Fiber Optic Cabinets, Cables, Pedestals and Terminals

It’s funny, but one thing I find myself doing as I am driving all over this country (and others for that matter) is looking at cell towers and seeing how they have changed over the years. The most obvious is the amount of antennas that are being added to the towers. I have to wonder just how the original engineer saw these towers being equipped and if he ever foresaw this increase in both loads and capacities.

I’ve been talking with people around the industry and have found that this is a very real problem. Tower loading in both the weight, as well as the wind shear, has become a very big deal. If you think about it, it’s not just the antennas themselves, but each of these has to be fed by a very large (usually about 2 inch diameter) cable. What occurs is loading of the tower in two different ways. Physical load: the cables can weigh as much as 2 pounds per foot. Wind load: thinking about it, a set of 2 inch wide cables serving 15 or so antennas…that’s 30 inches wide by the height of a tower…let’s just say 300 ft. That makes one big sail! So not only does the tower have to handle the increased weight, but also the lateral loading of the wind. This can cause some unbelievable stresses on the tower structure.

One answer to both problems is actually kind of simple: Clearfield’s FieldShield Microduct and Fiber. The nice part to this answer is that it decreases the weight of the cables by some 1000 percent (FieldShield microduct weighs .0314 lbs per foot) and decreases the wind loading almost completely, while providing bandwidth that cannot even be attained by the traditional copper cables.

A 10mm diameter microduct can house up to 24 fibers. One fiber has more capacity than all the copper cables combined! That is like removing the wind loading of a sailboat and reducing it to that of a feather… and giving increasing speed from that of a horse and buggy to a rocket!

Now, there are two schools of thought on how to deliver fiber up the tower. One is a hybrid cable that houses both the power conductors (6-8) and the fiber to feed the antennas (6-12). These are housed in a cable that is sized like a standard coax. The other is to run diverse legs of both fiber and power.

I happen to be fan of diverse legs since copper is prone to lightning strikes and the fact that the two technologies really require different types of technicians. The problem lies when a copper conductor is hit, it will destroy the fiber as well. FieldShield being dielectric isn’t affected by a lightning strike, so it really isn’t at risk. But by combining it with the power, we have just put it at risk. And we all know that our customers are not going to put up with loss of service for very long!

By running diverse legs up the tower, we can substantially diminish the potential for service interruption to the customer. Simply have a primary power leg and a secondary leg (run on different locations in or on the tower) and then a single (multiple fibers) FieldShield run up the tower for communication connectivity. This way, if one of the power legs is taken out by lightning, it can be quickly switched to the secondary leg. Then, a maintenance window can be used to replace the bad power leg. The fiber is not affected in any way. The point is to have uninterrupted service for our customers…so it would make sense to take measures to protect the components of the network..

And besides, as I’m driving down the road, staring at cell towers…Well, they will just look better.

So, take a look at Clearfield’s FieldShield family of products and see if we can unload something for you.

By Scot Bohaychyk