The Sub-harmonics Suppression Method in Terahertz Inverse Synthetic Aperture Radar Imaging

The inverse synthetic aperture radar (ISAR) is a commonly used method for remote sensing imaging. In addition, the terahertz (THz) ISAR is effective in realizing high-resolution imaging on both range and azimuth dimensions for its large bandwidth and short wavelength. However, in the real THz-ISAR imaging scene, the sub-harmonics easily occur because of the components ageing or the defects of the device-processing technology. The sub-harmonics embodied in both amplitude and phase terms lead to the deterioration of ISAR imaging quality. This paper analyses the property of the sub-harmonics appeared in the 330GHz ISAR imaging experiment and proposes a threefold correction method by reference signals of two reflectors to suppress the sub-harmonics.