Shared-Aperture Dual-Polarized Ku-Band and Single-Polarized Ka-Band Phased Array Antenna With Scanning Coverage Enhancement

A dual-polarized Ku-band and single-polarized Ka-band shared-aperture phased array antenna is proposed in this article. The endfire dipole antenna is designed as the radiating element of both bands. To eliminate the shading effect of the horizontal-polarized Ku-band antenna caused by the common ground, the director is loaded on the Ka-band antenna to increase the height of the equivalent phase center of the Ka-band antenna. The high-order mode of the horizontal-polarized Ku-band antenna is excited when the Ka-band antenna scans to a wide angle in H-plane within the frequency range of 33–34 GHz. An etched square ring is loaded on the Ku-band radiating arm to induce the reverse current to prevent such a high-order mode. The scanning blind spots occur at 33 and 35.8 GHz when the Ka-band antenna scans to 50° in E-plane owing to the mutual coupling between the Ka-band antenna and the vertical-polarized Ku-band antenna. A metallic strip is loaded on the vertical-polarized Ku-band antenna to eliminate the blind spot at 33 GHz. The feeding position of the vertical-polarized Ku-band antenna is elevated to eliminate the blind spot at 35.8 GHz. The periodic cell and finite array are simulated to verify the design proposed in this article. The results demonstrate that the design is effective and the beam-scanning coverage reaches <inline-formula> <tex-math notation="LaTeX">$\pm \mathrm{50}^{\circ }$ </tex-math></inline-formula> at both bands. The active voltage standing wave ratio (VSWR) is not greater than 3.5 at 15–17 and 33–36 GHz in the whole beam-scanning coverage. A prototype of the 4 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 Ku-band and 8 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 Ka-band shared-aperture array is fabricated and measured. The measured results agree well with the simulated ones.