Excitation and propagation of whistler waves in density depletion ducts in a magnetoplasma

Excitation and propagation of whistler-mode waves in a laboratory or ionospheric plasma containing a cylindrical magnetic-field-aligned density depletion duct are studied. Using a rigorous solution for the total source-excited field comprising both the discrete and continuous parts of the spatial spectrum of waves, the radiation resistance of a loop antenna located in such a duct is determined. Conditions have been revealed under which the power radiated from the loop antenna immersed in a density depletion duct is dominated by the contribution of either discrete- or continuous-spectrum modes.