Electromagnetic Wave Propagation Through Rain

Rating:
Summary: Difficult to Follow, Overly Empirical
Review: To start with, the title is really something of a misnomer. A better title would be "Empirically Estimating Long Term Attenuation Statistics of Terrestrial Radio Links". His results do not extend beyond radio frequencies and they are difficult to apply to anything other than terrestrial links. And he does not really provide much insight into EM wave propagation so much as empirical parameters which are difficult to validate.

Better for a tutorial on the subject of interaction of radio waves and the atmosphere is: Doppler Radar and Weather Observations by Richard J. Doviak, Dusan S. Zrnic or any of a number of books on radar meteorology. Apologies to the communications community but the radar guys have the most thorough treatment of the field, because it is the object of their study, rather than merely an impairment.

Crane's claim to fame is that you can use his book (and included Excel file) to make predictions about link availability for radio and radar installations. One shortcoming is trying to extend his result to other than surface to surface and surface to satellite links. It's possible, but I don't believe he's much help.

There is a similar ITU model and either is about as easy to use. I do not believe that one is decisively better than the other. Your choice of model may depend more on you institutions prejudices and traditions or your customers' "comfort level" with either model.

One problem with this book, IMHO is that its "derivations" are overly empirical and difficult to extend. (I do not think I am being uncharitable in expressing the opinion that they are mathematically unsound in places and the mathematically unsound derivations often depend on physical assumptions which he never really justifies.) I've seen people produce extremely slipshod analyses based on misapplication "Crane's model." And these results, inherited at third hand and barely understood, become gospel. Admittedly this is not so much the fault of Crane but of his would-be disciples.

Another problem is that his models are not easy to apply, as presented, one needs to depend on his spreadsheets. (This is Crane's fault.) It is difficult to extend his spreadsheet to mobile platforms, such as aircraft and ships. It would be nice to have the climate zone boundaries in tabular form so that one could model such platforms as they move around the earth.

The ITU models are more or less the same, the parameters and zone boundaries are different. Use whichever you're comfortable with. If you need to make ballpark estimates of link availability Crane's spreadsheet should be fine. If you want to learn about electromagnetic wave propagation through rain, go elsewhere.