Figure 2
From: Non-magnetic four-port electronic circulators based on \(90^\circ \) non-reciprocal phase-shifters
The \(90^\circ \) non-reciprocal phase shifter and its network properties: (a) input and output reflection coefficients. (b) impedance transparency \(\Gamma _{in} = \Gamma _{out}\) hence \(Z_{in} = Z_{out}\). (c) quadrature excitation for phase lead of terminal 2 results in short circuit input–output effective impedance. (d) quadrature excitation for phase lead of terminal 1 results in open circuit input-output effective impedance. (e) neutralization of a \(90^\circ \) transmission line load connected parallel to the \(90^\circ \) NRPS.
