Dawnco 8060 Series, Инструкция по установке и эксплуатации

Страница: 35 / 155

____________________________________________________________________________________________
____________________________________________________________________________________________
42S042G
SERIES 8060 6-METER EARTH STATION ANTENNA
4-1
SECTION 4 FOUNDATION INSTALLATION
(180° MOUNT)
GENERAL The pointing accuracy of the installed antenna is determined by the
stiffness of the mount, the reflector, and the foundation. Therefore,
antenna foundation preparation is an essential part of antenna
installation.
ANTENNA
CONSIDERATIONS
The foundation heading is critical to the performance of the
motorized antenna, but not to the performance of the non-
motorized antenna. The foundation heading establishes the center
of azimuth travel.
Proper electrical grounding shall be provided by the installing
contractor to meet local applicable codes. Depending on local soil
conditions, this may take the form of a buried grid or a suitable
copper stake. The antenna mount shall be electrically connected to
the ground.
Provisions must be made to provide suitable support for power,
RF, and control cables either by buried conduit or overhead
raceway. If conduit is supplied, it shall be at least 3 inches in
diameter. Lightning arrestors must be provided across all cables
leaving the antenna per applicable local codes and N.F.P.A. codes.
(Refer to Section 2 for information on required operational
clearances.)
FOUNDATION
DESIGN
CONSIDERATIONS
The antenna is designed to withstand an effective velocity pressure
of 31 pounds per square foot (151.4 kg/m2) in any orientation, or
40 pounds per square foot (195.3 kg/m2) if stowed. These
pressures represent 110 and 125 mile per hour (176 and 200
km/h)winds respectively at standard air at ground level. The
foundation should be designed to maintain the antenna integrity
under these same loads, with a safety factor of at least 1.5, and also
to not allow the mounting plane of the three antenna feet to tilt
more than 0.15°.
The loading for the above conditions is presented in Tables 4-1 and
4-2. Figure 4-1 depicts the sign conventions for the tables. The
loads for each mounting foot are listed in Table 4-1 and the
resultant foundation loads are listed in Table 4-2. If loads are
required for wind pressures other than those listed, they may be
calculated from the information in the tables using the following
procedure: