Chapter 5 - Propagation

Question 1

What 3 factors affect propagation?

Answer 1

refraction
reflection
defractrion

Question 2

Why radar horizon better than optical horizon

Answer 2

Because of refraction
The ray path follows the curvature of earth and this effect increases with wavelength

Question 3

Sub refraction

Answer 3

Question 4

Super-refraction.

Answer 4

Question 5

What effect creates the vertical lobe structure in surveillance radars?

Answer 5

Surface Reflection Multipath: The combination of direct and reflected radar waves from the surface creates constructive and destructive interference patterns, resulting in vertical lobes in the coverage diagram.

Question 6

What factors affect the number of lobes in a VCD?

Answer 6

Antenna Height - Higher it is, the closer the lobes
Frequency - Higher it is, the more lobes
Polarisation

No. lobes = height of aerial (m) / half wavelength of transmission (m)

Question 7

What are the causes of attenuation in radar

Answer 7

scattering
absorption