A study of microstrip transmission lines on substrates created using additive manufacturing and flexible or semi-rigid filaments

Additive manufacturing is becoming more affordable and in recent years new techniques on implementing this emerging technology into microwave circuits are being developed. Therefore, understanding the propagation behavior of printed microstrip transmission lines implemented with these manufacturing techniques is needed. In this paper, the use of flexible and semi-rigid filaments to create substrates using additive manufacturing for printed microstrip transmission lines is presented. In particular, NinjaFlex, PLA and Armadillo filaments are used to manufacture 1.57 mm thick grounded substrates for 50Ω microstrip transmission lines. The dielectric properties (i.e., complex permittivity) of these newly manufactured substrates are determined by comparing the following three results: (1) measurements with a Keysight N1501A-101 high temperature dielectric probe; (2) measurements of a known transmission line problem and (3) full-wave simulations. The results in this paper show a good comparison between the three aforementioned techniques and that a 50Ω printed microstrip transmission line can be created on substrates manufactured using the NinjaFlex, PLA and Armadillo filaments up to 3.0 GHz.