the vertical is high enough in wavelength, one radial is all
you really need for an efficient antenna. Two is the minimum
number needed to have a good omnidirectional pattern if you
run them out ground plane style 180 degrees apart.
One with a single radial acts more like a dipole than a vertical.
If the radial can drop down, you have a half wave vertical with
an omnidirectional pattern, but most will be using metal masts
to support the elevated vertical, and will have to fan it out
ground plane style. And that will skew the pattern a tad, but
not hugely so.
Of course, if you elevated a HF6V, you would need at least
one tuned radial for each band to use it on all bands.