Variable frequency microwave heating apparatus

A variable frequency microwave heating apparatus for processing selected materials, said variable frequency microwave heating apparatus including a microwave furnace which defines a multi-mode cavity for processing said selected materials, and said variable frequency microwave heating apparatus comprising:

• a microwave signal generator for generating a signal with a selected waveform, frequency, and amplitude;
• a first signal amplifier for amplifying said signal generated by said signal generator, said first signal amplifier producing microwaves in a sweeping fashion through a selected useful bandwidth defining a center frequency, said microwaves having an associated power with a selected magnitude, said first signal amplifier comprising a microwave electron device wherein said useful bandwidth is at least five percent of said center frequency, whereby a plurality of independent microwave modes is established in said multi-mode cavity such that a substantially uniform time-averaged power density is created over a working volume of said multi-mode cavity;
• a power supply for supplying power to said first signal amplifier;
• and
• a transmitter for conveying said microwaves produced by said first signal amplifier into said microwave furnace.