Experimental study of the relationship between the propagation distance and the polarization characteristics of whistlers

Wideband (0‐8 kHz) measurements were performed for VLF whistlers at Moshiri (geomag. lat. 35°N) in Hokkaido in January, 1983 to investigate the relationship between polarization characteristics of whistlers and their propagation distance after the ionospheric transmission in the Earth‐ionosphere waveguide. the phase differences of the two signals of whistlers detected by orthogonal (E‐W and N‐S) loop antennas have been measured and the following results found: (1) the polarization of whistlers which penetrate the ionosphere close to the observing station is righthanded over a wide frequency range; and (2) some whistlers are found to have propagated over a distance of ∼1500 km. These whistlers exhibit a right‐handed polarization at some frequencies and a left‐handed polarization at other frequencies. However, the averaging of the observed polarizations over a wide frequency results in a nearly linear polarization; this agrees qualitatively with previous theoretical calculations by Crary.