Design and performance analysis of 2D and 3D microwave filters using additive manufacturing techniques

Abstract

This thesis investigates whether three-dimensional microwave filter structures, enabled by inkjet-based additively manufactured electronics (AME), can improve performance or reduce the physical size of microwave filters compared to conventional two-dimensional designs. A third-order Chebyshev low-pass filter was implemented as the reference design in ANSYS HFSS and compared against six three-dimensional configurations, including modified ground plane structures, multi-level conductor arrangements, and geometrical variations of the signal path. The performance of each configuration was evaluated using S-parameters and electric field distributions. The results show that ground plane placement proved decisive for filter behavior across all tested configurations. Three-dimensional modifications can preserve acceptable low-pass filter performance, but only when the return current path remains controlled and transitions between filter sections are kept smooth. Among the investigated configurations, the most compact designs achieve reductions in planar footprint down to 28% and 32% of the reference, respectively, at the cost of modified frequency responses, while the most geometrically controlled three-dimensional structure maintains a cutoff frequency closely comparable to the reference filter. What matters is not simply adding a third dimension, but understanding and controlling what happens electromagnetically when you do.