Receiver protectors (RPs) shield sensitive electronics from high-power incoming signals that might damage them. Typical RP schemes range from simple fusing and PIN diodes to superconducting circuits and plasma cells-each having a variety of drawbacks ranging from unacceptable system downtime and self-destruction to significant insertion losses and power consumption. Here, we theoretically propose and experimentally demonstrate a unique self-shielding RP based on a coupled-resonator microwave waveguide, with a topological defect being inductively coupled to a diode. This RP utilizes a charge-conjugation-(C) symmetric resonant-defect mode that is robust against disorder and demonstrates high transmittance at low incident powers. When the incident power exceeds a critical value, a self-induced resonant trapping effect occurs, leading to a dramatic suppression of transmittance and a simultaneous increase of the reflectance close to unity. The proposed RP device is self-protected from overheating and electrical breakdown and can be utilized in radars, reflection altimeters, and a broad range of communication systems.