Low-Profile Ku-/Ka-Band Shared-Aperture Phased Array

In this article, a low-profile Ku-/Ka-band shared-aperture phased array (SAPA) antenna is proposed. The cell of the SAPA consists of one Ku-band slot element below and four Ka-band patch elements stacked above. Two types of slots are designed in each cell to achieve better impedance matching and dual-polarized ±45° beam scanning in E-/H-planes within 14–17 GHz (19.4%). The copper-clad plane surrounding dual-polarized slots serves as the ground plane for Ka-band patches, eliminating the need for an additional frequency selective surface (FSS). Moreover, shielding vias around the Ka-band feeding vias are employed, ensuring the normal feeding of the Ka-band patch elements and solving the parallel waveguide mode issues. According to the analyses of specific near-field reactions of the structures, the mirror arrangement of Ka-band patch elements is proposed, and its position is elaborately co-designed with the slots to avoid destructive strong coupling between the patch and slot. As a result, the Ka-band patches achieve ±30° beam scanning in both E-/H-planes in 33–36 GHz (8.7%), with minimal impact on the performance of the Ku-band dual-polarized slots below. Prototypes are fabricated and measured for Ku-/Ka-band performances verification, which is confirmed by the consistency of measured and calculated results.