Two distinct advantages of the EFHW: It's high feedpoint impedance means
a minimal counterpoise is required and very little power is wasted into
the ground system. Second, the high current part of the wire, which does
most of the radiating, is a quarter wave from the feedpoint, which can
usually be much higher than the feedpoint.
The EFHW can be used on harmonics.
The down side is that the high impedance is beyond the range of most
autotuners, so a transformer or external tuner is required.
I've been using a 40 meter EFHW for portable operations, mostly on 40
and 20 meters. I support it with a single 11.5 meter pole about 1/4 the
way from the far end, like a lopsided inverted V. It seems to work quite
well. I have a homebrew QRP tuner, but I use a commercial one for
higher power. I've used the same antenna on 15 meters and, with a
couple longer radials, on 80. (It's a quarter wave on 80, so there's
some "RF in the shack", but it hasn't been a problem as long as I keep
my fingers of the metal parts when I'm transmitting.)
I'll gladly share the design of the QRP tuner.
73,
Scott K9MA
On 2/8/2017 16:41, Dan Presley wrote:
Wanted to get some thoughts from folks about pros and cons of an end fed half
wave for portable/SOTA use, as opposed to just using a random length wire with
a counterpoise connected directly to either the KX2 or 3.(I think Eric
recommended somewhere around 28’ depending on the band coverage).Is there any
particular gain advantage? To me the only obvious advantage is not having to
deploy a counterpoise-with the end fed usually the length of coax will act for
this, and of course the need for a suitable Un-Un,usually 9:1. My preferred
antennas these days are lightweight resonant dipoles, which is fine assuming
you have room to erect them, and second is a magnetic loop which I’ve had good
luck with. I use the Alexloop-very light and easy to set up;ground and height
independent generally. But-since you never quite know what will work best I try
to be ready for whatever comes up. I have a variety of lightweight poles to use
with wires. I’ve had pretty good luck with throwing a random length in a tree
or pole with a counterpoise, usually elevated if possible.The auto tuners in
the elecraft rigs are excellent in my book. I think over the years I’ve used a
bunch of portable antennas except the EFHW-just curious what the advantages
might be.
Dan Presley N7CQR
[email protected]
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Scott K9MA
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