IEEE Microwave and Wireless Technology Letters

B. B. Pathak, R. S. Sangam, R. S. Kshetrimayum, J. Hong, M. A. Morgan, "Uniplanar Conformal Centre-Split M-Unit Cell employed SSPP Broadband Bandpass Filter for B5G Radio Stripe Networks", accepted for publication in IEEE Microwave and Wireless Technology Letters

Abstract: 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 0.002λg and a volume of 0.0052λg3, where λg 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).

R. S. Sangam and R. S. Kshetrimayum, "Comment on Hybrid Spoof Surface Plasmon Polariton and Substrate Integrated Waveguide Broadband Band pass Filter With Wide Out-of-Band Rejection", IEEE Microwave and Wireless Components Letters, vol. 30, no. 2, Feb. 2020, pp. 222-222.

Abstract: The dispersion diagrams for the proposed spoof surface plasmon polariton (SSPP) unit [1, Fig. 1(b)] and the substrate-integrated waveguide (SIW) unit [1, Fig. 1(c)] are plotted in [1, Fig. 2] , which are incorrect and the correct dispersion curves for the same are presented here, as shown in Fig. 1 . The dispersion curves are analyzed and plotted for mode-1 simulation in the eigenmode solver of CST microwave studio. Furthermore, the dispersion curve with optimized dimensions, Li and Wi , where i∈(5,…,8) for the SSPP part [1, Fig. 1(a)] , is shown in Fig. 2 . The lower and upper cutoff frequencies for the passband of the filter are defined from the structural parameters of SIW and SSPP units, respectively. It can be seen from the dispersion curves of SIW and SSPP units [1, Fig. 2] that the lower cutoff frequency obtained from the SIW unit is around 7 GHz, while the upper cutoff frequency obtained from the SSPP unit is around 6 GHz ( W=15 mm of the SIW unit and W=8 mm of the SSPP unit). However, only the cutoff frequency in the dispersion curve of the SIW unit is correct, from where the lower cutoff frequency of the proposed BPF is set around 7 GHz. The dispersion curve of the SIW unit [1, Fig. 1(c)] with correct distribution trend is shown here in Fig. 1(b) . The passband of the proposed hybrid SSPP-SIW filter is about 7–11 GHz, and hence, the correct upper cutoff frequency for passband of the filter, as it can be seen from our corrected dispersion curve of the SSPP unit [see Fig. 1(a) ], is about 11 GHz. It can also be noted that p is the period of SSPP in our corrected dispersion curves.