Ultra-Wideband Impulse Radiating Antennas and Discones

Ultra-Wideband antennas are a critical component of Ultra-Wideband communications and surveillance systems. Such antennas must cover a bandwidth of 20 MHz to 4 GHz, be omnidirectional, and be convenient to transport and deploy. We consider here how tomodify existing two antennas, the Impulse Radiating Antenna (IRA) and the discone, to achieve those goals. Commercially available IRAs already have demonstrated effective operation over the entire frequency range. Normally, IRAs are directional antennas,but a circular array of four of these devices will form a single omni-directional antenna. Such devices can be built from small 18-inch diameter umbrella-like reflectors, so the array can be integrated into a small compact package. We will also consider acollapsible loaded discone. Commercially available discones do not cover the needed frequency range and are not portable or deployable. We can improve the low-end response by adding distributed resistive and inductive loading to the antenna. We can improvethe high-end response by more carefully manufacturing the apex. We can make the discone convenient to deploy by making it collapsible, either in the form of an umbrella or by using tent-pole assembly. This research will lead to two Ultra-Widebandantennas that operate between 20 MHz and 4 GHz, a circular array of IRAs and a collapsible loaded discone. A prototype design of the circular array of IRAs will be built and tested during Phase I. Design calculations will be performed on the discone duringPhase I, and it will be built during Phase II.