LAUSR

A wideband, low-profile, tightly coupled antenna array with a simple feed network is presented. The dipole and feed networks in each unit cell are printed on both sides of a single RT/Duroid 6010 substrate with a relative dielectric constant of 10.2. The feed network, composed of meandered impedance transformer and balun sections, is designed based on Klopfenstein tapered microstrip lines. The wide-angle impedance matching is empowered by a novel wideband metasurface superstrate. For the optimum design, scanning to 70° along the E-plane is obtained together with a very high array figure of merit P_A = 2.84. The H-plane scan extends to 55°. The broadside impedance bandwidth is 5.5:1 (0.80–4.38) GHz with an active voltage standing-wave ratio value ≤2. The overall height of the array above the ground plane is $0.088\lambda _{\mathrm {L}}$ , where $\lambda _{\mathrm {L}}$ is the wavelength at the lowest frequency of operation. A prototype was fabricated and tested to confirm the design concepts.