The STO-0520300-T-E1 from ERAVANT is a Vector Network Analyzer Extender with Extended Frequency 150 to 220 GHz, Input Frequency 12.5 to 18.33 GHz, LO Frequency 12.5 to 18.33 GHz, Output Power -5 dBm (Test Port), Input Power 0 to 6 dBm (LO, RF). More details for STO-0520300-T-E1 can be seen below.
