Abstract
Being incident and polarization angle insensitive are crucial characteristics of metamaterial perfect absorbers due to the variety of incident signals. In the case of incident angles insensitivity, facing transverse electric (TE) and transverse magnetic (TM) waves affect the absorption ratio significantly. In this scientific report, a crescent shape resonator has been introduced that provides over 99% absorption ratio for all polarization angles, as well as 70% and 93% efficiencies for different incident angles up to theta =80^{circ } for TE and TM polarized waves, respectively. Moreover, the insensitivity for TE and TM modes can be adjusted due to the semi-symmetric structure. By adjusting the structure parameters, the absorption ratio for TE and TM waves at theta =80^{circ } has been increased to 83% and 97%, respectively. This structure has been designed to operate at 5 GHz spectrum to absorb undesired signals generated due to the growing adoption of Wi-Fi networks. Finally, the proposed absorber has been fabricated in a 20 times 20 array structure on FR-4 substrate. Strong correlation between measurement and simulation results validates the design procedure.
Highlights
Being incident and polarization angle insensitive are crucial characteristics of metamaterial perfect absorbers due to the variety of incident signals
The electric and magnetic responses of MTMs are different compared to natural materials
Combination of dielectric substrate and added sample to Metamaterial Perfect Absorber (MPA) structure creates an effective medium that changes the absorption characteristics. This method has been mainly used in sensing applications28,29. In36,37, lumped resistors have been added to MPA structure in energy harvesting applications to avoid wasting trapped signals in lossy substrates and convert them to usable energy
Summary
Being incident and polarization angle insensitive are crucial characteristics of metamaterial perfect absorbers due to the variety of incident signals. In the case of incident angles insensitivity, facing transverse electric (TE) and transverse magnetic (TM) waves affect the absorption ratio significantly. Permittivity and permeability of MTM structures are negative These properties lead to changing the behavior of electromagnetic (EM) waves facing MTMs. For instance, the Doppler effect and Snell’s law are no longer valid in the traditional way and work in opposite directions. Combination of dielectric substrate and added sample to MPA structure creates an effective medium that changes the absorption characteristics. This method has been mainly used in sensing applications.
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