An Efficiency Enhancement Method for Compact Active Integrated Antenna in Ultrawideband Vehicular Communication

In this communication, an efficiency enhancement method for active integrated antenna (AIA) is proposed to achieve power-added efficiency (PAE) improvement, ultrawideband operation, and size miniaturization. The proposed AIA integrates a multifunctional passive antenna element with a simplified power amplifier (PA) circuit. The multifunctional passive antenna element provides the optimal fundamental-frequency load impedance for the PA while enabling precise harmonic phase control over an ultrawide frequency band. Consequently, it eliminates the need for additional output matching networks, thereby reducing circuit insertion loss. Concurrently, it minimizes the overlap of voltage and current waveforms on the PA transistor, resulting in low power dissipation. These features collectively lead to a significant enhancement in PAE across a wide frequency band. For demonstration, an AIA operating in the frequency band of 1–3 GHz is designed and validated. The peak PAE of the AIA reaches 66.7% with the maximum effective isotropic radiated power (EIRP) of 44.4 dBm. The proposed AIA has the advantages of wide bandwidth, high PAE, and compact size, which make it a promising solution for wireless vehicular communication systems.