Antenna array measurement using multiport VNA

Measurements of antenna array's patterns are usually taken with feed networks, but for some digital beam forming arrays, feed networks are not included. To measure such arrays in traditional way, we must design a feed network first, which is too complex and inefficient when steering is required. A VNA can act as a multi-channel receiver to form a digital beam forming array for testing. Today's VNA may have many test ports (for example, 9-ports in Agilent E5091A multiport test set and 11-ports in Advantest R3986 multiport test set.) designed for multiport devices, which is very suitable for measuring small arrays without using feed networks. Another advantage of this method is that it can eliminate errors from imperfect feed networks. Automatic measurement program is required to calculate array patterns from S-parameters, which is easily developed using Labview or Matlab. Test results of a 3-elements adaptive anti-jam array with different jam DOA are demonstrated.