Abstract—Inhomogeneous radomes, characterized by stacked layers of continuously varying dielectric parameters, are potential in yielding excellent electromagnetic (EM) performance. This two-part sequence of papers presents a study on the EM per- formance of inhomogeneous airborne radomes based on imped- ance match, including comparison with the conventional constant thickness radomes (CTRs) and variable thickness radomes (VTRs). In this paper, study on the phase distortion of antenna aperture field caused by inhomogeneous radomes gives a physical insight into the cause of radome boresight error (BSE), and ex- plains why the substantial decrease of insertion phase delay (IPD) of inhomogeneous radomes, instead of leading to BSE improve- ment, increases the BSE. Based on the study, a method is proposed to estimate the IPD distribution which can be used to predict the
