Design of Compact Wideband Bandpass Filters Based on Multiconductor Transmission Lines With Interconnected Alternate Lines

A new compact wideband bandpass filter consists of one series and one shunt multiconductor transmission-line (MTL) structure with short-circuited alternate lines is proposed. Based on this topology, a three-pole filter with two transmission zeros at the edges of the desired passband, generated by the shunt MTL, and with a wide stopband can be easily designed. Therefore, a comprehensive study of the filter is carried out and useful closed-form design equations are obtained and assessed by means of measurements. A filter is designed, fabricated and measured for validation and excellent agreement between analytical and measured results is obtained.