This paper presents the development of a deployable Synthetic Aperture Radar (SAR) antenna tailored for a 16U CubeSat platform. The primary challenge addressed the need for large antennas in SAR satellites, which traditionally increase satellite size and cost to achieve high-resolution imaging. The proposed solution is a scalable 4×21 patch antenna array operating at 1.275 GHz, integrated into a flexible polyimide-based printed circuit board (PCB). This flexible design enables compact storage by allowing the antenna to roll during deployment, overcoming the limitations of rigid PCBs. However, polyimide’s higher losses and suboptimal performance than other microstrip substrates, such as FR4 and Rogers, pose challenges. Impedance matching is achieved using a quarter-wave transformer, and precise element spacing prevents field interference. Mechanically, the design leverages the bending properties of polyimide to fit the antenna within 8U of the CubeSat, with previous work ensuring that rolling does not affect the antenna’s structural integrity or torque during flight. Initial simulations using CST software for a 4×2 array show promising results, with future work aiming to prototype a 4×4 array. This flexible, scalable antenna design promises to reduce satellite size and cost while maintaining or enhancing SAR performance, offering a cost-effective solution for spaceborne radar applications and Earth observation