SINCLAIR ANTENNAS NAMING CONVENTIONS
HOW TO CHOOSE A CLAMP
This guide lists the Sinclair clamps available for most standard antenna installations. Each column identifies one or more clamps by the Sinclair number and indicates whether these are suitable for use with round support pipes or tower legs, 60 degree angles, 90 degree angles, or other mounting situations. For ease of reference, similar antennas are grouped together, as are similar clamps. An extensive range of non-standard mounting hardware is also available on a special order basis. If you have any other requirements or need further assistance, consult your Sinclair representative. Before ordering clamps or mounting hardware for your particular requirement, consider whether a professional review of all relevant factors is necessary. The information contained in this document is provided for reference only: the customer is responsible for compliance with all applicable engineering and safety standards and regulations. Click here to download the Sinclair Clamp and Side Mount Selection Guide.
SINCLAIR ANTENNAS WIND LOADING STANDARDS
The below listed standards and methods are used to calculate the Survival Wind Velocity and all other related moments, stresses and deflections:
Telecommunications Industry Assoc., Minimum Standards for Communications Antennas, Base Station Antennas.
TIA-329-C (August 2003)
Rated Wind Velocity-The Rated Wind Velocity and Loading for antennas is calculated using industry standard TIA-329-C. The calculation for rated wind velocity determines the maximum wind velocity at which the mechanical stresses in the antenna are below the yield point of the materials by a safety factor of not less than 1.65 as specified in 5.1.2 of the standard.
Rated Wind Velocity calculated using this methodology is the wind speed at which an antenna can endure sustained exposure without failure.
Survival Wind Velocity- The calculation for Survival Wind Velocity determines the maximum wind velocity at which the mechanical stresses in the antenna components are just below the allowable yield strength of the mast, boom and dipole material. Survival Wind Velocity calculated using this method is the wind speed at which an antenna cannot endure sustained exposure over longer periods of time without experiencing some degree of material deformation or malfunction. Inspection after the survival wind speeds is recommended.
Notes on how to calculate flat plate equivalent areas and horizontal wind thrust for antennas specified in Sinclair published catalogues. FPE is defined as the flat plate area that would result in the same wind load as the antenna under the same wind condition. To determine the flat plate equivalent area is to multiply the drag coefficient by two thirds of the projected area of a structural member.
1) The Flat Plate Equivalent Area, ft²: FPE= Cd 2/3 A, published value.
Where: FPE, is the Flat Plate equivalent Area, ft² 2/3, conversion factor for flat surfaces areas. A, is the projected area Cd, is the drag coefficient. The standard values for drag coefficients, CSA-37-94: For round members Cd=1.0 For flat plates Cd=1.5
Note: The drag coefficient is difficult to determine, it varies with the shape, aspect ratio and surface roughness of the antenna or its structural members. Published text book or data from standard associations i.e. CSA-37, TIA/EIA may be used for this calculation, however the most reliable drag coefficients are experimentally determined by wind tunnel trails. For the selection of the drag coefficient Sinclair makes use of both sources.
2) Calculation of Horizontal Thrust or Wind Load (W):
The horizontal thrust or wind loading is the product of the flat plate equivalent area (FPE) and the wind velocity pressure (P) which is expressed in pound force, Lbf.
Calculating the Wind Load acting on Antennas:
W= P (FPE), in Lbf.
Where: P, is the wind velocity pressure in pounds per square foot, lb/ft² FPE, is the Flat Plate Equivalent Area, ft² (see paragraph 1)
Calculating the wind velocity pressure, TIA-329C:
P=KV2, in lb/ft²
Where: K, is the wind conversion factor, a nominal value of K for pressure on the projected areas of flat surfaces is 0.0042. V, is the stated maximum wind velocity in miles per hour, mph.