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- Influence of some structural parameters on the dielectric behavior of materials for textile antennasPublication . Loss, Caroline; Gonçalves, Ricardo; Pinho, Pedro; Salvado, RitaKnowledge of the electromagnetic properties of textile materials is crucial in order to design wearable antennas. Despite the growth of research studies on textile antennas, the accurate characterization of the dielectric properties of the materials is still a challenge due to the intrinsic inhomogeneity and deformability of textiles. In this work, 11 textile materials were characterized using the resonator-based experimental technique. The results obtained using this method have shown that when positioning the roughest face of the Material Under Test (MUT) in contact with the resonator board, the extracted dielectric constant (ɛr) value is lower than the one extracted with this face positioned upside-down. Based on this observation, superficial properties of textiles were investigated. Thus, this paper relates the results of the dielectric characterization to some structural parameters of textiles, such as surface roughness and surface and bulk porosity. The results show that both surface roughness and surface porosity of the samples influence the measurements, through the positioning of the probes. Further, the influence of the positioning of the dielectric material on the performance of textile microstrip antennas was analyzed. For this, 12 prototypes of microstrip patch antennas were developed and tested. The results show that, despite the differences obtained in the characterization when placing the face or reverse-sides of the MUT in contact with the resonator board, the obtained average result of ɛr is well suited to design antennas, ensuring a good performance.
- Influence of the laminating manufacturing technique on the S11 parameter of printed textile antenasPublication . Loss, Caroline; Salvado, Rita; Gonçalves, Ricardo; Pinho, PedroThis paper describes the influence of the laminating technique normally used to produce printed textile antennas on their return loss (S-11) parameter. The cutting technique and the use of steam on the ironing process of conductive fabrics are considered. The surface roughness and superficial porosity of dielectric materials are analyzed. This paper concludes that despite the unwanted compression applied on the laminating process, the technique is well suited to fabricated printed antennas.
- Influence of some structural parameters on the dielectric behavior of materials for textile antennasPublication . Loss, Caroline; Gonçalves, Ricardo; Pinho, Pedro; Salvado, RitaKnowledge of the electromagnetic properties of textile materials is crucial in order to design wearable antennas. Despite the growth of research studies on textile antennas, the accurate characterization of the dielectric properties of the materials is still a challenge due to the intrinsic inhomogeneity and deformability of textiles. In this work, 11 textile materials were characterized using the resonator-based experimental technique. The results obtained using this method have shown that when positioning the roughest face of the Material Under Test (MUT) in contact with the resonator board, the extracted dielectric constant (e(r)) value is lower than the one extracted with this face positioned upside-down. Based on this observation, superficial properties of textiles were investigated. Thus, this paper relates the results of the dielectric characterization to some structural parameters of textiles, such as surface roughness and surface and bulk porosity. The results show that both surface roughness and surface porosity of the samples influence the measurements, through the positioning of the probes. Further, the influence of the positioning of the dielectric material on the performance of textile microstrip antennas was analyzed. For this, 12 prototypes of microstrip patch antennas were developed and tested. The results show that, despite the differences obtained in the characterization when placing the face or reverse-sides of the MUT in contact with the resonator board, the obtained average result of e(r) is well suited to design antennas, ensuring a good performance.
- Textile antenna for RF energy harvesting fully embedded in clothingPublication . Loss, Caroline; Gonçalves, Ricardo; Lopes, Catarina; Salvado, Rita; Pinho, PedroIn the context of Wireless Body Sensor Networks for healthcare and pervasive applications, textile antennas allow an ubiquitous monitoring, communication, energy harvesting and storage. This paper presents a smart coat with a dual-band textile antenna for Radio Frequency (RF) energy harvesting, operating at GSM 900 and DSC 1800 bands, which is fully embedded in the garment. Results obtained before and after the integration of the antenna into the garment are compared. The gain obtained in the simulation is about 1.8 dBi and 2.06 dBi, with radiation efficiency of 82% and 77,6% for the lowest and highest operating frequency bands, respectively.
- Development of a textile antenna using a continuous substrate integrating the ground planePublication . Loss, Caroline; Salvado, Rita; Gonçalves, Ricardo; Pinho, PedroThe exponential growth in the wearable market is boosting the industrialization process of manufacturing textile antennas. The patch of the printed antennas can be easily cut, embroidered or screen printed by machines. The conception of an optimal industrial substrate that meets all the mechanical and electromagnetic requirements is still a challenge. This paper presents a printed textile antenna for ISM band using a continuous Substrate Integrating the Ground Plane (SIGP). The SIGP is a novel textile material, which is a double fabric that integrates the dielectric substrate and the conductive ground plane in a single textile.