Electromagnetic characterisation of conductive 3D‐Printable filaments for designing fully 3D‐Printed antennas

Abstract

Additive manufacturing (AM) 3D‐printing technology is increasingly bringing benefits even in electromagnetics, with interesting prospects of application. Apart from the use of additive manufacturing for realising dielectric components of suitably shaped antennas, the ambitious target is, undoubtedly, the fully 3D realisation of radiofrequency and microwave circuits as well as radiating structures, including, therefore, conductive parts. In this regard, 3D‐printable filaments with interesting conductive properties are being produced. However, their rigorous conductivity characterisation is still missing, making it difficult to estimate the real behaviour of the final 3D printed electromagnetic device. To fill this gap, the conductivity of one of the most interesting conductive filaments, named Electrifi, is first experimentally evaluated in a frequency range as large as 0.72–6 GHz, accounting also for its roughness. Then it has been validated by designing, realising, and testing three fully 3D‐printed antennas. Specifically, two bow‐tie antennas, operating at 2.8 and 4 GHz, respectively, and an ultrawideband antenna, borrowed from the existing literature, operating between 1 and 7 GHz. The good agreement between simulated and measured results demonstrates the reliability of the performed electrical conductivity characterisation, even in the design of efficient radiating structures entirely realised with thermoplastic materials with copper nanoparticle additives.

The 3D-Printed Non-Radiating Edge Gap-Coupled Curved Patch Antenna

“…The dielectric permittivity of the PLA has been computed using the T-resonator method [16]. The metallization of the patches and ground plane has been provided using 50µmthick adhesive aluminum tape, manually cut to obtain the designed dimensions.…”

Evaluating the Effectiveness of Planar and Waveguide 3D-Printed Antennas Manufactured Using Dielectric and Conductive Filaments

“…The first configuration employed to investigate the potentiality of a hybrid solution is a 5-layer proximity coupled microstrip patch antenna (PCPA). The antenna substrates are manufactured using 3D-printed PLA, with dielectric permittivity 2.5 and loss tangent between 0.01 and 0.02 in the frequency range of interest [33]. The ground plane is made of copper, and the feeding microstrip is realized using a 35 µmcopper tape.…”

“…[34], [35]). Since the conductivity of the 3D-printed Electrifi filament depends on the frequency, as reported in [33] up to 6 GHz, three prototypes of the proximity coupled patch antenna have been manufactured, resonating at 2.5 GHz, 4.1 GHz, and 5 GHz. According to the characterization provided in [33], the corresponding values of the Electrifi conductivity, set in the design procedures, are 2800 S/m at 2.5 GHz, 3100 S/m at 4.1 GHz, and 3650 S/m at 5 GHz.…”

“…A thorough electromagnetic characterization of Multi3D Electrifi filament conductivity has been carried out in [33] across a wide frequency range (0.72 to 6 GHz), taking into account both the deposition of the conductive polymer on a printed PLA substrate and the roughness of the substrate and conductive parts. This characterization has been verified using fully 3D-printed monopole antennas covering the entire frequency range, confirming that Electrifi is a suitable material for designing 3D printed antennas up to 6 GHz.…”

“…More in detail, two antenna topologies have been selected for this scope: i) three different proximity-coupled patch antenna configurations based on the same layout, where only the patch has been implemented in Electrifi to focus on the achievable radiating efficiency and electromagnetic performance. They have been designed at three different frequencies within the band validated in [33] so exploiting the available electrical conductivity of the Electrifi; ii) a waveguide antenna working from 3.3 GHz to 3.8 GHz for 5G-NR band applications, with an improved bandwidth and gain achieved by exploiting the free-form advantages enabled by Additive Manufacturing (AM). In this case, three different prototypes have been fabricated and compared, consisting of Electrifi only, purely metallic, and a combination of 3D-printed Electrifi parts and standard metallic parts.…”