IMHO it should be plastic material or fiberglass or another material capable of letting TR/RX cells of the Phased array radar to be sent and receive it back.A very interesting pic,as it seems to highlight the differences in materials used in the radar turret section of the mast.The same also looks to be the case for the small cylindrical antenna on top of the mast extension.
The top cone it is again the same ECM equipment you can see in F76 Jamaran, Pakistanese origin (Chinese).
All in all it is a great achievement for IRIN. And most important, seems another unit in Bostanu shipyard will share same main radar and systems. I told two years ago that IRIN must standarize all their equipment. They must be capable of holding a large Naval Academy and homologue training crews with main systems, subsystems and weaponry and being capable of deployment in differents units in case of repairing or combat damage in any ship of the fleet.