Microwave dielectric resonator tuning with balanced loop-varactor circuit

The authors report a novel electronic tuning method for a shielded dielectric resonator (DR) operating in its dominant mode. The use of a balanced loop structure permits a wider tuning range while maintaining high unloaded Q₀. A tuning range of 3 MHz at the centre frequency of 950 MHz with unloaded Q in excess of 9000 have been obtained. A simple analytical expression is also derived for determining the tuning range of such a structure.