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Which Antennas Can Be Attached?
The size and type of antenna(s) that can be attached to this rotator will differ widely, depending on the
installation method, local terrain, and the maximum expected wind speeds at your location.
The following pages describe typical antennas which are acceptable for installation with the G-450A or
G-650A. The discussion below assumes maximum wind speeds of 30 meters per second (67 mph/108
kph), and it is recommended that you include a safety margin of at least 30% to account for higher wind
gusts or other factors which might potentially cause damage to your installation.
l Pole-Mounted Antennas
Mounting of the rotator on a pole or mast results in a significant de-rating of the size of the antenna
which can be mounted, due to the tremendous bending forces applied to the rotator's clamps. For
pole mounting, the attached antenna must have a net mounted weight (combined weight of antenna
plus mast) of 10 kg or less, and the product of multiplying the [Antenna Wind Load Area (in m
the [Height of the Antenna Mast (in m)] must be 0.25 or less (see Table 1 and Fig. 1).
[Antenna Weight] + [Mast Weight] £ 10 kg.
[Antenna Wind Load Area] ´ [Height of Antenna Mast]£ 0.25
Refer to the antenna manufacturer's specification sheet for determining the weight and the surface
area of the proposed antenna.
For a 50 MHz 5-element antenna of surface area of 0.3 m
Example
specifications for pole mounting will be met if (A) the antenna is mounted on a mast
not longer than 0.8 m (0.3 ´ 0.8 = 0.24 <0.25), and (B) if the mast weight plus the
antenna weight is less than 10 kg. However, if the mast is 1 meter long, the specifica-
tion will be exceeded (0.3 ´ 1 = 0.3 >0.25).
Band
Elements
(MHz)
7
2-element
1-element, w/loading coils
7
2-element, w/loading coils
7
3-element, w/loading coils
7
14
3-element
14
4-element
14
5-element
3-element
21
21
4-element
21
5-element
21
6-element
2-element, Swiss Quad
21
These are approximate values; Wind Loading Area will vary significantly depending on element
and boom diameters.
4
Less than 0.8m
Mast Clamp GC-038B (option)
Example of a 50MHz Band, 5-Element Yagi Antenna
Table 1: Wind Loading Areas for Common Antennas (Typical)
Area
Band
2
(m
)
(MHz)
3-element
2.2
28
4-element
0.2
28
5-element
0.6
28
2-element, Swiss Quad
1.1
28
3-element, trapped
0.7
7/14
4-element, trapped
1.2
7/14
3-element, trapped
1.7
14/21
4-element, trapped
0.45
14/21
0.6
21/28
3-element, trapped
0.8
21/28
4-element, trapped
3-element, trapped
1.3
14/21/28
4-element, trapped
0.3
14/21/28
Area
Band
Elements
2
(m
)
(MHz)
0.3
50
0.42
50
0.6
50
0.3
50
0.5
144
0.8
144
0.4
144
0.5
144
0.3
430
0.4
430
0.4
430
0.5
430
2
)] by
2
(see Table 1), the above
Area
Elements
(m
4-element
0.25
5-element
0.3
6-element
0.37
2-element, Swiss Quad
0.3
10-element
0.2
10-element, stacked
0.44
10-element, x 4
0.95
10-element, x 4 x 2
2.0
12-element
0.06
12-element, stacked
0.12
12-element, x 4
0.3
12-element, x 4 x 2
0.6
2
)
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