Miniaturised planar band-pass filter based on interdigital Arm SRR

Here, a small-size band-pass filter is designed using a new split-ring resonator (SRR). First, the geometric optimisation method is used to obtain the high miniaturisation of the proposed SRR compared to the conventional structures. Accordingly, the reduction rate has reached 51%. The second part of this study is devoted to the development of a band-pass filter using the proposed SRR topology. A Chebyshev-type band-pass filter has been designed. The purpose is to have a miniaturised structure, low insertion loss, and high out off-band rejection. This filter is composed of two integrated arms SRR placed in series with a defected ground structure (DGS) to increase the coupling between the resonators, and a low-pass filter integrated into the resonators to improve the level of rejection. The resonance frequency has been approximately measured at 1 GHz and the size has been valued at 0.114 λg × 0.083 λg , thus achieving miniaturisation up to 78% compared fabricated and experimentally validated. The measured insertion loss has been found to 0.8 dB and two transmission zeros helped to ensure the steep sides of the transmission band.