Microwave heating apparatus

Claim 2

A microwave heating apparatus comprising: a casing formed of electrically conductive metallic material and having an opening therein, a door closing said opening, said door and casing defining an enclosed chamber; a surface wave transmission line positioned within said chamber and dividing said chamber into a heating space for receipt of an object to be heated and a transmission space, said transmission space extending continuously along the entire area of one side of said surface wave transmission line; and a source of microwave power for generating microwaves, at least a portion of the energy from said microwave power source being coupled to said transmission space, said transmission space comprising means for transmitting microwaves to said surface wave transmission line over the entire area of said one side thereof, such that said surface wave transmission line forms a surface wave transmission mode which propagates within said heating space at a wave length less than the free-space operating wave length.

Claim 3

A microwave heating apparatus as claimed in claim 1, wherein said surface wave transmission line comprises an electroconductive plate member having formed therein a plurality of independent high impedance patterns, said high impedance patterns being equally spaced from each other by a distance not more than one-fourth of said free-space operating wave length.

Claim 4

A microwave heating apparatus as claimed in claim 2, wherein each of said impedance patterns is a slot.

Claim 5

A microwave heating apparatus as claimed in claim 1, wherein said surface wave transmission line comprises a dielectric plate member having formed therein a plurality of independent electroconductive patterns, said electroconductive patterns being equally spaced from each other by a distance not more than one-fourth of said free-space operating wave length.

Claim 6

A microwave heating apparatus as claimed in claim 1, wherein said surface wave transmission line comprises a plurality of metallic, electroconductive rods arranged on the same plane and spaced from each other by a distance not more than one-fourth of said free-space operating wave length.

Claim 7

A microwave heating apparatus as claimed in claim 1, wherein said transmission space is filled with a dielectric material.

Claim 8

A microwave heating apparatus as claimed in claim 1, wherein said spatial means has metallic electroconductive elements arranged therein for regulating the microwaves so as to propagate in a substantially zig-zag manner in the direction of transmission thereof.

Claim 9

A microwave heating apparatus comprising: a casing formed of electrically conductive metallic material and having an opening therein, a door closing said opening, said door and casing defining an enclosed chamber; a surface wave transmission line positioned within said chamber and dividing said chamber into a heating space for receipt of an object to be heated and a transmission space, said transmission space extending continuously along the entire area of one side of said surface wave transmission line; a source of microwave power for generating microwaves, the energy from said microwave power source being coupled to both said heating space and said transmission space, said transmission space comprising means for transmitting microwaves to said surface wave transmission line over the entire area of said one side thereof, such that said surface wave transmission line forms a surface wave transmission mode which propagates within said heating space at a wave length less than the free-space operating wave length; and means for selectively controlling respective amounts of said energy to said transmission space and said heating space and to thereby control the ratio of energy between said surface wave transmission mode within said heating space and a mode supplied directly into said heating space.

Claim 10

A microwave heating apparatus comprising: a casing formed of electrically conductive metallic material and having an opening therein, a door closing said opening, said door and casing defining an enclosed chamber; a surface wave transmission line positioned within said chamber and dividing said chamber into a heating space for receipt of an object to be heated and a transmission space, said transmission space extending continuously along the entire area of one side of said surface wave transmission line; a source of microwave power for generating microwaves, the energy from said microwave power source being coupled to both said heating space and said transmission space, said transmission space comprising means for transmitting microwaves to said surface wave transmission line over the entire area of said one side thereof, such that said surface wave transmission line forms a surface wave transmission mode which propagates within said heating space at a wave length less than the free-space operating wave length; and means for selectively controlling respective amounts of said energy to said transmission space and said heating space and to thereby control the ratio of energy between said surface wave transmission mode within said heating space and a mode supplied directly into said heating space.

Claim 11

A microwave heating apparatus as claimed in claim 8, wherein said controlling means comprises a pivotally supported electroconductive member.

Claim 12

A microwave heating apparatus as claimed in claim 8, wherein said controlling means comprises a variable impedance element.

Claim 13

A microwave heating apparatus as claimed in claim 10, wherein said variable impedance element is a discharge tube.

Claim 14

A microwave heating apparatus as claimed in claim 8, wherein said surface wave transmission line comprises an electroconductive plate member having a plurality of high impedance patterns which are constituted by at least one group of slots equally spaced from each other a distance not more than one-fourth of the free-spacing operating wave length of the microwaves and communicated to each other by at least one slot.