Body-UAV Near-Ground LoRa Links through a Mediterranean Forest

LoRa low-power wide-area network protocol has recently gained attention for deploying ad-hoc search and rescue (SaR) systems. They could be empowered by exploiting body-UAV links that enable communications between a body-worn radio and a UAV-mounted one. However, to employ UAVs effectively, knowledge of the signal's propagation in the environment is required. Otherwise, communications and localization could be hindered. The radio range, the packet delivery ratio (PDR), and the large- and small-scale fading of body-UAV LoRa links at 868 MHz when the radio wearer is in a Mediterranean forest are here characterized for the first time with a near-ground UAV having a maximum flying height of 30 m. A log-distance model accounting for the body shadowing and the wearer's movements is derived. Over the full LoRa radio range of about 600 m, the new model predicts the path loss (PL) better than the state-of-the-art ones, with a reduction of the median error even by 10 dB. The observed small-scale fading is severe and follows a Nakagami-m distribution. Extensions of the model for similar scenarios can be drawn through appropriate corrective factors

Naval structural antenna systems for broadband HF communications - Part II: Design methodology for real naval platforms

Recently, it was shown how to make a multipurpose broadband HF antenna system out of existing naval superstructures such as the funnel or a big mast. The idea was discussed by means of canonical structures, e.g., a cylindrical body of circular or square cross-section, placed onto an infinite ground plane. This paper investigates the critical aspects concerning the extension of naval structural antenna concept to real ship platforms with the aim to define a general design methodology for impedance matching and radiation pattern control. The method is described,with reference to a realistic, frigate model, whose big mast is transformed into a broadband HF antenna system able to perform communications by both sea-wave and sky-wave links. It is demonstrated that, even in a real environment, the multiport strategy permits to increase the system efficiency and to moderately shape the radiation pattern in order to overcome the shadowing effect due to other large objects

Twin Grid-array as 3.6 GHz Epidermal Antenna for Potential Backscattering 5G Communication

Emerging 5G infrastructures can boost innovative paradigms for future wearable and epidermal devices exploiting low-power (even passive) wireless backscattering-based communication. To compensate high body- and path-losses, and to extend the read range, array configurations are required. This work proposes a flexible monolithic epidermal layout, based on Krauss array concept, that operates at 3.6 GHz and it is suitable to be directly attached to the human body. The antenna involves a dual grid configuration with a main radiating grid backed by a grid reflector placed in touch with the skin. Overall, the amount of conductor an dielectric substrate are minimized with benefit to breathability. The antenna is suitable to surface feeding and produces a broadside radiation. Parametric analysis are performed and an optimal configuration of four-cells grid is derived and experimentally demonstrated to provide a maximum gain of more than 6 dBi

Multi-chip RFID Tags integrating Shape-memory Alloys for Temperature Sensing

This paper proposes a dual-chip UHF tag embedding Shape Memory Alloys (SMA) able to tranform the variation of the tagged item’s temperature into a permanent change of antenna radiation features. This event-driven antenna is hence able to selectively activate the embedded microchips according to the temperature above or below a given threshold. A general design methodology for the resulting two-ports tag antenna is here introduced and then applied to prototypes able to work at low (around 0◦C) and high (80◦C) temperatures. The devices has clear applications in supply chain management as well as general safety assessment

NIGHT-Care: A Passive RFID System for Remote Monitoring and Control of Overnight Living Environment

AbstractAn Ambient Intelligence platform, NIGHTCare, for remote monitoring and control of overnight living environment is here proposed. The platform, entirely based on RFID passive technology is able to recognize nocturnal behaviors and activities, generates automatic alarms in case of anomalous or pathological events and support diagnostics. The results of a complete test in real scenario are presented, together with a numerical assessment of electromagnetic safety issues

Wearable Soft Grid Array Antenna for S-band 5G Communication

Potential convergence of wearable and epidermal antennas for battery-less communication with the emerging 5G framework, may boost the ultrafast and delay-free monitoring of biophysical parameters. 3.6 GHz epidermal antennas have already been demonstrated to possibly provide the same performance of a conventional UHF RFID link but with much larger band. Even better performance can be achieved by using wearable grid-arrays that may increase the read distance up to 6m in battery-less mode while keeping the feeding and fabrication complexity low. Here, the optimal performance of on-skin grid-arrays are investigated and a first prototype is manufactured and tested onto a body phantom

Development of a new class of on-skin radio-sensors boosted by thin polymer-based batteries

Conductive polymers are currently collecting interest for the development of low-profile eco-friendly and biocompatible non-metallic batteries capable of providing a local power source for the next-generation flexible body-integrated electronics. In this contribution, we demonstrate the feasibility of an organic ultrathin and multilayered polymer-based battery integrating a radiofrequency identification (RFID) tag antenna by means of an electromagnetic characterization in UHF band of the polymeric films. The optimally modeling of the battery plus the antenna aimed to develop a new class of shape-conformable radio-sensors suitable to adhere to the skin as a tattoo as well as a plaster. A prototype of the device was manufactured and its communication performances were characterized through the measurement of the realized gain of the tag attached directly onto a volunteer's skin

Folded Comb-line Array for Backscattering-based Bodycentric Communications in the 5G sub-6 GHz Band

Growing interest in IoT and Healthcare pushes the exploration of innovative solutions for connecting our bodies to external systems. The need for devices interoperability combined with data rate considerations, and low power consumption make 5G backscattering-based communications a promising opportunity, especially in the low sub-6 GHz band. Starting from a monolithic array, this paper proposes a skin-mountable miniaturized antenna suitable for 3.6 GHz body-centric backscattering communications. The array is an improved version of the comb-line antenna, which simultaneously optimizes size and radiation features. The horizontal segments are folded such to place the radiating dipoles closer and increase the radiation efficiency of the structure by co-phasing a single component of the surface currents. Parametric analysis obtains optimal configurations in terms of gain and size. Compared to conventional layout, the miniaturized array has an efficiency 6 dB higher and an area 80% smaller while the improved structure provides a theoretical read distance of more than 4 m. Measurements on a volunteer corroborate the improved performance

A Tightly Integrated Multilayer Battery Antenna for RFID Epidermal Applications

For the acceptance 1 of biointegrated devices in daily life, radio systems must be developed, which are minimally invasive to the skin, and they must have ultralow-profile local power sources to support data-logging functionality without compromising shape conformability. This contribution proposes a tightly integrated multilayer battery-antenna system (65 × 23 mm2), that is, ultrathin (just 200 ?m), flexible, and lighter than 1 g, making it suitable for epidermal applications. The negative electrode (anode) current collector of the battery is a radio frequency identification tag antenna coated by a conductive polymer (Pedot:PSS) working as anode material. Since the battery is a dynamic device, subjected to discharging, the antenna design must include the variable dielectric properties of the conductive polymer which are here first characterized in the UHF band for real charge/discharge battery conditions. The communication performance of the prototype composite device is hence evaluated through the measurement of the realized gain of the tag antenna (?19.6 dBi at 870 MHz) when it is placed directly onto a volunteer’s forearm. The read range of 1.3–3 m is suitable for occasional data download from the epidermal data logger when the user comes close to a reader-equipped gate