Mobile N.V.I.S.

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Mobile N.V.I.S.

Postby Generation 2 » 10 Feb 2017 13:47

Looking to set up the truck for HF. I am pretty sure that I want to go with the FT-857D for the radio.

N.V.I.S. propagation is BOSS for my folks around here, which forces us into the 80 Meter band (3.8 MHz - 4.0 MHz)...so does anyone have any antenna recommendations for Mobile (while moving) N.V.I.S. antennas?

I have seen some rigs with N.V.I.S. Magnetic Loop antennas. Does anyone have any plans or designs for one of these?

How about whips on a spring mount, bent down to radiate "vertically"? Does anyone have any experience doing this? Which whip? Which mount?
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Re: Mobile N.V.I.S.

Postby Kolt » 23 Jul 2017 06:15

I don't know about 80 meters, but google some photos of antennas on military vehicles. They are often spring loaded and bent over as you describe for NVIS. I'm not sure how intentional it is, but generally that works for the distances. It is probably more often out of convenience to keep the antennas out of the trees.

Take care,
K
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Re: Mobile N.V.I.S.

Postby kmussack » 23 Jul 2017 09:14

FOR ENTERTAINMENT PURPOSES ONLY;

Here's a picture of Uncle Heinz having a confab from his perch in a Sd.Kfz. 251/3 - mittlere Kommandopanzerwagen (Funkpanzerwagen) equipped with Funkgerät, meaning "radio equipment".
Image

That isn't a roll-cage over his head that's a loop HF antenna. It looks like it's polarized vertically....mmmmm....NVIS?
(What do you do when your winter-white track is caught in a thaw???? Smear it with mud.)

Here's another pic of Uncle Heinz touring Europe in his Kommandopanzerwagen with the loop NVIS on top.
Image

And here's a pic of some of the boys touring North Africa in their NVIS/"bedspring" antenna equipped Schwerer Panzerspahwagen 232.
Image

And finally old Cousin Erwin getting directions while touring with the boys in North Africa, notice his overhead loop antenna.
Image
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Re: Mobile N.V.I.S.

Postby Kolt » 23 Jul 2017 09:49

That looks like an older militarized version of the ST940B Mobile HF NVIS Antenna .

Here are some links:

https://duckduckgo.com/?q=ST940B+Mobile ... &ia=videos

It is heavy, expensive, and not very efficient.

That is why I didn't originally recommend it.

The first few images here: https://duckduckgo.com/?q=HMMWV+antenna ... &ia=images

are what I was referring to.

MIL doesn't use 80 meters in vehicles though, at least very much unless they are really concerned about someone DFing them.

It would be interesting to see what the SWR on 80 M is though

Now, with a bit more looking, I find this...

http://www.hi-q-militaryantennas.com/mh-mobile.html

Not NVIS, but there are ratings for 2 MHz and 5 MHz and 80 meters is in the middle of that.

Hmmm.

More research needed.

Can we just change the direction of the mount/polarity for NVIS ops? Research...research.

Take care,
K
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"The prudent see danger and take refuge, but the simple keep going and pay the penalty." Proverbs 27:12
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Re: Mobile N.V.I.S.

Postby kmussack » 23 Jul 2017 12:55

My guess is that the Wehrmacht was looking for "hell for stout" as a top priority.
Efficiency was: "good enough for government work".

Those Stealth rigs out of the UAE are wicked expensive but are pretty much as good as it gets for HF mobile.
Image

http://stealth.ae/plugins/custompages/PDF/9310.pdf
I guess the whip could be bent for NVIS operation.

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Re: Mobile N.V.I.S.

Postby Kolt » 23 Jul 2017 14:32

Check out page 57 for some other ideas:

https://brushbeater.files.wordpress.com ... ooks-2.pdf

Take care,
K
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"The prudent see danger and take refuge, but the simple keep going and pay the penalty." Proverbs 27:12
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Re: Mobile N.V.I.S.

Postby kmussack » 23 Jul 2017 14:46

Golden!!!!
Great Data Dump.
Thanks,
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