In a synthetic aperture radar (SAR) system, the radar platform may move with a curved trajectory due to the existence of vertical velocity and acceleration, which may result in the failure of the conventional imaging methods. In order to deal with this problem, this paper proposes an improved wavenumber-domain imaging algorithm for high-resolution-high-squint SAR with a curved trajectory. It mainly includes three aspects. First, a modified equivalent range model for a curved trajectory is derived. Second, an improved wavenumber domain imaging algorithm based on the proposed range model is analyzed in detail. Finally, the imaging distortion caused by vertical velocity and acceleration is corrected via geometry and inverse projection. Simulated results and Ku-band real SAR data processing are used to validate the proposed model and imaging algorithm.

A paper-based electrostatic zipper actuator for printable robotics has been designed, fabricated and characterized. A simple fabrication process that utilizes paper with a carbon nanotube ink is used to create electrodes separated by either a mylar or parylene dielectric layer. A 5 cm × 1 cm actuator demonstrated a maximum static deflection of 1.8 cm and a bandwidth of approximately 12 Hz. Static power dissipation was under 1 μW. Two of these actuators are combined to demonstrate simple motion in a 6 cm × 1 cm × 1 cm robot using assymetric friction with the ground, achieving speeds up to 33 mm/min.