Non-linear Phenomenon in Ionosphere

Abstract

The phenomenon of ionospheric cross-modulation has been studied in a realistic case by taking into account the in homogeneity, arbitrary direction of the earth's magnetic field, the plane of polarization of the wave and the appropriate radiation pattern of the antenna. Unlike earlier workers, the change in the plane of polarization of an obliquely incident low power wanted wave is accounted for, and actual ray-path has been drawn when the wave passes through the portion of the ionosphere already perturbed• by the high power amplitude modulated disturbing wave. The amount of cross-modulation is obtained by integratina the expression of the modified modulation index along the actual ray-path of the wanted wave. To appreciate the theory, numerical results are obtained for a typical set of parameters available with All India Radio. It is found that the cross-modulation near the gyroresonance region is of the order of 11% for 50% amplitude modulation at 200 Hz for a disturbing transmitter of 1 MW power. This is in good agreement with the available experimental data.