A Dual-Band Bandpass Filter Based on Generalized Negative-Refractive-Index Transmission-Lines

A dual-band bandpass filter is presented. The filter is composed of generalized negative-refractive-index transmission-lines (NRI-TL) realized in microstrip. The filtering mechanism relies on all four of the generalized NRI-TLs' left-handed and right-handed passbands. Under the closed stopband condition, two passbands are achieved. A complete design procedure is described. A fabricated example measures 0.25 lambda(o) x 0.25 lambda(o), where omega(o) is the wavelength of the center frequency of the stopband. Maximum insertion loss in the passbands (centered around 4 GHz) is measured at 1.5 dB.