N. Othman

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.

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.

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.

Influence of bending of 900MHz textile antenna on specific absorption rate

In this paper, the interaction between a single band textile dipole antenna with human body is examined under several bending conditions. The numerical simulations of the single band 0.9 GHz patch dipole antenna are performed by using Computer Simulation Technology (CST) Microwave Studio. The Finite Integration Technique (FIT) method is utilized to determine the antenna performance. Results have clearly indicated that the human body has more prominent effect on the antenna resonant frequency if compared to antenna bending. However, bending of the antenna has caused the radiation to penetrate deeper into the muscle tissue compared to the normal flat antenna (fat tissue).

Investigation of crumpling effects on EM absorption and antenna performance at 2.4 GHz

This paper discusses the performance and SAR of dipole textile antenna under different crumpling conditions in the presence of human body close to the radiation source. The numerical simulations of the realistic complex two dimensional crumpling is performed by using Finite Integration Technique (FIT) which is applied in Computer Simulation Technology (CST) Microwave Studio. A realistic heterogeneous Voxel body model is used in the simulation and has been exposed to a simple dipole textile antenna at 2.4 GHz. Results have been compared with equivalent homogeneous model to further validate the results. The results obtained show that the antenna crumpling has prominent effect on the antenna performance and could enhance the 10 g SAR up to 18.2 % from the reference SAR (flat condition). Hence, the antenna crumpling may contribute to higher penetration of the radiation through human body tissue.

Specific Absorption Rate in the human leg and testicle due to metallic coin and zip

This research identifies and evaluates the effect of human body and conductive metallic objects in the vicinity of radiation source on Specific Absorption Rate (SAR). The presence of electronic devices in the vicinity of human body especially close to the human sensitive part especially when the antenna is left inside the trousers pocket could allow the radiated electromagnetic wave to penetrate inside human tissue. Realistic Voxel body model has been considered in the simulation. The excitation is provided by means of a simple dipole and PIFA antennas as the radiating source at 0.9 GHz and 1.8 GHz. Metallic coin and zip have been used in order to characterize the variation of SAR due to metallic objects. The results have shown that the presence of metallic objects near to human body could alter the energy absorption by the body. The presence of coin close to dipole antenna increases the 1g SAR in the leg by 58 %. In addition, the zip could significantly increases SAR inside the testicle by 30 % at 0.9 GHz.

Analysis on the Specific Absorption Rate due to the metallic objects exposed to radiation source

This paper discusses the simulation and measurement results of Specific Absorption Rate (SAR) due to the presence of common metallic items close to the radiation source. Numerical simulations are performed by using Finite Integration Technique (FIT). A heterogeneous Voxel body model is used in the simulation and has been exposed to a simple λ/2 dipole antenna at three different frequencies; 0.9, 1.8, and 2.4 GHz. In order to investigate the effect of metallic item, three types of common metallic objects are introduced and discussed in this paper. The results indicated that the presence of coin and ring significantly affect the value of point SAR. Higher increment of 16 times from reference SAR is observed at 1.8 GHz in the presence of 28 mm (diameter) ring. The measurement result is in good agreement with simulation results (at 2.4 GHz) indicating that the presence of metallic ring increases the point SAR by more than 10%.

The effects of straight-pin type earring worn on the head on SAR at 2.4 GHz and 5.8 GHz

This paper presents the effect of metallic items on the antenna performance and SAR at 2.4 GHz and 5.8 GHz. The simulations were performed by means of CST Microwave Studio. The patch antenna was used as the radiating source while the metallic items were modeled as λ/4 and λ/2 straight pin-type earrings respectively. The results have shown that the head has shifted the antenna resonant frequencies at both frequencies investigated. This study has also indicated that the additional metallic item in close proximity to the head has an additional effect on antenna resonance, albeit quite a small one. However, the straight-pin type earrings have significantly increases the amount of energy absorbed in the human head at both frequencies tested.