[Boatanchors] B-17 antenna connection

[Michael Hanz]

Looks like the 34kB image didn't make it through, so here is the text:

(e) _Antennae

_            The Liaison set employs either of two antennae.  The 
trailing antenna is held on a reel, Type RL-42, mounted on the lower 
left sidewall at Station 6D.  It is operated by a 24 volt D.C. motor 
controlled by a Type BC-461 control box on the upper left sidewall at 
station 5F.  A counter on the box indicates the amount of wire extended, 
and a warning lamp lights when both the landing gear and antenna are 
extended.

             The skin of the airplane serves as an antenna for the 
Liaison set with a lead-in connected to the left wing at the main tank 
gage cover and brought through an insulator in the upper left side of 
the fuselage just forward of Station 5O.  Both Liaison antennas are 
connected to the antenna changeover switch and through the switch either 
antenna may be connected to the set.  The antenna switch is on the upper 
left sidewall at Station 5G. _
_
end excerpt

On 11/27/2016 8:28 AM, Michael Hanz wrote:
> 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
>
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