On the Design and Simulation of Antennas on Ultra-thin Flexible Substrates

Flexible wireless systems are rapidly evolving in a wide spectrum of applications such as medical, entertainment and sport facilities. The aim of this paper is to investigate whether the ultra-thin substrates along with their permittivity are essential for the initial design stage of a flexible antenna, which is a key element of any wireless system, or it is merely a supporting structure. Three state-of-the-art simulation tools are used to evaluate the scattering parameter, S11 which are then compared against precise measurements conducted inside an anechoic chamber. These methods are the Finite Integration Technique (FIT) based Time Domain Solver (TDS) and the Finite-Element Method (FEM) based Frequency Domain Solver (FDS) of CST Microwave Technology and the (FEM) based HFSS of ANSYS. This paper attempts to provide an answer as to whether the substrate and other geometrically small features such as the feeding structure should be sufficiently discretized or else conventional default adaptive meshing should be enough. Three different flexible antennas with two fabrication techniques and feed lines have been used in the simulations and measurements.