Surface and Volume Clutter - MATLAB Simulations for Radar Systems Design - page 279

π 5
λ 4

----- K 2 Z

η =

(6.37)

where the weather clutter coefficient Z is defined as

N
∑

D i 6

Z =

(6.38)

i = 1

In general, a rain droplet diameter is given in millimeters and the radar reso-
lution volume is expressed in cubic meters; thus the units of Z are often

millimeter 6 m 3 expressed in ⁄ .

6.3.1. Radar Equation for Volume Clutter

The radar equation gives the total power received by the radar from a σ t tar-

get at range R as

P t G 2 λ 2 σ t
4( 3 R 4

S t = -----------------------

(6.39)

where all parameters in Eq. (6.39) have been defined earlier. The weather clut-
ter power received by the radar is

P t G 2 λ 2 σ W
4( 3 R 4

S W = -------------------------

(6.40)

Using Eq. (6.31) and Eq. (6.32) in Eq. (6.40) and collecting terms yield

N
∑

P t G 2 λ 2
4( 3 R 4

π

--- R 2 θ a θ e c τ i
i

S W = --------------------

(6.41)

= 1

The SCR for weather clutter is then computed by dividing Eq. (6.39) by Eq.
(6.41). More precisely,

S t
S W

8σ t

( SCR ) V == ------ -----------------------------------------

(6.42)

N
∑

πθ a θ e c τ R 2 σ i

i = 1

where the subscript V is used to denote volume clutter.