[Milsurplus] tank radio skip?

[Randy Moore]

A vertical antenna makes a very bad NVIS antenna.  I suspect the antenna 
is indeed a NVIS antenna.

Randy Moore
AI4CO


Hue Miller wrote:

>----- Original Message ----- 
>From: "Brooke Clarke" <brooke at pacific.net>
>To: <milsurplus at mailman.qth.net>
>Sent: Sunday, January 30, 2005 10:56 AM
>Subject: Re: [Milsurplus] tank radio skip?
>
>
> 
>  
>
>>That's an H.F. antenna designed for NVIS use, but may also send some 
>>signals into DX paths.  See:
>>http://www.tactical-link.com/WWII_NVIS.htm  where there are some 
>>drawings showing these H.F. antennas on German armored recon vehicles.
>>Brooke Clarke, N6GCE
>>    
>>
>
>I'd suggest that it's a wee bit presumptive to call this an "HF NVIS antenna".
>For tactical local communications where not using the low-vhf range, the
>German communications pretty much topped out around 7 MHz.  Much of
>their equipment, even mobile, covered frequencies that don't fit the HF
>designation of  3 - 30 MHz. For example, the 100WS transmitter, 200 - 1200
>kHz. The 30WS transmitter carried in command tanks and scout cars, in
>addition to the vhf gear, covered 1 - 3 MHz.   These antennas, and the antenna
>called a "star antenna, which looks like a vertical with 3 capacitive loading rods
>about 3 ft long that slant down like an umbrella, seen on the back deck of  "
>Command Panzers",  were all intended for use with the LF/MF equipment. 
>( I have the "star antenna", and it is really heavy: NOT aluminum at all.
>Still waiting to find a panzer - or maybe i should just sell the antenna. )
>If they had intended to use only HF, they would not have bothered with such
>a fragile and expensive antenna for just HF - they would have used a whip,
>just like the rest of the world did. 
>The thing that looks like a railing on scout cars or a laundry rack is a purely 
>capactive antenna.  Or consider it a top hat  hat with the vertical part of the
>antenna shrunk down to nothing. It was resonated with the loading coil inside
>the transmitter.  More capacity = less loading coil - and less coil losses. 
>I don't think NVIS was in their consideration as such - it was  just a way to get 
>current into the antenna at LF. With such a small antenna at LF, you have basically
>a point source for RF.  With LF/ MF, good ground wave range was what they 
>apparently were after. The crank up tower photo i suspect was not for any
>groundplane vhf antenna, i believe it was just a crank up vertical for actual HF 
>longrange communications in the range up to 10 MHz most likely.  ( Where the 
>KWEa receiver topped out, 10 MHz.)  Communications when parked, of course.
>I have not seen an actual German GP antenna in the paper i've looked at, but i'm 
>always ready to learn. I think i read that the frame aerials idea was kind of an idea
>that was dropped later in the war - i'd suppose these antennas too fragile and
>bothersome to maintain.  
>Germany was big on capacitive loading of short antennas. You can also find
>many photos of infantry and arty spotters using big boxes about the BC-654 
>size, with a vertical maybe 3 to 7 ft tall and a capacitive hat with 4 spokes of 
>about 14 inches each.  -Hue Miller
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