Contact-less near-field measurement of RF phased array antenna mismatches

Future RF transceivers are expected to integrate the entire system, from baseband to antenna. Many emerging applications use beam forming, which necessitates RF phased arrays and multiple antennas integrated on the same die. Integration of antennas onto the same die as the phased array and other electronics presents a test challenge since the output is combined in the air and no longer can be separated by physically connecting to the test equipment. This paper presents a novel contact-less test method for measuring the gain and phase mismatch of RF phased array antennas. The proposed method is based on using fully characterized receiver antennas to capture the combined EM output of the transmitter antennas. Near-field analysis is applied with a decoupling approach to determine both gain and phase mismatches so they can be calibrated in the baseband. Near-field measurements are preferable in the production test environment since they do not require large physical distances to be implemented on the load board. A phased array consisting of two elements is modeled and evaluated in near field to verify our test method.