> What are the gain bandwidth and SWR bandwidth characteristics that go
> with that very high F/B? I bet there's no free lunch.
>
> 73, Pete N4ZR
> Contesting is!
There never is Pete.
Actually the gain is quite good, because the real null is
intentionally moved up at a useful wave angle. It is only when the
null is placed directly off the back in a small endfire array that gain
is less than optimal.
Extremely high F/R ratios or very deep null depths do NOT
necessarily run contrary to maximum gain.
On the other hand a null placed directly off the back at zero degree
elevation angle does mean the antenna won't have maximum gain
in all cases I can think of. That's because you are forcing a null in a
small point, instead of a "cone", and forcing it at an angle where
there is already not much radiation (at normal heights).
Antennas only "get more gain" when we remove energy from areas
where there was significant radiation. In this case I did that.
Bandwidth of the deep null is narrow, but bandwidth of the antenna
is still quite acceptable.
73, Tom W8JI
w8ji@contesting.com
--
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|