Structural health monitoring (SHM) has been proven effective to prevent catastrophic failures. However, most engineered structures are large in dimension, complex in geometry and heterogeneous in materials. Comprehensive evaluation of the health status of the structure as a whole prefers distributed sensing to provide spatially-uninterrupted information along the entire span of the structure. Current distributed sensing technologies still have difficulty to meet the combined requirements. There is a continuing need for innovations in distributed sensing technologies to ensure the safe operation of various infrastructures. This paper summarizes our progress of recent research in developing new distributed sensing technologies for SHM based on the new microwave-photonic and coaxial cable sensor platforms. The two new platforms have the combined advantages of high measurement resolution, large strain capability, long span of coverage, easy-to-install/embed, spatial continuity (no dark zones), and flexible gauge lengths. The new distributed sensing technology may bring a revolutionary tool to address a number of insufficiently-studied areas in SHM, such as distributed monitoring of cracks and corrosion, post seismic monitoring to ensure mission-critical services in disaster responses and emergency evacuations, study of the progressive structural failures/collapses under extreme loads, and construction of high performance smart structures.