Terrestrial Natural and Man-made EM Noise

By Cesidio Bianchi and Antonio Meloni

5. Conclusions

In this paper the terrestrial natural electromagnetic noise and its main characteristics were described. Natural electromagnetic noise constitutes a background radio noise in which living systems are immersed and consequently evolved, since the origin of life on Earth. Superimposed to the natural background radio noise man-made radio noise is now strongly in occurrence. The main man-made radio noise sources and characteristics were are also described and compared with the natural ones. Artificial noise level has been constantly increasing in the last hundred years or so as the electromagnetic application have expanded. A digression of the main characteristics, features and sources, in the frequency range of non ionizing radiation, was made.
A brief excursus of the natural radio sources, starting from the lowest frequencies that the magnetosphere and ionosphere cavities can sustain, to the galactic and cosmic radio sources that penetrate the electronic density layers of the upper atmosphere, was undertaken. These studies, that have roots in the pioneer era of radio communication, when the knowledge of natural noise was essential for the assessment of an effective radio technology, have also revealed during the years their relevance in geophysical, spatial physics, astrophysics and many other research fields. In particular detailed knowledge of features of all natural electromagnetic waves current in the magnetosphere is, as expected, important for ground based communication systems, but can be relevant for example also in the design of earth-orbiting and interplanetary spacecrafts.