[Elecraft] Portable Antennas
Erik N Basilier
ebasilier at cox.net
Wed Apr 1 16:08:58 EDT 2009
The HFPACK yahoo group has conducted tests of shortened antennas which seem
to indicate that losses in loaded antennas are quite small when the total
antenna length is at least half the full length. They compared to reference
full-length antennas *at the same height*. As to bandwidth, the automatic
tuner in my KX1 easily takes care of that.
That said, I use both a BuddiPole and wire antennas, and often I prefer the
wires, depending on the situation.
Over Arizona's dry and rocky ground I often prefer horizontal polarization.
For 40m I replace the BuddiPole standard whips by the 6-section optional
whips that measure about 9'4", and I put extra tubing sections between the
center and the loading coils. (For 20 m this configuration is almost full
size.) It does stay up in calm weather on the BuddiPole tripod with the
short mast without guying. But his configuration weights a lot more than a
wire dipole!
For 20 m horizontal polarization, the standard BuddiPole works fine, but
weight still tends to favor wires in an inverted Vee configuration,
particularly if you use a small and light support pole, that may still be
taller than the BuddiPole short mast. (Some of the height advantage is
negated by the use of an inverted Vee vs the straight BuddiPole.) Where
weight is not a consideration I may use my DK9SQ mast for an inverted Vee.
In fact I use two of them in a beam configuration for 40 m. Using a 25 ft
spacing and a reflector plus driven element I get an almost perfect match to
50 ohms. On the other hand a fiberglass pole can be awkward to carry around.
For a recent hiking trip I put the longer BuddiPole configuration easily in
a backpack, worked a JA on 20 m in the afternoon using the KX1 at 2W.
Where soil conditions favor vertical polarization, the BuddiPole can be
configured as a vertical. The counterpoise can be the other half of the
dipole mounted horizontally. However, this configuration is heavy, poorly
balanced and requires guying. A single wire counterpoise lying on the ground
is better but a little less efficient. Two counterpoise wires stretched in
opposite directions is best. Using wire counterpoises, the BuddiPole
vertical is rather light; and where the soil is relatively conductive I
think this configuration is quite good provided you configure it physically
long enough for the band to be used.
73,
Erik K7TV
Jim Brown wrote:
> I like these simple wire options a LOT better than loaded whips like
> mobile
> antennas and the Buddy Pole simply because loaded whips are 1) lossy and
> 2)
> very narrow band. When we're running QRP, the last thing we need is loss.
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