Specifications

SG-231 MANUAL
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
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longer. In addition, the SG-231 is just as happy feeding a conventional V antenna as an
inverted V. The coupler is flexible in this regard.
4.1 Antenna Selection
The automatic antenna coupler will operate into almost any end-fed antenna with a
length of 2.5 meters or more, provided an effective ground is used. The antenna
efficiency will be proportional to length and in most applications will be maximum at a
length of 1/4 wavelength. This means that the longest possible antenna should be
selected for each installation.
Very short antennas are only recommended when there is no other alternative such as
in a vehicular mobile installation. The performance of short whip antennas is usually
very poor, particularly at the lower frequencies, and radiation efficiency will be only a
few percent of a full sized antenna. However, a special electrically long antenna such as
the SG-303 9-foot mobile antenna overcomes much of the radiation problem.
4.2 Whip Antenna
2.0 TO 3.0 Meters (7 to 9 feet)
This antenna is recommended only for vehicular mobile installations. The short length
will result in poorer performance compared with the longer antennas. A special high
performance 9-foot antenna, the SG-303, is manufactured by SGC specifically for this
problem. (SGC Part Number 55-27.)
7.0 to 8.5 Meters (28 feet)
This antenna is recommended for marine installation on smaller vessels. It may also be
used in base stations if there is no way of using a longer antenna. The SG-203 is this
type of antenna. (SGC Part Number 55-23.)
10.7 Meters (35 feet)
This is the preferred antenna for marine installation when there is no room for a long
wire antenna. It will also provide reasonable efficiency for base station use and is the
shortest recommended base antenna. (SGC Part Number 55-24 for the SG-204 35 foot
whip antenna.)
4.3 Long wire Antenna
23 Meters (75 feet); 46 Meters (150 feet)
For most applications, the long wire antenna will give the best results and is
recommended when practical. The diagrams at the end of this section show some
recommended methods of installation. These are only a few of the many possible
methods of installation, and frequently a different configuration will be the best at a
particular site. SGC’s long wire antenna, 60 feet in length, provides efficient operation
on low frequencies and high frequencies alike. (SGC Part Number 55-10.)