Southern Avionics Company SD100 Manual Do Utilizador
SD SERIES TRANSMITTER
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SOUTHERN AVIONICS COMPANY
antenna for land installations at frequencies below 250 KHz. The "T" Antenna is far superior at
all frequencies and should be used whenever space permits. The 50-foot Guyed Mast is recom-
mended for land installations where the "T" cannot be used. Calculated range over sea water with
the Mast Antenna and this transmitter is 40 miles at 200 KHz, increasing to 100 miles at 400 KHz.
all frequencies and should be used whenever space permits. The 50-foot Guyed Mast is recom-
mended for land installations where the "T" cannot be used. Calculated range over sea water with
the Mast Antenna and this transmitter is 40 miles at 200 KHz, increasing to 100 miles at 400 KHz.
Ideally, this antenna should be in a clear area; however, this is very seldom feasible on offshore
structures. Large obstacles close to the antenna will affect the directional properties and the tun-
ing of the antenna. If possible, the antenna should be installed with a clear area in the direction of
the most traffic.
structures. Large obstacles close to the antenna will affect the directional properties and the tun-
ing of the antenna. If possible, the antenna should be installed with a clear area in the direction of
the most traffic.
The Mast Antenna is electrically very similar to a 200 pF capacitor in series with a small resistor.
See the figure at the end of this section for a plot of the capacitive reactance.
See the figure at the end of this section for a plot of the capacitive reactance.
5.2 "H" Antenna
The "H" Antenna is used on the helipad of offshore structures where there is no clear area to
install the Mast Antenna. It is a wire structure that is installed on the perimeter of the helipad.
The transmitter is mounted directly beneath it so that the vertical portion of the antenna is the off-
shore structure itself. Electrical characteristics vary, depending mostly on the size of the helipad
but are generally similar to the Mast Antenna. Range is also comparable with the Mast in most
cases.
install the Mast Antenna. It is a wire structure that is installed on the perimeter of the helipad.
The transmitter is mounted directly beneath it so that the vertical portion of the antenna is the off-
shore structure itself. Electrical characteristics vary, depending mostly on the size of the helipad
but are generally similar to the Mast Antenna. Range is also comparable with the Mast in most
cases.
5.3 50-Foot Guyed Mast Antenna
This antenna is a guyed vertical monopole with capacitive top loading that was designed for land
installations where space is limited. The capacitive top hat consists of six 8-foot radials. The
counterpoise system consists of sixteen 60-foot radials made of #10 copper wire with 6-foot
ground rods at each end and one in the center. The antenna is guyed at the top and center.
installations where space is limited. The capacitive top hat consists of six 8-foot radials. The
counterpoise system consists of sixteen 60-foot radials made of #10 copper wire with 6-foot
ground rods at each end and one in the center. The antenna is guyed at the top and center.
The calculated range with the Guyed Mast Antenna exceeds the Mast Antenna but is less than the
"T" Antenna under the same conditions. This antenna is recommended for land installation where
space does not permit use of the "T" Antenna.
"T" Antenna under the same conditions. This antenna is recommended for land installation where
space does not permit use of the "T" Antenna.
The Guyed Mast Antenna is electrically very similar to a 300 pF capacitor in series with a small
resistor. See the figure at the end of this section for a plot of the capacitive reactance.
resistor. See the figure at the end of this section for a plot of the capacitive reactance.
5.4 Symmetrical "T" Antenna
The Symmetrical "T" Antenna is recommended if sufficient land is available. This antenna
requires a plot of ground approximately 150 feet by 350 feet.
requires a plot of ground approximately 150 feet by 350 feet.