Best information can be found in the maintenance manuals (AMM) found in your airline in the hands of its engineers.
These manuals should specify not just what weather radar is fitted to the aircraft, but include more detail with dimensions and detailed description of usage.
The chapter on weather radar in the AMM on B737 includes so many more pages then I've ever seen in any FCOM, including the beam width of 5.4 on the airframe it referred to, its hinging, dish dimensions etc etc