Novel E-Band (71–76 GHz) photodiode module featuring a hermetic grounded-coplanar-waveguide-to-rectangular-waveguide transition

This paper presents a novel concept of a hermetic E-Band Photodiode (PD) Transmitting Module for Radio-over-Fiber (RoF) applications. A commercial PD chip with 50 Ω coplanar waveguide (CPW) output is wire-bonded to a 50 Ω grounded coplanar waveguide (GCPW) based on ROGERS RT/Duroid 5880 substrate. From the GCPW board a hermetic transition that makes use of a double-slot coupling approach is designed and optimized for the 71-76 GHz band. This concept allows to efficiently coupling the electrical power delivered by the PD chip to a Rectangular Waveguide WR-12 output with an insertion loss of only 3 dB.