ection 2
Placing the System
The computer equipment and antenna(s) should be placed as close to each other as
possible to minimize radio signal loss and interf e rence. The computer and re c e i v e r
should be adjacent and easily accessible to an exterior wall and electrical outlet.
Locate the equipment so that is protected from water, sinks, and gas jets. The equip-
ment should be accessible to users but placed so that electrical and cable connec-
tions won’t be disturbed.
The antenna(s) will be located on the roof, away from power lines, electric motors,
and exhaust vents. The antennas should be grounded to a cold water pipe in order to
drain atmospheric static charges and to protect the computer and receiving equiment.
P o l a r-orbiter System Antenna
Antennas for polar-orbiter systems should be located at the highest point on the
building, away from surrounding objects such as air conditioning units. The antenna
can be attached directly to the building or mounted on a weighted plywood base.
Either technique re q u i res a standard exterior TV antenna mast and associated
mounting hard w a re. To mount the antenna, use a TV mast support tripod and bolt
the tripod to a 4' x 4'x 3/4"sheet of exterior-grade plywood. Place at least thre e
50-pound bags of cement or gravel on the plywood sheet for stability. If using bags
of cement, poke several small holes into the top of the bag to allow rain to wet the
c o n c rete and provide additional stabilization.
G e o s t a t i o n a ry System Antenna
Antennas for geostationary systems re q u i re an unobstructed, direct line-of-sight path
to the satellite. A geostationary ground station typically uses a six foot parabolic
reflector known as a satellite dish. (A TV satellite dish may be used but re q u i re s
sophisticated modification.) The satellite dish should be located on a flat ro o f.
Installation will be dictated by the desired mounting, but the mounting platform or
s t ru c t u re for the dish must be secured to prevent the dish from moving in the wind.
It should be weighted, as above.
A Yagi antenna may be used to receive geostationary images and should be installed
a c c o rding to the manufacture r ’s instru c t i o n s.
F e e d h o rn
A feedhorn is a metallic cylinder which collects the radio signal reflected from the
satellite dish. The feedhorn, available as either an open or closed cylinder, contains a
p robe which is the antenna. The closed feedhorn prevents birds from nesting and
p rotects the antenna from snow and rain. The feedhorn is mounted on a stru t ( s )
that positions it at a specified distance from the parabolic re f l e c t o r.
SE T T I N G- UP
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