Frequency-Diverse Bunching Metasurface Antenna for Microwave Computational Imaging

A frequency-diverse bunching metasurface antenna (FDBMA) that can be used for microwave computational imaging (MCI) systems is proposed in this article. The proposed FDBMA can generate low-correlated radiation patterns with a reduced frequency interval of 20 MHz and a bunching angle of
$45\mathrm {^{\circ }}$
from 32 to 36 GHz. The frequency interval is reduced by combining a disordered cavity and an optimized frequency-diverse random metasurface. The directivity of the radiation patterns is improved by leveraging the joint-bunching method that combines the metal baffle, the Fresnel dielectric lens (FDL), the quasi-gradient random metasurface, and the random-coherent superposition comprehensively. The performance of the proposed FDBMA is evaluated in terms of the reflection coefficient, singular value decomposition (SVD) of the sensing matrix, and correlation coefficients (CCs) of the measurement modes. The reduced frequency interval and the bunching characteristic are also demonstrated. Finally, MCI experiments are implemented using the proposed FDBMA. Comparative experiments are also carried out to validate the advantage of reducing the frequency interval and improving the directivity.