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.
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