RF MicroElectroMechanical Systems (MEMs) circuitry(15) on a first high resistivity substrate (17)is combined with circuitry (11) onsecond low-resisitivity substrate (13) by overlapping the first high resisitivity substrate (17)and MEMs circuitry (15) with the low resisitivity substrate(13) and circuitry (11) with the MEMs circuitry (15)facing the second circuitry (11). A dielectric lid (19) is placed over the MEMs circuitry (15)and between the first substrate (17)and second substrate (13)with an inert gas in a gap (21)over the MEMs circuitry (15). Interconnecting conductors (25,31,35,37,39,41) extend perpendicular and through the high resistivity substrate (17)and through the dielectric lid (19) to make electrical connection with the low resisitivity substrate (13).