[Boatanchors] B-17 antenna connection

[Michael Hanz]

I dug around my documents and found this excerpt from the manual for the 
B-17F concerning your question, shown below, Dave.  It was in effect a 
loop antenna.  Used on the earlier B-17s for the Liaison antenna 
(paradoxically, the command set was connected to a conventional top of 
the tail to radio compartment antenna.)  The early B-29 also used the 
loop (for the command set antenna,) with a short wire running between a 
lower feedthrough insulator on the starboard side of the fuselage to a 
point on the rear of the No. 3 engine nacelle, employing a portion of 
the skin of the wing and fuselage back to the ground of the transmitter. 
At HF frequencies, the aluminum skin between the nacelle and the ground 
connection point for the transmitter has a measurable complex impedance 
(aluminum is more lossy than copper in this regard), so there was 
apparently some radiation from the skin at those frequencies.  It could 
probably be argued that the majority of the loop radiation came from the 
wire between the wing and feedthrough insulator, but I have not seen any 
discussion on that issue in the literature.  Overall, the concept wasn't 
as efficient a radiator as a conventional longer wire antenna, so was 
eventually abandoned in favor for the more familiar tail top to fuselage 
configuration used in smaller aircraft.  The B-29 command set eventually 
used anindependent horizontal stabilizer to fuselage insulator long wire 
for the same purpose as the liaison fixed wire.  See my writeup on that 
at http://aafradio.org/NASM/RHAntennas.htm if interested.



  73,
Mike  KC4TOS

On 11/26/2016 9:58 PM, Dave Marquart wrote:
> OFF topic..  After reading the B-17 manual on radio equipment - I saw the
> following..
> The liaison receiver on the radio operator’s table covers a frequency range
> from 1500-18,000 Kc. It uses the same antenna as the transmitter: the skin
> of the airplane. This is connected to a throw switch on the left side wall.
> This switch can change over to the trailing antenna (also on left side
> wall). The trailing antenna is operated from a control box to the right of
> the change-over switch.
> Can someone tell me how they used the Skin of the aircraft for an antenna
> when the negative side of the Battery, generators, equipment were all using
> the frame (skin) of the aircraft?  What am I missing?  Thanks..
>
>
> Dave Marquart