Al Fansome wrote:
What exactly do counterpoise wires do for a vertical antenna? I realize
that they allow an impedance match, but what is physically going on with
the current that makes this possible?

Visualize a 1/2WL center-fed dipole with one element
laying on the ground. The wire on the ground is the
counterpoise. What happens to the radiation when the
wire is laying on the ground?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com