High-Q end-coupled half-wave coplanar line resonators are fabricated by using EuBa2Cu3O7-δ film sputtered on a MgO substrate. The maximum loaded Q value is 4500 and the unloaded Q value is 12500 at 28 K and 3.9 GHz. The surface resistance Rs is estimated from the Q values and the lowest Rs value is 28 µΩ at the same temperature and frequency. This value is two orders of magnitude lower than that of Cu. The minimum Rs sensitivity in the measurement with a coplanar resonator is also discussed. The estimated sensitivity is lower than 10 µΩ below 10 GHz.

High-Tc superconducting flux flow transistors were fabricated with co-evaporated thin films of YBaCuO. The vortex flow channels (2 µm in width) and the device patterns were formed by Ar ion milling. The three-terminal characteristics, vortex flow characteristics, transresistance, and current gain of the device were measured. The AC input-output characteristics of the device with an Au load resistor were also measured. The measured flow voltage, transresistance and current gain are discussed in relation to these AC input-output measurements.