Chris Scott,
I will analyze the HF antenna design of VC10, initial DC10 and the poor ones like in 767.
Will be a pleasure to do that.
Aft reception: When your antenna is at a/c tail you have a "ground plane to the front of it" making RX and TX much better than to the back of the a/c.
Just to brief you on the theory: if you drag a wire, bonded to fuselage, the aft sigs would be the same to the front. Better if the wire is quarter wavelenght of the operating QRG. In this case the antenna would be in the middle, symetrical (fuselage to the front and trailing wire to the back).
On St Elmo and static poor RX this could only be solved increasing the power out of ground station but unfortunately the days of the 12ACX and 4WTFA are gone. They are using lower power and this is an error. I will investigate the current power levels and antennas being used in DKR, REC and others.
I designed and used several antenna tuners and at certain QRG they simply donīt tune. (for a given antenna type). And frequently sparks due VERY HIGH voltage.
On trailing antennae see the one of E6 Tacamo:
Boeing: E-6 Tacamo - History
Trailing a wire roughly the same lenght of cruise FL, 30,000 ft.
The antenna is a dipole (end feed, similar to the one used in Zeppelin) and the radiating element is another wire, a short one. (~5,000 ft), feeded with a coil in the a/c antenna tuner.
The purpose for this is to put a signal to be received by a submarine. (E6 orbiting) in this case the dipole (horizontal) radiates to sea, sides an top of the a/c. For a ONE WAY comm to the sub. (Sub just in RX mode)
QRG around 17 KHz (under 20 KHz).
