I'm looking to build a loop antenna from a continental design that suggests using a particular type of plastic water pipe. It's made with a thin layer of aluminium between the plastic interior and the plastic exterior.

Not sure what the aluminium is for when the pipe is used for plumbing. It might be for heat insulation or as a barrier to stop muck leaching into the pipe. Seems unlikely to be for electrical safety.

Anyway, whatever the lining is for, this type of cheap bendy pipe is recommended as an easy way of making broadband loop aerials. The diameter doesn't matter much – ideally minimum 15mm but not too big (say 30mm) because fat pipes are harder to bend. The main objection to doing the job with ordinary copper water pipe is cost plus the extra difficulty of bending copper pipe into a perfect metre diameter circle. As it's an antenna, it's best to avoid joints.

I found a single supplier on the internet who confirms his rather pricey pipe has an aluminium shield but it's a trade wholesaler. It's a dead end. However, there are lots of plastic barrier pipes on the market that might be aluminium lined, but their specifications don't confirm it. To save me being arrested in B&Q for attacking pipe ends with a Stanley knife does anyone know of a source in the UK?

Thanks,

Dave

Excellent thank you! Michael's link takes me to a nice picture of the stuff:

And David's suggestion of Dekabon aka Synflex looks right too.

AN Other is definitely describing the right stuff – interesting it's commonplace and cheap in Europe and more expensive & unusual in the UK. Pro-warm is about a pound per metre. Possibly our versions are a higher grade for underfloor heating & instrumentation and the household version hasn't caught on here.

Thanks to Brian and Neil but those suggestions don't quite hit the target. In this particular type of broadband antenna the inductance of the loop should be as low as possible whilst enclosing the largest possible area. Consequently the loop should be a single round turn of a large diameter conductor made of either copper or aluminium.

As there are two or four loops in each antenna so I'm looking for about 20 metres, more if I experiment.

Many thanks for the info – now I know it can be bought I can look for bargains!

Cheers,

Dave

PS If anyone has 20 metres of 3" diameter copper tube left over from making a model loco boiler, I'd willingly pay £20 to take it away…

Edited By SillyOldDuffer on 09/12/2018 18:48:14

Edited By SillyOldDuffer on 09/12/2018 18:48:54

Now that's given me an idea – I live in the country and a farmer has abandoned a few off-cuts of blue pipe after re-plumbing a cattle-trough. If it's aluminised I can try one of the local agricultural suppliers.

Ta,

Dave

Thanks Vic, the more brand-names the better. Stuff is so much easier to find when you know what it's called!

My main concern now is that the UK stuff looks to be heavier and more expensive than the thinner version sold abroad. If it's too stiff I might as well use copper pipe. Typical – when you want a basic item you can only find quality and when you want quality you can only find basic…

Dave

I think a trip to Wickes is called for. The pipe's spec on John Guest's website dosn't say what the barrier is made of, just that it's blue. Could be anodised aluminium or perhaps a different type of plastic. Wickes stock a different make that might be aluminium: again the maker doesn't say so. Apart from checking for Aluminium it would be useful to see how easy the large sizes are to bend.

Got all excited looking at discarded farm water pipe, there's about 10 metres of 28mm diameter dumped in the hedge. Slight problem, it's plain plastic with no barrier of any kind as used by Larry's red-necks…

If I bite the bullet and order a 50m roll I can guarantee finding a skip full of the stuff within days!

Dave