Compact ultrawideband bandpass filter with triple notched-bands and sharp transmission zeros based on CSRR, DGS, AND FMRR configurations

ABSTRACT The folded multiple‐mode resonators (FMMR) with complementary split ring resonator (CSRR), and defected ground structures (DGS) are introduced for notched‐band ultrawideband (UWB) bandpass filter design in this article. Using the CSRR, FMRR, notched wide‐band responses can exist in the UWB passband for blocking the interference. Adjusting the size factor of CSRR, the wide tuning ranges of notch frequencies included the desired frequencies of 5.2/5.8 GHz are achieved. The lower insertion loss (0.31 dB), higher rejection level (−50 dB), wider bandwidth (FBW 75%), and wider stopband (extended to 2.01 f0 below −20 dB rejection level) of UWB band at the central frequency f0 = 4.58 GHz are obtained. Second, design a CSRR, DGS, FMRR, triple notched‐band UWB filter with the wider bandwidth (2.51 to 8.03 GHz, FBW = 124%), lower insertion loss (0.36 dB), and sharp transmission zeros (−49.77/−48.40 dB) of UWB band at central frequency f0 = 4.43 GHz are presented. Using the CSRR and interdigital couple, three notch responses can exist in the UWB passband for blocking the interference signals. Adjusting the size factor of CSRR and interdigital couple, the wide tuning ranges of notched‐band included the desired frequencies of 4.80/5.20/6.38 GHz are achieved. The wide tuning ranges of three notched‐band cover from 4.2 to 6.6 GHz. The design procedure related to the geometry is proposed. It is a simple way to control the notch responses. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2324–2330, 2014