A Compact Tapered EBG Structure With Sharp Selectivity and Wide Stopband by Using CSRR

A compact tapered electromagnetic bandgap (EBG) structure by using complementary split-ring resonator (CSRR) is presented. By employing CSRRs, open stubs, and spurline, three transmission zeros are introduced to improve performances of the EBG structure. Chebyshev tapering distribution reduces the ripples within the passband. In construct with the traditional EBG structure, the slope from the stopband to passband transition can be increased from 12.59 to 45.95 dB/GHz with the presented design. An ultrawide fractional bandwidth of 112.91% within the stopband below -20 dB is also obtained. The measurements agree well with the simulation results.