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

This paper investigates changes in specific absorption rates due to metallic spectacles in close proximity with a head of representative electrical properties. Here, the FDTD method is used with a Z directed plane wave to simulate a personal digital assistant held in front of the face. Results confirm that metallic spectacles can significantly change SAR levels at frequencies between 1.5 and 3GHz. Specific attention is given to the energy interaction in the eyes and the nose. Results are given for several common spectacle frame shapes as well as whole head energy absorption comparisons

A multi-band printed monopole antenna

In this paper, we present an antenna design for multiband applications which can cover the GSM 900 (890-960 MHz), DCS (1710– 1880 MHz) and PCS (1850–1990 MHz), UMTS (1920– 2170 MHz), and WLAN2.4GHz (2400-2484MHz) frequency bands. A prototype is built and measured. Results of return loss, radiation patterns, and efficiency are given. The antenna is small, cheap to manufacture, has a low profile and would be suitable for wearable applications, mobile phones and base stations

2.4 GHz plaster antennas for health monitoring

Commercial plaster material (polyacrylate) is used as an antenna substrate. Two 2.45 GHz patch antennas are introduced, both designed to be attached directly to the skin. Measured efficiencies are 70 % in free space and 60 % on-body. Measured on-body gains of each antenna are 6.2 and 1.4 dBi. Simulated 1 g specific absorption rates (SAR) of the two antennas are 2.3 W/kg and 1.6 W/kg using 1 W input power. 10 g SAR values are 0.6 W/kg and 1.2 W/kg. Antenna feeding using snap-on buttons is investigated and has been found useful

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

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

Cold-sintered temperature stable Na0.5Bi0.5MoO4–Li2MoO4 microwave composite ceramics

© 2017 American Chemical Society. A cold sintering process (150 °C, 30 min and 200 MPa) was employed to fabricate Na 0.5 Bi 0.5 MoO 4 -Li 2 MoO 4 (NBMO-LMO) composites with up to 96.4% relative density. X-ray diffraction traces, backscattered electron images and Raman spectra indicated the coexistence of NBMO and LMO phases in all composites with no detectable secondary phases. The pemittivity (ϵ r ) and temperature coefficient of resonant frequency (TCF) decreased, whereas microwave quality factor (Q × f) increased, with increasing weight % LMO. Near-zero TCF was obtained for NBMO-20 wt %LMO with ϵ r ∼ 17.4 and Q × f ∼ 7470 GHz. Functionally graded ceramics were also fabricated with 5 ≤ ϵ r ≤ 24. To illustrate the potential of these cold sintered composites to create new substrates and device architecture, a dielectric graded radial index lens was designed and simulated based on the range of ϵ r facilitated by the NBMO-LMO system, which suggested a 78% aperture efficiency at 34 GHz

Correlation of specific absorption rates in the human head due to multiple independent sources

This is a conference paper [© IEEE]. It is also available at: http://ieeexplore.ieee.org/ Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.This paper examines how the SAR in the head is combined when exposed to the field due to multiple sources. The mechanisms when the sources have the same and different frequencies are discussed. FDTD simulation results are included when an anatomically realistic head is excited by various sources including: plane waves, vertically and horizontally orientated dipoles positioned in front and by the side of the head. Results are presented for two sources over the frequency range 0.5 to 4GHz

Additively manufactured heterogeneous substrates for three-dimensional control of local permittivity

The concept of using additive manufacturing as a method to construct heterogeneous substrates from a single building material via stereolithography is introduced. The dynamic variation of air cavities within the bulk material is used to control the effective permittivity of the host medium. The digitally driven layer process enables full three-dimensional variation of the local permittivity. The high resolution of stereolithography enables sub-millimetre control of air inclusion features. Measurements of the effective permittivity with different air fractions have been compared to analytical results