You're right; my bad. I actually had an end fed full
wave on 40 meters 30 years ago and used to know this :-).
40 meters was a "free bonus" feature of my 80 meter half wave.
The cloverleaf pattern wasn't optimum but it did make
QSO's etc. It was a cloud burner at 55 feet anyway, so
it was never going to be anything great. The 4 nulls tend
to fill in at low heights.
This just reinforces the notion that the
EFHW should be considered a single band antenna, on
the frequency where the wire length produces half
wave resonance, as indicated by a high resistive
drive impedance. This will be a few percent less
than a half wave in free space.
For higher frequencies, the "magic" goes away and
it becomes a glorified "random wire" requiring a legitimate
counterpoise.
Random wires (> 1/2 wave) have random patterns!
Rick N6RK
On 7/1/2019 9:27 PM, K9MA wrote:
On 7/1/2019 22:24, Richard (Rick) Karlquist wrote:
On the frequency of full wave resonance,
they still make sense because they are two half waves in phase
and behave similarly to a half wave dipole.
For an end fed wire, this is not true. Its pattern has 4 lobes, a
cloverleaf. It is like a full wave fed 1/4 wave from one end. That's two
half waves OUT of phase. A center fed full wave is indeed two half waves
in phase, and has the dipole-like pattern, a bit sharper, with a bit of
gain over a dipole, and a very high feedpoint impedance.
Because of the cloverleaf pattern, an end fed full wave can be quite
useful. At higher harmonics, the lobes proliferate, and tend to get
concentrated towards the axis of the wire, which is often less effective.
73,
Scott K9MA
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