Realization of Via-free Microstrip Composite Right/Left-Handed Transmission Lines

Three via-free microstrip composite right/left handed (CRLH) unit cells are presented, which enable easy and low-cost fabrication of transmission lines exhibiting the infinite wave length phenomenon. All guiding structures are designed in an entirely printed circuit technology based on the transmission line theory and its equivalent circuit. Supported by EM simulation software the unit cells are optimized to operate at a frequency of 10 GHz. Appropriate experiment boards were fabricated and the measurements obtained from a microwave vector network analyzer are compared to the simulated results. Furthermore, an approach is worked out to determine the dispersion characteristics of the unit cells without the need of an equivalent circuit. The introduced and applied method allows to calculate dispersion relations directly based on simulated and measured ABCD parameters. Left and right-handed regions are pointed out by the dispersion diagram and the so-called infinite wavelength phenomenon is exhibited.