X-Band Low Noise Figure T/R Switch-Module Using a Superconducting T/R Switch

We have developed an X-band low noise figure (NF) T/R switch-module using a superconducting T/R switch. The superconducting T/R switch was realized by combining a six-port network, two impedance transformers and two varactor diodes. The six-port network consists of oneλ/4 transmission line, two λ/2 transmission lines and one 3λ/4 transmission line. For each λ/2 transmission line, a single varactor diode was connected to the center of a given λ/2 transmission line by using one of the aforementioned impedance transformers. The superconducting T/R switch was fabricated using a high-Tc superconducting material called YBCO. An insertion loss of 0.3 dB was measured in Rx mode. By combining the superconducting T/R switch with a limiter and a low noise amplifier (LNA), a low NF T/R switch-module was designed. Measurements performed at X-band show an NF of 0.7 dB, which confirms the design procedure of a low NF T/R switch-module.