Radiation resistance of a square loop in a warm plasma

A linearised hydrodynamic theory has been used to calculate the radiation resistance of a square-loop antenna in a warm plasma. It is suggested that cosinusoidal currents of two different propagation coefficients and amplitudes are simultaneously and independently present. Comparisons of the theoretical results with the measured values of the radiation resistance of a square-loop antenna on Ariel 3 satellite gives the ratio of the amplitudes of the currents in the two modes, for various values of the ratio of plasma to measuring frequency.