There is no relationship... In an AWGN channel, the received signal is equal to the transmitted signal plus noise. There is no attenuation of the transmitted signal.

However, if you want to know how much rainfall can attenuate signals, there are experimental papers that investigate this for different types of rain and carrier frequencies. One example is "Rain Attenuation in Millimeter Wave Ranges" by Zhao Qingling, Jin Li

Actually! There is no well established relationship between any kind of attenuation and rain fall at specific frequency band signal.But severe attenuation is found at the ghz frequency signal.Eventhough , water contains leaves in plant are also the cause of signal absorption falling on it.

Actually! There is no well established relationship between any kind of attenuation and rain fall at specific frequency band signal.But severe attenuation is found at the ghz frequency signal.Eventhough , water contains leaves in plant are also the cause of signal absorption falling on it.

One of the best book for understanding radio waves propagation for wireless comm is

https://www.springer.com/de/book/9783540771241 (Radio Wave Propagation, An Introduction for the Non-Specialist by John A. Richards)

The contents is accessible even without advanced knowledge of relevant mathematical concepts (e.g. Maxwell equations)

If your interest is for satellite communications, then the reference is

https://www.springer.com/de/book/9789401170291 (Radiowave Propagation in Satellite Communications by Louis J. Ippolito)

Both books are from Springer

Dear Oludele,

welcome,

The colleagues gave satisfactory answer to your question but I want to explain some fundamental points:

- The noise is generated in the receiver and it is modeled by an input noise power at the input of the receiver.

- There is the free path attenuation which depends on the frequency of the signal and the path length.

- There is extra path attenuation due to rain and fog.

- This attenuation is measured and given in characteristic curves that can be be found in the link budget calculations in the books of microwave and satellite communications.

Best wishes

Answers here are fine, though I will point out that there is a relationship between raindrop shape and polarization-dependent loss. I don't know if you are dealing with linear or circular polarizations, nor do you mention frequency, but if it is a sensitive channel design, be aware that raindrops are generally oblate spheroids, not spheres, so there's "more water" on one axis of the spheroid than there is on the other. This can have asymmetric effects on propagation of mixed-polarization or non-linearly polarized signals. There are plenty of papers out there on it as it has been studied at least since the 1980s; here's one to get you started: Article Electromagnetic wave propagation in rain and polarization effects

can we then conclude that the SNR occasion by rain drop at the receiver of a communication is significant? Thank you every one

Oludele: As several answers have stated - there will be attenuation depending on the frequency you are using and the amount of rain you are going through (e.g. straight up to a satellite or 100 miles between mountains through rainstorms). You need to account for this attenuation in your link model, which will affect total system SNR given your receiver will contribute noise. For example, at 10 MHz rain probably won't make much of a difference, while at 100 GHz attenuation is over 30 dB/km(!!!). Curves for attenuation vs frequency for various rainfall rates can be found here: Article Rain Effects on 5G millimeter Wave ad-hoc Mesh Networks Inve...

Presuming you are using a link budget model, you need in incorporate the losses shown in that paper in your link budget. High link losses will affect link SNR; low losses will not.

A simple summary of this thread: Rain doesn't add noise, it adds attenuation. Increased attenuation will reduce SNR of your link because of reduced power at the receive chain and the receiver's own noise. That atteunation (and thus link SNR) is very strongly dependent on the frequency of the signal. Please read one or two of the references provided in this thread and I'm sure you'll find what you need. It will be impossible for anyone to provide better answers without knowing the frequencies you are using and details of the link atmospherics.