Precise high frequency measurement method without connectors for small diameter coaxial cable

We had developed a high-quality flexible coaxial cable with a diameter of less than 1 mm. It is difficult to carry out precise measurement using the conventional coaxial connectors that are commercially available because this small-diameter coaxial cable has a specific structure. Therefore, we have proposed a precise high frequency measurement method for determining the characteristics of a small-diameter coaxial cable without expensive connectors. In this method, a time domain reflectometry (TDR) measurement system and a microwave vector network analyzer (VNA) are used with a microwave probe station. The cables are molded using resin and cut vertically with a cutting tool. The surfaces of the cable edges are polished to obtain a good electrical contact. In this measurement method, a 40 GHz microwave contact probe was used on the microwave probe station. We have experimentally demonstrated the precise measurement of the characteristics of 0.8-mm-diameter coaxial cables. The impedance distribution and S-parameters were successfully evaluated by TDR and VNA measurement respectively.