Quarter-Wavelength Coaxial Stepped Impedance Resonators With Inverted Geometry for High-Power Space Bandpass Filters

This letter presents a novel geometrical implementation of the quarter-wavelength coaxial stepped impedance resonator (SIR). Based on the inversion of the location of the coaxial sections in the resonator, this topology increases the distance between conductors, thus improving the multipactor threshold and fabrication tolerances. To demonstrate these advantages, we designed an L-band 4th-order filter. This filter was fabricated in aluminum and measured. The experimental results are presented and compared with their two- and three-section quarter-wavelength counterparts.