A Single-Layer Dual-Frequency Shared-Aperture SIW Slot Antenna Array With a Small Frequency Ratio

This study provides a solution to achieve a single-layer dual-frequency shared-aperture slot antenna array with a small frequency ratio (FR) based on a substrate integrated waveguide (SIW) technology. Cavity resonator principles are applied to a distinctive SIW antenna array cavity to obtain dual operational frequencies on two separate ports while sharing the same radiation aperture. A 24-element SIW array prototype is designed and fabricated to validate the solution. The prototype has dual frequencies and a shared aperture with a small FR of 1.03 while maintaining a single-layer planar configuration and low cost. The two ports operate at 5.701 and 5.888 GHz. Reasonable parameters are obtained from the simulation and measurements, and there is a good agreement between the results.