[TowerTalk] 2 ele 40; driven and director

[n4kg@juno.com]

On Tue, 25 Jul 2000  "Jamie Tolbert" <jtolbert@gremlan.org> writes:
> 
> Has anyone built/modeled a 2 element 40m beam using a driven element 
> and director? I'm looking to decrease the boom length/windload of my 
> "homebrew" 40-2CD. ( 23' boom) and would like to know how the dr+dir
works.
> 
> 73 Jamie WW3S
> 

There are two shortcomings to Director type 2L Yagi's, 
especially on 40M.

First, the gain-bandwidth is much more narrow for a director 
type 2L Yagi than for a reflector type 2L Yagi.  This means that 
the design is less forgiving of modeling and taper errors which
means that tuning is more critical.

Second, which is a subset of the first, a 40M director when tuned
for the CW band, looks like a reflector when operated in the SSB
portion of the band.  This was a fairly well known problem with the
original Hy-Gain linear loaded 2L40M antennas back in the 1960's.

de Tom  N4KG





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