Installation Antennas to rotator (Tower-Mounted Antennas)

In the preferred tower-mounting configuration, the antenna Wind Loading Area must be less than 1 m2 (G-450A) or 2 m2 (G-650A), and the “K” factor (see below) must not exceed 100 (G-450A) or 180 (G-650A), where K = [Antenna Turning Radius (m)] x [Antenna + Mast Weight (kg)]. Refer to the antenna manufacturer’s specification sheet for determining the turning radius and weight of the antenna

  

Example: In this example, a 14 MHz 3-element Yagi of Turning Radius 7.5 m, Weight of 14 kg, and Surface area of 0.7 m2 is proposed for tower mounting below a 3-element 21/28 MHz trapped Yagi of Turning Radius 3.5 m, Weight of 13 kg, and Surface Area of 0.3 m2 . The mast weight is 5 kg.

 The antenna system K factor, then, is the sum of the two antenna K factors:

 K1 = K factor of 14 MHz 3-element Yagi.

K1 = Turning Radius (7.5 m) X Weight (14 kg + 2.5 kg) = 123.75

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Antenna Weight      Mast Weight (5 kg ÷ 2)

  K2 = K factor of 21/28 MHz 3-element trapped Yagi.

K2 = Turning Radius (3.5 m) X Weight (13 kg + 2.5 kg) = 54.25

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Antenna Weight      Mast Weight (5 kg ÷ 2)

 KTotal = K1 + K2 = 123.75 + 54.25 = 178

 The antenna system Wind Loading Area is: 0.7 m2 + 0.3 m2 = 1.0 m2|

 Note: In such “Christmas Tree” installations, compute the mast weight separately for each antenna, using the relative heights of the two antennas to apportion the mast weight.
Refer to the antenna manufacturer’s specification sheet for determining the weight and the surface area of the proposed antenna.

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