An apparatus (20) for microwave vacuum-drying organic materials such as foods and bioactives has a plurality of microwave generators (50) actuated so as to cause interference between their respective microwave streams and evenly distribute the microwave energy across the vacuum chamber (34). The microwave-transparent window (36) in the chamber is arranged so the organic material to be dried is moved across it on a conveyor belt (60) and the microwave energy passing into the chamber (34) immediately encounters the organic materials, thus attenuating the energy and reducing arcing.
