Kavitha Arunachalam

The feasibility of non-contact and non-destructive evaluation (NDE) of planar aerospace dielectric composites using microwave is examined in this paper. Free space microwave measurement set up includes spot focusing horns to gather the scattering parameters of the composites with the help of (Gated-thru reflect line) G-TRL calibration. The dielectric properties are studied from the measured scattering parameters to characterize the material's defective and non-defective region. Particulate reinforced composite with an air gap of 0.1 mm thickness and 10 mm width is used for validation of the technique.

The focal plane characterization of spot focusing horn antennas used for microwave NDE is presented using three experimental methods. Reflections from a metal sphere were analyzed in time domain to quantify the focal spot and spot size in the first method. In the second method, a rectangular waveguide padded with absorber was used as the sensor. Finally, graphene based miniaturized electric (E)-field sensor printed on photo paper using inkjet printing was used to measure antenna focal plane characteristics. The focal plane measured using the metal ball and waveguide techniques was within 5% of the simulated value. Higher error was recorded in focal spot measurement (≥25%) for the first two methods. The focal plane and spot size measured by the miniaturized E-field sensor was within 10% of the simulated antenna characteristics. The results indicate that the flexible printed sensor has better measurement accuracy and simple setup for field measurement.