Cecil Moore, W5DXP wrote:
"For instance, a coil might be 10+j300 ohms or a cap might be 2-j500
ohms."

A small loop antenna with a perimeter only a small fraction of a
wavelength has almost uniform current throughout. Its impedance is an
inductive reactance in series with a resistance. The U.S. Bureau of
Standards published inductance formulas for single-turn and several-turn
loops in Bulletin 74. Results can`t take into account loss from
radiation so they are approximate.

Arnold King gives an approximate formula for the radiation resistance of
a small one-turn loop in "Transmission Lines, Antennas, and Wave
Guides":
Re = 20(Beta)to the 4th power times A squared
Beta=2pi/lambda
A=area enclosed by the loop.

Best regards, Richard Harrison, KB5WZI