A Review of PA-Antenna Co-design: Direct Matching, Harmonic Tuning and Power Combining

This article reviews the current state-of-the-art of active-integrated antennas co-designed with power amplifiers (PAs). Three strategies to improve output power and power-added efficiency are described using examples, namely direct matching between PA and antenna, tuning of harmonic reflections in the antenna, and in-antenna power combining from multiple PAs. An outlook is given on the challenges to be faced in the application of these strategies in wide-scanning phased arrays.