[MRCA] BC-654 Antenna challenge

[Tim]

Hi Mark.  I have had good results up and down the west coast with my
SCR-284 and GRC-9 driving a Windom, AKA the "Tee" antenna described in the
manual.  It's just a low, horizontal wire that radiates well at high
angles.  (They will also drive a low, resonant dipole or inverted L just
fine too.)

Since "NVIS" is not an antenna, but rather a technique, I'm sure that
anyone who wanted to make intermediate range contacts in the military or
ham radio soon realized that using low frequencies at night and higher
freqs during the day (up to around 8 mc or so) worked just fine with low
wires.  And were simple and easy to put up/take down.  A key attribute in
the mobile military, and cheap for a budding ham operator on HF.  Pretty
much Ditto for the SCR-694 and GRC-9 end-fed wires.  Commo Wire:  exactly...
Except for ground wave ranges or a need to operate while moving, verticals
are pretty useless for intermediate ranges in my experience..

The graph that Al posted, coupled with the time of day and frequency chosen
tells the story. Now it's called "NVIS".

I've always been somewhat amazed at the Godlike attributes that the AS-2259
seems to engender.  From an engineering point of view, it's just a low,
inverted Vee.  Well, two of them.  Well, self supporting when there isn't a
tree somewhere around.  It presents a complex impedance that the PRC-47 and
many others can match and drive.  I don't think it works any better than my
"bush dipole" with paralleled 80/40 meter elements hung from a tree (which
I often use with my PRC-47...).

All interesting topics and great for experimentation.

Anyway, my $ 0.02
Tim
N6CC

On Sun, Jan 21, 2018 at 8:35 AM, WW2RDO via MRCA <mrca at mailman.qth.net>
wrote:

> I know that the American, British and German Army first started using NVIS
> antennas for some of their HF radios during World War Two.  So far, I'm
> having trouble finding much information about how far each military went as
> far as NVIS antenna use, or any photos of any WW2 vintage antenna.
>
> So here's what I'm trying to build.  I'm looking to build an NVIS antenna
> for the BC-654 using only material available during WW2.  That would
> include any balun or any additional antenna tuner to be used with the
> radio, if they are needed.  I am unaware of any issue NVIS antenna issued
> for the BC-654.   Particularly concerning is the fact that the BC-654 did
> not use coaxial feed line for the antenna.  I know the AN/GRC106 had an
> NVIS antenna, the AS-2259GR ,  but I see that the AN/GRC106 used a coax
> antenna feed line.  I am not sure that the AS-2259GR  antenna, even if I
> could find one, would work with a BC-654.
>
>
> Mark D.
>
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