Profile-Reduced S/X-Band Shared-Aperture Antenna Array with Frequency-Selective Surfaces

Shared aperture antennas (SAAs) are becoming more popular due to their desirable traits such as miniaturization and cost reduction. However, incorporating a high frequency ratio in an SAA typically results in increased PCB fabrication costs or additional manufacturing complexity. In this work, we present the design concept and simulation results of a circularly polarized SAA with a profile of tenth of a wavelength at the lowest frequency. The SAA simulations indicate a −10-dB active reflection coefficient bandwidth of 292 MHz for the S-band and −9-dB total active reflection coefficient bandwidth of 1.071 GHz within a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$+/-40^{\circ}2\mathrm{D}$</tex> beam steering range for the X-band. The S-band element is realized with an inter-band filtering dipole that is co-located in the same plane as the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4\times 4$</tex> X-band array that utilizes slot antennas as radiating elements.