Electromagnetic Black Hole for Efficiency Microwave Heating Based on Gradient-Index Metamaterials in Multimode Cavities

In this work, an electromagnetic black hole based on gradient-index metamaterials is designed and fabricated by drilling holes in easily available materials to achieve efficient microwave heating in multimode cavities. This black hole shows superior performance in improving the utilization of microwave energy when the real part of the relative permittivity varies from 10 to 80 and the loss tangent of the heated material changes within 0.1–1. Different volume fractions of ethanol aqueous solution are used as test material to verify the effectiveness of electromagnetic black hole, and the experimental results are in good agreement with the simulation results.