In this paper, the concept of a fully photonics-based multiband radio-frequency transceiver is presented. In the proposed architecture, the precision, wide bandwidth, and flexibility of the photonic technologies allow generating and detecting simultaneous multiple wireless signals in an extremely wide frequency range, up to the millimeter waveband. This approach is therefore promising for future wireless base stations that will need to handle huge data traffic distributed on several different transmission protocols, while minimizing the hardware components. In the proposed system, the capability of easily treating multiple signals simultaneously, and the architecture based on a single pulsed laser for both the transmitter and the receiver sections, permit to reduce the complexity of the transceiver while increasing its functionalities, with a potential benefit in terms of system costs. The paper details the principle of operation of the proposed solution, and describes the implementation of a dual-band wireless transceiver simultaneously working in the X and S bands. The results from the characterization of the transceiver and from its verification in a wireless transmission experiment confirm the potentials of the solution and set the basis for a new paradigm of RF transceivers.