Near-field microwave heating system and method

A microwave heating system comprising:

• a variable-frequency microwave source having a usable bandwidth of at least ±1% about a center frequency;
• a waveguide capable of transmitting microwave energy in a traveling wave mode with an input side connected to said source and an output side terminating in a launch structure;
• and, a metallic reflector plate facing said launch structure, parallel thereto and spaced therefrom at a distance of no more than twice the microwave wavelength over the operative frequency range of said source, said reflector plate including a recessed area of a selected size and shape located facing said launch structure so that a material to be heated is placed between said launch structure and said recessed area for exposure to said microwave energy, wherein said selected size and shape of said recessed area is smaller in at least one dimension than said microwave wavelength.