[Elecraft] Miracle Whip Antenna

[Julian, G4ILO]

Frank,

I'm not sure how you can claim to know what's in the minds of everyone on
this reflector. Short whips may not be the most efficient antennas you
could use, but they have many benefits of convenience, and allow you to get
on the air from situations where you otherwise might not do so.

It's true that most vertical antennas need a good ground to work against,
however the Miracle Whip's transformer matching somehow seems to transfer
power quite effectively to the whip without one. Don't ask me how it works,
ask the designer. But if you have a MW you can see this quite easily for
yourself. You can connect a 4 foot whip to the back of the K2 and you'll
hear hardly anything. Even the KAT2 won't match it. If you connect the K2
to the shack ground you will still not get a match on some bands. Even if
you do, the MW seems to work as well or better, even without a ground
connection.

Of course, electrically lengthening the whip to make it resonant changes
the situation, but you still need a good ground to make it work. But that's
often hard to provide in a temporary location. I'm deeply sceptical of the
use of resonant counterpoises with short whips. They seem to act, not as a
ground, but as part of the antenna. Indoors, they pick up all sorts of
noise from the wiring etc, and doubtless radiate RF into it causing RFI.
Outdoors, they probably contribute more to the on-the-air performance than
the short loaded whip that is then acting as the other half of a dipole. 
But if you can put up half a dipole why not go the whole hog and put up a
whole one? By accepting the need for a counterpoise or radials you've
already lost most of the convenience and mobility offered by a whip.

If you want to be able to listen or operate without trailing bits of wire
all over the place I think the performance compromises made by the MW are
an acceptable trade-off.

--
Julian, G4ILO. (RSGB, ARRL, K2 #392)
Homepage: http://www.qsl.net/g4ilo

frank <fkamp@attbi.com> wrote:

Kevin,

Congradulations, you seem to be the only interested party on this reflector
who
has figured out that short whip antennas make lousy radiators.  It does not
matter who makes them or what they are called, they just don't work as well
as
conventional fixed station antennas.

They are good for mobile use, but only if they are allowed to work against
the
metal frame of the vehicle.  Take away the metal frame and stick them on a
pole
without radials in a fixed station application and you have handicapped
yourself beyond reason.  The only thing worse is no antenna at all, and
even
then the two conditions might have to be tested to make sure.

There are lots better soultions for inexpensive, fixed and portable
antennas
than a short whip.