Multi-band converged high-resolution ISAR based on photonic ADC reception

We propose a high-resolution inverse synthetic aperture radar (ISAR) imaging scheme based on bandwidth synthesis with photonic analog-to-digital converter (PADC) reception. In this architecture, multiple sub-band signals are transmitted sequentially, while the echoes from all synthesized frequency bands are directly sampled by a wideband PADC. By preserving the original echo information and avoiding analog-domain de-chirp processing, the proposed scheme enables high-fidelity digital bandwidth synthesis for ultra-wideband radar imaging. In experiments, an equivalent ultra-wideband signal spanning 2-18 GHz was reconstructed from four sub-bands with a synthesized bandwidth of 11.2 GHz, achieving a range resolution of 1.1 cm. Two-dimensional ISAR imaging results further demonstrate the feasibility of the proposed approach.