Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Jim Brown]

On 12/5/2020 5:37 AM, David Aslin G3WGN wrote:
> I note that the capacity hat extends to a significant distance down the vertical section. It's my understanding that will shield some of the radiation from the upper part of the vertical.

Yes and no. The sloping hat reduces the effective height, which reduces 
the radiation resistance, thus the feedpoint impedance, but most of the 
radiation is from the part of the antenna where current is greatest, 
which is at the base.

There are many ways to match it, as shown by other responses in this 
thread. Remember also that coax loss on 160M is small, so unless the run 
is quite long, the major concern is whether the power amp is happy with 
the load it sees. My 87As are picky, my KPA1500 is not.

And no matter the details of the vertical radiator, a serious 
radial/counterpoise is critical to minimize losses in the soil.

73, Jim K9YC