In Situ RF Current Assessment for Array Transmission and Optimization

In the increasingly congested wireless spectrum, phased-array transmitters can be used to provide spatial diversity as an additional measure of coexistence. Reconfigurable matching networks placed between the power amplifier device and the antenna can allow the amplifiers in the transmitter elements to maximize output power while maintaining the desired beam fidelity. A challenge with the use of reconfigurable matching networks in array transmitters is that they alter the system calibration. This article provides measurement validation of an in situ measurement approach to assess antenna input current using a dual-directional coupler placed in an array element. Measurement validation was performed using a two-port vector network analyzer (VNA) with a load-pull tuner emulating changing antenna impedance. This approach is expected to ease the process of maintaining the pattern and is expected to ease issues stemming from changing array calibration with reconfigurable array element circuits.