[Milsurplus] BC-224-A + BC-307-A

[Mike Hanz]

Like anything in this field, you gotta put a lot of technical qualifiers 
on just about any statement, Marty.  The 1942 Sandretto textbook has a 
good chapter on aircraft antenna design - including mention of all the 
geometries that were tried, as well as reasons for their discard or 
retention.  Some of the rationale was operational.  For example, they 
wanted a vertically polarized antenna for close-in communications with 
the tower, so the trailing wire antenna *without* the weight wasn't a 
good choice - it was almost all horizontally polarized.  *With* the 
weight, it worked fine.  A lot also has to do with the frequency.  The 
normal sloped antenna wire, from a short (4 foot) vertical mast and then 
15 feet to the tail, was profiled at both 5MHz and 10MHz.  At 5MHz the 
radiation was mostly vertically polarized, as you would expect - and 
which is what you were saying below.  At 10MHz, however, the horizontal 
component surpassed the vertical by a good amount, which was fine for 
long distance comms. 

Having said all that, I note with interest that the B-29 command antenna 
is almost completely horizontal - hooks to the tip of the starboard 
horizontal stabilizer.  'Course, they also had the SCR-522/ARC-3 with 
vertical polarization antennas for plane-to-plane and tower comms, so it 
was more of a backup liaison antenna than anything.

73,
Mike

Unserviceable but Repairable wrote:

>>you wouldn't say the 3 foot riser was the only radiating element. 
>>
>  The only VERTICAL radiating element
>
>I would say.  The horizontal component is a capacity hat & doeasn't radiate
>
>The acft fuselage is the 'ground plane' beneath which, in the math sense,
>is the "riser's" image.  This makes a short vertical dipole.
>
>But the horizontal part has no polar corralary & hence is a capacity hat.
>Might say, if grinch, only a gazouta, no gazinta.
>
>This is a fact unilaterally disunderstood by USN "tech pefressunals."
>
>Those ship-board "long wires" were JUST capacity hats agasinst the 
>hull's perfect ground."  The RISER was all that radiated.
>
>BC375s, etc. w. trailing wires did OK.  Fuselage was "ground plane."  But
>fighters w. '183s & ATAs, etc....  horrible hf efficiency fm the "riser."
>So fm that view, the 522 was a gettin'-out breakthru.
>
>Ask Marconi, Tesla, or a communications OFC.  But don't ask a radio ET.
>
>Don't mean to be a snot.  Just the facts maam.
>
>  'rm
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