Weather radars and health problems
17 March 2016 – “Omega News”, by Georgiy Ostroumov, Ph.D., microwaves, Finland
Weather radars send directional pulses of microwave radiation, on the order of a microsecond long. Between each pulse, the radar serves as a receiver as it listens for return signals from particles in the air. The duration of the “listen” cycle is on the order of a millisecond, which is a thousand times longer than the pulse duration.
The radar uses a series of typical angles (elevation angles of an antenna). After each scanning rotation, antenna elevation is changed. This scenario will be repeated on many angles to scan all the volume of air around the radar within the maximum range. Usually, this scanning strategy is completed within 5 to 10 minutes to have data within 15 km above ground and 250 km distance of the radar. The radars use angles ranging from 0.3 to 25 degrees.
Due to such angles (about 0.3 degrees) the radiation of the radar can easily penetrate into many living houses. Unfortunately in many cases there are no reasons to elevate antenna beam over the living houses because static obstacles often cannot disturb work of the radar. It is very bad that a big town may be the “static obstacle” too.
On the contrary, rotating blades of wind turbines often lead to essential mistakes for the radar. The wind turbines having appeared in Kotka (Finland), the antenna beam of the radar was elevated. At least power density(exposure) was reduced from 300 mW/m2 to 20 mW/m2 at fixed measurement place.
I have a friend who suffers even from weak microwave radiation. In this connection she is forced to live far from typical sources of the radiation. Some times ago she said that she began suffering from some new source of the radiation. When she moved to live into low place her negative symptoms disappeared. Unfortunately this place was not suitable for living especially in winter.
About the same time the newest weather radar started working. Distance of the radar to her home was about 100 km. She wanted to know whether the radar was cause for her suffering. Radiation and Nuclear Safety Authority in Finland (STUK) answered that maximum exposure of the radiation from the radar was 0.3 % of the national limit ( limit of the ICNIRP). This response was unable to help her. Thus she had to leave home to another place (often only, a caravan in winter forest).
Whether exposure of the radiation from the radar can lead to health problems if person lives at distance about 100 km to the radar ? To answer this question we need a reliable limit for long-term exposure of the radiation. I think that nowadays only the limit1(0.1) mW/m2 for long-term exposure worth using ((Resolution 1815, Parliamentary Assembly, Council of Europe,http://assembly.coe.int/nw/xml/XRef/Xref-XML2HTML-en.asp?fileid=17994&).
I could not help calculating.
If radiation power of the radar is 250 kW(peak) and antenna gain is 40 dB, the power density can be 20 mW/m2 at 100 km to the radar. Thus, the radiation might be detrimental, even if the distance is over 100 km from the radar!
How about 0.3 % ? It means “only” 30000 mW/m2. Here is no mistake in my calculation. The ICNIRP has permitted special limit for the radiation from the radar in thousand times as much as usual limit!
I suppose the most typical symptom from such radar can be tinnitus because the duration of the “listen” cycle is on the order of a millisecond.
Thus, if a country is using a network of these radars, health problems are possible for whole population of the country.
Georgiy Ostroumov, Ph.D., microwaves, Finland