Broadband-rejection filter topology with a reflectionless feature inspired by the orthogonal distribution of gradual-changing artificial transmission structures

Based on a metamaterial-loaded transmission system, a broadband-rejection reflectionless filter is designed in a microstrip line structure with gradual-changing arrays of complementary split ring resonators etched in the ground plane. The topology of the filter is presented, and the broadband properties are inspired by the orthogonal distribution of gradual-changing artificial structures. A filter prototype is fabricated and measured to validate the design. We hope that the proposed topology can be helpful in designing various of broadband reflectionless filters operating from radio to optical frequencies.