At 09:21 AM 2/24/07, Bill Tippett wrote:
>K1TTT wrote:
> >With 5 or 6 elements from here you can not
>cover all of Europe without rotating them.
>
> I strongly disagree. My 6 element KLM array
>has a 3 dB beamwidth of about 54 degrees, which
>is plenty for Europe.
The original comment was in the context of using fixed direction
Yagis in a stack.
>K3LR, K9NS and W3LPL use even longer booms with even narrower
>beamwidths, and they
>seem to do well.
AFIK, W3LPL's 15m stack of 6/6/6 is on a rotating tower and the
antennas in K3LR's 6/6/6 15m stack are independently rotatable on
rings. K9NS is another skip zone further from Europe which figures in as well.
As always in these comparisons, the # elements is probably the worst
parameter for comparison. Beamwidth goes as gain which goes at boom
length; # elements enters in as a secondary dependence, less for OWA
and LP driven element designs.
Nevertheless, the difference between the specified E-plane beamwidth
of an M2 15M4DX (4-el on a 27' boom) and a 15M6 (6-el on a 45' boom)
is just 3 degrees ( 51 vs. 48).
73,
Mike K1MK
Michael Keane K1MK
k1mk@alum.mit.edu
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