[Towertalk] Interlaced 15/20 Yagi

n4kg@juno.com n4kg@juno.com
Tue, 31 Dec 2002 22:43:25 -0600


I once put a 3L15 inside my Telrex 3L20.  It played 'fair'
but analysis showed it to be about 2 dB down from what
could be achieved if the 3L15 were in the clear.  The 20M
director acts as an 'inefficient' reflector in FRONT of the 15M
elements.  

F12 solves this problem by close coupling high band elements
around the lower frequency elements.  Notice on the C31XR there
are 7 10M elements but the gain figures are comparable to a 5L10.
They have TWO 10M elements, one on each side, of the 20M elements
which act as an "open sleeve' to decouple the 20M element.

Tom  N4KG

On Wed, 1 Jan 2003 02:04:25 -0000 "KK9A" <kk9a@arrl.net> writes:
> I am interested in building 4 el 15m and 4 el 20m Yagi on a single 
> 36' boom.
> Does anyone have any experience, sample designs or advise on what
> interaction I can expect?
> 
> 73,
> John
> 
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