Multiplexing High-Scanning-Rate Frequency-Scanning Antenna for Two-Dimensional Single-Shot Frequency-Diverse Microwave Imaging

This is the authors' abstract. We don't add key points for this paper.

Two-dimensional beam scanning is crucial for microwave imaging. For conventional frequency-scanning antennas, such as leaky-wave antennas, their beams typically scan along only one dimension (e.g., longitudinal, vertical, or radial scanning) as the frequency changes. While multiple-input multiple-output (MIMO) systems can enable beam scanning in the other dimension through digital beamforming, such multi-port systems are generally expensive. This paper introduces a single-port, two-dimensional frequency-scanning architecture that combines several one-dimensional scanning antennas using a multiplexer, allowing beam steering in two-dimensional space as the frequency changes. As a proof of concept, we design four high-scanning-rate substrate integrated waveguide (SIW) slot array antennas, each operating at a different channel, and connect them using a manifold multiplexer. Each SIW slot array antenna can scan its beam over a 74◦ range in the vertical direction as the frequency varies within a 50 MHz bandwidth per channel. Moreover, the four antennas, each operating within its respective channel, can work independently and simultaneously, effectively mimicking a MIMO system while utilizing only a single feed port. The entire system operates within the 3.975 − 4.325 GHz frequency range, with a relative bandwidth of 8.43%. A prototype is fabricated on a Rogers 5880 dielectric substrate, with compact dimensions of 7.17×4.24×0.02λ 3 0. By using this antenna for transmission and a conventional patch antenna for reception, we demonstrate a two-dimensional frequency-diverse imaging system. Several two-dimensional imaging examples are presented to illustrate the capabilities of this system.