Abstract: In this paper, an ultra-wideband electromagnetic-protected Vivaldi antenna is proposed, which leverages the wideband characteristics of the Vivaldi antenna and integrates C-shaped via structures and PIN diodes into the antenna feedline to achieve robust protection against high-power microwaves across a broad frequency spectrum; when a low-power signal impinges on the antenna, the induced voltage across the PIN diodes remains below the triggering threshold, ensuring normal operation, while when exposed to high-power microwaves, the induced voltage promptly reaches the triggering level, turning on the PIN diodes and establishing a direct ground connection via the C-shaped vias, inducing severe impedance mismatch, causing the antenna to lose its signal reception capability and effectively shielding downstream sensitive electronics from high-power microwave threats; experimental results show that when the PIN diodes are in the OFF state, the antenna exhibits a 50.7% relative bandwidth and a gain of 2.86 dBi at the central frequency of 1.3 GHz, and when the PIN diodes switch to the ON state, triggering the protection mode, the antenna has a protection level of more than 15 dB and provides a receiving power attenuation of over 14 dB.