On 19 jul, 20:58, 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

Hello Giovanni,

My first impression is for 80m go for the good ground site and for the
upper bands go for the clear area. From a man made noise perspective,
I would go for the clear area, but of course this one you can check
via S/N ratio of received stations. The clear area may result in less
interference from your signal in user equipment.

Regarding the buildings, are they very large in horizontal size and
height or do I have to think of just three isolated buildings without
any other buildings behind it (seen from the antenna)? If there were
many buildings, I would go for the clear area in both cases.

Regarding radiation pattern, I would not worry about this. If you can
put the antenna such that you have most of the long radials in two
opposite direction only, the effect on radiation pattern is
negligible.

For the DX case, you will rely on the vertical component only as the
horizontal component will vanish more rapidly under decreasing
elevation angle. Your radiation pattern (elevation pattern under
varying azimuth) depends heavily on ground properties several
wavelengths away from the antenna and you have no influence on that.

Best regards,

Wim
PA3DJS
www.tetech.nl
without abc, PM will reach me very likely.