Topband: Kinstar AM Radio Station Antenna Design

Tom Rauch w8ji at
Thu May 25 15:14:40 EDT 2006

> This answer may be too short.  Build this antenna over a 
> perfect radial field and the short answer may be correct. 
> But for those making do with less than a perfect radial 
> field, the Kinstar design could offer some improvements. 
> Don't let the words "Invention" or "Patent" preclude 
> closer consideration of this design.
> The first thing I did was to model the Kinstar vs. the 
> "cage" antenna.  Eznec calculated a higher gain for the 
> Kinstar.  Then I added series resistances of 10, then 20 
> ohms, simulating poor ground.  The Kinstar design then 
> calculated at a fractional dB loss vs. the "cage" 
> antenna's several dB loss.  I concluded that either Eznec 
> was in error, or that the Kinstar design DID offer some 
> advantage.

It could also be a modeling error. GI-GO :-)

If you modeled the antenna by inserting an independent 
series resistance in each leg, the program will show a gain 
in efficiency. Unfortunately this is not a model of real 

In real life all the wire ends are effectively terminated in 
parallel, and then current all flows to ground through a 
single series loss resistance.

VLF antennas many years ago attempted to use distributed 
grounds with much more spacing. The hope was the individual 
wide spaced grounds would act in parallel. It was later 
discovered when systems were rebuilt even wider spacing was 
no advantage in multiple drop antennas.

If you read Kinstars claims, they do not claim any 
improvement in ground loss. They also still use a full 
radial system. They do this for a good reason. They 
simplified the matching system, they improved bandwidth of a 
short monopole. They made the pattern of an Inverted L more 
"round". Nowhere do they claim anything else. 

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