A Mutually Enhanced Ka/W Dual-Band Shared-Aperture Horn Antenna

This article describes the design and realization of a novel Ka/W dual-band shared-aperture horn antenna employing the concept of mutual enhancement. The W-band antenna cells within the Ka-band antenna structure enhance the aperture utilization efficiency. The proposed design enables gain enhancement in the Ka-band horn antenna through incorporation of W-band horn antenna cells, while the W-band array antenna achieves low sidelobe levels by adopting a sparse array configuration. The W-band antenna consists of a radiation sparse array, an irregular interconnected waveguide-based network, and a power divider network. A mutually enhanced Ka/W dual-band shared-aperture horn antenna is fabricated and evaluated. The results reveal a gain improvement of 1.5 dB at 35 GHz compared to the original horn antenna. Moreover, the measured
$\vert \text { S}_{11}\vert \le -10$
-dB bandwidth of the W-band array antenna spans over 16 GHz (ranging from 92 to 108 GHz). At the central frequency, the maximal gain of the radiation pattern is approximately 20.8 dBi, with low sidelobe levels (in both the E- and H-planes) of less than −19.0 dB.