The approach which has been followed is to connect the antennas sequentially, to a receiver while the source remains essentially fixed in location. Thus, since the elements are to a first approximation identical, the effect is that of rotating the array. The sequential connection of the elements to the receiver must be done rapidly so the source and other potential variables can be maintained essentially constant during the period of a single rotation. For this purpose, scanning rates typical of goniometer speeds would appear to be appropriate. That is, in the range of 90 to 900 rpm, or 1.5 to 15 scans per second. Rather than use a rotating system, such as a goniometer, a discrete switching system has been devised. To permit the high speed switching necessary, electronic commutation techniques employing semiconductor diodes have been utilized. The signals to drive the diode switches are, in turn, derived from semiconductor digital logic circuits. This has permitted considerable flexibility of operation of the test system without excessive complexity.