A method and apparatus for improving a performance of a system. The coaxial cable comprises an inner conductor and an outer conductor surrounding the inner conductor, wherein the inner conductor comprises a first feed point connecting the connecting portion and a second feed point connecting the radiating portion, one part of the connecting portion is shortened serving as a shortened section between the first and second feed points. The pitch bearing has a first rolling element arrangement between the outer ring and the centre ring, and a second rolling element arrangement between the centre ring and the inner ring, wherein at least one of the first and the second rolling element arrangements includes at least two rows of rolling elements. 0 MPa; orb) a hardening temperature of from \u221220\xb0 C.