Efficiencies of elementary integrated-circuit feed antennas are calculated considering both the substrate and the optics. Calculations are made for dielectric constants of 4, for fused-quartz substrates, and 12, for silicon and gallium-arsenide substrates. The effect of substrate lenses, anti-reflection coatings, and adjustable backshorts is also considered. A feed efficiency of 60% is predicted for a slot on a substrate and substrate lens with dielectric constant 12, and 63% for a dipole on a substrate with dielectric constant 12 and lens of dielectric constant 4.