[ARC5] Antennas

[Mike Hanz]

By the way, the mast sheath would only have been used as a lead-in for 
the wire antenna if there was no VHF set installed.  Otherwise a 
separate downlead was required.  The Enola Gay has a good example, where 
two AN-104s had a sense antenna for the ARN-7 strung between them.  The 
early B/W photo  (http://aafradio.org/NASM/RHAntennas.htm ) shows only 
one VHF set installed, so the front mast was used as the downlead.  Both 
masts eventually became active VHF antennas, though, so a separate 
downlead had to be installed.

On 3/1/2011 9:24 AM, Mike Hanz wrote:
> On 3/1/2011 9:01 AM, Robert Eleazer wrote:
>> A discussion over at the Army Air Forces forum, where I explained to 
>> the assembled and no doubt awestruck multitudes that the "antenna 
>> mast" seen on some aircraft (Pacific P-40 was the example in 
>> question) was in fact simply the lead in for the real antenna - the 
>> wire going back to the tail - leads to this question:
>>
>> Was the AN-104 wooden metal covered antenna you can see in so many 
>> pictures (and in old Fair Radio catalogs) always simply just a way to 
>> hold the wire antenna for the 274-N up or was it also used as a VHF 
>> antenna?
>
> It was designed from the start as a VHF antenna, Wayne, was a improved 
> version of the AN-74 mast.  There were several different version of 
> these masts, at least one being uninsulated, but the AN-104 used a 
> copper cladding to provide an antenna that covered ~100-140MHz with a 
> remarkably low VSWR.  Somewhere around here I have a plot of VSWR vs 
> frequency but it's MIA at the moment.  Its use as a standoff for wire 
> antennas came as an aside, I suspect - drill a hole in the tip and you 
> have a convenient hanger.  The drawing I posted at 
> http://aafradio.org/sidebar/AN-104B_outline.png warns the installer 
> not to have the attachment wire to the insulator extend more than 2" 
> from the mast.