Investigation and Mitigation of Scan Blindness for State-of-the-Art Broadband Apertures

This paper describes a scan blindness investigation and mitigation study through the review and design of broadband (>4:1 with RL > 10 dB), wide-scan (±60°), dual-polarized (linear HV) and low-loss (<0.5 dB, >90%) active electronically scanned array (AESA) apertures suitable for military airborne applications. Two state-of-the-art broadband radiator candidates are assessed and compared: the Planar Ultrawideband Modular Antenna (PUMA) and a combined Bunny Ear / Banyan Tree Antenna (BE/BT-A). Given the constrained non-grating lobe free array grid spacing (d > λ
high
/2), scan blindness arising from parasitic current paths and cavities between array elements are shown to be critical both in terms of active impedance bandwidth and polarization purity. Upon scan blindness investigation and successful mitigation, the BE/BT-A proves to be a robust candidate against a non-optimally sampled grid. Thus, enabling low-loss and compact aperture and front-end electronics integration concepts to be included in future Multi-Function RF Sensor (MFRFS) systems.