De-Embedding for Coupled Three-Port Devices

De-embedding techniques have been introduced to evaluate the real electrical performances of a device under test (DUT), e.g., the traditional thru-reflect-line (TRL) and short-open-load-thru (SOLT) standards, where the transfer matrix (T-matrix) and its inverse form are adopted in the mathematical process. A DUT may have three coupled ports in the fields of radiofrequency (RF) and electromagnetic compatibility (EMC). The symmetry in the corresponding S-matrix breaks down, because the numbers of incident and reflected ports are not equal. Thus, it leads to a non-square T-matrix by definition. Given that the inverse expression of a non-square matrix does not exist, the conventional de-embedding methods are inapplicable for a coupled three-port network. In this paper, a de-embedding algorithm which is feasible for coupled three-port devices is proposed and verified through the measurement. The proposed de-embedding technique may also be applied on devices with more than three ports.