Page 166 - Satellite Communications, Fourth Edition

146 Chapter Six

z

θ g(θ, φ)

y
φ

x
(a)
z z

1 1

0.5 0.5
x-z 0.5 0.5
y-z

x y

(b) (c)
Figure 6.6 (a) A radiation pattern. (b) The beamwidth in the H-plane. (c) The beamwidth
in the E-plane.

Because the radiation pattern is defined in terms of radiated power, the
normalized electric field strength pattern will be given by 2g(
, ) .

6.8 Beam Solid Angle and Directivity

Plane angles are measured in radians, and by definition, an arc of length
R equal to the radius subtends an angle of one radian at the center of
a circle. An angle of
radians defines an arc length of R
on the circle.