Coplanar Side-Fed Tightly Coupled Ultra-Wideband Array for Polar Ice Sounding

We describe a planar ultrawideband (UWB) dual-polarized tightly coupled bowtie antenna array for ground-based polar ice-sounding radar. The array operates over 180–620 MHz with a bandwidth ratio of 3.4:1. The broadband performance is benefitted from the tightly coupled antenna elements. By carefully integrating the impedance matching network into one arm of the bowtie antenna and using a ferrite core for common-mode suppression, this coplanar side-fed array avoids the use of vertical balun and external antenna matching network. The size of the full array is 2.8 m $\times2.8$ m with a weight of only 90 kg, including 24 power distribution boards and 288 feed cables. The thickness of the array is 12.7 cm, which is only about $0.08\lambda $ at the lowest operating frequency. This antenna array was deployed to Greenland in summer 2019 as a part of a surface-based UWB ice-sounding radar to measure and characterize the Greenland ice sheet.