Millimeter wave characteristics of intrinsic Josephson junctions with planar equiangular spiral antenna in misaligned Tl2Ba2CaCu2O8 thin film

• An intrinsic Josephson junction microbridge with planar equiangular spiral antenna is fabricated.
• The millimeter wave characteristics of IJJ in Febry–Pérot resonator is investigated.
• The strong-coupling condition is presented by simulation and experiment.

An intrinsic Josephson junctions (IJJs) microbridge with planar equiangular spiral antenna (PESA) is proposed and studied by simulation and experiment. This IJJs circuit is simulated firstly to obtain the minimum of reflection coefficient and pattern. Secondly, IJJs with PESA are fabricated on misaligned Tl2Ba2CaCu2O8 superconducting film. The millimeter wave characteristics are investigated by a Febry–Pérot resonator, which consists of a spherical mirror antenna and a plane mirror. At 37.4 GHz, the IJJs and the millimeter wave show an optimum coupling, which deviate from the simulation for only 0.004 GHz. In addition, the extent of the coupling between IJJs and the resonator is discussed at different angle for the polarization direction of the spherical mirror antenna with the microbridge. The result shows that the strongest coupling is obtained at 0–30° angle. Good conformance of measurements and simulations illustrate the effectiveness of our design in strong coupling between sample and resonator.