Effect of defect location and corrugation phase on transmission in a defected coaxial Bragg structure with two corrugated surfaces

Numerical simulations are carried out to investigate the effect of defect location and corrugation phase on transmission in a defected coaxial Bragg structure with two corrugated surfaces. It is found that, the desired narrow passband can be generated only if the outer-wall and inner-rod ripples are both applied with a defect in the middle-section and their initial corrugation phase difference is set to π. A slight misalignment between the outer-wall and the inner-rod defect can be used to perform a fine adjustment on the characters of pass-band; however, if these defects are separated with a lager gap, several passbands can be generated, which provides a potential approach to construct multi-channel filters.