Electric field strength analysis of 216 and 270 kHz broadcast signals recorded during 9 years

Abstract

[ 1] The electric field strength analysis of Czech Republic (CZE) ( 270 kHz) and Monte Carlo (MCO) ( 216 kHz) broadcast signals, collected with a 10 min sampling frequency by a receiver located in central Italy from 1996 to 2004, is presented. The distance from transmitter to receiver ranges from 515 km ( MCO) to 818 km ( CZE). The daytime data and the nighttime data were extracted and then in the daytime data the data collected in winter ( 21 December to 21 March) were separated from the data collected in summer ( 21 June to 21 September). Under the hypothesis that the simple addition of the ground wave and sky wave contributions holds, at first, the analysis was focused on the comparison between the experimental and theoretical values of these waves. The theoretical values were calculated by the ground wave (GRWAVE) algorithm and the wave hop theory, respectively. Ratios between the experimental and theoretical values ranging from a few tenths of decibels to some decibels were obtained. Then the analysis of the sunspots' influence on the sky wave propagation mode was performed, and the electric field strength of the two radio signals reveals a reduction of some decibels in sunspot maximum years with respect to the values during the sunspot minimum years. In addition, an influence of the sunspots also was recognized for the ground wave propagation mode

A pre seismic radio anomaly revealed in the area where the Abruzzo earthquake (<i>M</i>=6.3) occurred on 6 April 2009

“…According to the wave hop propagation theory, the sky-wave signal received by an antenna can be considered as a ray starting from the transmitter and reflected one or more times (hops) by the lower ionosphere and by the ground. The MCO radio signal recorded at the mouth of the Amare cave was investigated in detail in a previous study (Biagi et al, 2006b); hence it results that at the time of the anomaly the ground wave practically is the day time signal and the sky wave (one hop) is the night time signal. From Fig.…”

On the generation mechanism of terminator times in subionospheric VLF/LF propagation and its possible application to seismogenic effects

“…The computation of sky waves is principally based on the ray theory, and the ground wave is calculated by the full-wave Sommerfeld integrations. More details are given in ITU (1992ITU ( , 2002, Wakai et al (2004) and its successful use has been given in Biagi et al (2006). The configuration of our problem is given in Fig.…”

Anomalies Observed in VLF and LF Radio Signals on the Occasion of the Western Turkey Earthquake (M<sub>w</sub> = 5.7) on May 19, 2011

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