propagation attenuation in radar

[senmeis]

Hi,

I want to calculate the power of a radar signal at the target. By now I have the equation:

PtGt/4πR²: power density

But I have to accoount for the propagation attenuation. I searched some materials and found it’s relative complicated. Are there any formulars with which this can be done. The arguments are: frequency, elevation and altitude.

Senmeis

 

[jiripolivka]

Hi,

I want to calculate the power of a radar signal at the target. By now I have the equation:

PtGt/4πR²: power density

But I have to accoount for the propagation attenuation. I searched some materials and found it’s relative complicated. Are there any formulars with which this can be done. The arguments are: frequency, elevation and altitude.

Senmeis

Propagation attenuation in a free space is calculated from the formula

L = 4 pi(R/lambda)squared for a

communication link (one-way), so in the case of a radar it must be taken twice (instead of 10 log you take 20 log).
Instead of the frequency, here is wave length. Elevation is irrelevant.

Then in case of precipitations there is an additional loss. Look in literature for details. There is not only the loss but also the dispersion and water emission, now the elevation becomes important.

 

[senmeis]

What you said is just free space attenuation which is already included in my formula. What I want is following:

Attenuation due to H2O and O2: frequency dependent
Attenuation in the troposphere: elevation dependent
Attenuation due to rain and fog

Senmeis

Propagation attenuation in a free space is calculated from the formula

L = 4 pi(R/lambda)squared for a

communication link (one-way), so in the case of a radar it must be taken twice (instead of 10 log you take 20 log).
Instead of the frequency, here is wave length. Elevation is irrelevant.

Then in case of precipitations there is an additional loss. Look in literature for details. There is not only the loss but also the dispersion and water emission, now the elevation becomes important.

 

[jiripolivka]

All those are functions of frequency and elevation, rain-cell size, etc. It is not possible to give you details, find radar books treating the problem.
Skolnik, for example, and there are many more modern sources. Try Google to find some.