Rain attenuation at X band

Hi all,

I need to design an X band Radar with a range of 100Km,

i was calculating the effects of rain attenuation for my frequency and found that the SNR will degrade at the range required.

also i read that the Circular polarized wave has lesser attenuation in rain..!

if it is the case can u please help me with dB/Km attenuation for the circularly polarized wave at 10 GHz ?

Use search engines - the results will overwhelm you.
Separate those articles aimed at region rain prediction, raindrop size for the region type, etc. You want the real deal in RF numbers.

Rain attenuation is not an exact science, and the models are based on experience/measurements. Different models vary, but do quite closely agree. Do not expect <1dB agreement, and you could well see as bad as 2.5 dB, though this is unusual.

There are 4 generally respected models .. CCIR, Medhurst, Ryde, and Crane. All cover X-Band. You can find them.

Somewhere I have a chart in a very old journal from generations before me. If I find it, we might extract a value. Designing your worst case from a straight dB/km number may have its problems, but I can understand your main interest is the radar - not the darned rain! :)

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Here is something like what you want.

Thank you for replying,

i have calculated the Loss due to rain and the results were alarming !

I got a attenuation of

14 dB/Km for 100 Km range with Horizontal polarization , 12.1 dB for vertical polarization and 13 dB for Circular polarization!

what did you expect ? ;) anything from a couple of GHz and up moisture in the air becomes more and more significant

Wait till you try 24GHz, over a 100km path on a sunny day, you can have no signal at all till the humidity drops below 50%
I could see the station's location through, the binoculars, at the other end of the 100km link but couldnt get a 24GHz signal through once the humidity got to ~ 40 - 45%, the signal was there


Dave

I also heard about X band its very useful and beneficial. I generally use TNC Attenuators as it is very well-known.