The quasi-superdirective reradiation and in-phase retroreflection are presented for the sake of monostatic radar cross-section enhancement. Two passive structures, including a post-loaded thin plate and a metasurface-coated cylinder, are proposed to demonstrate the validity of the concepts. For the thin plate loaded with posts, it is seen that surface currents with almost equal magnitudes but opposite directions can be induced on the loading two-post with each post height less than a quarter-wavelength. The resultant quasi-superdirective reradiation obviously enhances backscattering of the thin plate at edge-on incidence. Moreover, the design of a conformal gradient metasurface is proposed. It is observed that a polarization-independent enhancement of backscattering can be obtained through the efficient retroreflection produced by a cylinder coated with the designed metasurface. The achieved enhancement of backscattering is at least 10 dB for both designs.