M. E. Jalil

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.

Effects of human body and antenna orientation on dipole textile antenna performance and SAR

Wearable textile antennas are supposed to be integrated within the clothing or secured on the body. Therefore, the placement of the antennas and their orientation need to be carefully determined. In this paper, the interaction between a single band dipole textile antenna for wireless off-body communication applications 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 human body are taken into account and different antenna orientations, locations and 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 frequency investigated. Furthermore, the results obtained show that the SAR values are significantly influenced by the antenna orientation and position. SAR is increased by utmost 16 % when the textile antenna is horizontally orientated compared to antenna in vertical orientation.

Textile waveguide sheet with Artificial Magnetic Conductor structures for body centric wireless communication

This paper presented a textile sheet-like waveguide that incorporates Artificial Magnetic Conductor (AMC) structures. The aim is to investigate the possibility of a textile conformal waveguide in improving transmission between antennas when placed beneath them. Investigations were carried for small and belly size AMC waveguide sheets made of denim fabric. Both of the waveguide sheets exhibit promising results with S21 transmission of approximately -10dB at 5.8GHz resonant frequency. Transmission between two dipoles was enhanced with the introduction of AMC waveguide due to its inphase reflection characteristic. Promising results give future possibilities for practical realization of conformal AMC waveguide jacket made purely of textiles.

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.

Multiband antenna at ISM band using textille material

Two types of multiband antenna are proposed and discussed; straight dipole antenna and Koch fractal dipole antenna. Both antennas are designed to operate at three ISM band. The main aim of this paper is to design, fabricate and analysis the performance of the proposed antennas. The antennas performance was analyzed in term of reflection coefficient, efficiency, and gain. The simulations are carried out using CST Microwave Studio. The fabrication process involved conductive copper tape and denim textile as the substrate. The effect of different bending size on the antennas performance are discovered.

Investigation the performance of Koch fractal multiband textile antenna for on-body measurement

Kochs fractal multiband textile antennas are investigated for finding the best placement of antenna on the body. Two different conducting materials as the radiating element are investigated in this work; copper tape and SHIELD IT fabric. The substrate of antenna is a denim textile, which has permittivity of 1.7 and loss tangent of 0.025 at 2.5 GHz. This paper describes the investigation of antenna performance on the human body, which is the chest, the forearm, the arm and the back side of bodies. The comprehensive on-body measurements are conducted with two conditions; human with shirt and human without shirt. The experiment shows the copper tape material is better than SHIELD fabric. The suitable placement of the multiband antenna is on the backside of the body with vertical position.

Energy Detection Spectrum Sensing Measurement Using GNU Radio and USRP B200 at Wi-Fi Frequency

Spectrum sensing is one of the main tasks of cognitive radio, it decides whether the spectrum band is occupied by the primary or not. One of the techniques of spectrum sensing is energy detection (ED). Theory and simulation of ED are well established, however the real measurement of ED performance is not many, especially using Universal Software Radio Peripheral (USRP) B200 at Wi-Fi frequency. So, real measurement of ED performance using USRP B200 is collected and compared with theory. The result shows, that the ED performance measured using USRP B200 follows the theory.

Leaf-shaped dual band antenna for wearable application

This paper presents the design of leaf shaped dual band flexible textile antenna. The textile antenna designed at 1.8GHz suitable for Long Term Evolution (LTE) and 2.8GHz WiMAX application. To enhance the flexibility of the proposed antenna and for the comfort of the user, denim textile is used as a substrate material. The conductive copper tape is used as the conducting element. The study also describes the energy coupled effect of two different sizes of leaf shaped to the antenna current distribution where it change the impedance and radiation characteristic of the antenna.