Discussion on computational tools for evaluating the exact quality factor Q of small antennas

In this paper are presented several approaches to evaluate the exact radiating quality factor of antennas. These approaches are then compared to a numerical procedure using the FDTD method. This numerical method allows studying the Q factor of arbitrary and complex antennas. One of the analytical approaches is based on the derivative of the antenna input impedance. We present at the end, the drawbacks and advantages of the numerical and analytical methods.