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

A high-power handling TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub>-mode filter for high-power microwave (HPM) incoherent synthesis is proposed in this letter. Based on the waveguide boundary perturbation principle, the filter utilizes TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub>-mode resonators with nonsinusoidal deformed cross section, enabling effective separation of the TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> mode from its degenerate TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</sub> and other spurious modes in overmoded structures. Employing hexa-petal-type deformations, the TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> 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.