that time of year again. Winter is on the way and fall is
here, depending where you live. The lower frequency HF bands
are much quieter, now that the static from the summer thunderstorms is
gone. Do you feel left out when you hear other AMers talk
about getting on 160 meters because you don’t have room for
an antenna? Well, you may have room after all.
It’s true, a full-sized, half-wave dipole for 160 meters is
rather big - around 250 feet long. If you’re like
me, you don’t have enough real estate for that amount of
wire! However, you DO NOT need a full sized antenna to
produce a respectable, if not good signal on 160 meters.
let’s assume you already have a 75 meter dipole up.
If it is coax fed, you could connect the appropriate antenna tuner,
tune it up on 160 meters, and see what happens. This
arrangement will work, but at will require a pretty hefty tuner,
especially of you’re plan to run higher power AM. I
haven’t heard to many people with real good signals using
this setup, but it is probably the easiest way to get on 160 meters.
Another option is to short the center conductor and shield of the coax
together and use the tuner, once again, to to the system up on 160
meter. This approach often works better than the first
approach but it does require a ground system. This means
radials. There is tons of information on radial systems in
numerous antenna books. In short, the more the
better. If you don’t feel like messing with
radials, then stick with a balanced antenna. [You’re less
likely to have RFI problems with a balanced antenna too.]
The most common balanced antenna in amateur radio is the
dipole. Let’s go back to your 75 meter
dipole. If you are already feeding it with ladder line or
open-wire line, or are willing to change to the feed line from your
existing coax, many possibilities open up. The most simple is
a 75 meter dipole fed with open wire or ladder line, tuned up on 160
meters, as shown in Figure
1 - Basic 75 Meter Dipole
For best results on 160 meters, the tuner must be low
loss. I recommend using a link coupled, balanced tuner, as
shown in Figure 2.
This tuner isn’t something you can buy, so you’ll
have to build one. Fear not, it is easy to build. I
built mine on a piece of plywood, and made a simple cabinet from masonite. Simple hand tools and a drill was all I
needed. I’ll leave the construction details to your
own tastes and abilities.
2 - Link Coupled Tuner, Parellel-Fed
very likely that since you are using a short antenna, the link tuner
will work better (tune more easily and have higher efficiency - less
heating) if it is configued for series-fed tuning, as shown in Figure 3.
Figure 3 - Link Coupled Tuner, Series-Fed
Notice that Figure 2 and Figure 3
are nearly identical, just the position of the various jumpers is
changed. Once again, there are numerous mechanical options for
switching between the two feed methods, so use your ingenuity. Figure 4
shows one option if you have a big knife switch (it could be done with
jumpers too) and a split stator cap or two caps on a common shaft
Figure 4 - Link Coupled Tuner, Switchable
You can also use a commercially made,
unbalanced (generally a T-type circuit) tuner, with a balun to tune
this system. Be aware, many commercially made tuners are able
to tune the antenna system to resonance (you’ll see a low
SWR) but they won’t do it in a low loss manner. In
other words, they’ll get hot. Some will get so hot,
damage will occur. So, if you plan to use a commercial tuner,
make some test transmissions and then check the tuner and the balun for
heating. Any heat, means loss is occurring and your signal is
not as good as it could be. However, a slight amount of
heating is probably okay, especially if you are getting good signal
We can make it easier on our tuner by increasing the length of the
dipole. Right, you say. Except, I don’t have
room. Probably not in a straight line. But additional wire
can be added by dangling some vertically from the ends of your existing
dipole, as shown in Figure
3. Add as much as you can, at least till the
ends are within 15-20 feet from the ground. If the ends of
your existing dipole are at 50 feet, you can add 30 feet to each end
with no problem. Your 120 foot dipole is now 180 feet
. This length is a lot closer to the full half-wavelngth size
of 250 feet. It is much easier to tune, and much less likely
to cause your tuner to get hot. So, it should put out a
Figure 5 - 75 Meter Dipole with Vertical Sections Added
can also add length to the dipole by horizontally zig-zagging the wire,
as shown in Figure 4.
This can be done by itself, or in conjunction with the vertical
sections on the ends. By combining the two, you can add a
significant amount of wire in your existing space. You could
easily have 200-240 feet of wire up in the air. As you can
see, these lengths are getting very close to the half-wave size.
Figure 6 - Added Length with Horizontal Zig Zag
Another approach is to zig-zag vertically. I used this method
on the antenna system at my previous QTH. See Figure 5. I
used sections of ladder line to do this because, it’s light,
cheap and easy to install. On my antenna system, these ladder
line sections were 30 feet long. That means a total of 60
feet of wire is added (30 down and 30 back up) to each
leg of the dipole. I also had 30 foot vertical sections on
the ends as shown. The flattop portion was 120 feet
long. So adding up all the wire, I had 300 feet in
total. All this fit on a lot that was about 120 feet deep and
70 feet wide!
Figure 7 - Added Length with Ladder Line Sections
you have room for a separate antenna for 160, but not a full-sized one,
AND you really want or need to use coax and no tuner, there is hope. A
variation of the ladder line section approach as shown on Figure 6 can be fed
directly with coax and have a SWR of about 2:1. Since the coax loss on
160 is so low, and the SWR is relatively low, this arrangement will
work just fine. No tuner is needed. The tank circtuits in most vintage
AM rigs will tune and load just fine into such a small SWR.
Figure 8 - Coax Fed Shortie
you just HAVE to have a lower SWR, there are two things you can do. One
is to put a tuner in line. Since the impedance is very close to 50 Ohms
anyway, the tuner shouldn’t have to “work too
hard” and most of the heating warnings of above probably
won’t apply. But check anyway. Some commercial tuners
weren’t made to handle much AM power in any situation. The
second option is to put a 2:1 or 4:1 Balun at the feedpoint.
This will provide an almost perfect match to 50 Ohm coax. Joe, N2YR
proposed this idea to me about a while ago and I tweaked the design on
an antenna modeling program. He then built and erected one with the
help of Paul-K2ORC. The antenna worked very well. He’s used
it over the past two years on 160 with excellent results. So,
it’s not a theoretical fantasy. It works in the real world.
there you have it - some options for getting on 160 meters. There are
many more that we won’t delve into at this time -
Inverted-Ls, short verticals, various types of loops, and numerous
other loading schemes for shortened dipoles. The bottom line is not to
feel left out on the 160 meter fun this winter. Read, research, test
and experiment. You probably can get on 160. It will just take a little
extra work, but will be very much worth it.
numerous stations on 160 meters using one of these antennas (or a
variation) with great success. They work and are proven.
Catch you on 160 meters.