Numerical analysis and visualization of spherical waves absorbed by a thin metamaterial absorber

A thin metamaterial absorber has been used for measuring 2-d radio-frequency (RF) field distributions incident on the absorber surface. A matrix of lumped resistors interconnecting the metal patches on a grounded substrate work as a sensor array to measure the 2-d power and phase distributions of the incident RF field at the resonance frequency. In this study the field distributions on the absorber surface are numerically analyzed using plane-wave expansion of a spherical wave in the radiating near-field zone of an antenna. Results of the numerical analysis is compared with simulations and actual experiments to evaluate its accuracy. Such a detailed field distribution can be used to visualize the wave propagation from RF antennas or noise sources.