“…This can be, for example, double-sided microstrip resonators [15]- [18] or dielectric resonators (DRs) [14], [19], [20], as well as appropriate transmission lines [13], [4]. Another possibility is to design the impedances of the connecting output network in such a way that the conditions for oscillation are fulfilled for the odd-mode impedance only, but not for the even-mode impedance [4], [6], [10], [21], [22]. The phase-coupling network shown in Fig.…”