  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 (CRMW) 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
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.
