Low profile pattern switchable multiband antenna for on/off body communication

摘要

A low profile, a multifrequency microstrip patch antenna with patternreconfiguration is reported in this paper. The proposed antenna provides bothomnidirectional and directional radiation characteristics suitable for WirelessBody Area Network (WBAN). Pattern switching is achieved using PIN diodes.The antenna is designed to operate at multiple frequencies, viz. 0.915 GHz(Industrial Scientific & Medical band), 2.38 GHz (Medical body area network),3.5 GHz (Wireless Interoperability for Microwave Access), and 5.8 GHz(Wireless Local Area Network/Industrial Scientific & Medical band). The percentagebandwidths obtained are 2.89, 1.68, 2.85, 2.16 at the operating frequencies0.915, 2.38, 3.5, 5.8 GHz, respectively. The peak gain and total efficienciesobtained for OFF mode are 3.22/4.27/4.65/4.82 dBi, 82/85/87/89%, and in ONmode are 1.12/1.80/2.44/2.68 dBi, 65/67/71/74% at the said operating bands,respectively. The path loss model is evaluated by measuring the transmissionlink between the antennas on the human body. The LOS path ranges from30 to 45 dB and the NLOS ranges from 50 to 80 dB ensuring it satisfactory forWBAN application. Then human body loading characteristics are also studied.The SAR analysis is performed and it is found to be less than 1.6 W/Kg.