Dual-band single-layer substrate-integrated waveguide filtering antennas with independently controllable bands

A novel design method of dual-band single-layer substrate-integrated waveguide (SIW) filtering antennas with independently controllable bands is proposed in this paper. The basic two-pole dual-band filtering antenna is proposed by a dual-mode rectangular SIW cavity coupled to two single-mode SIW cavities with respective radiating slots. Single cavity multi-mode is realised by etching dumbbell-shaped slots and metallised vias to achieve the purpose of broadening bandwidth and miniaturisation. The dual-mode SIW cavity acting as a common structure is fed by a coaxial feeder. The two orthogonal modes are coupled to two single-mode cavities by coupling windows to produce two two-pole passband filtering responses, respectively. Metallised vias in radiating SIW cavities are employed to realise good impedance matchings in radiating pass-bands. The two filtering radiation bands can be controlled independently, which is analysed in detail. Based on the basic two-pole dual-band filtering antenna, three- and four-pole dual-band filtering antennas are further proposed and analysed. For demonstration, two-, three- and four-pole dual-band filtering antennas with two centre frequencies of 10 and 11.7 GHz are designed, fabricated, and measured. The good agreement between the simulated and measured results verifies the proposed design methodology of single-layer SIW dual-band filtering antennas.