Dual-Resonant Stacked Linear Array of Cross-Slotted Patches for Small SAR Satellites

A cross-slotted linear array antenna of four stacked patches is proposed for $X$ -band synthetic aperture radar (SAR) on a small satellite platform. Owing to the reliability, small size and mass restriction features of small satellites, the antenna is based on a thin dual-substrate topology with each element surrounded by metal vias to form a cavity-backed patch to result in a lightweight and high efficiency. Although inherently narrowband due to the thin substrate layer, cross-slotted patches were proposed to yield a dual resonance, and lower input impedance at the desired band to meet the SAR requirement. The fabricated prototype exhibits a peak gain of 12 dBi with a radiation efficiency of 84% at 9.44–9.87 GHz for $\vert S_{11}\vert dB.