Electromagnetic analysis and performance comparison of fully 3D-printed antennas

In this work, the possibility of directly prototyping antennas by exploiting additive manufacturing 3D-printing technology is investigated. In particular, the availability of printable filaments with interesting conductive properties allows for printing of even the antenna conductive elements. Three samples of a 2.45 GHz microstrip patch antenna have been 3D-printed by using different approaches and materials, and their performance evaluated and compared. In particular, the same dielectric substrate printed in polylactic acid (PLA) has been adopted in all cases, whilst copper tape and two different conductive filaments have been used to realize the conductive parts of the three antenna samples, respectively. Even if an expected radiation efficiency reduction has been observed for the conductive filament case, the comparative analysis clearly demonstrates that 3D-printing technology can be exploited to design working fully-printed antennas, including the conductive parts

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

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

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

3D printing is a technology suitable for creating electronics and electromagnetic devices. However, the manufacturing of both dielectric and conductive parts in the same process still remain a challenging task. This study explores the combination of 3D printing with traditional manufacturing techniques for antenna design and fabrication, giving the designer the advantage of using the additive manufacturing technology only to implement the most critical parts of a certain structure, ensuring a satisfying electromagnetic performance, but limiting the production cost and complexity. In the former part of the study, the focus is on three proximity-coupled patch antennas. It demonstrates how hybrid devices made of metal, dielectric, and 3D-printed (using Fused Filament Fabrication) conductive polymers can be successfully simulated and created for different operating frequency bands. In the latter part, the study compares three prototypes of a 5G-NR, high gain, and wideband waveguide antenna: respectively a fully 3D printed one made of electrifi (which is the most conductive commercial 3D-printable filament), an all-metal one, and a hybrid (3D-printed electrifi & metal) one. The results show a 15% reduction in efficiency when using the all-Electrifi configuration compared to all-metal one, and a 4-5% reduction when using the hybrid version

Designing UHF RFID tag antennas with Barcode shape for dual-technology identification

In this paper, a novel methodology to design Ultra High Frequency Radio-Frequency IDentification (UHF RFID) tag antennas with Barcode layout is proposed with the challenging goal of "fusing" both technologies in a single device. Specifically, after a brief recall of the well-known barcode standard, a procedure to design meandered barcode-shaped UHF RFID tags is introduced and discussed leveraging on electromagnetic evidence. The main steps of the proposed method are described by highlighting the constraints inherited by both the adopted technologies, as well as the useful opportunities to automatise the entire antenna design process after a preliminary simulation campaign through a full-wave simulator. Different RFID-Barcode tag antennas are designed, manufactured, and characterised in terms of maximum reading range and tag sensitivity. Obtained results demonstrate the validity of the proposed approach

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

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

A Curved Microstrip Patch Antenna Designed From Transparent Conductive Films

Transparent microstrip patch antennas suffer from low radiation efficiency and gain when manufactured using transparent conductive films (TCFs), mainly at low frequency (starting from the microwave S band). To address this problem, we propose a curved microstrip patch antenna designed using transparent materials. This new configuration has proven to be a simple and effective solution to improve the radiation efficiency and gain of TCF printed antennas. In fact, when typical values of the TCF surface resistance are considered (between 2 and 10 Ω/sq), the new antenna features a radiation efficiency of up to 72.3% and a realized gain of up to 5.3 dBi at 2.15 GHz, with a significant improvement in comparison with the flat transparent microstrip antenna (up to 17.7% radiation efficiency, and 0.5 dBi realized gain). Good transparency and lightweight is ensured by the deposition of the TCF on a polyethylene terephthalate film, which lies, in turn, on a 3D-printed curved polyethylene terephthalate glycol supporting frame. Simulations using Ansys HFSS are presented to demonstrate the potential of the proposed configuration. Then, a prototype of the transparent curved patch antenna is fabricated and measured to assess the simulated results

An IoT-Aware Smart System Exploiting the Electromagnetic Behavior of UHF-RFID Tags to Improve Worker Safety in Outdoor Environments

Recently, different solutions leveraging Internet of Things (IoT) technologies have been adopted to avoid accidents in agricultural working environments. As an example, heavy vehicles, e.g., tractors or excavators, have been upgraded with remote controls. Nonetheless, the community continues to encourage discussions on safety issues. In this framework, a localization system installed on remote-controlled farm machines (RCFM) can help in preventing fatal accidents and reduce collision risks. This paper presents an innovative system that exploits passive UHF-RFID technology supported by commercial BLE Beacons for monitoring and preventing accidents that may occur when ground-workers in RCFM collaborate in outdoor agricultural working areas. To this aim, a modular architecture is proposed to locate workers, obstacles and machines and guarantees the security of RCFM movements by using specific notifications for ground-workers prompt interventions. Its main characteristics are presented with its main positioning features based on passive UHF-RFID technology. An experimental campaign discusses its performance and determines the best configuration of the UHF-RFID tags installed on workers and obstacles. Finally, system validation demonstrates the reliability of the main components and the usefulness of the proposed architecture for worker safety

Design of On-Body Epidermal Antenna on AMC Substrate for UHF RFID in Healthcare

This article presents a compact AMC structure used as a shielding element for a generic wearable RFID tag at UHF frequencies for on-body applications, with an overall footprint limited to an area of only 0.03λ 02 (41.4×82.8 mm). Thanks to the isolation provided by the AMC planar structure, the tag antenna gain and reading range are increased by about one order of magnitude in comparison with the case of a conventional tag attached to the human body. The designed antenna is platform tolerant, with very good robustness and isolation with respect to the human body, exhibiting a high reliability. The AMC structure is implemented on a thin, flexible, and biocompatible high permittivity silicon-doped dielectric substrate, with apertures both in the substrate and in the ground plane to allow skin transpiration. Therefore, the presented device can be effectively used also as an epidermal antenna, allowing the 'on-skin' sampling of the most typical health parameters. The presented configuration has been designed using CST Studio Suite. A prototype has been fabricated and fully characterized, and measured results are in very good agreement with simulations

Improved method for the determination of neutron energies from their times-of-flight

International audienceThe kinetic energy of a neutron is determined experimentally by measuring its time-of-flight and flight distance from the source to the detector. However, this determination is vitiated by errors since the exact location of the interaction of the neutron within the detector is unknown. Moreover, more than one interaction may be necessary for the deposited energy to reach the detector threshold. We compare the different existing energy determination methods and introduce the method which gives the minimum-variance unbiased estimator of the neutron energy. The method is based of the inversion of the detector response function, for which we propose a universal algorithm. It is shown that the precision of the new method does not deteriorate with the length of the detector, which opens the possibility of conceiving detectors with a higher efficiency