Closed-loop control of dielectric permittivity for 3D-printed radio-frequency devices

Abstract

Additive manufacturing (AM) offers significant advantages over traditional manufacturing methods for the fabrication of radio-frequency (RF) devices due to lower production costs, flexibility to produce complex geometries, and ability to vary the internal composition of a part. Because AM processes are typically run without any online feedback control, printed parts may be compromised by defects. This paper proposes a feedback control algorithm to enable closedloop control of a graded-index (GRIN) RF lens produced using a Fused Filament Fabrication printer. As a GRIN lens relies on spatially-varying permittivity, differing densities were printed on a layer-by-layer basis, thus changing the permittivity through the lens depth. The control system used a split ring resonator to measure the permittivity of printed material, and the control action was applied by updating the printed infill density in each layer. The results indicate the controller could detect and adjust for errors, demonstrating the potential of closed-loop control for precise fabrication of high value-added RF devices.

Control of Additive Manufacturing for Radio Frequency Devices With Spatially Varying Dielectric Properties

“…Contributions: The idea of using feedback to control the additive manufacturing of components that have a spatial variation in permittivity has been introduced in [45], but the main results of this paper are:…”