"Richard Harrison" wrote in message
...
Art Unwin wrote:
"The particular case I was referring to was where multiple reflectors
were used to dampen radiation to a maximum."

It works. Taken to an extreme, you have a grid-dish reflector.



No, No, No Richard! I do not


A grid-dish reflector is where the reflector assembly has voids in the
reflector panel
that R.F. cannot penetrate. A similar instance is the perforations in a
transmitter housing.
Maybe it was the term "dampen" that led you to think I had a "grid" type
reflector which is not the case.
My antenna consists of 8 - 1/2 wave elements of which one is fed. All others
are resonant reflectors
set on a parabolic curve as is the driven element, thus it does not
"focus".This can be
fabricated using standard straight dipole elements . Advantages are to be
had using elements
that are "shaped" to minimise "reactance" coupling and also the physical
turning radius.
It is this variation that I am building now to see if it becomes quieter
especially when static is around.
It is times like this that light telescopic fishing poles can be used to
advantage together with
aluminum tubular mast. You may remember that I sent a 60 foot boom yagi
picture to you
years ago with 13 elements ( 26 fishing poles) which was also light weight
and thus desirable
when testing or experimenting to find out where the knoweledge envelope can
be pushed.
Regards
Art





Additional reflectors in the plane of the other Yagi-Uda elements don`t
make best use of materials aloft. Placed ahead of the driven element,
additional elements are in a strong field where they may work as
directors to sharpen the forward gain. Placed behind the reflector which
has already reversed most of the energy in its direction, a parasitic
element is less effective as rhere is less energy to work with.

Best regards, Richard Harrison, KB5WZI