A New Class of 3D Wideband Frequency Selective Structures based on Multimode Resonators

In this paper, a new class of 3D wideband bandpass frequency selective structures (FSSs) based on multimode resonators (MMRs) has been proposed. At first, stacked slotlines which acted as feeding lines are used to convert incident spatial waves in the free space to guided waves in this type of FSSs. Then, the MMR between the feeding lines can be constructed by either slotline or microstrip line. By virtue of the MMR, wideband filtering response with multiple transmission poles can be finally obtained. To confirm this design concept, two prototypes on the slotline and microstrip are designed, fabricated, and measured, respectively. Wideband filtering responses are experimentally validated for both design examples.