Novel Design of UWB Band-Stop Filter (BSF) Based on Koch Fractal Structures
Keywords:
Band-stop filter, DGS, Koch fractal, UWB applicationAbstract
In this paper, a novel design of compact microstrip Ultra-Wideband (UWB) BandStop Filter (BSF) for wireless applications is proposed. The proposed BSF structure is based on Koch fractal geometry where its third iteration operates over a very wide bandwidth and improves the impedance matching. The microstrip filter configuration consists of a transmission line with pairs of Koch fractal Radial Stubs Loaded Resonators (RSLRs), and a modified ground plane with triple modified Defected Ground Structures (DGSs). Operation frequencies of the filter can be easily controlled by changing the iteration of embedded fractal structure. The DGS slots evolved from Photonic Band Gap (PBG) is embedded to achieve a good impedance matching and the required filter’s characteristics. The proposed BSF has a flat rejected-band characteristic around of 3.1-10.6 GHz with an insertion loss which is larger than 45 dB and a return loss less than 0.5 dB at the centre of the band-stop frequency range. An excellent agreement between measured and simulated was obtained. The proposed microstrip filter is fabricated on a Rogers RT/Duroid 5880 substrate with a relative dielectric constant of 2.2 and has a small size of 10×15×0.635 mm3 . The proposed filter configuration is and can be integrated into any UWB system.
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