A fully-planar 6:1 antenna array aperture

Measurements and simulations are reported for an ultra-wideband, wide-scan electronically scanned array (ESA) aperture. The aperture is fully-fabricated as a single, low-cost, multi-layer printed-circuit board and is less than λ/2 thick at the high operating frequency. Elements are spaced at the Nyquist (λ/2) interval and fed directly via standard 50Ω coaxial lines to be compatible with existing Vivaldi-based ESA system front-ends. A dual-polarized 256-port (128 elements per polarization) prototype array operating over 3.53–21.2 GHz (6:1) is built, measured, and compared with a full-wave finite array solver. The aperture scans out to 60° with active VSWR <3.8 under H-plane scan. Embedded element cross-polarization levels are better than −15 dB out to 60^° in the D-plane over the operating band.