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Wind Load-Schmind Load – Why Kathrein’s Updated Wind Load Values Impact Your Bottom Line

                                                                 

Wireless tower structures are going through a bit of an overhaul as mobile operators move to densify their networks and keep up with subscriber demands.  As coverage and capacity needs continue to soar, operators are deploying increasingly more infrastructure – specifically higher port base station antennas, small cells, fiber connections, and specialized mounts.  All this equipment adds load to the towers, not only due to their size but also in regard to dynamic loading caused by wind. The result is towers are reaching their limits in terms of load capacity. Therefore, understanding the impact of wind loading is critical to your tower design choices and resultant affects to lease costs and ultimately your bottom line. 

Until recently, comparing wind load values between manufacturers was not an apples to apples exercise.  It could be confusing at best.  Even though most manufacturers  “adhered” to the EN 1991-1-4 standard, the procedures were not uniform or even conducted with the same wind speeds.  In early 2016, with Kathrein’s leadership in the NGMN working group, antenna manufacturers developed a methodology for calculating wind load values consistently and accurately with the goal of implementing into future revisions of the BASTA standard. As a result, it will be easier for mobile operators to accurately compare values when evaluating antenna selection and the impact to their networks.   

So what is wind load and how do wind load factors impact the densification of your network? What is the methodology for calculating wind load, and how does this impact your bottom line?  We explain why and how Kathrein is reporting dramatically reduced wind load values.

What is Wind Loading?

Wind loading is a measurement of the force or drag that wind causes when blowing against a tower mounted antenna.  Manufacturers report both frontal and maximum wind load values for every antenna they make.  Wind load values are represented as XXXX N where the N represents a Newton (which is one kilogram meter per second squared).  The U.S. measurement is listed in pounds of force (lbf). Think of an antenna on a tower as a sail on a ship.  The size and shape of the antenna affects how much wind drag that antenna places on the tower structure.   As with golf, a lower number is a very good thing.

In the mid 2000’s, the European Standard for Wind Load Calculations was updated with the introduction of the EN 1991-1-4 standard.  Like other antenna manufacturers, Kathrein bases its wind load reporting on this standard.  Until the BASTA meetings in 2016, Kathrein had been very conservative with its reported wind load values.  After the meetings with other leading manufacturers concerning the testing and reporting of wind load values, Kathrein has revised wind load calculations and values based on the latest, more accurate methodology.  

What Changed?

Antennas are not perfect rectangles, and wind doesn’t always hit a base station antenna straight on (orthogonally). Taking these facts into consideration, new calculations are being used in compliance with the standard based on an antenna body with a rectangular cross section with rounded-off corners.  Wind tunnel tests have shown that the results obtained from previous calculations, based on the standard, are considerably higher than the real wind loads.

Since it’s too expensive to test every antenna in a wind tunnel, manufacturers report wind load values based on the standard formula: Fw = cf ∙ Aref ∙ qp, where the wind load, Fw, is the product of the force coefficient, cf, the projected area Aref (m2), and the dynamic pressure qp (N/m2). 

While the formula remains the same, the change is in how the force coefficient, cf, is calculated.  It now includes a radius reduction factor, Ψr , that accounts for antenna cross sections with rounded edges- which are more aerodynamic. The more favorable the shape for the airflow, the smaller this value.  As for wind speed, manufacturers have agreed to test wind load at 93 mph (150 km/h).

The bottom line: the new method of calculating wind load has proven to more accurately reflect real world wind conditions and antenna body characteristics, resulting in trustworthy wind loading values that can be calculated without the need for further wind tunnel testing.

Kathrein’s Updated Results:

Due to the radiation-optimized shape of Kathrein’s base station antennas, the revised wind load calculations show reductions from 5% – 40% or more across the board, proving that Kathrein’s previously documented wind load values were far too conservative.

Here is a sampling of the results:

Wind load of 80010865, 6-Port Antenna (377mm wide):

  • using the original method:           Maximum 1210 N (272 lbf) | Frontal 1160 N (260 lbf)| 
  • using the improved method:       Maximum   730 N (164 lbf) | Frontal   630 N (142 lbf)|
  • 46% reduction in frontal, 40% reduction in Maximum Wind Load Specification 

Wind load of 80010965, 8-Port Antenna (508mm wide):

  • using the original method:           Maximum 1650N (371 lbf) | Frontal 1270N (186 lbf) | 
  • using the improved method:       Maximum 1140N (256 lbf) | Frontal  1130N (254 lbf)
  • 11% reduction in frontal, 31% reduction in Maximum Wind Load Specification

To confirm the revised wind load calculations, third party tests were carried out in the wind tunnel at Dresden University.  Not only did they confirm the new results, but showed that the frontal and maximum wind load values are the most important for describing the behavior of an antenna in the wind flow.  

If you would like more information on Kathrein’s wind load results, and a complete list of wind load values for all current base station antennas, go to https://www.kathreinusa.com/wind-load/

Kathrein USA Meets Austin, Texas

It has been a busy start of the year for Kathrein USA with the Verizon IBTUF Event and the Kathrein USA Quarterly Sales Meeting both taking place in awesome Austin Texas, the “Live Music Capital of the World”  –  nice change of pace from the usual Las Vegas craziness for tradeshows.  The two events also had a common theme:  How to Meet the Challenge of Growing Mobile Data Usage by Supplying Strategic Solutions (such as Kathrein USA’s antenna and filter products).

Kathrein USA’s Inaugural IBTUF 

It was Kathrein USA’s first time attending IBTUF (In Building Technical Users Forum), and the tenth IBTUF hosted by Verizon Wireless.  It was an unqualified success, as this Verizon specific show had exhibits and technical presentations on par with the best industry tradeshows. 

The Kathrein booth was not the only one featuring Kathrein antennas- ConcealFab, located down the hall, also featured Kathrein antennas with the ConcealFab enclosures designed for Passive Intermodulation (PIM) performance and mechanical integrity – a great fit for Kathrein’s antennas and filters.   

There were numerous discussion opportunities among vendors around the best way to combine complementary products for Verizon’s  densification initiatives.  As an example, CablCon provided an immediate “consultation’ for new jumpers with 4.3-10 DIN connectors that Kathrein needed for a Verizon trial in Detroit the following week. 

KUSA booth at IBTUF

Kathrein USA’s booth at IBTUF

Of all of the IBTUF presentations, a favorite was “Spectrum – Where are We? Where are we Headed?” with Scott Townley, Fellow, Network Technology, RF Technology Planning, Verizon.  Scott gave indications of future directions of the Verizon network and what Verizon vendors need to do to meet those needs.  Starting with the fact that mobile data usage will increase fivefold over the next five years, Scott showed the need for network densification to properly handle this increasing data demand.

Scott went on to reveal the “densest square mile” in various cities requiring network densification – Western US cities that many in the audience believed to be quite spread out, such as Los Angeles, San Diego, Phoenix, Seattle and Denver. According to Scott Townley, “Microcell is happening” almost everywhere (not just in the biggest cities).  Kathrein’s new small cell antennas and filter solutions fit nicely with this widespread need for network densification.

Scott Townley presentation for IBTUF

Scott Townley- Spectrum Presentation: IBTUF

 

RF solution providers, such as Kathrein USA, were very interested in Tom Bell’s (Anritsu) presentation that made a clear case for the importance of improving PIM, as more carriers are added at each site as network densification occurs.   Tom pointed out additional challenges, such as Intermodulation products derived from the new FirstNet spectrum, that will be added for public safety considerations in future network designs.  Again, Kathrein is leading the way with PIM performance by constantly improving manufacturing techniques and using components like the 4.3-10 DIN connector (all of which Kathrein tests extensively in the lab and in the field before deploying).  To view a video explaining how Kathrein solves PIM issues with the 4.3-10 connector, click here.

Austin- The Perfect Place for a Quarterly Sales Meeting

After IBTUF, Kathrein USA remained in Austin to kick off 2016 with our Annual Sales Meeting.  This continued the theme of Kathrein USA supporting the wireless industry with new products to provide solutions for increased mobile traffic needs in the coming years.  Kathrein’s innovative Product Roadmap, with new small cell antennas alongside existing macro and higher port size antennas, fits the bill for the densification of networks.    

The Sales Meeting included the Executive team, Regional Sales Managers, Marketing, Technical Support, Sales Engineering and Customer Service; employees from all over the United States and Rosenheim, Germany.  One of the most anticipated sessions was Stefan Kohl’s Kathrein Product Roadmap.  Mr. Kohl,  Kathrein Germany’s Head of Sales for Mobile Communications, laid out an exciting plan for new solutions and updates to existing solutions. 

Stefan Kohl at KUSA sales meeting

Stefan Kohl, Head of Sales-Mobile Communications, Kathrein

For the Small Cell and oDAS antenna products, there are many new developments for existing antenna designs.  Kathrein’s lineup of Slim Pole antennas, Smart Pipe antennas, “Super” Canister antennas, F-Panel antennas and the new Kathrein Street Connect antenna all have product enhancements in 2016.  The classic Canister antenna is now going into production with extended high band frequencies to extend performance to 2690 MHz.  There are also plans to extend the Slim Pole and Smart Pipe antennas to the lower frequency bands.  The latest Kathrein Street Connect antenna system provides a great solution for difficult zoning situations and will be deployed in the United States this year after successful trials in Switzerland.  The current version of these antennas can be viewed in the Kathrein Catalog.  Kathrein has also continued research and development on their line of Filter products to support and supplement the antenna products. 

Concurrently, Kathrein development proceeds full steam ahead with its roster of macro cell antennas featuring 8-port, 10-port and 12-port antennas, as well as improvements to existing antennas (e.g. starting preparation for the 600 MHz auction).   Kathrein macro cell antennas, with increasing numbers of ports, allow for increased network data requirements in their own way by increasing the spectrum possibilities and carrier aggregation. Again, Kathrein Filter products play an important role in providing a complete system solution. 

At Kathrein USA, the motto is “Work Hard, Play Hard”, so after a full day of informative presentations and meetings, the team enjoyed an evening of “Top Golf”, regardless of their golfing ability. 

KUSA employees at Austin capital building

KUSA Executives, Sales, Engineering, and Marketing teams at the Texas State Capital in Austin

top golf montage

Ron Zielke, KUSA CFO and longtime employee takes his golf seriously, Cisco Ortiz, Sales Engineer and newest KUSA employee, not so much. Scott Nagel, Content Marketing Manager, perfecting his Dr. Jekyl jelly filled donut.

 

 

Both the Verizon Wireless IBTUF and the Kathrein USA Communications Sales Meeting highlighted the importance of Kathrein providing new antenna and filter solutions for the ever increasing mobile data demand in 2016 and beyond.