Topband: Inverted J antennas?

[sawyered at earthlink.net]

Mike,  All ¼ wave verticals have the same elevation angles.  The question is
what is the feedpoint efficiency which is dominated by the ground.  That
ground is a combination of your soil characteristics and the radial field
design.  In my opinion, 2 elevated radials about 5 ft above the ground is a
poor ground system for good performance.  Elevated 160M radials really need
to be more like 20 – 25 ft above the ground to be efficient.  Otherwise, my
experience has been you are way better off putting a lot of them on the
ground vs a few in the air – below 10 ft.

 

One thing to try is take a Z + R reading at the actual feedpoint as it is
now and add 2 more radials.  If the R drops by more than 0.5 Ohm, then keep
adding.  

 

I started with an R of about 24 Ohms with 4 radials on the ground and got it
down to 12 Ohms by adding radials.  I have 44.  I could not see any
difference with the last 4 so I stopped.  I have 2 T top verticals in phase
and they are 260 ft apart.  And the same result occurred on both.  That is
highly a function of my rocky (Granite) soil here.

 

73

 

Ed  N1UR