A method and system for measuring an antenna radiation pattern of a harvester antenna printed on a substrate of an Internet of Things (IoT) tag are disclosed. The method includes sweeping a power level of a source radio frequency (RF) signal transmitted at a particular direction, wherein the source RF signal is received by the harvester antenna; measuring a transmission rate of signals transmitted by the IoT tag, wherein the transmission rate is proportional to the power level of a source RF signal received by the harvester antenna; determining if the measured transmission rate is substantially equal to a predefined threshold; registering, at each measured direction, a power level of a signal reaching a transmission rate is substantially equal to the predefined threshold; and plotting the antenna radiation pattern based on the registered power levels.