Temperature-Dependent Electromagnetic Performance Predictions of a Hypersonic Radome Based on Variable Thickness Gradient Dielectric Multilayer Walls

High temperatures in hypersonic conditions induce variations in the dielectric parameters of radome materials, leadi- ng to a decline in electromagnetic (EM) performance, such as bor- esight error (BSE) and transmission loss (TL). This letter introdu- ces a model for variable-thickness gradient dielectric multilayer walls, developed based on the 2-D steady-state temperature field with consideration of thermal conductivity variation at high tem- peratures within a porous Si
₃
N
₄
ceramic radome. The BSE and TL of the radome within the Mach 5-7 speed range were computed using the time-domain finite integral (FITD) method. The findings indicated that the EM performance degradation was most pron- ounced in the radome nose area, with the extent of deterioration escalating as speed increased, while changes in other regions is slight. The concept of asymmetry in insertion phase delay (IPD) was proposed to quantitatively describe the distribution characte- ristics of IPD, and its relationship with BSE is identified. The proposed model enables more accurate prediction of the EM performance of hypersonic radomes and provides guidance for correcting and optimizing their performance in operation.