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.