Adaptive High-Impedance Surface for Prevention of Waveguide's High-Intensity Wave

This article presents an adaptive high-impedance surface (A-HIS) that can be applied in the prevention of high-intensity wave propagating in X -band waveguide. Once the embedded diodes loaded on A-HIS are switched from OFF- to ON-states by the high-intensity incident wave, the boundary condition of the waveguide's bottom wall would adaptively change from a perfect electric conductor (PEC) to a perfect magnetic conductor (PMC), and the propagation would be prevented. To demonstrate this nonlinear characteristic, eigenmodes of the periodic unit-cells in two states of diodes were calculated, and the dispersive performance was analyzed. The bandwidth was further derived through the bandgaps between its intrinsic modes. Finally, a prototype with 5\times 10 elements was designed, fabricated, and measured in a WR90 waveguide. The results indicate that, on condition of incident wave with relatively low power intensity, signals can propagate through the A-HIS with a low insertion loss by no more than 1 dB; in the case of relatively high power intensity, this loaded A-HIS can attenuate the incident wave by more than 10 dB and absorb more than 80% power within its operation bandwidth.