A study of transient radiation from the Wu-King resistive monopole-FDTD analysis and experimental measurements

The cylindrical monopole antenna with a continuous resistive loading is considered as a radiator for temporally short, broad-bandwidth pulses. Specifically, the variation of the resistance used along the monopole is one proposed by Wu and King (1965). This antenna is analyzed by the finite-difference-time-domain (FDTD) method utilizing a new, efficient technique for handling the thin-walled, conducting tube that forms the resistance. The electromagnetic field in the space surrounding the antenna is determined as a function of time, and quantities useful for describing the performance of the antenna are then calculated from these results. Graphical displays of the results are used to give new insight into the physical processes for transient radiation form this antenna. An experimental model is constructed using a discretized version of the Wu-King profile formed from a set of precision, high-frequency resistors. Measurements of both the reflected voltage in the feed line and the time-varying radiated field are in excellent agreement with the theoretical calculations.<
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