A study of changes to specific absorption rates in the mucous membrane close to perfectly conducting spectacles within the radio frequency range 0.8 to 2.6 GHz.

Abstract—this paper investigates the effects of metallic spectacles on the Specific Absorption Rates (SAR) in the mucous membrane in the human head, using the FDTD method. The excitation is a vertically polarised plane wave traveling from the front of the face to the back of the head. The frequency range considered is 0.8 to 2.6GHz. Metallic spectacles were found to significantly change the SAR in the mucous membrane

Applications of a genetic algorithm for identification of maxima in specific absorption rates in the human eye close to perfectly conducting spectacles

Relative changes in specific absorption rates owing to perturbing metallic spectacles in proximity to the face are investigated. A representative electrical property biological matter model with twenty five distinct tissue types based on images of an adult male is used with the FDTD method. Both plane wave and dipole source stimuli are investigated and are used to represent a mobile cellular-enabled personal digital assistant held in front of the face. Results show that metallic spectacles may alter significantly specific absorption rate (SAR) level distributions within the head. The frequency range investigated is 1.5–3.0GHz. Specific attention is given to energy interactions with the eyes. Results are given for several common spectacle frame shapes in addition to whole head energy absorption comparisons. Whole head and single mirrored half head sensitivity data are also presented. A Pareto ranked genetic algorithm (GA) is used to search for the spectacles that cause the highest and lowest SAR in the eye

On specific absorption rates in the human mucous membrane with conducting spectacles at mobile phone frequencies by FDTD simulation

An anatomically correct FDTD head phantom was used to study SAR levels in the mucous membrane found in the lining of the nose, sinuses and ears. The membrane is found to absorb significant levels of energy when illuminated by a plane wave from the front of the head. The frequency range considered is 0.8 to 2.6GHz. Metallic spectacles were found to significantly change the SAR in the eyes and mucous membrane

A study of changes to specific absorption rates in the human eye close to perfectly conducting spectacles within the radio frequency range 1.5 to 3.0 GHz

This paper investigates relative changes in specific absorption rates due to perturbing metallic spectacles in proximity to the face. A representative electrical property biological matter model with 25 distinct tissue types based on magnetic resonance imaging data is used with the finite-difference time-domain method. Both plane wave and dipole stimuli are investigated and are used to represent an excitation from the front of the head. The frequency range investigated is 1.5 to 3.0 GHz. Results show that metallic spectacles may significantly alter SAR level distributions within the head. Specific attention is given to energy interactions with the eyes. Results are given for several common spectacle frame shapes

Implications for SAR when using a symmetric phantom exposed to RF radiation using the FDTD method

This paper investigates the implications of SAR when using a symmetric head compared to a whole head. The excitation is a vertically polarised plane wave traveling from the front of the face to the back of the head. The frequency range considered is 1.5 to 3.0GHz. In general actual human heads are not symmetric. For example one eye may be slightly higher than the other and a nose maybe somewhat bent. Recently researchers also have evidence of brain torque (i.e. rightward frontal and leftward occipital asymmetry) in humans. In this FDTD model the head is modeled as two identical mirrored halves. By this method the field values need not be calculated twice thereby reducing computation time and memory requirements. Our results show whole head versus mirrored head comparisons for the maximum 1 and 10g SAR in the head and gives particular attention to the SAR in the eyes

Recognising people using smart phone antennas: A fuzzy biometric

Many calls are made to mobile phones by machines and for nuisance avoidance it would be useful to know if the caller was human or not. Also for convenience it would also be useful to know if the person using a mobile was the same as the one normally using it and if that person was an adult or a child. A wrong result could be used to trigger a request for a key code. Using the hand and four mobile frequency band antennas this paper has investigated the effects of different people on the input impedance of mobile phone antennas with the aim of establishing whether the effect is distinct enough to allow a fuzzy biometric to be achieved. Hands were placed at a range of distances from the antenna, using a test rig designed specifically for this experiment. The frequencies of operation were 900 MHz, 1800 MHz, 1900 MHz and 2.4 GHz. Results showed that the effect of each volunteer on the antenna's input impedance varied significantly when their hand was 30 mm or less from the antenna and that below 10mm they were distinct between volunteers

3D printed utility dielectric core manufacturing process for antenna prototyping

A prototyping method for dielectrically loaded antennas is presented. Dielectric loading has been used with horn antennas, feeds, and lenses. Dielectrics have also been used for coating antennas submerged in water and biological matter and have led to improvements in bandwidth and efficiency as well as antenna miniaturisation. The authors present a new technique to produce variable dielectrics with permittivity from 6 to 28 using two commonly available powders, titanium dioxide (used in foods) and magnesium silicate (used in talcum powder). An example spherical helical ball antenna is used to demonstrate the process. In this antenna, the mixed powders were encased in a 3D printed shell that achieved a reduction in diameter of the spherical antenna by a factor of 1.85. The technique aids rapid prototyping and optimisation using search algorithms

Focusing effects of metallic rim-less spectacles at mobile communication frequencies on the energy absorbed in the head

This paper presents simulated and measured results from a study looking at the Specific Absorption Rates (SAR) inside the head due to metallic rim-less spectacles, when the head is irradiated by a dipole source in front of the face. The study concentrates on the GSM1800, PCS1900 and UMTS 2100MHz frequency bands. Simulations were carried out using the homogeneous Specific Anthropomorphic Model (SAM) phantom and a heterogeneous head model developed from the Visible Human Project. SAR measurements were carried out using a DASY4 with the modified rear-entry Loughborough SAM head. The measurements and both sets of simulations show that the metallic crossbar can increase the peak 1g SAR inside the head by approximately 5 times in the GSM1800 uplink frequency band

Coupled dipole antennas for on/off-body communications at 2.45 GHz

In this paper, three experiments with coupled dipoles were carried out in order to determine the optimal distance where an efficient communication link can be established. The simulations results showed that when the subcutaneous dipole is installed adjacently to the surface of the skin, the dipole mounted above the skin level should be in the range of 20 mm to 25 mm for efficient communication. Subsequently, the influence of the dielectric parameters of the human tissue on wave propagation has also been presented in this work

A software defined radio comparison of received power with quadrature amplitude modulation and phase modulation schemes with and without a human

This paper presents the application of software-defined radio to the study of received power with and without a human in close proximity to a receiver transmitter pair. Software defined radio is increasingly being used in radio related research and teaching in Universities, Schools and Colleges. For teaching it is typically being used in the classroom in close proximity to users/observers. Because several transceiver sets are needed to compare two or more modulation techniques in conventional radio this presents significant challenges with matching, synchronisation and noise. Two or more separate systems are needed. In contrast with software defined radio simple changes to the ratios of I and Q modulators can execute several modulation methods using the same system. This paper examines the use of a typical software defined radio in close proximity to a user which is typical in a classroom situation. The most suitable of two modulation techniques for use with communication systems close to humans as a function of received power for a typical office environment is presented