Wideband passive microwave components using left­ handed/right-handed transmission lines

Abstract

Power dividers, branch line couplers and ring hybrids are widely used passive devices in microwave systems. However, such conventional passive devices are just operating at narrow frequency band. To extend the operating frequency range, the left-handed (LH) transmission line technique which supports backward waves propagation (e.g. phase velocity is opposite to the direction of energy flow) is introduced. The negative value of the propagation constant compare to that of the traditional right-handed transmission line increased the variation of the electrical length of the transmission line within the operating bandwidth. Therefore, their operating bandwidths and sizes often have a better performance than traditional right-handed transmission line. In this project, both lumped and distributed components are utilized to realize LH transmission line and a Wilkinson power divider by using such LH TL is proposed. The simulated and measured results show a good agreement and the desirable operating frequency range is obtained.