[TowerTalk] radials for shunt fed tower

Tom Rauch w8ji at contesting.com
Tue Dec 7 06:12:33 EST 2004


> If I may kibbitz, I'd like to inquire as to what degree
mass may
> compensate for length?

You need electrical mass Doc (low impedance) or electrical
inertia, not physical mass.

The job of a radial is to spread the voltage and current
around. By definition that must include electric and
magnetic fields that occur at voltage and current points.

This is why a few elevated resonant radials are such a bad
thing for loss when the radials place intense electric and
magnetic fields in the loss media below the antenna.

This is also why we should never trust a model that uses
homogeneous media ( a media that doesn't even match the
actual soil in the application) would tell us how to
optimize a system.

Adding more radials over a larger area spreads the fields
around, making the fields and directly coupled current less
dense. The spreading is what decreases losses, not the
physical mass or resonance.

73 Tom



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