[GCARC] Can Short 75 Meter Antennas work for NVIS/EMCOMM?

[Tony Starr]

Karl,

I have enough real world experience with short, loaded HF antennas, from my
HF mobile experiments, and from trying to fit 160m antennas into a suburban
backyard, that I can offer you some advice that will improve your chances
of success with this. First off, stay away from Hamsticks, Buddi-Poles, and
anything that is helically wound. The losses in these types of antennas are
just too great to make them worth the trouble. What you want is high-Q
loading coils, preferably mounted midway between the feed point and the end
of the radiating element, to lower the resistive losses. Capacitance hats,
especially in combination with the afore-mentioned coils, are another
low-loss way to shorten a radiating element. You can make a better version
of a Buddi-Pole by mounting up a pair of center-loaded mobile antennas, or
better yet, a pair of trap verticals, and placing them atop your 20 to 30
foot high mast. That arrangement will get you the NVIS radiation pattern
that you seek, without the massive resistive losses of the dummy load
sticks.

Another option would be a wire inverted-vee, but shortened with high Q
coils.  Some companies, like Alpha-Delta, and Hy Power Antennas, offer some
solutions like this ready to hang, right out of the shipping box. Or, you
could take a pair of 16 foot fiberglass fishing poles, and some wire, and
make your own rigid dipole. You would have to wind your own loading coils,
but that is not difficult. Some online calculators can get you close to the
dimensions that you need. The main thing to remember is that mounting an
antenna like this close to the ground will give you an NVIS radiation
pattern, but mounting it TOO CLOSE will give you significant ground losses.
I think you are on the right track with the 20 to 30 foot height. Now all
you need to do is put something together that works. That is the fun part.
I have built a lot of antennas that worked pretty well, and a few that
worked poorly, but I always enjoyed the process, and always learned
something new. Sounds like a great testing project for a Tech Saturday!

Good luck with this, and if you have any questions or need to discuss any
ideas, give me a call or  shoot me an e-mail.

73 Tony K3TS

On Mon, Aug 4, 2025 at 9:42 AM Karl Frank W2KBF via GCARC <
gcarc at mailman.qth.net> wrote:

> Hi All,
>
>             Does anyone have ACTUAL EXPERIENCE using very short rigid
> antennas (e.g. BuddiPole or Hamsticks) as horizontal dipoles (or Inverted
> VEEs) for 75 Meter EMCOMM/NVIS work?  In particular, how much gain do we
> lose relative to a full length inverted VEE wire antenna using a 20 - 30
> foot mast (e.g. -5, -10, -15, -20db)?  I am asking first in order to avoid
> the trouble, expense and probable disappointment of doing this experiment
> myself.
>
>             I imagine that everybody has an opinion on this but I am
> looking
> for actual real-world experience.  The rationale behind this question is
> that 75 meter NVIS is useful for both Intra- and Intercounty short range
> backup to VHF and we might not always have the space or support structures
> (e.g. trees) to run full length horizontal wire antennas (and verticals are
> not good for NVIS).
>
>             Karl W2KBF
>
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