Reflector on a quad - Capacitor use?
 

http://www.cebik.com/quad/quad2.html

why is a reflector using a capacitor a tad bit better on gain/rejection
on a quad?

Blue Dawg wrote:
http://www.cebik.com/quad/quad2.html

why is a reflector using a capacitor a tad bit better on gain/rejection
on a quad?

Hi Blue, If you will notice the sizes are different for an unloaded,
inductive and capacitive loaded reflector. The current distribution in
the 3 examples will be slightly different, resulting in different
gain/rejection. I think the idea is to make all three reflectors
perform the same, but as you see, there is a slight difference.
If you have a modelling program, such as EZNEC, you can model a quad.
Then change the reflector length and note the change in current
distribution, gain, and F/B. You can also add loads and see the
changes.
Gary N4AST

"Blue Dawg" wrote
http://www.cebik.com/quad/quad2.html

why is a reflector using a capacitor a tad bit better on
gain/rejection
on a quad?

==================================
Because the loading capacitor requires a tad bit greater length of the
loaded element which, for the same frequency, slightly changes the
radiation pattern.

When a loading coil is used the element is a tad bit shorter and,
combined with the small loss in the loading coil, it has the opposite
effect.
----
Reg.