A dual-band and dual-polarized shared-aperture synthesis method for phased array applications is proposed. Dual-polarized slot-coupled microstrip patch elements operating in the Ku <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</i> band are arranged in a regular array configuration. Two orthogonal probes share a common radiating patch structure and are fed by two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula> -shaped coupling slots. Sidewall metalized cavity waveguide elements operating in the W-band are fed by a substrate-integrated waveguide and arranged in a sparse array configuration, which is based on an optimization algorithm proposed in this work. Furthermore, the feeding locations are regularly determined, which is beneficial to transceiver/receiver design, thus reducing the cost of a phased array system. By exploiting this compact array topology and optimization algorithm, two-phased arrays with a large frequency ratio employing a shared aperture simultaneously exhibit wide-angle scanning properties. A 64-element array is designed, fabricated, and measured. The measurement results show that the Ku-band dual-polarized antenna exhibits a wide impedance bandwidth of 20% in the 14.3–17.6 GHz frequency range for two orthogonal polarizations and high isolation (>20 dB) between the feeding ports. The W-band antenna exhibits a 5.4% fractional impedance bandwidth covering 90–95 GHz frequency range with a ±45° scanning angle in the E <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</i> and H-planes.