A High-Power TE011-Mode Filter With Nonsinusoidal Deformed Cross-Sectional Cylindrical Cavity

A high-power handling TE₀₁₁-mode filter for high-power microwave (HPM) incoherent synthesis is proposed in this letter. Based on the waveguide boundary perturbation principle, the filter utilizes TE₀₁₁-mode resonators with nonsinusoidal deformed cross section, enabling effective separation of the TE₀₁₁ mode from its degenerate TM₁₁₁ and other spurious modes in overmoded structures. Employing hexa-petal-type deformations, the TE₀₁₁ single-mode filter achieves a relative bandwidth of 9.16%. Moreover, spurious resonances are effectively suppressed by incorporating a different coupling structure strategy. Small signal experiment indicates that the filter’s center frequency is 9.25 GHz, with a 200-MHz bandwidth and an insertion loss below 0.2 dB. No parasitic passbands were observed between 8.6 and 10 GHz. HPM tests on an X-band relativistic backward wave oscillator (RBWO) platform indicate that the filter power handling exceeds 250 MW with pulsewidth about 25 ns.