I’m investigating the visualisation of electromagnetic fields, part of our exploratory process to look at the materiality of RFID. What are we talking about when we say ‘touch-based interaction’ or ‘near field’ for instance? This investigation threw up an interesting company: Indexsar specialises in:

“Turnkey test systems for the measurement of SAR (Specific Absorption Rate) and the Over The Air (OTE) testing of wireless devices. Our product range includes E-field probes for use in both air and in tissue-simulant liquids, equipment for accurate testing of the dielectric properties of phantom liquids and a system to give a 3-Dimensional presentation of mobile handset radiation and sensitivity. We can supply suitable RF amplifiers and directional couplers for wireless product testing and can offer suitable phantoms (heads, hands and liquids) for testing radiated emissions.”

Their test setup includes 6-axis industrial robots to move sensors around models of human anatomy (or “phantom geometry” in official testing language). Their setups include geometry for the head, and the right hand (no left hands yet). In the test rig below a liquid model moves while the sensors are stationary. It looks like it has been hacked together from meccano and a Wacom pad.

These are some visualisations of bodily electromagnetic fields from Flomerics MicroStripes and Hugo:

Microstripes software is a 3D electromagnetic simulation & synthesis tool:

“MicroStripes is widely used to design antenna and microwave structures and assess their installed performance, to optimize RFID systems, to analyze radar cross-section (RCS), EMI/EMP and lightning effects on vehicles, ships and aircraft, and to predict absorption of EM fields in human tissue.”

Another visualisation:

Leafing through the manual for my Nokia E60 I noticed that it includes guidelines on holding the phone, in order not to degrade the performance, and thus battery life of the antennae.

As we move towards multiradio devices, this analysis is going to become more important. I wonder what the fields look like around the RFID/NFC phones like the 3220...

Technorati Tags: EMF, electromagnetic fields, testing, experiments, mobile, radiation

30 August 2006 by Timo