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View Full Version : The effects of Harmattan, Kamsin or other dust storms on linking systems


Liam
07-02-2008, 05:05 PM
Does anybody have any information on the effects of dust storms on RF propagation?

The articles I've managed to find state it has a similar effect to rain fade, but none of them provide a tangible or quantifiable way of calculating what this loss is likely to be.

Is it fair to assume that the effects will be reduced at frequencies below about 5GHz?

Thanks in advance guys,

Liam.

Lars H-L
07-24-2008, 09:35 AM
Dust storms may have great effect on RF propagation (fading on microwave links) but this is due to refractivity changes of the air mass, not attenuation by the dust particles. Strong fading is so caused by atmospheric side effects (multipath, duct entrapment).

The attenuation by the dust content per se for a given optical visibility (dust mass density) increases with radio frequency and water content of the dust particles. Assuming a visibility of 10m (severe dust storm) the attenuation is reported to be 0.1 dB/km at 10 GHz for 10% by mass water content of the dust particles (high water uptake).

See also a previous thread initiated by Thato (search on "dust storms").

Liam
07-27-2008, 10:00 AM
Has anybody managed to find any further information on this?
I found the following article which may prove of interest: http://journals.tubitak.gov.tr/physics/issues/fiz-03-27-2/fiz-27-2-8-0211-7.pdf

Liam
07-27-2008, 10:02 AM
Thanks for the information Lars.

Lars H-L
07-31-2008, 05:27 PM
I found this short article about the strong fading during Harmattan:

Leontakianakos, A. N.: "C-band clear air propagation and ducting in coastal West Africa", IEE Electronic Letters 1996, Vol.32, No.25, pp. 2331-2333 (see www.ietdl.org/EL).


I have looked into the other article fiz-27-2-8-0211-7.pdf concerning the Harmattan in Nigeria, but I find it misleading - at the least. I am surprised that it has managed to get published.

Liam
08-12-2008, 02:50 AM
Thanks again Lars.

I've just sent Dr Leontakianakos an email. Perhaps he can suggest some other articles of interest.

There doesn't seem to be a lot of information regarding Harmattan available in the ITU-R recommendations either.

If I hear back from Dr L I'll post an update.

Hossam_El_Meadawy
12-14-2008, 11:17 AM
I am wondring about the importance of studing such phenomina if it only occures once a year for 5-6 hours or so, this rare occurance and small duration would not affect our calculation, ie you are not going to invest double the amount of money to enhance the availability during these couple of hours.
Since you don't plan for a 100% availability then you can withstand some errors and these should be one of them.