Optimization Method for Key Structures of Absorbers at Specific Frequencies Based on Fitting Functions

Metamaterial absorbers (MMAs), which can be designed to achieve perfect absorption of specific frequency electromagnetic (EM) waves, have attracted much attention in recent years. However, the inverse design of MMAs with specific absorption frequencies is rarely studied. Based on a resonator-dielectric-grounding three-layer structure, this paper investigates the fitting numerical relationship between the structural parameters of a simple resonator and its resonant frequency. According to the fitting numerical formula and iterative optimization, methods were proposed to optimize the structural parameters of the resonator by inputting the target resonant frequency, which can realize the inverse design of the single-band and multi-band MMAs in the frequency range from 4GHz to 17GHz. Different types of MMAs including single-band, dual-band, triple-band, and four-band were designed according to the target resonant frequency, and their absorption performance was verified by simulations and experiments. In addition, we separately analyzed the error between the target frequency and the calculated frequency, and the error between the simulated standard frequency and the calculated frequency. Based on the target resonant frequencies, this method successfully realized the inverse design of single-band and multi-band MMAs in C-, X- and Ku-bands, which has broad prospects for application in radar detection, antenna, satellite, and microwave sensor fields.