Finite difference time domain analysis of electromagnetic radiation from shaped-end radiators

The FDTD (finite-difference time-domain) technique was applied to the analysis of electromagnetic radiation from shaped-end radiators (SERs). A shaped-end radiator is a circular tube with a beveled cut on one end. The antennas and waveguides are modeled in the standard FDTD manner (i.e., staircased). Pattern plots are presented for a straight-cut circular waveguide ( theta =90 degrees ) using a sinusoidal excitation radiating the TM/sub 01/ mode as a reference. Results are also presented for SERs with cut angles theta =30 degrees and theta =50 degrees using sinusoidal excitation and also using an excitation with Gaussian time dependence. All FDTD results computed using sinusoidal excitation are compared with measured data.<>