RadioBanter - View Single Post - SUPER J-POLE BEATS YAGI BY 1 dB

February 7th 05, 02:59 AM

On 6 Feb 2005 18:10:11 -0800, wrote:

snip

It was an unusual use of the YO
program, in that we used two reflectors
and NO directors, to get the shape we
wanted. We actually couldn't use the
optimizer, because it would actually
try to narrow the beam too much.
Remember that you must keep the
pattern about 180 degrees, and the F/B
ratio should be no more than about 11 dB.

Slick

Slick,
Could you explain the use of two reflectors? I've heard that if you
are building a two element yagi it's best to use a radiator and
reflector but haven't really learned anything about using more than
one reflector. Have seen antennas that use 3 reflectors, but they
were mounted perpendicular to the plane of the elements and there were
several director elements - if memory serves me it was Cushcraft that
did that. Haven't seen them added behind the first reflector and am
curious as to what characteristic of the antenna's performance it is
meant to enhance.

Thanks,
Howard
Howard