Low-profile ultra-wideband inverted-hat monopole antenna for 50 MHz-2 GHz operation

A compact low-profile UWB monopole antenna is proposed to operate from 50 MHz up to 2 GHz. The developed double-ellipse inverted-hat antenna (IHA) is 15 inches in aperture, 6 inches tall, and achieves 215 dBi gain at 75 MHz (when it is lambda/10 in aperture size) in the presence of a finite 21 inch diameter ground plane, with the corresponding frequency being 50 MHz for an infinite ground plane. Calculated and measured gain data are given with reasonable agreement. The triple-ellipse IHA is investigated to resolve impedance matching issues at higher frequencies. Gain performance against antenna height and aperture are also studied. The proposed antenna is especially suited for small unmanned aerial vehicles.