Radar theory Flashcards
What principle does radar work on
Echo
What does the quality of a radar return depend on
Size of object
Shape of object
Material
Can you receive when you’re transmitting
No
What is a phased array
Sweeps electronically
Requires 3/4 for 360° sweep
What is a parabolic dish
Required 1 for 360° sweep
Better coverage than a phased array
What beam width is better for accuracy
Smaller beam width
What size dish is better for beam width accuracy
Bigger dish = smaller beam width = better accuracy
What happens to unambiguous theoretical range as pulses per second increase
Range decreases
What happens if pulse repetition frequency (PRR) / pulse recurrence rate (PRR) is too high
May receive target echos from wrong pulse
What happens to unambiguous range with a high PRF
Less range
Dish rotates quickly
What is the formula for max unambiguous range
81000nm / PRF
What is the max range or radar
Line of sight
1.23 ( * squareroot* height of transmitter + squareroot height of receiver)
What is the min theoretical range of radar
Pulse width 1 microsecond = 150m
What happens below min theoretical radar range
Dead area
What effect does atmospheric conditions have on radar
Radiowaves degrades by:
- water vapour / temperature changes / pressure changes
Energy absorbed by water vapour and converted to heat
Further radar signal travels = the more atmospheric attenuation
More pronounced at high frequencies
