Enhanced-Isolation Dual-Polarized Aperture-Fed Patch Antenna with Air Cavity for 5G Communication

This paper proposes a method to enhance the bandwidth and port isolation characteristics of a dual-polarization patch antenna using an aperture-coupled feeding structure with isolation vias. Initially, a feeding structure composed of a stripline integrated with a transformer is considered. A U-shaped aperture structure is added to it, along with two isolation vias to improve port isolation. A 0.5-mm-thick air cavity, realized using a 3D-printed structure, is introduced between the U-shaped aperture and the patch antenna. Through this approach, a highperformance dual-polarization patch antenna operating in the millimeter-wave band with excellent isolation performance is achieved using only four metal layers. The proposed antenna was fabricated and measured, demonstrating a port-to-port isolation of less than −33 dB, a minimum antenna gain of 6.7 dBi, and a peak gain of 8.7 dBi within the target frequency band. Additionally, the antenna achieved a fractional bandwidth exceeding 10%, indicating its potential for 5G millimeter-wave band applications.