Performance Optimization of Microstrip Antennas for Low SAR

Abstract

Due to extensive use of communication devices like Mobile Phones, Tablets, Laptops, Wi-Fi routers, Smart Television sets, Bluetooth Devices, Base stations etc. are acting as a source of rise in electromagnetic radiation within the house and nearby locality. Handheld devices used in close proximity to humans have several adverse effects on health of humans. Several expert groups have been reviewing health hazards throughout globe and are proposing solutions to curb health hazards. Some of dominant effects are thermal effects, cognitive effects, electromagnetic hypersensitivity, and behavioral effects. It is proposed by various researcher s that these harmful effects are due to Radio Frequency exposure of humans and prolonged use of handheld RF devices such as mobile phones. Some of solutions proposed are limit the use of mobile phones, use text messages to communicate or use speaker phones. Mobile phones have become integral part of our life and to restrict its use is not possible and to limit its use is possible but to some extent.Human tissues absorb heat radiated by the mobile phones and to minimize the impact of exposure of RF-EMF on humans alternate solution is required, the amount of microwave energy absorbed by human tissue is evaluated by specific absorption rate (SAR), so need have arisen to design and develop mobile phone antennas with low SAR. Several techniques have been discussed in various findings to minimize SAR. The techniques quoted are use of auxiliary elements with main radiating antenna, use of ferrite sheets for loading antenna, use of metamaterials, use of artificial magnetic conductors, use of defective ground substrate, and use of electromagnetic bandgap (EBG) structures. The research work deals with the study and implementation of reduction in SAR for different microstrip antennas. SAR reduction is achieved in antennas using electromagnetic bandgap structures and defective ground structure. Single band circular microstrip antenna with and without EBG structure is designed for LTE band 3