An historical, theoretical and experimental study of the broadband antenna problem with application to short pulse probing radars

The influence of finite radiating elements on the transmission and reception of large instantaneous bandwidth signals is considered. A description of simple broadband radiators is given together with a detailed explanation of both frequency independent and travelling wave phenomena as applied to antennas. The response, to transient excitation, of conventional broadband radiators is examined on the basis of a literature survey and criteria summarizing the essential antenna characteristics are established. The properties of several transient antennas are evaluated in this context and one, the Wohlers antenna, is selected for further study.Topics such as the characteristic impedance of planar transmission lines, the principle modes existing on coaxial and biaxial transmission lines, the continuous impedance transformer, and the open termination of resonant structures, are considered in some detail and the results are employed in the fabrication and testing of several prototype Wohlers antennas. The physical and electrical characteristics of the Wohlers antenna aie related in an empirical manner and the overall performance is evaluated using both pulse and monocycle waveforms. The results of preliminary tests, involving the location of dielectric interfaces in lossy media, are given and those aspects of the UHF short pulse radar requiring further refinement are indicated.