Don,
As I said earlier in this thread, if the radio is on the ground, or near the
ground, then the antenna is a vertical. I don't care what the slope is, it has
a vertical component. A Beverage is a horizontal wire, but it is vertically
polarized and works against ground. It may be lousy ground (which is actually
required) but nevertheless there is a connection to earth.
I think the fallacy here is that folks believe that a 1/4 wave wire, which
wouldn't have such an intractable feedpoint impedance, requires "ground" and an
EFHW doesn't.
Now if the battery-powered radio is dangling above the earth at the end of a
horizontal wire and the keying is via Bluetooth I guess there is some ground
independence. But in that case I would recommend putting the radio in the
middle of the wire and saving some grief. Likewise, if you want to fool with a
Zepp feed why not use center feed?
If maximizing far field strength is of no concern then I recommend a 50 Ohm load
on the output of the radio :-) You could crank the power down to save the
battery and it would have no effect whatsoever on the signal strength at the
receiving end. A win-win!
Wes N7WS
2/12/2017 11:29 AM, Don Wilhelm wrote:
Wes,
I do not doubt what you are saying about 1/2 wave verticals, but most EFHW
antennas are mounted as a sloper or a horizontal antenna.
For portable operation, the main concern is for the ability to feed the
antenna, and not about maximizing the far field strength.
73,
Don W3FPR
On 2/12/2017 12:34 PM, Wes Stewart wrote:
Alas, if only this was true.
Google "radial system design and efficiency in hf verticals" and you
should get a cached version of Rudy Severns' paper of the same name. In
it he states:
"Alternately we can graph efficiency in terms of Ga as shown in figures
3 and 4. Unfortunately this also shows how inefficient verticals are
even over very good ground. Very depressing! For example, with very good
soil (0.02/30) and 128 1/2-wave radials, the efficiency of a 1/4-wave
vertical is still only -2.76 dB (53%)!"
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