Compact metacavity antenna with enhanced radiation uniformity for narrow-band microwave computational polarimetric imaging

To facilitate microwave computational polarimetric imaging (MCPI) within a limited operating frequency bandwidth,a frequency-diverse compact metacavity antenna (CMA) using an aperture-rotation technique is proposed in this communication.The proposed CMA is fundamentally a cavity-based leaky-wave antenna, featuring a compact double-layer cavity and a set of cross-shaped leaky irises. The double-layer cavity, consisting of a disordered cavity as the lower part and a metacavity as the upperpart, is designed to provide frequency-dependent excitations.Meanwhile, the cross-shaped leaky irises, with various structural parameters and orientations, exhibit diverse radiation characteristics, allowing for the radiation of spatially low-correlated dual polarized field patterns across different operating frequencies and rotation angles. Furthermore, due to multiple modulations inside the double-layer cavity and random orientations of the leaky irises, the radiated fields exhibit consistent amplitude levels under different conditions (i.e., frequency and rotation angle),demonstrating enhanced radiation uniformity. The performance of the proposed CMA is evaluated from two aspects: antenna related metrics and MCPI-related metrics. Both the simulated and measured results confirm the CMA design as a promising solution for narrow-band MCPI applications.