The automatic shielding is a powerful feature in Shapemaker that reduces the wind loads on ancillaries when they are positioned behind one another. When ancillaries are clustered closely, those located behind others experience reduced wind exposure. This feature calculates the reductions automatically, helping users achieve more accurate and efficient tower analyses.
Shapemaker uses the method presented in TIA-222-I, Section 2, Figure 2-13: Shielding Limitations and automatically finds the effect of shielding for each ancillary and then calculates the shielding factors. The shielding factors are calculated in each direction and for each ancillary, considering their size and position in space.
The examples below illustrate how shielding is automatically applied in simple arrangements. Shapemaker can handle complex ancillary configurations, including multiple antennas, equipment, and supporting steel mounts, with wind from any direction. In such dense arrangements, it automatically evaluates the potential shielding effects for each ancillary. However, if the exact shielding impact on a specific ancillary cannot be clearly determined—due to excessive overlap or uncertainty in spatial relationships—the most conservative applicable shielding factor already calculated is used. This ensures safety without overstating the shielding effect.
Example 1
Small antenna/equipment behind large antenna
Shielding Factor Calculation:
Ka_A3 = ( (1130 - 756) x (1 - 0) / (1512 - 756) ) + 0 = 0.5
Shapemaker report shielding factor values:
Example 2
Large antenna behind small antenna/equipment
Shielding Factor Calculation:
Ka_A1 = 1 - (Area_A2) / (Area_A1) = 1 - (420 x 342) / (2438 x 378) = 0.84
Shapemaker report shielding factor values:
Example 3
Large antenna behind small antenna and inside partial shielding zone
Shielding Factor Calculation:
Maximum shielding effect: 1 -A2/A1 = 0.84
Minimum shielding effect: 1
Ka_A1 = ( (1030 - 684) x (1 - 0.844) / (1368 - 684) ) + 0.844 = 0.922
Shapemaker report shielding factor values:
