[TowerTalk] Length of Inverted-L.

[Richard (Rick) Karlquist]

On 10/5/2018 11:15 AM, Joe Subich, W4TV wrote:
> 
> The longer inverted L moves the maximum current up into the vertical
> section resulting in a higher feed impedance and more efficiency.
> The higher the maximum current (to a point), the less loss in the
> dirt.  Further, the radiated field is proportional to the integral
> of the current so putting the maximum current half way up the vertical
> portion of the inverted L results in maximum radiated (vertical
> polarized) field.
> 
>     ... Joe, W4TV
> 

I did some modelling on this topic and found that making the
horizontal part on an inverted L longer does not increase the
vertically polarized wave that comprises the useful radiation.
It instead increases the useless horizontally polarized
radiation.  Now if you have a top loaded vertical (T shape)
then more wire upstairs does mean more useful signal out.
There is a price to be paid for using an inverted-L vs
symmetrical top loading.  (I realize not everyone can achieve
the latter.)

73
Rick N6RK