A new method to design compact multi-band filters with enhanced selectivity

A new method to design multi-band filters is proposed by inserting electric and magnetic resonances to increase the selectivity of the lower and upper edge of the passband. A dual-band filter composed of regular hexagon cascaded complementary split rings resonator pairs (RH-CCSRRP) and regular hexagon cascaded complementary ring resonator (RH-CRR) are designed. Simultaneously, the proposed filter has been detailed investigated by the method of electromagnetic (EM) parameters extraction process. For verification of the new method, a tri-band filter is designed. The results show that both the filters have a good performance of compact dimensions, which is only 0.19 λ_g × 0.14 λ_g, low insertion loss and sharp selectivity.