Abstract: In this paper a design method for filtering antennas based on substrate integrated waveguide ( SIW) technology is proposed. A SIW filter is designed based on the traditional coupling matrix synthesis method, and then combined with half-mode substrate integrated waveguide (HMSIW) technology to obtain a filtering antenna. This method is simple and effective, and can introduce an additional transmission zero to improve the frequency selectivity of the filtering antenna. In this paper a third-order filtering antenna is taken as an example to verify the effectiveness of this method. Based on the TE101 mode, two SIW cavities and one HMSIW cavity are used to form a third-order filtering response. The SIW cavity is used as a high Q resonator, and the HMSIW cavity is also used as a radiation cavity. The measured center frequency is 6.52 GHz, with a -10 dB bandwidth of 7.4% (6.26 GHz to 6.74 GHz). The measured gain within the passband is basically 5 dBi, and a transmission zero is generated in the lower stopband, effectively improving the frequency selectivity of the filtering antenna at low frequencies. The measured results are in good agreement with the simulation results, verifying the effectiveness of the design method.