Efficiency variations in electrically small, meander line RFID antennas

Not all meander line dipole antennas (MLDAs) plotted on the same grid necessarily have similar characteristics. MLDAs can be optimized for best efficiency, lowest resonant frequency or highest impedance. Different structures were investigated using a 5 times 10 array of rectangular grid points in 4times9 mm2 area and, all symmetrical MLDA that incorporate all grids points were modeled to determine the resonant frequency and efficiency. Based on the NEC simulation results for all possible family members, the range in resonant frequencies was 3.51 to 4.71 GHz and the range in efficiencies was 58.48% to 83.17%. The most efficient structure and the structure with the lowest resonant frequency were determined from the entire population of 1072 different antenna structures. The most efficient antennas have identical structures close to the feed point and all have an efficiency of greater than 83%.