[TowerTalk] 40 meter dipole

Jim Brown jim at audiosystemsgroup.com
Mon Oct 2 14:02:07 EDT 2023


On 10/2/2023 10:19 AM, Steve Babcock wrote:
> However Yagi performance IS a function of the narrow bandwidth of a shortened PARASITIC element. (not the driver)

No debate on that, but I'm specifically talking about dipoles.

Higher frequency bands in fan dipoles also exhibit reduced SWR 
bandwidth, as low frequency bands in multi-band loaded dipoles (like the 
common 2-band dipole with a loading coil near what would be the resonant 
point of the second harmonic of the band for which the loading coils are 
used. For example, 80/40 and 40/20. I was first introduced to the idea 
from commercial versions of those designs for 80/40 and 160/80, and did 
my own designs of a 40/20 versions using both wire and aluminum elements 
for CQP expeditions. Again, efficiency and pattern are not significantly 
affected by loading, acting like ordinary half-wave dipoles on both bands.

73, Jim K9YC




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