**2.1 Electromagnetic wave**

Electromagnetic waves are a form of energy emitted and absorbed by charged particles, which shows wavelike behavior because it travels through space [7]. Electromagnetic waves are transverse waves that oscillate and consist of electric field and magnetic field vector components as shown in **Figure 4**.

 Electromagnetic energy propagates in waves with several parameters that can be measured, namely, wavelength, frequency, amplitude (amplitude), and speed.

**Figure 4.**  *Schematic propagation of electromagnetic waves.* 

#### *Metamaterial: Smart Magnetic Material for Microwave Absorbing Material DOI: http://dx.doi.org/10.5772/intechopen.84471*

Amplitude is the wave height, while the wavelength is the distance between two peaks. Frequency is the number of waves that pass through a point in a unit of time. The frequency depends on the speed of the wave climbed. Because the speed of electromagnetic energy is constant (the speed of light), the wavelength and frequency are inversely proportional. The longer the wave, the lower the frequency, and the shorter the wave, the higher the frequency.

 The general characteristics of electromagnetic waves are that changes in the electric and magnetic fields occur at the same time, so that both fields have maximum and minimum values at the same time and at the same place. The direction of the electric field and magnetic field is perpendicular to each other, and both are perpendicular to the direction of wave propagation, electromagnetic waves are transverse waves, and electromagnetic waves experience events of reflection, refraction, interference, polarization, and diffraction. Fast propagation of electromagnetic waves depends only on the electrical and magnetic properties of the medium that it passes through.
