Noor Asmawati Samsuri

Design, implementation and performance of ultra-wideband textile antenna

Communication technology is increasingly pervading everyday life. The rapid progress in wireless communication besides the increasing interest in wearable antennas and electronics in civil, medical, sport wear and military domains promises to replace wired- communication networks in the near future in which antennas are in more important role. Recently, there has been growing interest in the antenna community to merge between wearable systems technology, Ultra-Wideband (UWB) technology and textile technology. All these together have resulted in demand for ∞exible fabric antennas, which can be easily attached to a piece of clothing. In this paper, three difierent structures of UWB antennas using clothing materials and suitable for wearable application were fabricated and presented. The substrate of the designed antennas was made from jeans textile material, while radiating element and ground plane are made out of copper tape. The operating frequency of all three designs is between 3GHz and 12GHz. Measured results are compared with simulations and good agreement was observed.

Embroidered Fully Textile Wearable Antenna for Medical Monitoring Applications

Telecommunication systems integrated within garments and wearable products are such methods by which medical devices are making an impact on enhancing healthcare provisions around the clock. These garments when fully developed will be capable of alerting and demanding attention if and when required along with minimizing hospital resources and labour. Furthermore, they can play a major role in preventative ailments, health irregularities and unforeseen heart or brain disorders in apparently healthy individuals. This work presents the feasibility of investigating an Ultra-WideBand (UWB) antenna made from fully textile materials that were used for the substrate as well as the conducting parts of the designed antenna. Simulated and measured results show that the proposed antenna design meets the requirements of wide working bandwidth and provides 17 GHz bandwidth with compact size, washable and flexible materials. Results in terms of return loss, bandwidth, radiation pattern, current distribution as well as gain and effciency are presented to validate the usefulness of the current manuscript design. The work presented here has profound implications for future studies of a standalone suite that may one day help to provide wearer (patient) with such reliable and comfortable medical monitoring techniques.

FRACTAL KOCH MULTIBAND TEXTILE ANTENNA PERFORMANCE WITH BENDING, WET CONDITIONS AND ON THE HUMAN BODY

A multiband Fractal Koch dipole textile antenna is proposed for wearable applications. The antenna is designed to operate at 0.9GHz, 2.45GHz and 5.8GHz. Denim materials as the substrate are selected aiming to obtain robustness, ∞exibility and a lightweight textile antenna. The antenna model is designed, simulated, optimized and analyzed using Microwave Studio CST software. Two types of multiband antenna prototypes are fabricated and evaluated with difierent conducting elements (Shield It fabric and copper foil tape). Antenna performance is observed in terms of return loss, bandwidth, radiation pattern and realized gain. Three difierent comprehensive analyses are taken into consideration: measurement antenna with difierent bending sizes, on-body measurement and under wet conditions. The antenna performances are evaluated based on resonant frequency (fo) and bandwidth (BW). The antennas performance with bending on the human body (arm & forearm) is compared and investigated. A suitable placement on the body has been discovered between the chest and backside. The antennas have also been tested under wet conditions to ensure a stable characteristic under the in∞uence of water.

Textile UWB Antenna Bending and Wet Performances

The vision and ideas of wearable computing systems describe future electronic systems as an integral part of our everyday clothing that provides the wearer with such intelligent personal assistants. Recently, there has been growing interest in the antenna community to merge between wearable systems technology, ultrawideband (UWB) technology and textile technology. This work aimed to make closer steps towards real wearability by investigating the possibilities of designing wearable UWB antenna where textile materials are used for the substrate as well as the conducting parts of the designed antenna. Two types of conducting materials have been used for conducting parts, while a nonconducting fabric has been used as antenna substrate material. A set of comparative results of the proposed design were presented and discussed. Moreover, effects on the return loss by means of measurements for each fabricated antenna prototype under bent and fully wet conditions were discussed in more details.

The effects of human body and bending on dipole textile antenna performance and SAR

In this paper, the interaction between a single band textile antenna with human body is examined. The simulations are performed by means of CST Microwave Studio with a single band 2.4 GHz patch dipole antenna as the radiating source. The effects of bending and different distances from the body are also considered in this study. Results have clearly indicated that the human body has notably shifts the antenna resonant frequency and modifies the radiation pattern at the frequencies investigated. Furthermore, the results obtained show that the SAR values are significantly influenced by the amount of curvature of the antenna and the separation distance between the antenna and the human body. The averaged SAR value is increased up to 92.3 % when the curved textile antenna is bent and placed 1 mm away from the body.

Triple band circular ring-shaped metamaterial absorber for x-band applications

This paper presents the design, fabrication, and measurement of triple band metamaterial absorber at 8GHz, 10GHz and 12GHz which are in the X-band frequency range. The unit cell of the metamaterial consists of three concentric copper rings at difierent radii, printed on 0.8mm thick FR4 substrate in order to obtain triple resonant frequencies. The highly symmetrical ring structure in nature makes this absorber insensitive to any polarization state of incident electromagnetic (EM) waves for normal incident waves. The proposed structure is capable to operate at wide variations angle of incident wave. The simulated result shows that the triple-band metamaterial absorber achieves high absorbance for normal incident electromagnetic waves of 97.33%, 91.84% and 90.08% at 8GHz, 10GHz and 12GHz, respectively, when subjected to normal incident electromagnetic. With metamaterial absorber maintaining 50% of absorbance value, the corresponding full width half maximum (FWHM) are 5.61%, 2.90% and 2.33%. The operating angles in which the metamaterial structure can maintain 50% absorbance at TE mode and TM mode are 67 - and 64 - , respectively. The experimental result verifles that the absorber is well performed at three difierent resonant frequencies with absorbance greater than 80%.

Wideband Antenna with Reconfigurable Band Notched Using EBG Structure

A wideband antenna with band notch function using electromagnetic bandgap (EBG) structure is proposed. The antenna is capable of reconfiguring up to three band notch operation. Three EBGs are aligned underneath the feed line of the wideband antenna. The transmission lines over EBGs unit cells perform as a band stop filter. A switch is placed on each of the EBG structure, which enables the reconfigurable band stop operation. The simulated and measured reflection coefficients, together with the radiation patterns, are shown to demonstrate the performance of the antenna.

Chipless RFID tag based on meandered line resonator

A meandered microstrip transmission line resonator is proposed for the design of chip-less RFID tag. The 6 bit resonator is operates from 3 to 5 GHz. The tag consists of a micro strip open stub resonators and two Ultra-wide Band (UWB) monopole antennas. The 30 mm × 35 mm chip-less RFID tag is designed on Taconic substrate with permittivity of 2.75. The modification technique from the straight line of micro strip open stub toward meandered line is introduced.

Comparison on the effect of homogeneous and inhomogeneous body on antenna performance and SAR

This research quantifies the effect of homogeneous and inhomogeneous body model on Specific Absorption Rate (SAR). Quarter wave monopole antenna is used as the excitation source at 2.4 GHz. The simulation results are calculated by means of CST Microwave Studio based on Finite Integration Technique (FIT). Male Voxel model is modelled as an inhomogeneous and homogeneous models and filled with standard dielectric properties (σ,εr) of 2.4 GHz as recommended by the FCC. The antenna is placed in front of the body model in the area of human wrist and the distances are varied (5, 10, 20, 31, 50, and 62 mm). The results are presented in terms of resonant frequency, radiation pattern, and SAR. The effect of homogeneity is negligible on the return loss and radiation pattern. However the 10g SAR is increased by 20% when the homogeneous model is used.

Wetness experiment for compact CPW-fed ultra wideband antenna using textile material

The design of coplanar waveguide-fed ultrawide-band antenna with elliptical structure is presented that will cover from 1.6GHz to 13.5 GHz frequency band. Denim material have been selected as the substrate of textile antenna due to its thickness and permittivity. Different conducting part of antenna; copper tape and Shieldit fabric are compared and analyzed to evaluate the performance of antenna with different conducting material. The wetness experiment is required to investigate the performance of antenna in wet condition. The result of return loss will describe the performance of antenna in wet condition in this experiment.