[ARC5] Re: [Milsurplus] Re: Antenna tricks

[Hue Miller]

Dave, if that horizontal run IS paralled to the ship, then as you say, it's a transmission
line, whether it's long or short is immaterial, isn't it, because the currents top and bottom
are out of phase and cancel any radiation, yea or nay ?

But i think maybe not so many of the aircraft wire antennas were really exactly parallel
to the ship. Some were; in fact the first example i thought of were some of the Nippon
fighters with a antenna mast right in front of the cockpit. If i recall, the fore and aft
wire was pretty darn parallel to the airframe. But on many planes, the run to the tail
was actually a rise. ( I think ) this is like a "space saving" dipole folded back on itself,
the more  you fold it from open (standard dipole) to , to a "V", to completely folded on
itself (like transmission line), the more the radiating field is cancelled out.

I'm thinking also some aircraft had a V antenna from a forward mast to top of each
of the twin tails. ( Like Earhart's twin tail Lockheed 10, for example. ) ( Like a Beech
18 also, but not all of those used the V pattern antenna. ) Clearly that antenna didn't
parallel the airframe greatly.

This occurred to me also - i dunno if it's valid: The airframe actually has some height to 
it too. The RF currents have skin effect, so the current will distribute itself about the
skin of the ship. So what i'm saying instead of your inches mast maybe you count 
total vertical as standoff mast + every vertical point on the ship, including the bottom
+ vertical rise in the horizontal wire.

If a ground station had a horizontal antenna, and heard the aircraft with varying strength
as it turned, maybe that would indicate that radiation was not by vertical mast alone.

What somewhat still boggles my mind is the German armored vehicles with the
"roof antenna" or "pipe rack antenna" comunicated down into MF territory
with an effective rise, at its least,  300mm off the vehicle roof. That 30 cm, or about 
one foot. 

Another interesting thing is that the situation apparently isn't reciprocal for
receiving - you can use a transmission line type thing for receiving, if it's 
resonant or resonated as a tuned circuit.  -Hue Miller