Self-cleaning microwave convection oven

A combination microwave and convection heating system comprising:

• an enclosure supplied with microwave energy;
• a vapor outlet region in the rear of said enclosure comprising a plurality of apertures whose maximum dimensions are substantially less than a half wavelength of said microwave energy;
• a blower system positioned outside said enclosure and adjacent said vapor outlet region;
• an elongated gas ribbon burner having a plurality of substantially parallel ribbons defining rows of ports, said burner being positioned outside said enclosure beneath said outlet region, said burner having a fuel-air mixture drawn therethrough by said blower system for providing a flow of combustion products past said outlet region to said blower system for circulating said combustion products through said enclosure;
• and
• said burner comprising means for restricting the height of the combustion region above said burner to retard ionization of vapor in said vapor outlet region, said restricting means comprising a longitudinal secondary air source dividing said burner into two substantially parallel sections.