Technique to Tackle Resonant Frequency Variations for 3D-Printed Microstrip Patch Antennas

Due to design freedom, waste minimization, and capability to construct complex geometries, additive manufacturing is a promising candidate for large-scale manufacturing of radiofrequency (RF) components. However, 3D-printed microwave substrates suffer from a relative permittivity variation of 4-9%. Thus, the antennas realized on these substrates can have variations in their intended resonant frequencies. This issue is critical for narrow-band microstrip patch antennas (MPA). In this work, we propose an easy-to-implement post fabrication technique to compensate for the permittivity variations of the 3D-printed substrates (particularly for MPA). The proposed technique corrects the resonant frequency by introducing blind vias at specific locations. We show, by experimentally applying this technique, that resonant frequencies can be shifted to lower or higher values as desired. The maximum shift in the resonant frequency, without significantly affecting the MPA performance, can be up to 13%, which is sufficient to cater for typical variations of material properties in 3D printed substrates.