Since the 1990s there has been an explosive growth of mobile communications,
with billions of subscribers around the world. Fourth generation systems are bringing
broadband wireless internet access to the mobile user. The safety of electromagnetic
fields has been the subject of much debate, originally concerned with fields
from power lines and more recently with radiated power from handsets, laptops,
and base stations. It is an emotive topic and it is important for protagonists on both
sides of the debate to make sure that their opinions are drawn from in-depth study
of the topic—it is all too easy to pick on the results of one study that confirm a
strongly held personal opinion. Sometimes the press can use scientific terms
loosely—for example, failing to make the distinction between electromagnetic fields
and ionizing radiation is certain to lead to alarm amongst the public. Even specialists
in the study of the effects of nonionizing radiation on the human body have differing
opinions, and there are varying exposure limits and standards across the
world. This is because the study of the effects of high frequency fields on the human
body has many facets; frequencies of interest cover a vast range from HF through
microwave to THz and infrared. Biological materials have frequency-dependant
properties and the human body is not simple to model. The biological interactions
may be thermal, from dielectric heating, or more complex nonthermal
bioelectromagnetic effects.