Surface and Volume Clutter - MATLAB Simulations for Radar Systems Design - page 281

where x m is the median of the random variable x , and σ is the standard devi-

ation of the random variable ln () .

The Weibull distribution is used to model clutter at low grazing angles (less
than five degrees) for frequencies between and . The Weibull proba-
bility density function is determined by th e Weibull slope parameter

1 10 GHz

a (often

tabulated) and a median scatter coefficient σ 0 , and is given by

b x b

– 1

x b
σ 0

 

f () = -------------- exp – ----- ; x ≥ 0

(6.45)

 

σ 0

where b = 1 ⁄ a is known as the shape parameter. Note that when b = 2 the

Weibull distribution becomes a Rayleigh distribution.

6.5. ÐMyRadarÑ Design Case Study - Visit 6

6.5.1. Problem Statement

Analyze the impact of ground clutter on ÐMyRadarÑ design case study.
Assume a Gaussian antenna pattern. Assume that the radar height is 5 meters.
Consider an antenna sidelobe level and a ground clutter coef-
ficient . What conclusions can you draw about the radarÓs
ability to maintain proper detection and track of both targets? Assume a radar
height

SL = – 20 dB

σ 0

= – 15 dBsm

h r ≥ 5 m .

6.5.2. A Design

From the design processes established in Chapters 1 and 2, it was determined
that the minimum single pulse SNR required to accomplish the design objec-
tives was when non-coherent integration (4 pulses) and cumula-
tive detection were used. Factoring in the surface clutter will degrade the SIR.
However, one must maintain

SNR ≥ 4 dB

SIR ≥ 4 dB in order to achieve the desired prob-

ability of detection.

Figure 6.11 shows a plot of the clutter RCS versus range corresponding to
ÐMyRadarÑ design requirements. This figure can be reproduced using the
MATLAB GUI Ðclutter_rcs_guiÑ with the following inputs:

Symbol Va l u e Units

sigma0 -15 dB

thetaE 11 (see page 45) degrees