Abstract: There is disclosed an apparatus to test an antenna. A transmitter generates a test signal radiated by the antenna under test. A near field scanner includes a field sampling probe to capture electromagnetic energy radiated by an antenna under test. An x-y positioning system including x and y positioning motors moves the field sampling probe over a measurement surface disposed proximate to the antenna under test. A quasi-optical beam transport system couples at least a portion of the captured electromagnetic energy from the field sampling probe to a scanner output port. A receiver is coupled to the scanner output port.