Matching bandwidth limits for linearly polarized scanning arrays above a ground plane

Wideband phased arrays have become critical components for a new generation of radar and wireless communications systems. The authors have previously shown that arrays that are conformally installed on a ground plane will have reduced bandwidth due to the ground plane´s reactance. Fundamental limits for such low profile arrays above a conducting ground plane were derived [Doane et.al., IET Electronics Letters, 2012], yielding simple expressions for the maximum realizable bandwidth under either TE (H-plane scanning) or TM (E-plane scanning) excitation. However, a general bandwidth limit for arbitrary polarization has yet to be presented. In this paper, we present improved bandwidth limits for linearly polarized arrays scanned to any angle, including the inter-cardinal planes where both TE and TM modes are simultaneously excited. For the latter, TE-TM coupling is accounted for.