Design of a Wideband and Miniaturized Dual-Band Shared-Aperture Antenna With Planar Single-Layer Structure

This article presents a novel wideband and miniaturized microwave (MW)/millimeter-wave (MMW) dual-band shared-aperture antenna. The antenna operates as a horizontally polarized dipole antenna in the MW band and functions as a vertically polarized SIW array in the MMW band. In the MW band, a dual-element array composed of two electric dipoles of different lengths is used. Two dipoles are closely arranged to minimize the antenna footprint, while two resonant modes are constructed to broaden the operating bandwidth in the MW band. In the MMW band, an H-plane SIW unit is first designed. It has two resonant modes within the Ka-band. By introducing a C-shaped slot on the SIW surface, an additional resonant mode can be excited at high frequency. Subsequently, three matching vias are embedded inside the SIW to improve the low-frequency matching of the SIW unit, ultimately achieving broadband coverage. After completing the designs of the dipole antenna and SIW unit separately, the MMW SIW unit is expanded into a 1 × 4 SIW array, with beam-steering capability achieved by applying gradient phase shifts to the units. Subsequently, through double-sided printing of the driven dipole of the MW dipole antenna and loading metal vias, it can be reused as four SIW radiating elements in the MMW band, thereby accomplishing the shared-aperture integration. Consequently, the antenna achieves measured bandwidths of 56.9% (2.16-3.86 GHz) and 41.2% (26.3-40 GHz), nearly covering the entire S-band and Ka-band. Moreover, the channel isolation between the dipole antenna and SIW array exceeds 50 dB in the S-band and reaches 28.5 dB in the Ka-band. In addition, the proposed antenna adopts the simplest planar single-layer structure with compact dimensions of 0.52 × 0.19 ×0.015λ03. It shows promising potential for application in miniaturized satellite communication systems operating in the S/Ka-bands.