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For most wireless communication systems, the signal environment is dominated by ambient noise and interference, which means that improving the efficiency of the antenna does not increase performance much. When the signal comes from the sky (think radio astronomy and satellite communications), the situation is very different. High aperture efficiency, radiation efficiency, spillover efficiency, and low noise electronics are everything in terms of the performance of a receiver. Bent metal antennas (horns and parabolic dishes) are very efficient and for the last century have been working just fine. The catch is that these kinds of receivers are “dumb” and offer only a fixed beam pattern. We would like to use smart antennas, phased arrays, and adaptive antennas for astronomy and satellite applications to have more control over the beam and more flexibility in selectively receiving signals of interest, but existing phased array technologies are too expensive, lossy, noisy, and most of all, too inefficient. Over more than a decade, my group has used numerical modeling, antenna design optimization, network theory, microwave noise analysis, and array signal processing theory to produce some of the most sensitive phased arrays ever built. This presentation will tell the story of this research field and show how the results have enabled new sensors, satellite receivers, scientific instruments, and influenced the IEEE’s latest version of the governing standard for definitions of antenna terms.