Microwave electric field imaging of metamaterials using thermoemissive films

A new characterization technique for metamaterials is presented for measuring electric-field patterns. The electric-field frames are obtained through a thermoemissive film, located in the near-field domain of the metamaterial. Using an infrared camera, sub-wavelength details can be identified. We applied this technique to antennas based on composite right/left-handed transmission lines (CRLH TLs), also called zeroth-order-resonator (ZOR) antennas. The electric-field distributions of zeroth-order-resonator antennas at frequencies corresponding to longitudinal modes between 4 GHz and 12 GHz were determined. These field frames were in agreement with numerical results obtained by finite-element analysis. This paper addresses techniques for the experimental validation of numerical computations.