Topband: Inverted L redux

[Richard (Rick) Karlquist]

On 9/2/2019 12:08 PM, N4ZR wrote:
> More as an experiment and a thought-provoker than anything else, I've 
> started adding 50-60-foot, on-the-ground radials to my 135-foot inverted 
> L.  In the latest incarnation I'm up to 4 radials.  On my ancient 
> MFJ-259B the lowest SWR is 1.3:1 at 1825 KHz, with an R of 77. X=0 (the 

The radiation resistance depends somewhat on the vertical vs horizontal
components of the 135 feet which you didn't specify.  It is easy to
model on EZNEC what the drive impedance is over ideal ground then you
can compare that to what you are measuring to determine ground 
resistance.  I suspect most of your 77 ohms is in the antenna, not
ground.  So you probably don't need a huge radial field.

The problem with inverted L's is that a lot of the drive impedance
represents useless horizontally polarized energy.  If you want to make
it better, change to T top loading.

Rick N6RK