kwaigonegin
Colonel
Why wouldn't the mast be a major contributor to RCS? Given the curvature of the earth, the hull wouldn't be visible to other shipborne radars until they're only a couple dozen kms away, while the mast would be visible from much farther distance. I'd think that mast stealth would be more important, and the 055 appears to have significantly improved mast stealth.
From an academic standpoint you are correct. The mast height or the height of the highest object as it correlates to the curvature of the Earth plays a critical role in returning the RF energy. A typical SSR has a range of 30-50 Nm again because of the limitations of the Earth. Obviously the higher the target object is and the higher the broadcasting node is plays a critical role in the searches.
From a real life argument however things are not always so clear cut. First off we just do not know how effective the RF shielding is of that mast (if any) or even if it's made from some exotic anti stealth material or if it even has any stealth coating/paint etc.
While generally speaking an enclosed mast is certainly 'stealthier' than a regular mast we just do not know how much stealth shaping or materials is involve in 055s mas aside from the fact that is is enclosed. My guess is not much again because 055's primary role is not as a stealth warship. And you are incorrect in saying that the hull is the ONLY big thing that return RF energy. Even if we assume the mast is 100% stealth (which it isn't) there are plenty of things above the hull that will return conventional RF signatures like the weapons mount (CIW, HQ-10 etc), the gun and the antenna that sits atop the main mast and the helo.
2nd/3rd point. In any modern warfare if a ship relies strictly on her own non OTH radar to find the opfor she might as well be as good as dead. Again no ship in any modern navy would rely strictly on that for target acquisition or to bug out because of the limitations of the Earth's curvature. You are also forgetting OTH which now bread and butter of most modern navy. Earth's curvature is becoming less and less important with OTHRs, satelites and obviously airborne assets.