Reflector-based satellite communication (SatCom) terminals require high sensitivity to minimize overall antenna size, and in view of their simplicity and high radiation efficiency, horn antennas are used almost exclusively as reflector feeds. As these terminals become more complex, smaller and more compact feeds that can be directly integrated with microstrip circuits are desirable. Standard microstrip antennas (MSAs) have unacceptably low radiation efficiency for use as reflector feeds. We show that the stacked shorted annular patch (SSAP) can be used as a replacement for horn feeds and achieves higher radiation and spillover efficiencies than conventional patch antennas due to the absence of distribution networks and dielectric substrates. Using a half-wavelength stacked patch as a director realizes a pattern that achieves high illumination efficiency with standard parabolic reflector geometries. Simulation and measurements show that the compact SSAP may be the first reported nonwaveguide feed antenna to achieve sensitivity comparable to that of a conventional horn feed.