> Thomas KN4LF Says:
> My experience is opposite. When my 3/8 wave L floats it degrades F/B on
> my pennant antenna's. When the L is grounded it is electrically invisible
> and everything is normal. My transmit and receive antenna's are separated
> by 2 wavelengths!
It depends WHERE you ground or float the antenna, and how long
the antenna is. I'm sure Mauri was speaking of the specific case of
a 1/4 wl inverted L and disconnecting at the antenna....not in the
house or anywhere else but at the antenna.
With a 3/8 wl long antenna, you are better adding inductance from
the antenna to earth at the antenna to detune it. Any capacitance
will increase re-radiation.
You can add inductance by shorting the end of a short
transmission line, depending on the matching network. Other
lengths will require opening the line to detune the antenna.
I do that with my 200 foot tower by choosing the length of line to a
switch that I open when I want to detune the tower. If I used a
length of line exactly a 1/4 wl longer, I'd have to short the line to get
the same effect.
I see changes in F/B on antennas hundreds of feet away, so I
routinely detune all unused antennas.
73, Tom W8JI
w8ji@contesting.com
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