Advice

What do I choose? Tower or mast?

Main difference between towers and masts is comfort of use and amount of space needed for installation. There is an economy to consider as well. In general towers are more expensive than masts at the same height, but take up much more space. So decision here is: do I buy/rent more land and save on the construction (cheper mast) or do I buy more expensive tower and save on parcel size.

Some other factor is service cost. Masts need much more attention  – frequent servicing is advised, guy wires tension must be regulated, u-bolts changed, and finally if something goes really bad – the chance is that mast will fall down. Towers are less human dependent. We check bolts once in couple of years and see if welds are still okay and that’s it. It’s rather unusual for the tower to fall down even if badly injured.

Towers (especially T1000 series with internal ladder) are quite comfy to use. Range of additions like safety platforms, outer platforms make service people life on the tower even nicer. This is not the case with masts, especially other than M1000.

The final word here is about nature. In some regions (eg in Germany) you cannot use guy wired constructions due to risk for birds. Then tower might be the only possibility.

 

Are welded constructions any better than bolted?

A big communication towers form problems with transportation. For example Altruss H32 tower has base size of 4,5 by 4,5 by 6 meters. Not an easy piece to drag on a higway. Most of our constructions are hybrid  – lower sections are bolted, and upper (small ones) welded. Welded sections are quicker to install on site, and less things may go wrong with them during installation, but they are more prone to frost cracking, and welding errors. Bolted sections are little more expensive to manufacture and take more time to assembly, but transportation is cheaper and easier, plus there is nothing that may go wrong with them when assembled (bolts may become rusty after couple of years, but not much more).

As for stiffness (that is common concern) they perform the same. Bolted constructions show advantage when they are done with the job in one place (easier to disassemble and sell, or bring to another location)

Why do I need separation crown?

The main reason to use separation crown is to separate antennas from each other accordingly to producer specifications. Antennas have backward radiation that may lead to interference and high noise bed. Because electromagnetic radiation force decreases with the square of the distance, even small separation is sufficient to improve the situation.

Second task of a separation crown is increasing the mast torsional stiffness (with additional set of guy wires). Truss masts are quite robust for vertical forces (inherit feature of a truss), average for horizontal forces (thanks to guy wires), and relatively non resistant for torsional forces (hence idea to help here). Twisting is most problematic during high winds and service jobs. This is especially problematic for radiolink, because it may interfere with or even break connection.

How do we attach antennas the smart way?

Telecommunication mast, as each truss construction has nodes or joints, that are the most robust places in the whole structure.  Every force we use on the mast shall concentrate around these nodes, no matter if during building or choosing a place for guy wire mounting points or finally when mounting antennas. The node is a place where cross members meet on the corner pipe.

 

Service of mast and tower, why sould I bother?

Masts and towers, both aluminum and steel are constuctions of high risk. Damage may cost loss in property or even life, so it is good to service your mast before it breaks.

Aluminum masts are resistant to corrosion, but not so much to frost cracking. Once each year, in spring preferably, qualified personel should chceck for any signs of frost damage. Any cracks found shall be welded, some poles echanged for new, and drainage patented. Altruss masts are well prepared to handle unwanted water, so less prone to frost cracking.

Second issue –  guy wires. In older installations it was usual to use 3 mm wires. Most of them were zinc-plated years ago and now are very fragile because of corrosion. We recommend usage of good quality guy-wires 1×19 type, minumum 4 mm made in Europe  – even for smallest masts.

Third thing is guy wire tension – this has to be corrected due to natural wire wear that results in wire lenght increase. Always chceck with mast producer what amount of tension shall be used. If possible measure it (some tensors have a gauge for this).

Aluminum towers are much more robust and require less work. All that has to be checked is: signs of frost cracking and corrosion to the bolts. Once in 5-10 years a verticality check is suggested (done by land surveyor). As gound under the towers settles unevenly the whole tower may change its centre of gravity. This can be changed with correction rings.

In case of steel constructions a anti-corrosion checek must be conducted, and any stained spots must be repaired. During u-bolts change (and other metal on metal components as well) we shall take under consideration electrochemical potential of used materials. High difference here may lead to amazingly quick corrosion that may be dangerous for the structure rigidity.