Craig,
For the home station, your first consideration is build or buy. It is
quite easy to build a pair of dipoles, one for 40 and one for 20 if
those are your most desirable bands. Get some wire, and some good coax
and a good common mode choke for each antenna and use the ARRL handbook
section on dipoles to build your own - it is not difficult.
Look at what you have for antenna supports - the higher the better, but
for 40 meters, 50 feet is a suggested minimum for good performance.
If you have only one support that high, an inverted Vee works nicely.
Use resonant dipoles center fed and feed with 50 ohm coax. Low loss
RG8X is almost as low loss as RG8 but not as heavy. If you are going to
run power, use the RG-8 or RG-213 right from the start.
With a single tall support, for an inverted Vee configuration, position
a 40 meter radiator at right angles with a 20 meter radiator and feed
both with a single feedline. Being placed at right angles to each
other, there is little if any interaction. Get the ends of the
inverted Vee radiators up as high as possible - if you can get the ends
up to the same height as the center, that is great - you will have a
pair of dipoles, so much the better.
Put the dipoles up, cut a bit long from what the "formula" tells you,
and then trim it a bit at a time for the lowest SWR or for a reactance
of zero should you have access to an antenna analyzer at the midpoint of
your operating frequency.
If you have room for another dipole, consider adding a multiband antenna
such as a G5RV so you can explore bands other than 40 and 20.
Use a good common mode choke at the antenna feedpoint (for the G5RV at
the junction of the parallel feedline and the coax). You will need a
tuner for a G5RV or most any other multiband antennas.
If your horizontal space is limited, try a vertical. I can recommend
the GAP Titan, being a halfwave vertical, it needs no radials. Mount
the base 10 feet off the ground so the loop for 40 meters is above head
level and use a good common mode choke at the feedpoint.
This is just for starters on your antenna quest. That quest is an
ongoing exercise for most hams.
Do not strive for the "best" antenna for starters, just get something up
in the air and start operating - with time you will be able to determine
how you want to improve your antenna farm.
For portable QRP operation, take a look at the End Fed Halfwave antennas
offered by LNR Precision - They work and they have a good "trail
friendly" lightweight version. An EFHW can be easily deployed with one
end in a tree and the other end near the transmitter.
If your field operations are more of the picnic table variety than the
backpacking type, then consider a 32 foot heavy duty telescoping pole to
hold up the center of an inverted VEE antenna. Tie the center of a
dipole antenna to the top of the pole and push it up - anchor the pole
to whatever vertical support is available with bungy cords. Extend the
radiator ends out to whatever bushes or other supports are available.
So my suggestion is to start simple with homebuilt dipoles or other wire
antennas, then grow your antenna farm after you get on the air and
determine what you really want, and that may be a 150 foot tower with
stacked rotating beams sometime in the future. If you have space and
want "beam" antennas using wire, consider 4 130 foot wires spaced 45
degrees apart (total of 180 degrees spread) and you will have V-beams
that can be steered - a very effective beam on 20 meters, but does
require some feedline switching to select the pair of radiators to
properly direct the radiation (it is bi-directional).
73,
Don W3FPR
On 12/7/2015 5:13 PM, CRAIG SCHROEDER wrote:
I am pretty new ham and a brand new KX3/PX3 owner excited to try my hand at
DX'ing! If you were buying your first HF base antenna, primarily looking for
performance on 20 and 40 meters, what would you recommend? Also, what do you
suggest as a high performance field antenna for QRP?
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