Whistler mode resonance-cone transmissions at 100 kHz in the OEDIPUS-C experiment

A radio transmitter was operated at one end of the tethered sounding rocket double payload OEDIPUS C, and a synchronized receiver at the other end. Both the transmitter and the receiver were connected to "double-V" dipoles. On the flight downleg after the tether had been cut, direct bistatic propagation experiments were carried out successfully with the transmitter-receiver pair. This paper addresses the transmission of 300-mu s pulses at a carrier frequency of 100 kHz between the dipoles over distances of about 1200 m. The waves of interest propagate in the whistler mode close to its resonance cone, where the transmitter is situated in the cone apex. The radiated field under these conditions is computed as well as the resonance response of the receiving antenna, i.e., its effective length. In the whistler mode, the influence of the plasma is important and it results in qualitative changes in the structure of the radiated field and in the value of the receiving antenna effective length as compared to the free space case. Our main concern is the excitation and reception of a pulsed signal when time and space dispersion play important roles in both the delay and spreading of such a signal.