[TowerTalk] Re:

n4kg@juno.com n4kg@juno.com
Wed, 1 Mar 2000 23:31:20 -0600

Do you have the W2PV Yagi Antenna Design Book?
If so, compare the plots of 4L and 6L Yagi's on a .75 WL boom.

You will notice the very narrow bandwidth of the gain curve 
with only 4 elements.  I would expect the SWR bandwidth
to also be more narrow.  Coupling is "light" and everything
seems more critical with widespaced 4L designs.

5 elements on a .75 WL boom makes for a very nice design.
You can pick up another 0.5 dB of gain going to 6L on a .8 WL

Most commercial antennas seem to have 1 more element than
needed for the boom gain.  I suspect the reason is better 
bandwidth and a more forgiving design.

In the maximum bang for the buck department, a 3L Yagi on
a 0.35 WL boom is hard to beat. (Remember Telrex?)

de  Tom  N4KG

On Wed, 1 Mar 2000 18:24:37 -0600 "Tom Hellem" <redpines@cybrzn.com>
> Here's another one for the yagi guys:
> Is there any advantage to putting more than 4 elements on a .75 
> wavelength
> boom? It appears that the difference in gain and f/b is minimal when 
> going
> from 4 up to 6 elements.
> K0SN

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