The SAR effects of popular jewellery on the human head

This paper investigates the effects of metallic jewellery on the SAR in the human head. A CW dipole is placed in front of the head to represent a mobile enabled personal data assistant. The FDTD method has been used to simulate an eyebrow ring near a homogeneous SAM phantom at 1.8GHz. Measurements were made on the Loughborough SAM head with the DASY4 measurement system. Simulations were also made with eyebrow rings on the surface of the skin and pierced through the eyebrow of a heterogeneous anatomically realistic human head. Common sizes of eyebrow ring and eyebrow stud have been considered over the frequency range 0.6 to 4.6GHz. Jewellery which was small compared to a wavelength had little effect on the SAR in the head

A study of the effects of metallic pins on SAR using a Specific Anthropomorphic Mannequin (SAM) Head Phantom

This paper presents the effects of facial metallic pins on the Specific Absorption Rate (SAR) in the head, when radiated by a microwave source placed in front of the face. A Specific Anthropomorphic Mannequin (SAM) is adapted for use with a DASY4 and a digitised SAM head is modelled using inhouse Finite-Difference Time-Domain (FDTD) code, enabling comparisons between measurements and simulations. A continuous wave (CW) half-wave dipole is placed in front of the face, representing a communications enabled personal data assistant mobile communications equipment (PDAMCE). Parametric studies have shown that metallic pins that are roughly half a wavelength long placed along the eyebrow, increase the 1g and 10g SARs at 900MHz by around five fold. A greater than five fold increase is seen at 1800MHz. Measurements show very good agreement with simulations

Specific Absorption Rates in the human head due to circular metallic earrings at 1800MHz

This paper investigates Specific Absorption Rates (SAR) in the human head due to circular metallic earrings at 1800MHz. A Finite-Difference Time-Domain (FDTD) code was used to analyse different sizes and positions of circular earrings near a homogenous cubic phantom. Results showed good agreement with measurements using the flat section of the SAM twin phantom with the DASY4 measurement system. The excitation was a half wave dipole. Metallic loops with a circumference of approximately one wavelength and positioned 14mm away from the phantom increased the 10g SAR by 5 times. The FDTD code has also been used to analyse the effect of metallic earrings when ‘pierced’ through the ear of an anatomically realistic digital human head based on the Visible Human Project. The head is not symmetric and both ears were considered to allow comparison between different heads. The shape of the ear and the size of the earring were found to be very significant when earrings were hung from the human ear

Frequency reconfigurable RF circuits using photoconducting switches

Designs for a frequency switchable dual-band branch-line coupler and a reconfigurable S-band power amplifier input matching network with photoconducting switches are presented. Frequency switching is achieved by increasing the power of the laser applied to the highly resistive silicon wafer and changing the properties of silicon under optical illumination. The advantages of this approach are high-speed switching, electromagnetic transparency (no interference) and thermal and electrical isolation between the device and the control circuit. A branch-line coupler frequency shift of 35% and 10% has been achieved from all switches off to all switches on in lower (900 MHz) and upper (1800 MHz) frequency bands, respectively. Frequency switchable class AB power amplifier with silicon switch in the input matching circuit has obtained the frequency tuning range of 2.5-3.5 GHz with no significant loss in efficiency and linearity

A study of perturbations in linear and circular polarized antennas in close proximity to the human body and a dielectric liquid filled phantom at 1.8 GHz

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box phantom filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss (S11). Results show that both linear and circularly polarized antennas produce an optimal return loss closer to the surface of a typical phantom than the back of a human volunteer

A study of the effects of metallic pins on SAR using a specific anthropomorphic mannequin (SAM) head phantom

This paper presents the effects of facial metallic pins on the Specific Absorption Rate (SAR) in the head, when radiated by a microwave source placed in front of the face. A Specific Anthropomorphic Mannequin (SAM) is adapted for use with a DASY4 and a digitised SAM head is modelled using inhouse Finite-Difference Time-Domain (FDTD) code, enabling comparisons between measurements and simulations. A continuous wave (CW) half-wave dipole is placed in front of the face, representing a communications enabled personal data assistant mobile communications equipment (PDAMCE). Parametric studies have shown that metallic pins that are roughly half a wavelength long placed along the eyebrow, increase the 1g and 10g SARs at 900MHz by around five fold. A greater than five fold increase is seen at 1800MHz. Measurements show very good agreement with simulations

Multi-band material loaded Low-SAR antenna for mobile handsets

Previous studies have shown that monopoles loaded with material of equal permittivity and permeability values give increased bandwidth and radiation efficiency for a given size reduction. Positioning the monopole orthogonally to the head directs pattern nulls towards the head, which leads to low Specific Absorption Rates (SAR). Simulated results of the material loaded monopole showed dual-mode behaviour. In this paper, the simple monopole is translated into a compact antenna design suitable for mobile handsets. Metallic strips are printed on the material block to increase the number of modes and realise a small, quad-band, low-SAR handset antenna

Switchable frequency selective surface for reconfigurable electromagnetic architecture of buildings

A frequency selective surface (FSS) that is electronically switchable between reflective and transparent states is tested. It can be used to provide a spatial filter solution to reconfigure the electromagnetic architecture of buildings. The FSS measurements show that the frequency response of the filter does not change significantly when the wave polarization changes or the angle of incidence changes up to +/- 45 degrees from normal. The FSS is based on square loop aperture geometry, with each unit cell having four PIN diodes across the aperture at 90 degree intervals. Experiments demonstrated that almost 10 dB additional transmission loss can be introduced on average at the resonance frequency, for both polarizations, by switching PIN diodes to ON from OFF state

The SAR effects of popular jewellery on the human head

This paper investigates the effects of metallic jewellery on the SAR in the human head. A CW dipole is placed in front of the head to represent a mobile enabled personal data assistant. The FDTD method has been used to simulate an eyebrow ring near a homogeneous SAM phantom at 1.8GHz. Measurements were made on the Loughborough SAM head with the DASY4 measurement system. Simulations were also made with eyebrow rings on the surface of the skin and pierced through the eyebrow of a heterogeneous anatomically realistic human head. Common sizes of eyebrow ring and eyebrow stud have been considered over the frequency range 0.6 to 4.6GHz. Jewellery which was small compared to a wavelength had little effect on the SAR in the head

Specific Absorption Rates in the Human Head Due to Circular Metallic Earrings at 1800MHZ

This paper investigates Specific Absorption Rates (SAR) in the human head due to circular metallic earrings at 1800MHz. A Finite-Difference Time-Domain (FDTD) code was used to analyse different sizes and positions of circular earrings near a homogenous cubic phantom. Results showed good agreement with measurements using the flat section of the SAM twin phantom with the DASY4 measurement system. The excitation was a half wave dipole. Metallic loops with a circumference of approximately one wavelength and positioned 14mm away from the phantom increased the 10g SAR by 5 times. The FDTD code has also been used to analyse the effect of metallic earrings when ‘pierced’ through the ear of an anatomically realistic digital human head based on the Visible Human Project. The head is not symmetric and both ears were considered to allow comparison between different heads. The shape of the ear and the size of the earring were found to be very significant when earrings were hung from the human ear