Sentinel-1 dual polarization decompostion was not right?

after i have done the H Alpha Dual Pol Decomposition using the s-1 slc data,i made an analysis,but i found that:
the water alpha was between 50-79 and the entropy was very high, is that right? I think the alpha should be between 0-45 and the entropy should be very low.
hope someone can help me ?thanks alot.
the decompositon show as follow:

here are some notes on dual-pol decomposition: H-Alpha Plane Problems
Have a look at the HAlpha plane in SNAP. You will see that all pixels lie within the valid range but their distribution to different scattering zones is just not as effective as with quad-pol data.

I also had similar problems.The following note may help you.