Dual-Band SIW Filtering Antenna With High Selectivity and Individually Adjustable Bands

This paper proposes a high-selectivity stable-gain dual-band SIW filtering antenna with independently controllable frequency bands. The proposed antenna structure uses an orthogonal dual-mode rectangular SIW cavity as the common resonant cavity, with the feeding position located inside the cavity. The TE₁₂₀ and TE₂₁₀ modes in the common cavity are coupled to four radiation cavities through coupling windows. Mixed electromagnetic coupling occurs between the rectangular SIW cavity and a circular patch cavity by introducing a radiation null at the high-impedance side of the dual-band operation. Additionally, nine metallized vias are strategically placed to create another radiation null at the low-impedance side. To improve gain performance, a new configuration is implemented by adding a second layer of copper sheet supported by metal posts on the first metal surface. Experimental results show that a gain of 11.3 dBi with a –3 dB bandwidth of 6% in the low-frequency band and a gain of 12 dBi with a –3 dB bandwidth of 6.8% in the high-frequency band can be achieved. Furthermore, the cross-polarization levels remain below –40 dB on both the E-plane and H-plane throughout the dual-passbands.