"Bob Haberkost" wrote (clip):
The nice thing about the low radiating impedance
of a vertical radiator is that the high base current
necessary for a given power means that the magnetic
vector is bigger than the electrostatic vector, and since
ferrite loops used in most AM radios respond to the
magnetic vector, the "connection" is more intimate.

This concludes your antenna theory class for the day. ;-)
____________________

The above calls for a bit of discussion, IMO

The base current of a MW vertical radiator depends on the resistive term of
the base impedance of that radiator, according to the equation I =
sqrt(P/R), where P is the applied power and R is the base resistance.

However current is not uniform over the height of the radiator. It must
satisfy the physical reality that a current node (minimum) always must exist
at the top of the tower. Other current nodes occur at 1/2 -wave intervals
below the top, if the tower is tall enough.

Between the nodes, current rises to a loop, or maximum, at intervals of 1/4
wave. The maximum current present at the loop(s) is a function of the
amount of power applied to the base of the radiator -- not to the base
impedance of the radiator.

So for a given input power, the same absolute value of current will be
present starting 1/4 wave below the tower top, and repeating every 1/2 wave
below that -- regardless of the base impedance of the radiator.

Far-field radiated EM waves from MW vertical radiators of any height are
identical in that they all have equal electric and magnetic vectors at right
angles to each other. A ferrite receiving antenna performs well on MW
frequencies for reasons unrelated to the ratio of the E & H fields in which
it is immersed.

RF

Visit http://rfry.org for FM broadcast RF system papers.