Disclosed are passive reflector radio communications systems, such as for UHF frequencies or greater than UHF frequencies, and related deployment systems and devices that provide underground communications. Embodiments of the system include reflector elements to provide passive radio communications, structural frameworks to support and orient the reflector elements, methods for calculating reflector size, shape, and position corresponding to a desired wavelength, and deployment methods and devices to install the communication system at a desired location. The passive reflectors can be placed in a folded or otherwise compact mode, for transport into underground tunnels. Once at the desired installation location, the system can be installed, with the reflectors positioned appropriately for the radio frequencies used at the location. Some of the embodiments include any of vertical or horizontal foldable reflector poles, reflective sheets, reflective mesh sheets and/or ropes, inflatable reflective pucks, and rapid deployment systems and methods.