Engineers at Aalto University in Finland said they optimized how antennas transmitting and receiving power interact with each other, utilizing the phenomenon of “radiation suppression.” According to university engineers, this results in a better theoretical understanding of wireless power transfer than the conventional inductive approach, a significant advancement in the field.

Recent findings by Aalto University engineers reveal that maintaining high efficiency over extended distances can be achieved through the suppression of radiation resistance in loop antennas responsible for power transmission. Previously, the same lab created an omnidirectional wireless charging system that allowed devices to be charged at any orientation. Now, they have extended that work with a new dynamic theory of wireless charging that looks more closely at near (non-radiative) and far (radiative) distances and conditions. In particular, they show that high transfer efficiency, over 80%, can be achieved at distances approximately five times the size of the antenna, utilizing the optimal frequency within the hundred-megahertz range.

“We wanted to balance effectively transferring power with the radiation loss that always happens over longer distances,” said Lead Author Nam Ha-Van, a postdoctoral researcher at Aalto University. “It turns out that when the currents in the loop antennas have equal amplitudes and opposite phases, we can cancel the radiation loss, thus boosting efficiency.”