In this work, a UWB BPF based on the uniform MMR using a pair of MMRs is proposed. All three resonant frequencies within the UWB BPF are reassigned and the spacing g between the two parallel-coupled MMRs is properly regulated, a UWB filter with high performances is obtained. Measured results show high performances with insertion loss lower than 2 dB (from 3.1 to 7.5 GHz lower than 0.5 dB) and return loss higher than 10 dB (from 3.2 to 8.9 GHz higher than 15 dB) as well as group delay variation less than 0.18 ns within the UWB passband (3.1-10.6 GHz).

A -LU decomposition-based direct method enhanced second-order Krylov subspace projection based model order reduction (MOR) is presented. The construction of the projection matrix is the most important process in the Krylov subspace projection based MOR where an inverse of the sparse matrix is involved in the construction of the projection matrix. It will be intractable for the computational capacity of a personal computer when the size of the problem is large. A -LU decomposition-based direct method is employed to the MOR. Numerical results for the analysis of the substrate integrated waveguide (SIW) bandpass filter demonstrate the validity of the proposed algorithm.