Parametric acoustic antenna in the atmosphere

We consider the principles of development of a parametric antenna in the atmosphere. It is shown that to excite an infrasound at a frequency lower than 1 Hz in the atmosphere, one can use an acoustic system emitting simultaneously two waves whose frequencies differ by the infrasound frequency. In the pump-wave frequency range 20–500 Hz, the main contribution to infrasound emission is given by the region located at altitudes from 30 to 75 km, in which the oscillatory velocity in the pump wave is maximum. We propose an algorithm for calculation of the infrasound amplitude in the E and F layers of the ionosphere. Realization of a parametric antenna in the atmosphere makes it possible to broaden the capabilities of experiments based on the modification of the ionosphere by an infrasound. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 7, pp. 570–576, July 2006.