论文部分内容阅读
1.引言由全球闪电活动引起的地—电离层波导内的自然极低频(3Hz—3KHz)无线电噪声基本上由垂直电场和水平磁场组成。舒曼谐振简单地说是地球—电离层圆球壳体腔体谐振器内全球闪电活动产生的大气噪声场。电磁波在地球表面传播的衰减在极低频低端很低(5Hz时大约为0.2dB/Mm),衰减随着频率增高而增大。闪电产生的无线电噪声在极低频低端具有准连续特性,但极低频高端就变成单脉冲性而且衰减超过30dB/Mm。大气噪声场渗入地
1. INTRODUCTION Natural extremely low frequency (3Hz-3KHz) radio noise in earth-ionospheric waveguides caused by global lightning activity consists essentially of vertical and horizontal magnetic fields. Schumann resonance is simply the atmospheric noise field generated by the global lightning activity in the cavity-ionospheric cavity resonator. The attenuation of electromagnetic waves propagating on the Earth’s surface is very low (about 0.2 dB / Mm at 5 Hz) at the very low frequency and the attenuation increases with increasing frequency. The radio noise generated by lightning has quasi-continuous behavior at the very low frequency, but the high frequency at very low frequency becomes monopulse and decays more than 30 dB / Mm. Atmospheric noise field into the ground