Two antennas are provided in a base station, one antenna AT1 is arranged at the root of a right handle grip 1R and the other antenna AT2 is arranged at the root of a left handle grip 1L. The controller can change the variable write parameter to compensate for a transient temperature profile of the head during the initial stage of a write operation. The under-bump-metallurgy layer comprises an adhesion layer, a barrier layer and a wettable layer.