A Broad Bandwidth Microwave Window Based on Metamaterial

In this paper, a low voltage standing wave ratio (VSWR) broad bandwidth microwave window based on metamaterial was presented for W-band gyro traveling wave tubes (Gyro-TWTs). The microwave window is designed on a dielectric surface, where the dielectric is boron nitride (BN). A sandwich-like structure is adopted, the top and the bottom layers are dielectrics, and the middle layer is metal. The thickness of each piece of dielectric is 0.4mm, and the thickness of metal is 0.0008mm. In the cold-test simulation, it achieves a bandwidth of 13.5GHz with VSWR below 1.2 at W-band, which is broader than that of pure BN dielectric.