Abstract:In this paper, an ultra-wideband tightly coupled array element loaded with a novel low-profile coupled superstrate is presented. Equivalent circuit model (ECM) is employed to analyze and optimize design parameters. The low-profile coupled superstrate is employed to replace the traditional dielectric superstrate, which solves the problem that array radiates ineffectively at certain frequency point due to the high order mode surface wave, and improves the array’s scanning performance. Marchand balun is employed to feed dipole element. A ptototype is simulated and results show that over the operation frequency band of 2-18 GHz (9:1) the scanning range of E plane and H plane are 60° and 45° with VSWR<3. Compared with the traditonal antenna, this design is more beneficial to realize design requirements of wide-angle scanning, low-profile and lightwight.