Instrumentation and Measurements of Magnetic Coil Schumann Resonance Receivers

Schumann resonances (SR) are the result of global lightning activity and occur in the waveguide between the Earth and the ionosphere. SR appear in the extremely low frequency (ELF) region of the spectrum, presenting peaks from 8 to 45 Hz. The electromagnetic field caused by this phenomenon consists of two components: the electric field component, which is vertical; and the magnetic field component, which is horizontal and usually analyzed in two dimensions, one for the North-South (N-S) orientation and one for the East-West (E-W) orientation. Measurements have shown that the electric field has strength of few hundred of nanovolts per meter (nV/m) whereas the magnetic flux density is of the order of tenths of pico-Tesla (pT). In addition, in some cases, local lightning activity is inevitably a source of noise in the measurements [1]. Furthermore, there are other sources of interference such as the 50/60 Hz power lines and various man-made electromagnetic interference [2].