Radio Frequency Fields Group TIME DOMAIN ELECTROMAGNETICS PROJECT Robert T. Johnk : Project Leader Purpose: The Time Domain Electromagnetic Project's primary focus is to perform ultrawideband electromagnetic measurements using swept frequency or direct pulse systems. Both time-domain and frequency-domain electromagnetic quantities can be extracted from our measurements. These systems exhibit high spatial resolution which can be exploited to perform a wide variety of measurements and obtain useful information in quick and accurate manner. We have developed ultrawideband systems to perform the extraction of materials properties from dielectric panels (low-loss & high-loss), RF Absorber evaluation at both normal and oblique incidence angles, electromagnetic (EM) facility characterization (anechoic & semi-anechoic chambers, shielded rooms, reverberation chambers, and OATS facilities), ultrawideband RCS measurements, shielding performance of materials, and electromagnetic penetration into commercial aircraft. We have performed antenna and sensor calibrations up to 14 GHz on our Cone and Ground plane facility. We are currently designing the Co-Conical Field Generation System a closed system test cell capable of testing antennas,sensors, and probes from 10MHz-45 GHz. EM modeling and analysis is an integral part of our program. In addition to standard EM theory, many numerical techniques such as finite difference time domain (FDTD), finite element modeling (FEM), and variational methods are used to predict system performance and improve as well as validate our measurements. in addition, we are currently engaged in an aggressive effort to characterize the measurement uncertainties of our systems. Small sample absorber evaluation Cone and Ground Plane Sensor Calibration CFGS 1m prototype Anechoic Chamber Evaluation