KC02 - EM Radiation

Question 1

Define EM Radiation

Answer 1

Electromagnetic (EM) radiation is a self-propagating wave in space with electric and magnetic components

Question 2

Describe EM Spectrum Utilisation

Answer 2

EM Spectrum: The frequency ranges which modern day equipment utilises for its intended application.

• Radio - 1Hz to 300GHz range
• Radar - Typically C to K band range (1GHz to 30GHz)
• Infrared - 300GHz to 375THz range
• Visible Light - 375THz to 430THz
• U/V - 430THz to 100PHz
• X-ray/Gamma/Cosmic - Greater than 100PHz

Question 3

List and describe basic EM properties

Answer 3

All EM waves have the following properties:

an Electric and Magnetic component,
a frequency,
a wavelength,
a polarisation,
and travels at the speed of light when propagating in free space.

Question 4

List and describe factors affecting EM Propagation

Answer 4

The factors that affects the propagation of EM waves includes the following:

Spreading
Interactions with materials
Attenuation by Atmospheric Conditions
Diffraction and Scattering
Reflection
Radar Horizon
Interference

Question 5

List the 2 forms of Atmospheric Attenuation

Answer 5

The 2 forms of atmospheric attenuation on an EM wave are absorption and scattering?

Question 6

State the relationship between atmospheric attenuation and frequency (RF)

Answer 6

cattering increases as frequency increases = attenuation increases = range reduces

affecting the operation of the Radar System

Question 7

Polarisation (Orientation)

Answer 7

Polarisation is defined as the orientation of the EM wave, this is determined by the direction of the electric component of the wave.

Horizontal, Vertical, Circular