The LNF-CIC4-12B from Low Noise Factory is a Single-Junction Cryogenic Circulator that operates from 4 to 12 GHz. It has an insertion loss of 0.3 dB with an isolation of 20 dB. This circulator can handle an input power of up to 1 W (~30 dBm). It has been designed to meet the strict requirements of ultra-low temperature physics research and has a gold-plated OFHC copper body to ensure minimum loss. It is available in an industry-standard slim module that measures 21.46 x 16.00 x 10.16 mm and has SMA (female) connectors.
