COSMOS helps antennas withstand the elements

Company EMS Wireless Industry Electrical/Electronics Location U.S.A. Product Used COSMOSDesignSTAR Type of Analysis Linear Static Frequency Analysis Thermal Analysis More Details

The Challenge
EMS Wireless, a division of EMS Technologies, Inc., is the performance leader in RF solutions and the largest base-station antenna manufacturer in the United States. EMS Wireless creates antenna families that include the smallest profile antennas with improved RF performance. The EMS Wireless AcCELLeratorT series re-packages the three sectored triangular structure commonly seen on towers into a cylindrical structure no more than 36" in diameter. This approach allows even a three-sector site to be camouflaged as a flagpole, which is popular with zoning boards requiring unobtrusive cell site structures.

The challenge was to design a structure that would allow two AcCELLerator structures to be stacked in a flagpole design. In order to ensure consistent, reliable performance from EMS Wireless antennas, engineers needed to rigorously test each part of the structure against the elements, especially excessive wind. Anything less than accurate design analysis might produce parts that could hinder antenna performance and thereby require expensive and time-consuming re-tooling.

The Solution
EMS Wireless engineers were tasked with designing a structure that would support wind loading of 100 mph. They ensured robustness and reliability by performing static finite element analyses (FEA) using COSMOSDesignSTAR.

The EMS Wireless team used FEA to optimize the parts during the design phase, before expensive hard tooling was ordered. After creating the model in Autodesk Mechanical Desktop, EMS Wireless used COSMOSDesignSTAR to analyze the deflection, stress and strain of the assembly.

The AcCELLerator support structure is a weldment of extruded and machined components. The main structural member, a triangular extrusion, requires an expensive extrusion die that would be costly to re-tool. Three gussets are also extruded with a similar die. EMS Wireless needed to ensure that the structure would be structurally sound-before tooling was ordered. Also, this structure needed to limit deflection (to less than two inches) to avoid damaging the antennas enclosed in the assembly.

Sara Phillips, mechanical project engineer, EMS Wireless, used COSMOSDesignSTAR to prevent design errors by doing 'what if' analyses on this welded assembly. These analyses helped Phillips optimize the profile of the triangular extrusion to improve the strength and reduce the weight.

Summary and Metrics

• Optimized profile of triangular extrusion to improve strength and reduce weight.
• Realized substantial savings in time and cost.
• Analysis time on a complex analysis was two-thirds of competitor's product.

"The ease of setting up problems makes it effective to use COSMOSDesignSTAR even on a simple analysis." Sara Phillips, Mechanical Project Engineer