We study an antenna system consisting of a current loop exciting resonance cones and of an electric dipole generating ion sound waves. The transformation of lower oblique resonance waves on quasineutral density perturbations in the near field of an antenna gives rise to whistler waves on combination frequencies. Their amplitude may exceed several times the amplitude of linear whistler waves excited by the loop itself. The system may be regarded as a parametric antenna for enhanced excitation of whistlers in the ionosphere.

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