Yup ... I was wrong again, but the trouble is I can't figure out why. I
mean, it's easy to verify the cloverleaf pattern with EZNEC and I have
done so, but I know that I have modeled something similar with an
off-center feed in the past and gotten an end-fire pattern. As soon as
I figure
I've gotten to the point, that before I say anything about a model, I
actually run it and play with it, to make sure I haven't forgotten
something, or remembered something wrong.
As to that particular antenna a center fed half wave antenna is troublesome.
The better version of that if one wants
Sorry to interject, but a fullwave fed at the 25% point has a clover leaf
pattern. It only has the two halfwaves in phase colinear behavior when fed
very near the center. Even fed at 45% it has a significant cloverleaf lobe
and a NULL in the center Easy to verify with any modeling program. 73,
Another simple end fed antenna was described by W2FRH in QST, March 2011, A
Near End-Fed Antenna... . I just returned from a week at the Outer Banks and
used this antenna with my K2 working DX from Europe and South America, plus
several states. No trees near the beach house so it was a sloper
Steve Yates, AA5TB, has a very informative web page on EFHW antennas and how to
build a parallel tuned circuit with a link coupled feed at the radio end to
reduce the 1800 to 5000 ohm impedance to a 50 ohm non-reactive load. He has
examples of both QRP and QRO versions of the circuit. I built
And for those with more money than brains (that would be me) you can
purchase an end fed halfwave antenna from the Emergency Radio Club of
Hawaii for $42. I bought one and it works great with the entire
Elecraft family. Great to have a simple yet efficient portable antenna
that fits into a
Stan, that's not a true half wave radiator on most bands. They suggest a
wire length of 20 or 30 feet, which will be efficient on 12 through 6 meters
where it's at least 1/2 wavelength long, but on the lower frequency bands
it's just a short random length wire with an auto-transformer to assist
Ron, the one I purchased for $42 is for 20 meters and came with a 33
foot radiator. A mathematical half wave at 14 MHz would work out to
32.8 feet. It did not come with a counterpoise nor was one recommended.
It loaded up nicely for me as received. I later tried a short
counterpoise and did
33 feet is a 1/2 wave on 20 meters all right. I was using the figures given in
the homebrew article that suggested a much shorter wire.
Yes, Wayne came up with the 28' radiator with 33'counerpoise as a combination
that the little ATU in the KX1 could handle on all the bands it covers. The KX1
Just speculating -- I bet a half-wavelength wire in inverted-L configuration
fed at the
base with a parallel-tuned circuit would work well. The high-current part of
the vertical
piece would be at the top, there would be plenty of current in the horizontal
part too,
and very little local
...@riousa.com
Subject: [Elecraft] KAT2 with EFHW antenna
To:elecraft@mailman.qth.net
Message-ID:lnejjggbopigkcikmckdeegoiaaa.ph...@riousa.com
Content-Type: text/plain; charset=us-ascii
I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire
for portable use (like SOTA
Shepardph...@riousa.com
Subject: [Elecraft] KAT2 with EFHW antenna
To:elecraft@mailman.qth.net
Message-ID:lnejjggbopigkcikmckdeegoiaaa.ph...@riousa.com
Content-Type: text/plain;charset=us-ascii
I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire
for portable use (like
Actually Dave, a full wavelength wire will have a 4 leaf clover
pattern - that is neither broadside to the antenna, nor off the ends.
Check out the pattern for a 1 wavelength long wire in the ARRL Antenna
Book. The maximum radiation is about 28 degrees from the wire - the
radiation from the
I believe you must get into several wavelengths before you get significant
end directivity from a long wire. My reference says that the angle of the
main lobe to the antenna is about 55 degrees when the wire is a wavelength
long, compared to 90 degrees at 1/2 wavelength. It takes a wire more than
Yes, Don ... you are totally correct. For some reason I was thinking
about a full wave antenna fed at the 25% point (I have built such
antennas before), which looks like two colinear half waves fed out of
phase. The current phasing along the antenna would indeed be much
different and give a
I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire
for portable use (like SOTA). The 20m antenna is 33' long and I use one or
two 16' counterpoise wires. It seems to work well for what it is and 10W.
I just built and installed the KAT2 ATU into the K2 to lighten my pack
Phillip Shepard wrote:
I put it in ALT mode, and it spent a
long time searching before it got down to between 3:1 and 4:1, depending
on
the 20m frequency. I added about 2 of wire to the antenna, and the tuer
got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'),
and
it
The simple answer to your question is no. An end fed halfwave would
theoretically present a few thousand ohms to your feedline, giving you
an SWR of several tens to one.
Consider this it is likely that the tuner with the greater loss
will more easily give you a match to a difficult
...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of David Gilbert
Sent: Tuesday, August 23, 2011 4:20 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KAT2 with EFHW antenna
The simple answer to your question is no. An end fed halfwave would
theoretically present a few
Phil,
As others have responded, attempting to tune the end of a half-wave wire
is beyond the range of most tuners, including the KAT2.
Your added wire provided a compromise length, because the feedpoint
impedance was reduced.
Because the impedance of the EFHW is high, my favorite tuning
-boun...@mailman.qth.net]On Behalf Of Phillip Shepard
Sent: Tuesday, August 23, 2011 4:00 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] KAT2 with EFHW antenna
I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire
for portable use (like SOTA). The 20m antenna is 33' long
...@mailman.qth.net]On Behalf Of Phillip Shepard
Sent: Tuesday, August 23, 2011 4:00 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] KAT2 with EFHW antenna
I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire
for portable use (like SOTA). The 20m antenna is 33' long and I use one
22 matches
Mail list logo
