Tunable low-pass filter using fractal shaped complementary split ring resonator with ultra-wide stop-band and excellent selectivity

This paper presents novel Hilbert fractal shaped complementary single split ring resonator (CSSRR) with a tunable transmission zero realized by negative effective permittivity of it and multi-band property attributes to Hilbert fractal geometry. Transmission characteristics of several CSSRR cells have been assessed by using full-wave electromagnetic simulation. Also miniaturization performance as well as its equivalent circuit model has been deeply investigated. Then a tunable assembled low-pass filter by periodically loading the Hilbert shaped CSSRR has been designed and simulated. Simulated results show that the designed filter has good performances such as low insertion loss (maximum 0.5dB) in passband, ultra-wide stop-band (from 2.47 up to 25GHz) as well as steep rejection with sharp transition band (2.2 to 2.47GHz) out of band. Excellent property of it has demonstrated the correctness and effectiveness of the designed concept.