Development of Longitudinal Coupling Impedance Measurement Platform for BEPCII

A coaxial line impedance measurement platform is developed for BEPCII under the collaboration between Tsinghua University and IHEP. A pair of gradual change impedance matching section is designed and fabricated by numerical control milling machine. The special designed RF connector is applied to strengthen the inner conductor. The algorithm of TRL calibration is applied in the system to avoid the usage of a reference pipe for each device under test. The measurement is accomplished by a VNA under the control of the software written in LabView.