Re: Counterpoise and MMC demise

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Interesting point... eddy current losses in the ground...
In "real ground" it's resistive enough that you probably don't get a huge
amount of loss... there's probably a "sweet spot".. you want either very
high conductivity (i.e. low loss, but higher induced current) or very low
conductivity (low induced currents).  Somewhere in the middle is probably
worst.
This is definitely an issue with antennas mounted close to the ground.

 > Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<Mddeming-at-aol-dot-com>
 > >Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > ><jimlux-at-earthlink-dot-net>
 > >
 > >I should think a combination of both.. The counterpoise serves as the
 > >"other plate" of a capacitor formed between it and the topload.  From an
 > >E-field standpoint, you want to have something that extends far enough
out
 > >to cover most of the flux.  From a losses standpoint you want to have low
 > >impedance within the plate, so high "solidity" is important, although I
 > >suspect that chicken wire (aviary netting) is more than solid enough.
 > On the other hand, "solidity" results in much higher eddy current losses.
 > IIRC, eddy currents are a problem anywhere you can form a closed loop in a
 > varying field.A large number of bare wires laid out in a radial pattern
 > will minimize eddy currents, but with less "solidity". Like most things in
 > TC work, it is a balance between one type of losses and another.