Design and Analysis of Multiband Fractal Antenna

Abstract

Miniaturized Multiband antenna design is an important and challenging task for communication industry. Several constraints like size, position of the antenna, feasibility, reflection coefficient, Specific absorption Rate (SAR), make it more difficult to design a multiband antenna. Current trend suggests that one device (Mobile, Tablet PCs etc.) should cover multiple communication applications (Like GSM, LTE, Bluetooth, Wi_ etc.). It implies that antenna design should not only satisfy the constraints but also cover wide multiband range. In this research work, design, analysis and measurement of fractal antennas, are carried out, for such multiband applications. Revised cantor geometry is proposed for antenna design, which produces more than 5 resonances in second iteration only (feasible design). The three dimensional Finite Difference Time Domain (3D-FDTD) Method is used for analyzing the reflection coefficient of the antenna. Revised cantor geometry based compact, low profile LTE fractal antenna is proposed here, for Mobile and Tablet PC applications. The proposed antenna is appropriately covering several wireless applications, including LTE 1.7-1.8 GHz band, 2.3 GHz, 2.6 GHz and 2.9 GHz applications, WLAN 2.4 GHz and 5.8 GHz applications, GSM, UMTS, DCS, ZigBee, PCS, applications. This antenna is designed and analyzed using MATLAB code based on 3D FDTD method. Antenna finger dimensions are optimized using observations in MATLAB and CST Studio Suite. Radiation Patterns show, for all the observed frequencies, Directivity between 7.72 dBi to 8.17 dBi and Radiation Efficiency, within the range of -0.98 dB to -1.95 dB. Experimental reflection coefficient results present accurate matching with theoretical results. Theoretically analyzed SAR is less than 1.6 W/kg for 10 g tissue, without mobile circuitry. SAR reduction technique is also been presented.