A wave guide assembly for a control and diagnostic system for a machine, the wave guide assembly includes a housing defining an exterior surface and an internal cavity extending between distal ends. A wave guide is defined within the internal cavity. At least one open conduit is defined within the internal cavity providing a space for routing conductors through the housing. A fluid passage is defined within the internal cavity separate from the wave guide. A control and diagnostic system for a machine and a gas turbine engine are also disclosed.