A Non-Isolated Power-Combining Antenna for Outphasing Radio Transmitters

In this work, we propose a two-port antenna which can fulfill the extra function of power combiner in an outphasing radio transmitter. The antenna has an equivalent circuit nearly identical to that of the quarter-wavelength transmission line power combiner terminated by a resistive load representing the separate antenna. Therefore, it has the typical characteristics of a non-isolated combiner: low losses at cost of no port isolation. The proposed concept is verified by simulations based on a theoretical model and validated with measurements from a prototype for the case of a 2.4-GHz QAM64 transmit signal.