Embodiments of the zero-resonance microwave oven are described herein that include a cooking cavity, an opening that allows access to the cavity, one or more microwave-transparent walls surrounding the cavity, a microwave-opaque housing also surrounding the cavity, and a reservoir disposed between the microwave-transparent walls and the microwave-opaque housing. The reservoir is filled with a dielectric material, and has a depth greater than or equal to half the penetration depth of microwaves in the dielectric material and less than or equal to twice the penetration depth of microwaves in the dielectric material. Other embodiments of the zero-resonance microwave oven are also described herein.