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Abstract. During a routine analysis of whistlers on the wideband VLF recording of the DEMETER satellite, a specific signal structure of numerous fractional-hop whistlers, termed the "Spiky Whistler" (SpW) was identified. These signals appear to be composed of a conventional whistler combined by the compound mode-patterns of guided wave propagation, suggesting a whistler excited by a lightning "tweek" spheric. Rigorous, full-wave modelling of tweeks, formed by the long subionospheric guided spheric propagation and of the impulse propagation across an arbitrarily inhomogeneous ionosphere, gave an accurate description of the SpW signals. The electromagnetic impulses excited by vertical, preferably CG lightning discharge, exhibited the effects of guided behaviour and of the dispersive ionospheric plasma along their paths. This modelling and interpretation provides a consistent way to determine the generation and propagation characteristics of the recorded SpW signals, as well as to describe the traversed medium.

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A study is made of the radiation from a pulsed loop antenna immersed in a cold collisionless magnetoplasma. Using a rigorous solution for the total field of such an antenna, the energy characteristics of its radiation are determined. The radiated energy and its distribution over the spatial and frequency spectra of the excited waves are analyzed as functions of the antenna and plasma parameters. Numerical results referring to the case where the frequency spectrum of the antenna current is concentrated in the whistler frequency range are reported. The results obtained can be useful in understanding the basic features of wave excitation by pulsed sources in a magnetoplasma.

The advanced electromagnetic wave detector and analyzer, Signal Analyzer and Sampler 2, successfully operated on board of Compass‐2 satellite (launched May 2006). One of the peculiarities of this experiment was that the efficient sensitivities of both electric and magnetic channels were very close to being identical. Between the interesting events detected we found the evidence of whistler mode signals propagating in higher‐ (third‐) order guided mode, most probable between two layers (i.e., “onionskin” structure was in the plasmasphere at this time). We present in the paper the real full wave ultrawideband interpretation of these propagating signals using the exact solution of Maxwell's equations in this boundary problem.

Representing lightning discharge current source by a Dirac delta function, Maxwell's equations are solved to derive the expression for wave-electric field as a function of frequency and distance including the effect of interparticle collisions. The exact time-dependence of the propagating non-monochromatic signal for the realistic magnetospheric model is computed for low latitude stations (in India). The computation is extended for the wave propagating through different regions of the magnetosphere and results are compared with the measured data. Points of agreements and differences are illuminated.