Abstract: In this paper, a novel miniaturized Substrate Integrated Waveguide (SIW) dual-mode filter is presented. By adopting an orthogonal input and output feed line, and an inclined slot line for disturbing two degenerate modes, two Transmission Zeros (TZs) are created. A 15 GHz SIW dual-mode filter with 350 MHz bandwidth is designed and fabricated using the proposed method. The filter has a very simple structure, low cost and is easily fabricated. The measured results are in good agreement with the simulated results, which show that the design of the proposed filter is correct and effective.