A High-Order Mode-Based Multifunctional Antenna Using Substrate-Integrated Waveguide Technology for Millimeter-Wave Applications

To address the growing demand for multifunctional antennas, this article presents a novel antenna design that integrates high-order mode theory with substrate-integrated waveguide (SIW) technology. The proposed antenna leverages liquid metal to dynamically control and reconfigure excitation conditions, enabling multiple functionalities such as multifrequency difference-pattern radiation, dual-frequency high-gain directional radiation, quad-band multibeam radiation, and beam-switching. The proposed multifunctional antenna can support a total of five distinct operating states, significantly enhancing multifunctionality across frequency, radiation, and polarization domains. Additionally, an equivalent resonant mode analysis method is introduced to examine the internal electric field distribution in a square ring resonant cavity, alongside the development of a radiation slot structure that enhances mode utilization and overall antenna performance. The proposed single-layer, low-profile antenna offers key advantages such as lightweight, cost-effectiveness, and high robustness. By achieving multifunctionality with reduced design complexity, this antenna provides an innovative solution for widespread deployment in wireless systems, optimizing spatial resource utilization while minimizing system complexity.