Focal plane reflector feeds with shared aperture are a promising solution for the increasing number of beams required in Ka-band satellite services. Stringent manufacturing tolerances and coupling between feeds tend to penalize performance, which is aggravated for dual-band. This manuscript proposes a new design of a shared aperture antenna intended for multi-spot single-feed-per beam satellite applications that allows recovering singlefeed performance, minimizing the usual impact of adjacent feeds on the field distribution and ultimately on the antenna directivity and gain. We present a newf focal-plane dual-band Fabrv-Pérot cavity antenna (FPCA) design, which allows more reliable fabrication, closer agreement with simulations and larger bandwidth than reported solutions. It uses only one double-sided printed FSS to form the dual-band FPCA, and it is fed through a novel arrangement of double-layer slots in the FPCA printed ground plane. This favors impedance matching and higher isolation between adjacent feeds. The effectiveness of the solution is experimentally demonstrated for a single-feed Ka-band (20GHz and 30GHz) prototype. The generalization for a complete multifeed configuration with filters is show’n by full-wave simulations. The de-coupling slots on the FPCA ground plane enable restoring single-feed performance in the multi-feed system, over the bandwidth of interest.