Whistler wave excitation by a pulsed loop antenna located in a cylindrical duct with enhanced plasma density

Pulsed radiation from a loop antenna located in a cylindrical duct with enhanced plasma density is studied. An expression for the radiated energy is derived and its distribution over the spatial and frequency spectra of the excited waves as a function of the source and duct parameters is analyzed. Numerical results referring to the case where the frequency spectrum of the current is concentrated in the whistler range are reported. It is shown that under ionospheric conditions, the presence of an artificial duct with enhanced density can lead to a significant increase in the energy radiated from a pulsed loop antenna compared with the case where the same source is immersed in the surrounding uniform magnetoplasma.