Simulation of 420MHz Electromagnetic Fields Leakage from a Helicopter Ambulance

Wireless medical telemeters that remotely monitor patient biological information using 420 MHz radio waves are widely used in Japan. In recent years, many hospitals use medical telemeters, and subsequently radio interference with neighboring hospitals often occur hindering stable signal transmission. Such medical telemeters are also used in helicopter ambulances. In this study, we investigated the electromagnetic fields leaking from medical telemeters installed in a helicopter using an FDTD simulation. The simulated space was <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(33\ \mathrm{x} \ 23\ \mathrm{x}\ 24)$</tex> m with cell size of 12.5 mm and total cell counts of about 1.8 billion. The simulation results were very similar to the actual measurements suggesting the possible interference as far as 50 m from the helicopter.