A Radio-Frequency Computational Magnetic Metasurface for Extraction of Specific Harmonics from a Periodic Current

This paper introduces a computational magnetic metasurface able to extract specific harmonics from a periodic current flowing in an input coil and operating in the radiofrequency regime. A theoretical model based on the circuital approach is derived and employed to obtain the loads that must be applied to each unit cell to secure the desired mathematical output. Then, a numerical test case comprising an input loop, a metasurface constituted by 8 resonating spirals and 8 output coils is realized. By performing accurate full wave simulations, we validated the conceived model and showed promising results. In detail, the proposed structure is able to accurately transfer to the output cells the first 8 harmonics with fundamental frequency of 5 MHz of the input loop periodic current. Such metasurface can be easily fabricated and reconfigured through variable loads, thus providing a valid alternative to the current analog computational metastructures exploiting higher frequency regimes. Moreover, the employed approach can be generalized and applied to more complex and accurate mathematical operations, such as properly evaluating a truncated Fourier series of a periodic signal.