Six-port wave correlator theory and practical application to RF network analysis

This tutorial lecture is intended to introduce the basic concept and principle of the six-port wave correlator, and to present the latest advancements in its theory and techniques. The lecture starts with some fundamentals on the six-port reflectometer dating back to its first proposal by G. F. Engen. The key feature of the scheme is to measure the reflection coefficient of RF circuits without resorting to heterodyne conversion. This implies a possibility to measurement of S11 in both magnitude and phase, free from frequency limitation. Next, the concept is extended to a six-port wave correlator on which we focus from the viewpoint of establishing a new scheme for characterizing the full S matrix, like what can be carried out by vector network analyzers. Finally, we explore some specific microwave applications of the six-port network, such as beam direction finding, Doppler frequency measurement, etc.