Compact and Wideband Octuple-Mode Filter Based on Hybrid Substrate Integrated Waveguide and Spoof Localized Surface Plasmon Structure

Abstract

In this brief, we propose a novel wide-bandpass substrate integrated waveguide (SIW) filter in a compact circular cavity. It is implemented by etching spoof localized surface plasmon (SLSP) structure for more modes excitation. The dominant mode of SIW cavity and the seven modes of SLSP are employed to realize octuple-mode wideband filtering feature. Moreover, the two edges of the filter passband can be adjusted independently by changing the parameters of SIW or SLSP. Compared to traditional SIW wideband filters, the proposed structure dramatically increases the bandwidth meanwhile balances the size, complexity, and loss. A sample was fabricated and measured to validate the design. The measured results are in good agreement with the simulated ones, showing that a 3-dB relative bandwidth about 63% is achieved.