The D4C3742 from DiTom Microwave is a RF & Microwave Circulator with Frequency 3.7 to 4.2 GHz, Average Power Forward 20 W, Peak Power 50 W, Insertion Loss 0.25 dB, Isolation 23 dB. Tags: Coaxial Circulator. More details for D4C3742 can be seen below.