Here's an article by Brian Pease. He'd appreciate comments.

• Computer Modeling Thru-The-Earth Communications Antennas,
  by Brian Pease

With the recent interest shown within the cave electronics community about radio frequencies and their relationship to overburden, we're re-publishing Ian Drummond's early series of ten articles on the topic.

Click on the links below to view the articles:

• MAGNETIC MOMENTS, Number 1, by Ian Drummond

• MAGNETIC MOMENTS, Number 2, by Ian Drummond

• MAGNETIC MOMENTS, Number 3, by Ian Drummond

• MAGNETIC MOMENTS, Number 4:
    FERRITE CORE ANTENNAS, by Ian Drummond

• MAGNETIC MOMENTS, Number 5:
    THE PHASE PROBLEM, by Ian Drummond

• MAGNETIC MOMENTS, Number 6:
    THE TRANSITION ZONE, by Ian Drummond

• MAGNETIC MOMENTS, Number 7:
    ELECTROMAGNETIC NOISE - NATURAL SOURCES OF NOISE, by Ian Drummond

• MAGNETIC MOMENTS, Number 8:
    ANTENNA NOISE, by Ian Drummond

• MAGNETIC MOMENTS, Number 9:
    GROUND CONDUCTIVITY BY ELECTRO-MAGNETIC (EM) METHODS, by Ian Drummond

• MAGNETIC MOMENTS, Number 10:
    AN RF PROBE, by Ian Drummond