Electron Bernstein wave coupling through the ordinary-extraordinary-Bernstein (O-X-B) scheme has been modelled for reversed field experiment-mod (RFX-mod) overdense plasmas. The compromise between constraints from plasma parameters and from a viable launcher design highlights the commercial frequency of 28 GHz as a promising candidate. At this frequency a steerable quasi-optical launch system has the flexibility necessary for tuning the optimal operational window for the O-X mode conversion. According to the results of a two-dimensional full-wave code (Köhn et al 2008 Plasma Phys. Control. Fusion 50 085018), the maximum O-X mode conversion efficiency amounts to 58% for a single pass.