Abstract: Based on the CST software, numerical simulations are carried out for the frequency response in a coaxial Bragg structure with tapered ripples. The bandwidth of the coaxial Bragg structure with positive taper can be narrowed by increasing the tapering angle, whereas the bandwidth of the coaxial Bragg structure with negative taper can be expanded by increasing the tapering angle. The residual side-lobes of the frequency response can be effectively suppressed by employing the window function technique, using Hanning, Hamming and Blackman window functions. These characteristics of a tapered coaxial Bragg structure are favorable to improvement of its performance as a reflector or a filter.