Investigations of transmission lines and resonant structures on flexed liquid crystal polymer (LCP) substrates up to 67 GHz

This paper deals with the effects of bending flexible circuits on liquid crystal polymer (LCP) substrates in the gigahertz range. It investigates how the performance of passive circuit elements is influenced by the bends. For this purpose, four common types of transmission lines and a band-pass filter on flexible LCP substrate are analyzed concerning possible effects caused by sharp bending. Field simulation and measurements up to 67 GHz show that the occurring effects are small and negligible for several broadband applications. However, bending the substrate leads to small material deformation which could shift the frequency characteristics of resonant structures in a significant manner.