Design of Miniaturized Dual Band-Pass Filter for ISM and Sub-6 GHz Spectrum by Employing Square Complementary Split Ring Resonator

In this proposed work, a miniaturized dual band-pass filter with enhanced selectivity and tunable transmission zero is proposed for an ISM and Sub-6 GHz application. The conventional open and short circuited stubs are employed to operate dual band resonance. This prototype consists of a Square Complementary Split Ring Resonator (SCSRR), a unit cell interdigital circuit, and short and open circuited stubs. Further, the selectivity of the filter is enhanced by employing the SCSSR on the ground plane of the filter. The
D-CRL resonator consists of a set of interdigital lines that act as main section of the filter which provides dual band-pass filter at ISM and sub-6 GHz bands with the bandwidths of 0.3 GHz and 0.75 GHz, respectively. The experimentally validated filter has 39 and 59% 3-dB fraction bandwidths, maximum insertion losses on both the bands below 0.31 dB, passband impedance matching more than 31 dB, group
delay in the range of 0.25 to 0.61 ns, stopband to passband selectivity 89 dB/GHz, and passband to stopband selectivity 93 dB/GHz. The presented dual-band prototype is a better candidate to use in ISM and sub-6 GHz spectrum based high speed digital communication.