Antenna Investigation by a Thermoelastic Optical Indicator Microscope: Defects Measurement and 3D Visualization of Electromagnetic Fields

Using the thermoelastic optical indicator microscopy (TEOIM) technique, we perform the visualization of the near-field distribution of a patterned frequency modulation (FM) antenna. For the defect characterization, subtraction of images is done, whereas a background image is used for the defect-free antenna image. The electromagnetic fields distribution in the overall antenna structure is changed due to the defects, and this indicates the local impedance changes of the antenna pattern. The sensitivity of the proposed inspection technique is estimated to be in orders of a few milliwatts. In addition, a 3D visualization of the antenna transmission is realized to describe the field intensity and distribution dependences on the distance from the antenna surface. This type of investigation with a visualization opportunity may become an important tool for engineers and researchers, and it can successfully be a supplement for existing measurement techniques.