radio interference from wind farms

This is slightly off topic for wireless LANs but may be of interest for other types of wireless.

UK has lots of fixed link microwave and radio / TV transmitters, so the regulator had some field trials done to see what the effect of all that spinning metal in a wind farm might have on the signals.

At the moment wind farms are built out of the path of fixed wireless links, but it is difficult to do that for a TV or radio broadcast transmitter.

wind farm radio interference

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brings a whole new meaning to multi path.....

Regards

Stephen

Reply to
Stephen
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The "study" does not even touch on tower and blade construction methods.

Most wind machines have composite blades, no significant metal components except in the fixed tower and even many of these are now filament wound composite.

Reply to
News

Ok - my fault for not knowing that.

doesnt seem to make the thing radio transparent though.

Reply to
Stephen

In fact, it does a great job of that.

Reply to
News

I never could download the PDF. It hung at about 50%. I tried it on several computers with identical results. All the previous pages on the Ofcom site work, but not the PDF download:

Can someone email me a copy?

Yep. Officially, the blades are "pultruded glass-reinforced plastic" also known as fiberglass:

The blades are fairly transparent to RF, but not totally. Depending on the filler and additives used, the blades can act as an RF absorber. While not as dramatic as a rotating metal blade, a rotating absorber will have some slight effect on RF reception, especially in weak signal areas.

Cute little blades:

Reply to
Jeff Liebermann

Scented:-)

Reply to
bod43

just sent you an email with it attached....

Reply to
Peter Pan

They also affect ATC radar.

Reply to
Geo

And the paint on them.

Reply to
Bill Kearney

A study was carried out in the UK in 2002. The report is available in four parts at Even then they identified 13 different manufacturers and 37 different designs.

Reply to
LR

: >The blades are fairly transparent to RF, as an RF : >absorber. While not as dramatic as a rotating metal blade, a rotating : >absorber will have some slight effect on RF reception, especially in : >weak signal areas. : : They also affect ATC radar.

Likely that is a bit of self servicing misinformation from the anti groups. I would more expect a claim against Doppler wind sheer detection devices and perhaps weather radar.

On that note: I see lots of weather radar reports from all over but not one mention of any notice of a wind farm. Recall weather radars are designed to detect things that go round and round.

Reply to
NotMe

Negative. In a particular case in the North of the UK a major airport's radar system has been moved about 20 miles from the airport to reduce the problems created by a large windfarm.

Reply to
Geo

Jeff loves the smell of solder in the morning.

Reply to
Neill Massello

Nope. The BWEA (British Wind Energy Assoc) is a industry group representing the interests of wind power producers in the UK.

One would expect their report to reflect their self-serving interests.

Nope. Wind shear radar works on two levels. One beam points high, while the other points low. If there's any differential doppler shift between the two beams, it's wind shear. Everything else is ignored including doppler effects that only appear on the lower beam, as would be the case with wind turbine induced doppler.

Wind shear detection in aircraft is mostly by IR (infrared) detection (i.e. temperature stratification at different levels). I think this may be the patent:

Incidentally, the largest source of doppler interference to ATC radar is from vehicles moving on elevated roads (i.e. freeways). One of the minor reasons that ATC radar is usually located on high mountain tops is to avoid ground clutter and doppler returns from objects moving on the ground.

Sorta. ATC radar is easy as all aircraft are require to have transponders and encoding altimeters that squawk whatever the tower assigns. When outside the TCA (tower controlled airspace), they squawk 1200. Unless someone install a transponder on a wind farm, it should be easy to distinguish a wind turbine from an aircraft.

While there may be some flashes and shadows caused by wind farms, unless its on the approaches, the tower isn't going to be overly concerned as they're always in the same location. ATC radar has an "ignore this" feature, where a simple stab of the light pen, will either blank or reduce the sensitivity in the selected area.

The NOAA weather radar photos are heavily massaged. I once attended a talk which included before and after images. There's quite a bit of air traffic flying over the SF Bay area, which has to be removed from the doppler weather radar photos before posting. There were plenty of other artifacts on all the radar images that were subsequently removed with image processing.

Thanks to all those that sent me copies of the Wind Farm Report PDF. I still don't know exactly what happened. I cleared the browser caches and vaporized the temp directory for IE and Firefox on both my machines, and was able to finally download the PDF. Weird. I'm still reading it (87 pages).

Incidentally, using a wind turbine tower as a cell site or telecom antenna farm has been proposed, tested, and patented. I know of only one such installation. One would think that if the blades were detrimental to RF transmission, such an arrangement would not work:

Reply to
Jeff Liebermann

Sorta - but in the UK not all light aircraft (yet) have to have a transponder.

Unfortunately the specific wind farm which resulted in the radar facility having to move is on high ground and occupies (estimated) 120 degrees of the available

360.
Reply to
Geo

It has been considered and that the developer of the windfarm would have to sponsor the consultation and costs. "5.3.2 Mandatory Transponder Carriage areas Any operational mitigation requiring a change to current airspace rules is likely to require full regulatory consultation. Consultation would include the effects on other airspace users as well as any environmental, business and cost impacts on anyone affected. Should any developer consider this approach, they will generally be expected to sponsor and initiate all consultation and cover all costs. For a Mandatory Transponder Carriage area to be effective mitigation, the size of a particular development may still require the removal of wind farm clutter displayed by the Primary radar. This is not only to prevent aircraft identification labels from being obscured by the clutter but also to manage the human factors issues associated with pronounced displayed clutter and the impact on controllers? efficiency."

ATC in the UK also have certain contractual obligations to the Mod so one cannot allow the possibility of a low flying target being obscured in windfarm clutter. It may be that extra Radars have to be provided.

Reply to
LR

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