A valve for communication of a measurement while drilling system includes a first structure having a central portion and one or more elongate portions radially extending from the central portion, and a second structure having one or more portions which substantially bound a central orifice region and one or more elongate orifice regions radially extending from the central orifice region. At least one of the first structure and the second structure is configured to be rotated about a rotation axis to produce a relative rotation between the first structure and the second structure such that a flow path through which mud can flow varies as the at least one of the first structure and the second structure rotates about the rotation axis. The central portion has a maximum inscribed circle encircling the rotation axis and having a first radius and the central orifice region has a maximum inscribed circle encircling the rotation axis and having a second radius greater than the first radius.