Systems and methods for calibrating out the radiation channel matrix in a multiple input, multiple output (mimo) over-the-air (ota) radiated test system

A method for performing a non-cable-conducted, over-the-air (OTA) radiated test of a device under test (DUT) in a test system operating in a multiple-input multiple-output (MIMO) environment, the method comprising:

• locating a DUT in an anechoic chamber, the DUT having a plurality of antenna elements electrically coupled to respective antenna ports of the DUT, the chamber having a plurality of probe antennas disposed therein;
• during a calibration mode of operations, causing predetermined signals to be transmitted over a transmission channel comprising a non-cable-conducted, over-the-air (OTA) interface between the probe antennas of the chamber and the antenna ports of the DUT and obtaining measurements of received power and relative phase for the predetermined signals;
• using the measurements obtained during the calibration mode of operations to construct a radiation channel matrix associated with the transmission channel;
• obtaining an inverse matrix of the radiation channel matrix;
• and
• during a test mode of operations, performing a non-cable-conducted, OTA radiated test that applies the inverse matrix to DUT performance measurements obtained by the test instrument to calibrate out the radiation channel matrix from the DUT performance measurements.

A computer program comprising computer code for execution by a test instrument of a test system operating in a multiple-input multiple-output (MIMO) environment for performing a non-cable-conducted, over-the-air (OTA) radiated test, the computer code being embodied on a non-transitory computer-readable medium, the computer code comprising:

• a first code portion that causes predetermined signals to be transmitted over a transmission channel comprising a non-cable-conducted, over-the-air (OTA) interface between probe antennas disposed in a anechoic chamber and antenna ports of the DUT and obtaining measurements of received power and relative phase for the predetermined signals;
• a second code portion that uses the measurements obtained by the first code portion to construct a radiation channel matrix associated with the transmission channel;
• a third code portion that obtains an inverse matrix of the radiation channel matrix;
• and
• a fourth code portion that applies the inverse matrix to DUT performance measurements obtained by the test instrument while performing a non-cable-conducted, OTA radiated test to calibrate out the radiation channel matrix from the DUT performance measurements.