Abstract:—This paper proposes a novel wideband filtering antenna based on a double-mode substrate integrated waveguide (SIW) resonator. By etching butterfly-shaped slots on the upper surface of the SIW resonator, mixed modes based on TE110 and TE120 are introduced, which enhances the antenna"s bandwidth. Additionally, the incorporation of a defected ground structure (DGS) suppresses out-of-band radiation and improves the overall filtering performance of the antenna. The final design achieves a center frequency of 2.41 GHz with an impedance bandwidth of 11.71%. Compared to other filtering antennas, the proposed antenna features a compact size, wide bandwidth, excellent filtering performance, and ease of integration, meeting the high-integration and miniaturization requirements in wireless communication systems.