{'fraction_non_alphanumeric': 0.033524121013900246, 'fraction_numerical': 0.006541291905151268, 'mean_word_length': 4.856459330143541, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
An Efficient Algorithm Based on CSA for THz Stepped-Frequency SAR Imaging

An efficient algorithm based on chirp scaling algorithm (CSA) for terahertz (THz) stepped-frequency (SF) synthetic aperture radar (SAR) imaging is proposed in this letter. We call this efficient algorithm SF-CSA for convenience. THz imaging techniques have good prospects in the fields of military, public safety, and nondestructive defect identification. In these fields, real-time imaging is very important. CSA is an efficient algorithm suitable for SAR real-time imaging, but it can be only used for linear frequency-modulation (LFM) SAR imaging. The main contribution of this letter is the successful application of CSA in THz SF SAR imaging. Compared with other existing THz SF SAR imaging algorithms, SF-CSA has higher efficiency and is more suitable for real-time imaging. The validity of SF-CSA is demonstrated by theoretical derivation, simulation, and experiment in this letter. In the simulation and experiment, the radar operates at 300 GHz providing a maximum bandwidth of 28.8 GHz, leading to a range resolution of 5.2 mm. The simulation and experiment results show that SF-CSA has high quality and efficiency for THz SF SAR imaging.