  In this work, a planar phased array antenna was engineered with
ultra-wideband (UWB) performance that covers portions of the L-, S-, and
C-bands. The unit cell design contains a driven layer that is directly
connected to a single coaxial feed and a parasitic layer located above the
driven layer separated by free space. This design does not require a balun or
any vias between the antenna ground plane and the driven layer, resulting in a
simple antenna stack-up consisting of only planar layers, aside from the feed
structure. As a consequence, the complexity, and potentially sensitivity to
mechanical tolerances, is reduced. The simulated results of this unbalanced
phased array are discussed and experimentally validated.
