On 4/5/2019 10:16 AM, Peter Bertini wrote:
4 to 8 ohms seems to be rather low for an inverted L... that seems to be
more in line for a short vertical? I measured closer to 26 ohms using my
analyzer at resonance. I'd expect some improvement in R losses, but I was
more curious about the elevation pattern for the system.
Pete
1. If 26 ohms is the driving impedance including ground loss,
you may simply have a lot of ground resistance. If it is the true
driving impedance less ground loss, see #2.
2. 4 to 8 ohms is the radiation resistance relevant to vertically
polarized radiation. The horizontal portion will add its own
radiation resistance relevant to horizontally polarized radiation.
We can debate whether horizontal waves are useful for DX. In
any event, you will measure the sum of the useful (vertical)
radiation resistance and the questionable (horizontal) radiation
resistance. IMHO, the horizontal component is effectively dissipation
loss the same as ground loss.
The vertical radiation resistance is given by 36 X (H/130 ft) squared,
where H is the height of the vertical section.
I will assume the original poster doesn't have the option to make
the antenna a T top.
73
Rick N6RK
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|