Realization of Quasi-elliptic Quadruplets with a Single Type of Coupling

A phase reversal scheme for changing the polarities of so-called electric and magnetic couplings between distributed resonators is explored. It demonstrates that the phase reversal can be achieved by shifting the excitation to the symmetric point of an open-ended half-wave resonator without altering the coupling geometry. Based on this technique, the polarities of conventional electric and magnetic couplings can be easily toggled. Two quasi-elliptic microstrip quadruplets are synthesized, fabricated and measured for demonstration.