Analysis of Wire-Bonded Multiconductor Transmission-Line-Based Stubs

Wire-bonded multiconductor transmission lines (MTLs) can be used as shunt stubs as a way of overcoming the limitations regarding impedance levels and frequency response of single transmission-line (TL) stubs. The wire-bonded MTL is a particular case that provides greater bandwidth by eliminating high-frequency undesired resonances. In this paper, a general analysis of the behavior of this structure is presented. The performance of all eight possible configurations and an arbitrary number of strips is assessed and some physical insight into their frequency behavior is provided. Six of them allow the implementation of shunt stubs with impedance levels that are complicated or unapproachable with a single stub, while the other two provide additional degrees of freedom that are of interest for the design of filtering structures. The usefulness and validity of the proposed analytical design equations are illustrated by designing, manufacturing, and measuring two artificial TLs with left-handed bandpass response and improved out-of-band rejection. The excellent agreement between the designed and experimental results suggests that the presented analytical equations are most convenient for a quick and reliable design of many passive and active microwave circuits.