**6. Novel substrate integrated waveguide bandpass filter with broadside-coupled complementary split ring resonators**

A novel SIW BPF using broadside-coupled complementary split-ring resonator (BC-CSRR) pairs was implemented for the first time by [14]. **Figure 16** (left) shows

**Figure 13.** *Schematics of two-stage SIW BPF.*

**Figure 14.** *(a) Current distribution in the passband. (b) Current distribution in the stopband.*

*Analysis and Design of Miniaturized Substrate Integrated Waveguide CSRR Bandpass Filters… DOI: http://dx.doi.org/10.5772/intechopen.104733*

**Figure 15.** *Frequency response of two-stage SIW BPF.*

**Figure 16.**

*Broadside-coupled SRR (BC-SRR), left and broadside-coupled CSRR (BC-CSRR), right.*

the structure of the BC-SRR (broadside-coupled split-ring resonator. It can be derived from EC-SRR by substituting one of the rings with another ring situated precisely at the opposite side of the substrate. From the duality principle, the negative image of the BC-SRR is termed as the broadside-coupled complementary split-ring resonator (BC-CSRR), as shown in **Figure 16** (right).
