A Compact Bandpass Filter Based on Right- and Left-Handed Transmission Line Sections

A new type of a compact second-order bandpass filter (BPF) with two transmission zeros based on transversal signal-interference technique is proposed in this letter. Unlike other transversal filters published, the proposed structure is composed of artificial right- and left-handed transmission lines, instead of traditional distributed transmission line sections. Such an approach is not only helpful in size reduction, but also promising for frequency-asymmetrical stopband performance achievement. Design equations and guidelines to adjust filter performance are provided in the letter. To validate the proposed design approach, a two-pole BPF was designed, fabricated using multilayer liquid crystal polymer (LCP) technology and measured.