A J Gasiewski remote sensing course notes lecture8 PDF
Preview A J Gasiewski remote sensing course notes lecture8
ECEN 5254 Remote Sensing Signals and Systems Professor Albin J. Gasiewski Lecture #8 – February 9, 2012 EECCOOTT 224466 303-492-9688 (O) [email protected] Classes: ECCS 1B14 TR 9:30-10:45 AM 1 ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder Last Lecture • HHerttziian ellecttriic ddiipolle • Antenna gain, efficiency, matching • Half-wave dipole • AAppeerrttuurree aanntteennnnaass 3 ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder Today’s Lecture •• FFoouurriieerr ttrraannssffoorrmm rreellaattiioonnsshhiipp • Circular apertures, Bessel functions • Aperture field autocorrelation • Reflector antennas • Phase uncertainty & Ruze’ equation 4 ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder Aperture Radiation Problem Consider plane wave illuminating arbitrary hole in infinite perfectly condducttiing screen: yy SSoouurrccee ? x 5 Radiation from Electric Current Sheet yy AA zz x 6 Symmetric Maxwell’s Equations 7 Radiation from Magnetic Current Sheet yy Duality: AA zz x 8 from Balanis, 2005 9© from Balanis, 20051 0© Equivalent Aperture Problem Can replace aperture field distribution and source(s) behind screen with y eeqquuiivvaalleenntt ccuurrrreenntt sshheeeettss iinn aperture plane: ^ n z x Radiation in z > 0 found by superposiittiion off raddiiattiion from J and M is identical to that of the original problem. s s 11
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