Electromagnetic radiations are regions of energy that are constantly present in the terrestrial environment. These radio signals may have artificial or natural origins. Natural electromagnetic radiation origins are usually cosmic or atmospheric while artificial ones result from technological applications, communications or power transmissions (Bianchi & Meloni, 2007).
The main difference between natural and manmade radio signals is the source. Natural radio signals may be produced by the sun, from extra-terrestrial nuclear activity or from terrestrial sources such as radioactive decay (Bianchi & Meloni, 2007). Some natural radio signals are created by interaction between waves and particles from outer space with the plasma of the magnetosphere. Another natural source is located within the ionospheric cavity. This is where the activity of lightning produces voltages which create and propagate natural radiation. Other natural sources are cosmic microwave radiation, pulsar quasars and fire. Artificial electromagnetic radiation is created mostly by technological applications which utilize electromagnetism concepts such as radio and broadcast communication, radar, satellites, computer networks and navigation systems (Bianchi & Meloni, 2007).
Other than the source, another difference between natural and artificial radio signals is in their use. Artificial radio waves are used in a variety of ways. X-Rays are used for medical inquiry; microwaves are applied for industrial as well as home use; radio waves and infra-red are used for communications and thermal imaging, tracking and keyless entry (Epa.gov., 2010; WHO, 2010). Natural electromagnetic radiations are mostly used for natural processes such as photosynthesis which is the source of energy for plant life. The third difference is in the information carried by the signals. Most artificial radio waves are intelligent as compared to natural radio waves. This means that they carry deliberate information which may be deciphered by the receiver.
References
Bianchi, C., & Meloni, A. 2007. Natural and man-made terrestrial electromagnetic noise: an outlook. Annals of Geophysics, 50(3), 435-445.
Epa.gov.2010. Basic Information. EPA. Retrieved October 25, 2013, from http://www.epa.gov/radtown/basic.html
WHO. 2010. What are electromagnetic fields?. WHO. Retrieved October 25, 2013, from http://www.who.int/peh-emf/about/WhatisEMF/en/
