Characteristics of high power capability for high temperature superconducting microwave multiplexer

A high temperature superconducting (HTS) multiplexer consisting of two branch line hybrids and two identical parallel-coupled-line type bandpass filters was fabricated with a center frequency of 10.9 GHz and a bandwidth of 100 MHz. We used single sided YBa₂Cu₃ O_7-δ (YBCO) epitaxial thin film on MgO substrates prepared by using in situ pulsed laser deposition. Electric connection between adjacent multiplexers was easily done with a microstrip transmission line at the terminations so that the size and weight of the multiplexer could be significantly reduced. The multiplexer showed approximately 0.8 dB insertion loss and 100 MHz bandwidth in a range of -10 dBm to 30 dBm. We observed the third order intercept at 94 dBm and the fifth order intercept point at 86 dBm by using intermodulation distortion (IMD) measurements at T=80 K. Our results demonstrate the possibility of realizing a narrow band HTS multiplexer for high performance