Transistor-loaded isolator based on both frustrated propagation and field cancellation mechanisms

A novel microwave isolator operation based on non-reciprocal vectorial magnetic field cancellation in Magnet-less non-reciprocal Metamaterial (MNM) is proposed, analyzed, and its superiority to the previous concept is fully confirmed by prototype device. The field cancellation is realized by a traveling-wave ring resonator pair with structural perturbation in order to obtain asymmetric vectorial field excitation, which leads to vectorial field cancellation. Compared to the original design, isolation ratio (|S21|–|S12|) is improved from 10 to 35 dB with insertion loss of 2 dB.