Miniaturized Triple-Band Filter Design Utilizing Composite Planar Multilayered and Substrate Integrated Waveguide Structures

A novel design for miniaturized triple-band filter based on composite planar multilayered structure and special substrate integrated waveguide (SIW) cavity is proposed. Both structures generate three operating modes, respectively. The special SIW cavity with its four sides virtual magnetic walls decreases the first three resonant frequencies in the related conventional SIW cavity significantly. Three transmission zeros are also produced. A triple-band filter centered at 2.28, 5.94, and 9.50GHz with a very compact size of 18.6×17.0×0.964mm³ and relative dielectric constant of 3.66 is designed. Simulated and measured results are presented to show its good performances.