Low-cost mm-wave coplanar waveguide bandpass filter using inkjet printing of silver nano-particles on flexible plastic substrate

This paper demonstrates the feasibility of realizing millimeter wave coplanar waveguide (CPW) bandpass filters through ink-jetting of conductive inks on commercially available plastic sheets such as Polyethylene Terephthalate (PET) (plastic as an RF substrate). A silver nanoparticle colloidal solution was used as the printing ink. The millimeter wave third order CPW bandpass filter, which consists of a cascade of alternating quarter wavelength CPW open end series stubs and quarter wavelength CPW connecting lines, was simulated with Agilent Momentum and printed with a DMP-2800 Series inkjet printing system. The principle of achieving such high-quality circuits is detailed and is also confirmed by theoretical and experimental results, which are in reasonable agreement up to at least 70 GHz. Finally, this work is one step further towards the development of low-cost ink-jet printing of passive microwave and millimeter-wave components for commercial wireless applications.