Design and CM Analysis of Fractal Inspired Frequency Reconfigurable Antenna for RFID Application

In this paper, a fractal inspired frequency reconfigurable antenna for wideband UHF and SHF RFID applications is presented. A triangle-shaped Sierpinski Gasket fractal bow-tie antenna is designed which provide frequency reconfigurability. A characteristic mode (CM) analysis of the proposed antenna is also presented in this paper. The proposed antenna consists of four-pin diodes and therefore, for State-1 (when all didoes are switched OFF), the antenna operates in the RFID SHF band (2.4 GHz) and for State-2 (when all pin diodes are switched ON), the antenna operate in the UHF band (900 MHz). A functional prototype of the antenna is fabricated and measured. The proposed antenna exhibits a wide measured impedance bandwidth of 21% for State-1 and 38.5% for State-2. It is observed that the result obtained from measurement agrees with the results obtained from full-wave EM simulation and CM analysis.