A Fully 3-D Printed Waveguide and Its Application as Microfluidically Controlled Waveguide Switch

This paper reports the design, fabrication, and characterization of a fully 3-D printed waveguide (WG) and a microfluidically controlled WG switch, operating at K-band. The WG body is printed using a benchtop 3-D printer with thermoplastic substrate acrylonitrile butadiene styrene, and the conductive layer is incorporated using the same printer by automated deposition of conductive silver ink. The measured total insertion loss of the 3-D printed WG is in good match with the simulations showing better than 0.11 dB/cm for the entire K-band. The 3-D printed WG is characterized, and its attenuation and propagation constants are computed for the K-band using a multiline technique. In addition, microfluidically controlled eutectic gallium-indium and galistan liquid metals are integrated with the 3-D printed WG, and a novel reflective WG switch is implemented. The insertion loss and isolation of the switch are measured to be better than 0.5 dB and better than 15 dB for the entire K-band, respectively. Furthermore, the switch's performance with respect to changes in ambient temperature has been studied. To the best of our knowledge, this is the first time that fused deposition modeling printing and automated ink dispensing is used to fabricate fully 3-D printed WGs, and a 3-D printed WG switch is developed, exhibiting the potential of such technology for rapid prototyping of RF devices.