Mirrored Aperture Synthesis Radiometric Imaging Based on Spatial Bandpass Sampling and Quad-Beam Antennas: Design and Numerical Validation

Mirrored aperture synthesis radiometry (MAS) has been proposed for passive microwave remote sensing with high spatial resolution and relatively few antenna elements. However, low incident angles and improper azimuth angles result in oversized reflectors, posing difficulties for practical deployment. To address this issue, the center of the imaging region is shifted from the incident angle of 0° to the oblique direction of (θ = 45°, ϕ = 45°) in this paper, which is quite different from conventional aperture synthesis radiometry architecture. The problem of oversized reflectors and the necessity of shifting the imaging region are discussed. To match the shifted imaging region, a new design scheme based on spatial bandpass sampling and quad-beam antennas for MAS imaging is proposed. Instead of the Nyquist baseband sampling adopted in conventional aperture synthesis, the spatial bandpass sampling is adopted to process the spatial bandpass signal caused by the imaging region shift. Then, antennas with quad-beam pattern are proposed and designed to receive the incident wave and three reflected waves. Numerical simulation experiments are conducted to demonstrate the feasibility of the proposed method. This work focuses on the conceptual design and principle validation, and does not involve hardware implementation or prototype fabrication.