IN FUTURE, mobile phones could deliver ten times less radiation to a user鈥檚
head without the need for any shielding device.
Researchers at the University of Surrey in Guildford have developed a smart
antenna that actively directs its signals away from the head. It could be in use
by 2002 in the next generation of mobile phones.
The Surrey team鈥檚 鈥渁daptive quadrifilar helix antenna鈥� consists of four
antennas twisted around each other to form a helix. By shifting the phase and
varying the amplitude of the microwave signal emitted by each antenna, emissions
can be cancelled out in some directions and boosted in others. The antenna
continually works out where a user鈥檚 head is by detecting reflections of its own
signal. It then adapts its emissions to maintain a 鈥渘ull zone鈥� in this
direction.
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In addition, by identifying the strongest incoming signal, the antenna can
also work out the best direction to send its outgoing signal back to the
communications mast. The resulting gains in efficiency should greatly increase
battery life.
