Abstract:
Mobile phones use Monopole antennas for communication. They have an omnidirectional
radiation pattern in the plane perpendicular to the monopole. Mobile phones
transmit high power electromagnetic waves to base stations. Some of these signals enter
the user brain. Electromagnetic radiation associated with these signals can heat the brain
and can cause damage to the brain tissues. In this research the specific absorption rate
(SAR) of the electromagnetic field inside the brain was calculated for different values of
incident waves. Assuming the brain to be divided into 1000 cubic cells, calculations of
SAR values were carried out for three cases of brain alone; for the brain and skull
together; and for the brain, skull and the ears all together. The SAR values appear to be
higher at middle than at the periphery of the brain and the maximum value of the SAR is
below the safety standards set by British safety levels.
However, the exact biological effect due to electromagnetic radiation is not well
understood, and therefore it is best that attempt is made to minimize such absorption.
This is because that there is some evidence to suggest that use of mobile phones could
bring health hazards. Thus, an attempt was made to design a better antenna for the mobile
unit, which would reduce the electromagnetic wave propagation to the head of a user. A
two element square-patch micro strip antenna was designed, and tested. The antenna
showed a broad beam with an approximation cardiod shape where the two elements were
separated by a / 2 ( X is the wave length) and two elements were fed by units of equal
magnitude and phase by n. The antenna array thus appears promising for the handheld
unit.
