Effects of Additive Manufacturing on the Performance of RF Components on Flexible Substrates

The problem this SBIR program addresses is determining the effects of additive manufacturing processes on the performance of radio frequency (RF) components formed on flexible substrates. Specifically, voids may be introduced during fabrication that will increase the impedance of printed electrically conductive microstrip waveguides, feeds, filters and connectors, decrease the gain and modify the far field radiation patterns of patch and bowtie antennas and arrays, and decrease the quality factor of frequency selective surfaces (FSS). Additionally, the RF performance of additively manufactured RF components may vary differently in response to thermal cycling, vibration and flexure than similar components manufactured on flexible substrates using conventional masking and etching techniques. The result of this SBIR program will be documentation of these effects in RF components fabricated using three additive manufacturing processes on several different flexible substrates at frequencies from L-band to Ku-band, and demonstration of the use of micro x-ray computerized tomography to nondestructively evaluate (NDE) the internal structure of additively manufactured RF devices. NanoSonic will fabricate RF components using three different additive manufacturing processes, nondestructively analyze the fabricated components to quantify void size and distribution and evaluate their RF performance using S-parameter measurements and far-field antenna radiation pattern scanning. Measurements will be performed using in-house L-band to Ku-band equipment and an indoor copper and RF absorber-lined antenna range. The void content and RF performance of the additively manufactured components will be compared with that of similar components fabricated by masking and etching copper-clad dielectric substrate materials such as Kapton and duroid. The additive manufacturing processes will be ink jet printing (IJP), electrospray deposition (ESD) and fused filament fabrication (FFF). NanoSonic has used IJP to fabricate RF components on flexible substrates for more than ten years and has related current programs involving ESD and FFF. Substrates will include Kapton, PEN, PET, PDMS and high temperature flexible thermal protection system (TPS) materials under development through a separate program. Test components will include microstrip waveguide, feeds, filters, bowtie and patch antennas, and patterned frequency selective surfaces. NanoSonic will work with RF and materials engineers in two divisions of a major US defense contractor and with a US-based manufacturer of materials production equipment. Approved for Public Release | 20-MDA-10643 (3 Dec 20