Input coupler for the KEKB normal conducting cavity

The input coupler for the normal conducting RF cavity of the KEK B-factory (KEKB) was designed comprising a disk-type coaxial ceramic window and a door-knob transition. We designed two different types of window structure; one is a choke-type structure and the other is a under- and over-cut structure. The fabrication of two types of coupler is underway in order to confirm the RF properties.