Investigating Distribution Characteristics of Electromagnetic Reflection Intensity and Intrapulse Doppler Frequency Coupling Mechanism of Plasma-Sheath-Covered Target

Due to the high velocity of hypersonic target, the target surface is covered with plasma sheath. For radar detecting on hypersonic target, the spatial distribution characteristics of plasma sheath cause significant differences in echo intensity and frequency offset at different areas of the target surface. In order to further investigate the reflection characteristics of each area of the target, this study adopts a difference-equivalent transmission line method to calculate the distribution characteristics of reflection intensity of the plasma-sheath-covered target and reveals the coupling mechanism of intrapulse Doppler frequency of the reflected wave by utilizing frequency offset effect. First, based on numerical calculation results of surface flow field, we analyzed the spatial distribution characteristics of the electron density and velocity of the plasma sheath. Second, we obtained the influence laws at different altitudes and carrier frequencies on the reflection intensity distribution and frequency offset of the plasma-sheath-covered target in each area. Finally, by constructing 1-D range profile of target radar echo, we further revealed the influence mechanism of the reflection characteristics of plasma-sheath-covered target on radar detection. Our research results lay a solid theoretical foundation for calculating the scattering characteristics of plasma-sheath-covered targets, reliable and robust radar detection, and even electromagnetic (EM) stealth performance under active modulation.