Resistance Selection of High Impedance Surface Absorbers for Perfect and Broadband Absorption

High impedance surface absorbers comprising of lossless dielectric substrate and resistive pattern were studied based on equivalent circuit method. Resonant conditions in terms of potential resonant frequencies and corresponding equivalent resistance were deduced. Theoretical calculation, numerical simulation and experiment showed that expected absorption was obtained by matching the capacitance, inductance and the resistance. We demonstrated that the optimal resistance of frequency-dispersive was between 0 and 377 Ω. For square, dipole and square ring pattern, a mean resistance value was required to achieve broadband absorption. It offered a way to create broadband and perfect absorbers by controlling the surface resistance of sub-wavelength structures.