Introduction to Radar Basics - MATLAB Simulations for Radar Systems Design - page 13

v

v

v

θ

tgt1 tgt3

tgt2

Figure 1.10. Target 1 generates zero Doppler. Target 2 generates
maximum Doppler. Target 3 is in between.

v

θ a

θ e

Figure 1.11. Radial velocity is proportional to the azimuth and elevation angles.

1.5. The Radar Equation

Consider a radar with an omni directional antenna (one that radiates energy
equally in all directions). Since these kinds of antennas have a spherical radia-
tion pattern, we can define the peak power density (power per unit area) at any
point in space as

Peak transmitted power
area of a sphere

watts
m 2

--------------

P D = -------------------------------------------------------------------

(1.38)

The power density at range away from the radar (assuming a lossless propa-

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gation medium) is

P t
4π R 2

P D = ------------- (1.39)

4π R 2 where is the peak transmitted power and is the surface area of a P t

sphere of radius . Radar systems utilize directional antennas in order to

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