Compact dual-band filtering power divider based on half-mode substrate integrated waveguide cavity loaded with CSRRs

A compact filtering power divider with high performance and compact size is proposed. The filtering power divider is implemented using a half-mode substrate integrated waveguide (HMSIW) and loaded with the proposed strongly coupled complementary split-ring resonators (CSRRs). The proposed filtering power divider operates below the cutoff frequency of the waveguide. Firstly, the structure of HMSIW loaded with first-order CSRRs is analyzed, and the corresponding equivalent circuit is presented for the first time to facilitate analysis. Based on the first-order CSRR structure, a second-order CSRR structure is innovatively proposed, and its electric field distribution is analyzed. On this basis, filtering power dividers with equal power division and unequal power division are realized through cascading. The center frequencies of the two passbands can be adjusted by changing the dimensions of the CSRR structure and the central metal microstrip structure. To verify the proposed concept, a filtering power divider with equal power division is designed, fabricated, and tested. The measured results are in good agreement with the simulated ones. The proposed filtering power divider features compact size, dual-band operation, and good return loss.