Antenna Array Inter-Element Coupling impact on Linearization of Active Phased Array

The new generation of 5G mobile and inter-satellite communication systems are using mmWave active phased array (APA) which have up to hundreds of individual analog transmitter and receiver chains and antennas. When moving to high integration scenarios, the isolation between the array and the power amplifiers (PAs) is often removed. Since the array elements are electromagnetically coupled, the waves fed to the antennas are also driving the output ports of the PAs. This effect creates a possible variable load at the output of each PA, depending on steering angle and radiated power at each element in the array. In this system, the behavior of each PA cannot be fully described solely as a function of its input, as it will change according to the coupled signal. In this paper the inter-element coupling of a 4x4 planar patch antenna array and the resulting variation in output impedance of the PA connected to each patch is simulated by using computer simulation tool (CST). The impact of the interelement coupling has been verified on linearization procedure of the active array.