Feature Selected Validation and verification (FSVV) of CEM code predictions using IR thermal images of EM fields

An infrared (IR) thermal measurement technique is presented to independently validate and verify (V&V) numerical codes used for computational electromagnetic (CEM) field predictions using feature selected validation (FSV) routines . The thermal technique is applied in this paper to V&V new aircraft scattering codes. IR thermal images (temperature distributions) of the electromagnetic (EM) field scattered from a simple, canonical aircraft are measured for selected microwave frequencies, angles-of-incidence, and polarizations. Using a color-temperature table calibrated at NIST/Boulder, the temperature distributions are converted into equivalent field-intensity distributions of the scattered EM field being measured. These IR thermal images (thermograms) are compared to the predicted images (contour plots or relief maps) of the scattered fields calculated with a selected CEM simulation code over the same measurement plane to V&V that the field patterns and the intensity levels are correct. In addition, the measured field can be visualized with the IR thermogram images. A ldquopicture-to-picturerdquo correlation code is used to compare the predicted and measured results and to assess and score their similarities. This is the first step in a progressive approach using a suite of CEM codes to compare predicted results of more sophisticated aircraft geometries with the measured results from the IR thermograms to develop confidence in the complementary measurement and simulation methods.