"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.

Additional reflectors in the plane of the other Yagi-Uda elements don`t
make best use of materials aloft.

Generaly I can agree with that but it is NOT TRUE in all cases.

1 It can NEVER reflect all radiation from the rear
2 Coupling is reduced as the directors move away from the driven element
to the point where little current flows.!

A yagi does have an advantage in simplicity together with the ability
to "focus" the forward lobe but not at the expense of removing rearward
radiation.

This post is starting to be remoniscent of the old days where Guru's stated
that more
than one reflector was pointless and unproductive because they could only
think
Yagis to the ommission of all others . Need W8TI to complete the full circle
(On a prior post I brought up the corner reflector antenna but I had
temporarily forgotten
that the reflectors carried little current and thus could not be a good
contender
for high F/B)





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.

HUM.... isn't F/B values retarded when maximum gain occurs?
This suggests that max gain occurs when there is MORE energy to
work with at the rear does it not?
Regards
Art

Best regards, Richard Harrison, KB5WZI