2 - Wave Propagation

Question 1

Two types of Waves?

Answer 1

1. Mechanical
   
   1. Requires a medium for propagation (SONAR)
2. Electromagnetic
   
   1. Does NOT require a medium for propagation (RADAR)

Question 2

What is Phase?

Answer 2

The angular argument where a sine wave begins; defined at some arbitrary point.

Positive shift - Advanced wave

Negative shift - Retarded wave

Question 3

Electromagnetic Wave Generation

Answer 3

• Transverse
• No medium

Question 4

Two types of polarization

Answer 4

1. Linear
2. Circular

Question 5

Media boundaries with dissimilar propagation speeds

Answer 5

Reflection

1. Specular Reflection
   
   • Surface is smooth relative to wavelength
2. Diffuse Reflection
   
   • Surface is rough relative to wavelength

Question 6

Bending of EM ray when it transmits from one medium to another

Answer 6

Refraction

• Not all of the wave is reflected
• Some of the wave goes in the medium at some angle
  
  • Snell’s Law

Question 7

Three kinds of attenuation (electromagnetic signal loss)

Answer 7

1. Spreading
2. Scattering
3. Absorption

As attenuation goes up, distance the signal will travel goes down

As attenuation goes up, frequency goes up

Question 8

Beamwidth

Answer 8

The angle (radians) between the points where the power has dropped to one-half the maximum

Question 9

What are the two types of interference?

Answer 9

1. Constructive

Phase shifts between 0 and 120º or 240 and 360º are constructive

2. Deconstructive (destructive)