A novel low-profile frequency-independent inverted-hat antenna for UWB application

We introduced a new low-profile UWB monopole antenna to achieve overhorizon operation from low VHF frequencies up to 2 GHz. The curvature profile of proposed Inverted-Hat Antenna is logarithmically related to the distance from the feed point, and thus results in a frequency-independent performance. The eleven-ellipse IHA is the most frequency-independent design. Other outer surface growth profiles were also considered to find the optimal impedance performance for the specified antenna size requirements. Specifically, a modified elevenellipse IHA was found more attractive at lower frequencies and was fabricated for design validation. The calculated and measured gain and impedance were in a good agreement. Overall, it was found that the IHA is an excellent candidate for future UWB communication with ground vehicles or small aircrafts.