4 - RADAR Ranges

Question 1

Maximum Detection Ranges

Answer 1

Function of:

1. R_OTH - Based on Line-of-Sight
2. R_unamb - Based on PRT/PRF
3. R_max - Based on return signal strength

Smallest value of the three is the Maximum Detection Range

Question 2

Over-the-Horizon Range (R_OTH)

Answer 2

Max Line-of-Sight between a target at height H_T and RADAR (H_R)

Question 3

Max Unambiguous Range (R_unamb)

Answer 3

The maximum accurately calculated range of a contact

Unambiguous: Return of echo prior to transmittal of next pulse

Ambiguous: echo from first pulse arrives after second pulse sent

Question 4

Max Range (R_max)

Answer 4

Determines if the return signal has sufficient strength to be identified as a contact

Question 5

Directive Gain (G_dir)

Answer 5

“Directivity”

• Ideal ratio of beam’s intensity compared to intensity of omnidirectional propagation
• Assumes all energy is concentrated within BW

Question 6

Power Gain (G)

Answer 6

Actual ratio of spherical spreading losses compared to power contained in the beam

Question 7

RADAR Cross Section

Answer 7

Determined by:

• Material
• Aspect Angle
• Size
• Shape

Question 8

Minimum Signal for Detection (S_min)

Answer 8

Minimum P_received required by the RADAR to detect a return signal

If contact range goes further, Power received goes down and is less than S_min therefore No detection