[TowerTalk] Two 15m yagi stacking

[Michael Keane K1MK]

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 at alum.mit.edu