Flexible SSPP Low-Pass Filter Employing Trapezium-Mounted Semicircular-Shaped Unit Cell for B5G NR FR1 Radio Stripes Network

This letter reports a uniplanar and flexible spoof surface plasmon polariton (SSPP) based low-pass filter (LPF). The filter comprises proposed trapezium-mounted semicircular unit cells positioned on each side of the central metal coplanar waveguide (CPW) line. The reported unit cell achieves a lower asymptotic frequency than some commonly used unit cells with identical lateral sizes. The LC equivalent circuit model (ECM) of the proposed filter structure and unit cell is presented, showing good agreement with the full-wave simulations. The measured 10-dB return loss bandwidth covers the range of 0–7.12 GHz with out-of-band rejection higher than 43 dB and peak insertion loss (IL) of 1.1 dB. The fabricated filter’s performance is also experimentally measured over different bending states, indicating that its performance remains almost consistent with the flat state. Due to attributes, such as conformability, low volume, and ultrathin profile, the proposed filter presents itself as an appropriate choice for the beyond fifth generation new radio frequency range one (5G NR FR 1) radio stripe network (RSN).