Numerical and Experimental Analysis of Bow-tie Antennas with Changing of Shield's Height

In this paper the properties of the transmitted waveforms and VSWR of the bow- tie antenna are studied when the shielded height is changed. The results of the simulations and the measurements show agreement well, which can ofier the reference to design of the bow-tie antenna. Bow-tie antenna is a transflguration of the dipole antenna. Bandwidth of the dipole antenna is broadened when the diameter of the wire is broadened. So the double cone antenna, and further- more, bow-tie antenna as a transflguration of the double cone antenna, have been introduced. The antenna is designed to work with a widen bandwidth in actual applications. From the transmission line theory when the shield and the terminal resistors with proper value are added to the antenna, some advantages, such as working at the traveling wave state, increasing the radiation e-ciency, having better transmitting waveforms and the shield efiect, coupling more EM energy into the desired direction, appears. In this paper, the efiects of shield's height on antenna's property are studied. 2. STRUCTURE The planform of the bow-tie antenna is shown in Fig. 1. The angle between two neighbored arms is 30 - . In order to achieve the traveling wave state, the loaded resistors are added between the ends of the antenna and the shield. These resistors are used to attenuate the currents coming from the feed points. Both the antenna and the shield are flxed on the ∞oor.