[Lowfer] 8 kHz VLF loading coil idea

[Bill Ashlock]

Hi Ed,

You say: "A Q of 100 (for the loading coil) sounds too low by orders of 
magnitude!"

The system Q, meaning the combined Q of the coil, the top hat (along with 
all the tree losses), and the ground, is seldom better than 50 on most 
Lowfer antennas despite the fact that some go hog-wide in designing loading 
coils with incredibly high Qs. A lowfer loading coil having 3.5mh and Q of 
500 has an effective series resistance of 7 ohms at 160kHz. The same loading 
coil having a Q of 100 would have a series resistance of 35. If the ground 
resistance is 35 ohms and the tree loss is 8 ohms, the radiation power gain 
in going to the better coil would be the ratio of the two total system 
resistances. That's 50 ohms compared to 78 ohms. This is 1.56x or 1.93 db - 
hardly detectable in a normal receiving situation. Due to the extremely low 
reactance of the top hat at 9K, and the huge inductance needed to resonate 
this, a Q of 100 in a coil this big would be all one could hope for. And if 
one could, in fact, gain 1.93 db by a better coil, it would be a whole lot 
simpler to just multiply the power input by 1.56X.

What do you think?......

Bill

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