The design and use of a simplified, highly efficient, waveguide-based wireless distribution system are provided. A low-loss waveguide is used to transport wireless signals from a signal source or sources to one or more receiver locations. One or more adjustable signal coupling devices partially insert into the waveguide at predetermined locations along the length of the system to provide variable, controlled extraction of one or more wireless signals. Low-loss impedance matching circuitry is provided between the waveguide coupling devices and output connectors to maintain high system efficiency and the capability of supplying signals of high strength and quality to a large number of receivers in a wide wireless coverage area via a plurality of signal radiators. Some embodiments of the system are adaptable for wireless distribution service in HVAC plenum spaces while others disclose the combined functions of fire extinguishing and waveguide wireless distribution.