"Reg Edwards" wrote in message
...

Take a close-wound wire helix of diameter D metres and having N = 500
turns
per meter. Wire diameter approx 2mm.

All formulae available from Terman, Kraus, ARRL, etc., etc.

C = 55.5 / (Ln( 2 * H / D ) - 1) picofarads per meter.

L = Square( N * Pi * D ) / 10 microhenrys per meter.

TransLine impedance, Zo = Sqrt( L / C ) ohms.

Propagation Velocity = 1 / Sqrt( L * C ) metres per second.

Take a length of H =1.5 metres of this helix and use it as a short
vertical
antenna above a good ground.

It will resonate as a 1/4-wave vertical at 3.5 MHz.

Zo = 3243 ohms.

Velocity factor = 0.0701

Radiation Resistance = 0.176 ohms.

etc., etc.,

It's so simple you can't believe it. ;o)
----
Reg.



Somehow this doesn't seem right.

For example, RG58 has a Zo of 52.5 ohms = sqrt(L/C). It also has C=28.5
pF/ft or 93.5 pF/meter. Solving for L gives 267.8 nH.

So, are you saying that a 1 meter length of RG58 will resonate at
fo=1/sqrt(L*C) or 31.8 MHz? If that's not what you're saying, where does
your Zo=3243 come from?