A wireless communication system for closed environments including a plurality of antennas parallel line coupled to the coaxial cable of a coaxial cable radio frequency transmission system. Each RF coupler assembly includes a quarter wavelength long conductor positioned between the center and outer conductors of the coaxial cable. The conductor is supported by a conductive bar clamped to the exterior of the coaxial cable, and is axially aligned to the cable and insulated from the center and outer conductors by the cable's dielectric core. The conductor is connected to a radiating or non-radiating element which transfers RF energy between the interior of the coaxial transmission cable to a point at which an antenna or other coaxial cable line can be attached.