CRAF greatly welcomes the establishment of this forum. We are of the opinion that an expert discussion of the subject is overdue.
Radio interference from industrial sources is and has been a permanent concern for radio astronomy. Large observatories have been built in remote rural areas in order to provide terrain and distance shielding from industrial radio noise. Hence the idea of siting wind parks with fast switching power converters close to RAS stations goes against this initial protective measure and can be a direct threat to the operation of the stations.
Interference can have different origins:
1 Emissions from the equipment
2 Reflections of emissions from other stations (e.g. FS, Broadcasting, radio location) by wind power devices on shared bands overcoming current topographical shielding between the emitter and the RAS station.
3 at close range: modulation of the sky background temperature by the moving vanes of the rotor. Note that the sky background is at a noise temperature of a few Kelvin whereas the rotorblades emit at 300 K. Radio astronomy routinely measures noise temperature differences of the order of milli-Kelvins or less.
CRAF has been studying this problem for many years and there has been a workshop in Onsala (Sweden) on the subject. Please see [dead link removed] for this. We have also published a document explaining the background and proposing a guideline for case by case compatibility studies (http://www.craf.eu/CRAF-11-01.pdf and attached). Last but not least, we have presented a paper to radio scientists and engineers at the German U.R.S.I. Forum in 2012 . The peer reviewed article is also attached for your convenience.
Let me again emphasise, that we are extremely grateful for the opportunity to discuss these problems affecting nearly all RAS stations in the CEPT area and elsewhere. It will be my pleasure to participate in the new forum and I look forward to our future discussions.
Max-Planck-Institute for Radio Astronomy