[TowerTalk] 40m 4el KLM - replacing linear loading with coils

[David Gilbert]

Agree on all of that, which is why I agreed it isn't a dominant effect.  
And of course you and K6STI have a good point about the additional wind 
loading of mid-element coils.

Every commercial coil loaded shorty-40 antenna that I know of puts the 
coils out on the elements, though, so I suspect it may be worth the 
bother if done right.

73,
Dave   AB7E



On 4/28/2020 10:03 PM, Jim Brown wrote:
> On 4/28/2020 6:50 PM, David Gilbert wrote:
>> Whether NEC accurately models the current isn't the point.  You don't 
>> need a model to know that if you push the coil out away from the 
>> center the portion of the current between the coil and the center is 
>> higher than it would be between that same point and the center if the 
>> coil was at the center.
>
> Yes, BUT you DO need a model to QUANTIFY how much better (or worse) 
> the performance is for variations of a design to answer questions like 
> "Is it worth the trouble to do all this?" W6GJB and I spent a lot of 
> time optimzing an 80M vertical for portable operation. We used several 
> variations of top and bottom capacitive loading combined with several 
> variations of inductive loading. None of our designs used a base 
> loading inductor, but we did vary their position. There were some 
> designs that worked awfully well electrically, but were a problem to 
> build, or had issues with wind.
>
> And it's also worth it for what you can learn by going through the 
> process.
>
> 73, Jim K9YC
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