Design and Fabrication of 3-D Printed Inline Coaxial Filters With Improved Stopband

This article presents a new class of filters, conceived for the fabrication with additive manufacturing technologies, with a wide stopband. The resonators are made of a coaxial line where supports are the coupling elements between them. The wide stopband is obtained using two different solutions. The first is the use of stepped-impedance resonators, whereas the second is the use of quarter wavelength resonators. Several prototypes have been built, and the experimental results show the validity of the solution.