Glass Fibre Antenna Poles - The Windy Files.

Fibreglass (or glass fibre) poles are, to most hams, an essential and manna-from-heaven product.  Lightweight and relatively inexpensive, they allow us to make tall verticals, quad and Moxon support spreaders, and all sorts of things in between.

This article is about making your pole last in strong winds.  For temporary use on a beach or field day, it's likely that you'll get away with just a fence post and some cable ties at the bottom.

My pole can bend dramatically at the top on occasion, but after several years in very strong winds, I think my mounting system works!

But can you use standard fishing poles over extended periods of time in windy situations, where the installation is, essentially, permanent?

The answer is an emphatic 'yes!'  It's also an answer derived from my direct experience over many years, living on an Atlantic storm-swept ridge in north Wales.

The basic installation is a 10m glass fibre pole, with the top two metre sections removed because they are too weak to carry weight.  That leaves you with a roughly 8m pole.  Now, I'm a great user of delta loops, but the story holds for any antenna, such as a vertical dipole or GP, held up at 8m or so.

Attach your pole to a half-round or square fence post.  Drive it a reasonable distance into the ground, but don't overdo it, as in the end, it's not the business end of the set-up.  Those are the guy ropes.  I find it's always necessary to level the pole vertically, then screw in lengths of timber either side parellel to the bottom section.  That stops the pole becoming lop-sided.

Attach your pole to the fence post using at least three high quality, broad cable ties.  The breadth spreads the stress a bit.  I use at least two at the upper and bottom ends of the fence post.  It's an idea to replace these every year or so, as sunlight and weather do weaken even the best ones.

Now comes the most important part - the guy ropes.  There are a number of ready-made guying rings available.  Some are better than others.  Avoid ones that are either thin, made of metal, or both.  That's because thin rings place all the stress of the windload in a small area of the pole, making it more likely to snap at that point.  Metal ones are obviously much harder than fibreglass, so unless padded, will quickly rub a cut into your pole, and early failure will ensue.  Some broad, plastic guy rings look good, but often have holes drilled too close to the edge of the outer ring, so that unless it's really tough nylon or similar, it's likely to be worn away and let your guys loose.  You can machine your own, improved ones, of course.

From experience of the 2012 winter and 2013 autumn, which has already thrown a couple of extreme wind events our way, that a fishing pole tends to snap somewhere near the middle at gusts in excess of 60mph.  The mechanism of failure is a splitting of the upper part of a section, which is where the pole is trying to prevent the section above it from bending excessively.  All things have limits!  I have now tried some very tightly wound weatherproof ducktape around the top of each section of a new pole - just a couple of wraps so that each section can still be retracted into the one below it.  This may give a modicum of added strength, or perhaps prevent very small cracks that develop over time becoming larger ones when the wind really blows.  More time will tell.  Ducktape, incidentally, is very good for repairing broken poles, provided you wrap it tightly.

But I've used only broad, high quality cable ties for the guy rings, which are tightened only lightly, and to which lightweight, UV-resistant guying rope is tied.  Use a separate cable tie for each guy rope, so that if one breaks, the others might not and give your pole some chance of surviving.  In fact, you can use two cable ties per guy rope, for redundancy.

As to the position of the guying rings, there are mathematical formulas to work this out, but usually based on metal and not fibreglass poles.  By experiment and worrying through stormy nights, I've found that attaching the guy ropes to the bottom of the fourth section up (at roughly 4m), works very well.  It stops the base from shifting around, whilst allowing the top 4m, which is thinner, to flex.  In a strong wind of 50-60mph, this bending can be dramatic!

How many guys?  Four is best, but I started with three at about 120 degree spacing, and have stuck with that number, though the third has to be moved sometimes when the wind shifts a lot.  It's not been a problem for me.

There are many types of often quite expensive guying ropes out there, so I won't recommend any as I've used only polypropylene rope and then upgraded to an unknown thinner guying rope that came with an end-fed I once bought.  Both seem to be well-suited to tolerating sunlight and weather in general.  But do check your ropes often, and use secure, self-tightening knots.

So there you go.  Real-world testing of a cheap fibreglass pole on a hill often exposed to hurricane-force winds (and I use the word correctly, not for dramatic effect!)   One other thing to look out for is the quality of your pole.  Inspect your poles as soon as you get them, looking at each section.  If any slivers of fibreglass fall out, send your pole back because it's unlikely to be of acceptable quality and will fail early.

Because it's only fair to tell others about good quality suppliers, I recommend you use Paul's Angling Supplies, who runs a shop on Ebay.  I've never had a bad pole from him, and delivery times are excellent.

Should you ever bring your pole down when set-up like this?  If the wind exceeds about 60mph for a few hours, I'd say it's worth retracting it.  Likewise, if you have a direction where the wind becomes both strong and turbulent, then retract.  Steady, laminar flows of even strong winds are much less damaging than weaker winds that swirl around a lot, buffeting your pole and rapidly shifting the forces acting on it.

Also remember to secure your pole sections.  I use what have turned out to be very high quality hand-operated jubilee (hose clamp) clips from FEP Hydraulics, who let you select just one of each size if you want; others insist on buying boxfulls of them.  For a standard 10m pole reduced to 8m, you need  one with the range 20mm, 17-25mm, 22-30mm, 25-35mm and 25-40mm.  I use strips of silicone rubber under each one, cut from egg-microwaving cups.  This has excellent non-slip properties on a pole, and stops the clip from damaging the fibreglass.

Finally, if you are using a delta loop on your pole, it's always a good idea to cable-tie the wires either side of the top insulator together.  This stops the pole slipping along the wire, rendering it likely to become bent over to one side, which is then difficult to correct and makes your set-up look amateurish.  It also means that, if the pole does break, you just need to slip off the top insulator with the delta still attached to it, stick it on a new pole and presto!  You're back on air in about an hour.