In this paper, novel triple-mode wideband filters based on a compact sixteenth-mode substrate integrated waveguide (HMSIW) resonator are presented. The proposed design achieves a remarkable size reduction of a conventional substrate integrated waveguide (SIW) circular cavity—while maintaining the same resonant frequency. The proposed filters demonstrate excellent potential for improving the performance of advanced telecommunication systems.In this paper, novel triple-mode wideband filters based on a compact sixteenth-mode substrate integrated waveguide (HMSIW) resonator are presented. The proposed design achieves a remarkable size reduction of a conventional substrate integrated waveguide (SIW) circular cavity—while maintaining the same resonant frequency. The proposed filters demonstrate excellent potential for improving the performance of advanced telecommunication systems.