Miniaturized Substrate Integrated Waveguide Filtering Crossover With Distinct Frequencies for Dual Channels

A miniaturized substrate integrated waveguide (SIW) filtering crossover (FCR) featuring distinct frequencies for dual intersecting channels is presented in this paper. Innovatively, the fundamental mode TE101 and the first higher-order mode TE102 in a central dual-mode SIW rectangular cavity are employed to construct the two intersecting channels for the first time. Compared to the scheme using orthogonal dual modes of TE102 and TE201, the footprint of the FCR using our scheme can be reduced effectively. SIW feeding structures are used as the input and output ports to not only obtain a high inter-channel isolation at lower band due to the cutoff characteristic of SIW but also enable an easy interconnection with other passives in SIW beamforming networks. Meanwhile, the isolation at upper band can be guaranteed by placing the coupling windows near null electric fields of TE102 mode. As a proof of concept, the third-order filtering responses are designated and designed for both intersecting channels, and the simulated results show satisfactory filtering responses and an excellent inter-channel isolation performance for both channels.