The ATc20-21.5 from Narda-ATM is a RF & Microwave Circulator with Frequency 20 to 21.5 GHz, Average Power Forward 2 W, Peak Power 50 W, Insertion Loss 0.3 to 0.4 dB, Isolation 22 to 24 dB. Tags: Coaxial Circulator. More details for ATc20-21.5 can be seen below.