3-6
Figure 3-3.—Parabolic radiation pattern.
Figure 3-4.—Basic paraboloid reflector.
You may see several variations of the basic paraboloid reflector used to produce different beam
shapes required by special applications. The basic characteristics of the most commonly used paraboloids
are presented in the following paragraphs.
Truncated Paraboloid
Figure 3-5A, shows a TRUNCATED PARABOLOID. Since the reflector is parabolic in the
horizontal plane, the energy is focused into a narrow beam. With the reflector TRUNCATED (cut) so that
it is shortened vertically, the beam spreads out vertically instead of being focused. This fan-shaped beam
is used in radar detection applications for the accurate determination of bearing. Since the beam is spread
vertically, it will detect aircraft at different altitudes without changing the tilt of the antenna. The
truncated paraboloid also works well for surface search radar applications to compensate for the pitch and
roll of the ship.
