**4. Conclusions**

In the perfective of considering propagation to be the fundamental basic of dynamic electromagnetic phenomena, the comprehensive space/time/frequency analysis method of near-field propagation was proposed. Based on this, detailed knowledge of behavior and physical effects of the structures and/or objects to dynamic electromagnetics was revealed, and these also are basic for the refined optimization in design. With the fundamental basic and generality, applicability of this analysis technique is not limited to the example cases of this work. Besides Vivaldi antennas, this analysis technique can be applied for the analysis, designs, and optimization of any sort of traveling-wave antennas or transmission structures.
