Wave propagation experiments at medium frequencies between two ionospheric satellites, 2, Whistler‐mode pulses

Abstract

Intersatellite whistler‐mode propagation experiments at 0.48 MHz have been performed between the two ISIS spacecraft during rendezvous. Transmitted pulses of 100 μsec length are temporally dispersed by 100 times and more. The shape of the received pulse envelope depends on the orientation of the dipole antennas with respect to the ambient magnetic field. The distortion is greatest when both transmitting and receiving antennas are perpendicular to the field and least when they are parallel. Received pulse amplitudes and shapes have been compared with existing theory. For propagation well inside the resonance cone, received pulse amplitudes are within about two orders of magnitude of theoretical prediction. Near the resonance cone where large amounts of energy appear to be radiated, primary and secondary pulses are observed which are evidence of the antenna resonances of the finite‐length dipole. Because the occurrence of highly elongated whistler‐mode pulses and irregularities in the ambient electron density are correlated, it is deduced that irregularities are efficient scatterers of whistler‐mode waves.