Flexible and Transparent Circularly Polarized Patch Antenna for Reliable Unobtrusive Wearable Wireless Communications

Abstract

This paper presents a circularly polarized flexible and transparent circular patch antenna suitable for body-worn wireless-communications. Circular polarization is highly beneficial in wearable wireless communications, where antennas, as a key component of the RF front-end, operate in dynamic environments, such as the human body. The demonstrated antenna is realized with highly flexible, robust and transparent conductive-fabric-polymer composite. The performance of the explored flexible-transparent antenna is also compared with its non-transparent counterpart manufactured with non-transparent conductive fabric. This comparison further demonstrates the suitability of the proposed materials for the target unobtrusive wearable applications. Detailed numerical and experimental investigations are explored in this paper to verify the proposed design. Moreover, the compatibility of the antenna in wearable applications is evaluated by testing the performance on a forearm phantom and calculating the specific absorption rate (SAR).

Design and Evaluation of a Button Sensor Antenna for On-Body Monitoring Activity in Healthcare Applications

“…Our three-layer standard body model has a volume of (skin = 4, fat = 8, muscle = 30, and air layer under the tissue layers = 8 (in mm)) and the four-layer phantom model has the volume of (skin = 2, fat = 8, muscle = 40, bone = 30, and air layer under the tissue layers = 8 (in mm)). The performance of the designed BSA device was evaluated for different tissue layer morphologies as well as spacing from the phantom model, according to the standard methods discussed in [ 51 , 52 , 53 , 54 , 55 ].…”

“…The muscle layer has an ε r of 52.7 and 48.2 and a of 1.95 S/m and 6.0 S/m at the lower and upper-frequency bands, respectively. The bone layer has an ε r of and a 11.4 of 0.39 S/m, and of 9.674 and 1.1544 S/m at 2.45 and 5.8 GHz in the lower and upper frequencies, respectively [ 55 , 56 , 57 , 58 ]. For modeling the arm, a simple layered cylindrical model was utilized.…”

Slot Antennas Integrated into 3D Knitted Fabrics: 5.8 GHz and 24 GHz ISM Bands

“…Currently, the research of textile circularly polarized antennas dominantly covers flexible and transparent antennas for reliable wearable applications [ 27 ], conformal textile antenna arrays for wearable devices [ 28 ], UWB antennas for body-centric communication [ 19 ], and multiple-input multiple-output one [ 29 ]. In all those emerging concepts, the fundamental principles presented in this paper can be applied to move the operation frequency of textile-integrated radiators higher.…”

Wearable Antennas for Sensor Networks and IoT Applications: Evaluation of SAR and Biological Effects

“…Furthermore, in order to estimate the applicability of antennas for body-worn wireless devices, the antenna parameters and characteristics need to be studied both in free space and on the human body [ 4 ]. Several types of flexible wearable antennas for embedding into garments or accessories have been presented that fully or partially meet the design requirements: patch antennas [ 5 , 6 , 7 , 8 , 9 , 10 ], textile slotted waveguide antennas [ 11 ], monopole textile antennas [ 12 , 13 ], and fully-textile loop antennas [ 14 , 15 ]. The effects of the human body on antenna parameters and characteristics has been numerically investigated by employing homogenous (cylindrical [ 11 ], rectangular [ 11 , 14 ], forearm [ 5 ], full-scale human body model [ 7 ]) and multilayer (cylindrical [ 6 ], rectangular [ 15 ]) human body models.…”

“…The SAR limits for local exposures in the considered frequency range were established in recent ICNIRP guidelines and IEEE C95.1-2019 standard [ 17 , 19 ]. Several previously reported works on fully textile and optically transparent wearable antennas showed that the simulated peak 1 g and 10 g average SAR generated from the antennas in a homogeneous flat phantom [ 14 ], in the chest, upper arm, and the wrist of the HUGO human body model [ 7 ], in a multilayer cylindrical human body model [ 6 ] and in a forearm phantom [ 5 ] varied from 0.22 to 0.533 W/kg (SAR 1 g) and from 0.148 to 0.695 W/kg (SAR 10 g), at 2.45 GHz at a net input power of 100 mW.…”