Flomerics' Micro-stripes software helps Indexsar predict how mobile phone radiation is absorbed by brain tissue

Citation

(2002), "Flomerics' Micro-stripes software helps Indexsar predict how mobile phone radiation is absorbed by brain tissue", Sensor Review, Vol. 22 No. 3. https://doi.org/10.1108/sr.2002.08722caf.005

Flomerics' Micro-stripes software helps Indexsar predict how mobile phone radiation is absorbed by brain tissue

Flomerics' Micro-stripes software helps Indexsar predict how mobile phone radiation is absorbed by brain tissue

Keyword: Radiation

Public concerns about the possible carcinogenic effect of electromagnetic (EM) radiation on human tissue, especially within the brain, has made EM and the measurement of specific absorption rates (SAR) an important area of research for makers of any mobile device that transmits data via radio or microwaves. A complete EM radiation simulation model built within Flomerics' industry leading Micro-stripes EM analysis software has been crucial to the accurate calibration of a cost-effective new device, which promises to simplify the compulsory EM radiation absorption or SAR pre-compliance testing for mobile device manufacturers (Plate 4). The Micro-stripes model predicted the absorption rates of a brain tissue substitute very accurately and showed a high degree of correlation with measured results. Also with Micro-stripes being able to display a snapshot at frequencies of interest the simulation was able to reveal ripple effects that are not measured using the usual peak or average detectors, furthering our understanding of EM radiation within human tissues (Plate 5).

Plate 4 IndeXsar SAR test device

The way EM radiation, transmitted by radio devices, is absorbed by human tissue is assessed via SAR. This has many implications for mobile device manufacturers especially now that the Bluetooth™ wireless application standard (which uses near microwave 2.45GHz frequencies) is becoming more common within laptops and palm computers, etc. SAR is important, first, as part of the product certification process and to allay public health concerns over mobile phones, etc., but also because it has performance implications for mobile devices. If human tissue is absorbing the signal it will affect the transmission quality and characteristics and mean that battery life suffers as modern devices fluctuate transmission strength depending on received signal strength.

Plate 5 A complete EM radiation simulation model built within Flomerics' industry leading Micro-stripes EM analysis software has been crucial to the accurate calibration of a cost effective new device, which promises to simplify the compulsory EM ration absorption or SAR pre compliance testing for mobile device manufacturers.

The device that Micro-stripes helped to calibrate was designed and built by IndeXsar, a company that specialises in SAR research and the manufacturing of SAR test systems. Its new product MapSAR is a SAR measurement device designed to make the testing of new products quicker and far more cost-effective. MapSAR uses a fully calibrated, isotropic SAR probe and a range of phantom simulating liquids to accurately measure the SAR into brain tissue of different mobile devices. (Due to the way brain tissue reacts to changes in electric field frequency, dependent materials are needed to simulate head tissue when different frequencies are being measured. FLO/EMC is capable of modelling these frequency dependent materials as a Debye/Lorentz representation, so only one simulation is needed to model a wide range of frequencies.) It is unique as it performs 3D calculations, to give complete, volume-averaged SAR results. By dispensing with much of the expensive equipment the MapSAR device is far cheaper to produce and use than traditional measuring equipment.

The Micro-stripes model was designed to test the MapSAR device with a well-understood transmitter – a balanced dipole source – to aid with its calibration. It was monitored at three frequencies similar to those used by current and future mobile phone and Bluetooth frequencies: 900MHz and 1800MHz (GSM) and 2450MHz (3G and Bluetooth). The specific objectives included:

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  Characterising the electric field determination within MapSAR.

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  Investigating the effects on different head tissue substitutes.

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  Verifying the method IndeXsat used for calibrating MapSAR.

Working together closely, Flomerics and IndeXsar were able to hone the model to give consistently accurate results. These showed that the 2D base data could consistently and accurately be extrapolated to give a 3D field penetration within MapSAR and that radiation penetrated further into brain tissue at lower frequencies. All three head tissue substitutes displayed a similar centre line (overall) decay profile. The simulation results have helped to give the MapSAR a sound theoretical underpinning, which is now being boosted by further research.

Mike Manning, director, IndeXsar said, "With 3G and Bluetooth becoming industry communication standards SAR research is going to become even more important to all sorts of technology manufacturers. Flomerics' analysis and theoretical validation of the MapSAR system has given us the theoretical underpinning necessary to back up our 3D calculations in this important area of research. Flomerics worked hard to get the best from the analysis and has provided the most complete analysis of the MapSAR system so far. We will use the Flomerics results along with those from other sources to demonstrate the veracity of our MapSAR unit."

John Maggs, EM engineer, Flomerics, commented, "This kind of research, with its health implications, proved to be very interesting work and demonstrates the power and flexibility of the Micro-stripes package for all aspects of EM design and analysis. The electromagnetic model built within Micro-stripes predicted the actual brain tissue absorption rates accurately showing a high degree of correlation with the measured results. The simulation undertaken by Flomerics is the most complete thus far on MapSAR and displayed the sound theoretical basis behind IndeXsar's latest test fixture."

The full report can be downloaded at www.indexsar.com

Further information on Flomerics products and services can be obtained from Mike Reynell, Director of Marketing, Flomerics Limited, 81 Bridge Road, Hampton Court, Surrey KT8 9HH, UK. Tel: +44 (0)20 8941 8810; Fax: +44 (0)20 8941 8730; Web site: www.flomerics.co.uk; E-mail: mike.reynell@flomerics.co.uk