Uniplanar Conformal Center-Split M-Unit Cell Based SSPP Broadband Bandpass Filter for B5G Radio Stripe Networks

In this letter, a single-layer flexible broadband bandpass filter using spoof surface plasmon polariton (SSPP) is presented. The filter consists of center-split M-shaped unit cells arranged on either side of the central metal CPW line. In the proposed design, interdigital structures are placed in the arms of the unit cell to control the lower cutoff frequency, whereas the SSPP structures of unit cells can adjust the higher cutoff frequency. The filter has a height of $0.002\lambda _{g}$ and a volume of $0.0052\lambda _{g}^{3}$ , where $\lambda _{g}$ represents the guided wavelength at the operating bandwidth’s central frequency. The measured passband has a relative bandwidth of 59% with an insertion loss (IL) of 1.2 dB. The characteristics of the presented filter, such as low volume, flexibility, ultrathin profile, and wide bandwidth, make it an excellent contender for applications in beyond fifth-generation (5G) radio stripe networks (RSNs).