Ring of Four Overlapped Microstrip Hybrid Couplers

The ring of couplers known from Butler matrix, correlators and direction finding systems has been discussed in the paper. The ring of four hybrid couplers is a regular pattern of a fundamental eight-port forming a set of four output responses. The responses can be excited in two orthogonal modes. The eight port with ring of five hybrid couplers has been included as an extension of the basic ring of four couplers. The pentagonal ring enables four way distribution in three modes. All available modes have been discussed on the base of perfect scattering matrix. Both the rings were embodied using broadside coupled Overlapped Microstrip lines with PTFE substrates and were measured in frequency ranges 2-16GHz and 10-20GHz. The presented results prove existence of recognized modes in real imperfect embodiments within approximate bandwidth of an octave. The rings are devoted for widely meant analog signal processing.