High squint helicopter-borne terahertz ViSAR vibration compensation imaging algorithm

With advantages such as fast imaging frame rate, high resolutions and penetration through dust and smoke, video synthetic aperture radar (ViSAR) has a broad application prospect. But for ViSAR that works in terahertz carrier frequency, helicopter platform's tiny high frequency vibration will cause obvious changes in echo phase and degrade the imaging quality. According to helicopter platform's vibration characteristics and based on the squint platform vibration imaging geometry model, this paper proposes a terahertz ViSAR vibration phase error compensation imaging algorithm in high squint mode. First, the squint imaging is equivalent to side-looking imaging based on motion compensation principle, and then modified Doppler Keystone transform is performed to correct the range cell migration induced by platform vibration in 2D frequency domain. Finally, the analytic expression of vibration phase error is gained in range-Doppler domain and the phase error compensation is achieved via parametric autofocus method. Simulation results verify the effectiveness of the proposed algorithm.