A Ku-band cavity backed microstrip patch antenna sub-array suitable for dual linear/circular polarization is being developed based on substrate integrated waveguide (SIW) technology for DBS applications. SIW cavities have been emulated using vias and the patches are fed using microstrip line feed network. A 3??4 sub-array has been fabricated, tested and its results demonstrated a relatively high efficiency performance along the DBS 12.2-12.7 GHz band. The design for dual polarization could be used for either dual linear or dual circular polarization and provides adequate isolation between them. Larger array designs can be easily modified to use waveguide feeds along with probes to sustain its high efficiency performance.