Measurements using Optic and RF Waves

Chapter 1Electromagnetic Environment¹

 

 

 

1.1. Electromagnetic radiation sources

In his environment, man is subjected to radiations due to various electromagnetic fields. These fields are either of natural origin, or of domestic or industrial origins. In the following, we present this electromagnetic environment by separating the optical irradiations (i.e. low wavelengths) from the radio frequency (RF) irradiations (i.e. long wavelengths).

1.1.1. Optical sources

Light can be regarded either as an electromagnetic wave or as a beam of photons (phôs or photos = light). Thus, when frequencies ν of the electromagnetic waves are increasing (and thus the wavelengths λ are decreasing), energies of the photons E_photon are also increasing (E = h ν, h being Planck's constant).

1.1.1.1. Solar radiation

Energy from the Sun, produced by thermonuclear reaction, is emitted in space in the form of electromagnetic waves. This solar energy reaching the Earth drives almost every known physical and biological energy cycle in Earth's system.

The Sun is a giant fusion reactor, located 150 million km from Earth, radiating 2.3 billion times more energy than the energy that strikes the Earth — which itself is more energy in a hour than the entire human civilization directly uses in a year. Our Sun is the largest known energy resource in the solar system. Near the Earth at the top of the Earth's atmosphere, every square meter receives 1.366 kW of solar radiation. To reach the ground, this luminous energy ...