Development of an Electrically Small Vivaldi Antenna: The CReSIS Aerial Vivaldi (CAV-A)

Radar operation from the CReSIS Meridian UAV requires a broadband antenna array composed of lightweight, thin, end-fire antenna elements. Toward this goal four Vivaldi antenna designs were simulated, fabricated, and characterized. The final design, dubbed the CReSIS Aerial Vivaldi – Revision A (CAV-A) provides operation over a band extending from 162 MHz to 1.121 GHz. The CAV-A measures 40 cm long, 51 cm wide, and 0.125 inch thick with a weight of 3.22 lbs., thus satisfying the requirements for UAV operation. Due to size, weight, and bandwidth requirements, a simple frequency scaling of a previously published design was unachievable. Most published single-element Vivaldi antenna designs were constrained by traditional thought that says the antenna length should be multiple free-space wavelengths and the antenna width should be a half free-space wavelength, both at the lowest frequency of interest. Contrary to convention, the CAV-A is an electrically small antenna, with an antenna width and length on the order of a quarter free-space wavelength at the lowest frequency of operation.