A Dual-Band X/Ku Copolarized Shared-Aperture Waveguide Slot Antenna

In this letter, a dual-band X/Ku copolarized shared-aperture waveguide slot antenna is proposed. The frequency ratio is 1.4:1. Both frequency bands utilize broadside longitudinal slots for radiating. To achieve a shared-aperture design for the dual-band waveguide arrays within a confined space, structural optimization is primarily conducted on the linear array for the lower frequency band. Based on the design of the X-band radiation waveguide, longitudinal slots distribution at the center of the broadside achieves consistent feeding phase, which further facilitate the design of the X-band linear array within a limited width of only 0.13<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula>. The proposed shared-aperture antenna exhibits good impedance matching and radiation characteristics. Furthermore, the proposed antenna features a modular design, which is advantageous for flexibly changing the scale of the antenna array as needed. Due to the abovementioned characteristics, the proposed antenna array is a promising candidate for airborne and spaceborne synthetic aperture radar systems, especially for those that require simultaneous operation in different frequency bands.