> The EWE is ground dependent; if you have good conductive
ground, it'll
> work well. The K9AY loop as well as a pennant/flag/delta
loop is not
> ground dependent.
That's not quite accurate Phil. ALL of these antennas "act
like" a pair of phased verticals. None of them act like
loops. The termination really just serves to cause uniform
current around the entire length of the conductor making up
the antenna. The horizontal component of the wire functions
as a phase delay line, while the vertical component actually
forms the desired radiating (receiving) section of the
antenna. ALL of these antennas require "good ground" below
the antenna to null the high angle radiation from the
undesired high angle horizontal component of the conductors
and accent the response from the desirable vertical
component. The better the ground, the more the vertical
component is increased and the more the undesired high angle
horizontal component is reduced. All are optimum over
perfect ground.
The K9AY is very ground dependent. It is nothing more than a
folded up EWE. The single ground connection at the center is
what gives it the ability to receive in one direction. It
actually is more "ground critical" than the EWE because the
single ground must isolate currents feeding the forward and
rearward elements. It also isolates the feedline for common
mode current. Without that ground isolating the currents,
the pattern would not have directivity.
In the EWE, the poor ground would primarily hurt efficiency
(unless the ground loss resistance is larger than required
termination resistance). Good ground of course, as in all
these similar operating antennas, increases vertical
re-enforcement and decreases horizontal high angle response
(caused by undesired radiation from the horizontal wire) in
this antenna, like any of these small antennas. That's
understandable because they ALL operate from exactly the
same effects.
In the Flag or Pennant antennas, like in the EWE, the
feedline and termination are moved to opposite ends of the
system. The feedline requires higher isolation for common
mode, there is no ground to "assist" with common mode
current reduction as with the EWE or K9AY. But once again
the mode of operation is the same, and both the Flag and
Pennant require ground to improve pattern even though they
do not depend on conductive ground below the antenna to feed
or terminate the system. The Flag and Pennant are merely
balanced versions of the EWE, but still benefit greatly from
the presence of good conductivity ground below the antenna.
All of these antennas are primarily vertically polarized and
have slightly worse patterns than two independent verticals
with a phasing system would produce.
73 Tom
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