Abstract: A Hybrid Artificial Magnetic Conductor (AMC) antenna reflector improves performance of an Archimedean spiral antenna across all bands. The AMC reflector provides uni-directional radiation over a 1-5 GHz frequency range. The AMC reflector provides at least 3 dB of gain compared to the same antenna without a reflector. The AMC reflector includes a traditional Perfect Electric Conductor (PEC) reflector portion, used to reflect higher frequencies, and a capacitively loaded AMC reflector portion, used to reflect lower frequencies. The AMC patch size and capacitor values are optimized for best response across the 1-2 GHz frequency range. The center, high frequency section of the AMC reflector portion is removed to provide an optimized standoff distance from the antenna to allow direct reflection from the PEC reflector portion. The AMC reflector reduces the PEC reflector thickness dimension and provides improved antenna pattern symmetry at higher frequencies.

Abstract: A system and method for correcting automatically the distortions in electron background diffration (EBSD) patterns which result from magnetic fields produced by some scanning electron microscopes (SEMs) used for collecting such patterns from polycrystalline sample materials. The method may be implemented as a software program running on a computer which is part of a conventional system for obtaining and analyzing EBSD patterns to obtain crystallographic information about the sample material. The method includes a calibration procedure and a correction procedure. In the calibration procedure, a distorted EBSD pattern obtained from a calibration sample is displayed on an operator display and user interface. Using an input device, an operator defines segment endpoints along a Kikuchi band in the distorted EBSD pattern image. From the user defined segment endpoints, correction parameters are calculated based on a mathematical curve (e.g., cubic spline) fitting the endpoints.