This letter presents an S-shaped complementary split ring resonator (S-CSRR) for application in compact differential filters. The working principle of the proposed S-CSRR is explained and a circuit model is developed and validated through electromagnetic simulations. It is shown that an S-CSRR-loaded differential microstrip line with series gaps can be used in the design of compact differential bandpass filters (BPFs) with common-mode suppression. The filter design procedure is explained and the theoretical concept is validated through fabrication and measurement of a compact (0.09λg × 0.25λg) third-order differential BPF with common-mode suppression. © 2014 IEEE.
- Differential filter
- S-shaped complementary split ring resonator (S-CSRR)
- electromagnetic interference (EMI)