ACCURATE ANALYSIS OF TEM HORN ANTENNAS FOR PULSE RADIATION

In the past, various approximate theoretical models have been used to analyze TEM horn antennas, Because of the limitations of these approxi mate models, there has been, to date, only qualitative agreement of me asurements for TEM horn antennas with the predictions of the theories, In this paper, the finite-difference time-domain (FDTD) method is use d to accurately analyze TEM horn antennas for pulse radiation, First, the metallic triangular-plate TEM horn antenna is considered, Computed results for the reflected voltage in the feeding transmission line an d the time-varying radiated electric held are shown to be in very good agreement with new experimental measurements, Graphs of the electric field in the space surrounding the antenna (magnitude of field plotted on a color scale) are used to give physical insight into the process of radiation, Next, the method is used to analyze two TEM horns that w ere previously designed for pulse radiation. The geometry and electric al properties of these antennas are more complicated than for the meta llic, triangular-plate horn, One has shaped metallic plates with a res istive termination at the open end; the other has plates whose resista nce varies continuously along their length, The computed results for t hese antennas are compared with previously made experimental measureme nts.