[Elecraft] B&W Folded Dipole over an Armory

[Roger D Johnson]

Cebik, W4RNL, modeled two versions of the T2FT. One 165ft long and the other 100ft.
Here is what he said about these antennas:

Terminator Resistor Losses
Although transmitting uses have been made of the T2FD, its chief use appears to 
be as a short wave reception antenna. In this application, the excess available 
receiver gain can largely make up for losses incurred in the terminating resistor.

The losses in the terminating resistor are considerable, ranging from nearly 
half power to amounts in excess of 90% of the available RF power. The pattern of 
losses is not a simple smooth curve, but varies throughout the operating range 
of the antenna. The following graph plots the losses in terms of dB. For 
reference, a 3 dB power loss represents half the power being dissipated in the 
resistor. Higher values indicate more of the power being dissipated rather than 
being radiated (or transferred to the receiver).

73, Roger


On 8/13/2017 3:36 PM, Fred Jensen wrote:
> Ummm ... let's be truthful here.  The B&W folded dipole can be found in radio catalogs from the 50's.  We all knew [I was a kid with a new license then and even I knew] that the doohicky at the center of the top wire was a 400 or so ohm non-inductive resistor, and half the power [3 dB] heated it up.  There was no subterfuge and B&W wasn't "conning" anyone, it was very clear in the specification sheet.  300 ohms at the feed point, hams often fed them with 300 ohm TV twinlead of the day to a balanced link coupled to the final tank circuit.  A 4:1 transformer netted 75 ohms which nicely matched that twinlead too.
>