Abstract-This paper presents a broadband switchable 3D structure, which can be used to protect the information equipment from high intensity microwave wave. Compared to other designs, the proposed structure in this paper has wider working band. When the amplitude of incident wave within working band is low, the structure will allow them to pass with little loss. As the amplitude of incident wave is high enough to activate diode, the wave will be reflected. The full-wave simulations are performed in CST to analyze the transmission performance. The simulated results verify the transmission performance and defending function. Its working principle is explained through change of the effective material parameters at two states. A prototype is fabricated. The protection property of the structure as a function of intensity of incident wave is verified in waveguide simulator.