Access tunnel and attenuator for microwave ovens

Claim 2

In a microwave system for the treatment of materials by the application of microwave electromagnetic fields, a microwave oven, means forming at least one access port to said oven including, an access tunnel and attenuator for use therewith comprising means forming a plurality of conductive walls constructed and arranged to couple to said port and to provide an access tunnel thereto, means for forming a directional coupler for transferring microwave energy from the interior of said tunnel to the exterior thereof, said coupler means being distributed throughout at least said one wall of said tunnel, a microwave absorber positioned outside of said conductive tunnel walls to receive microwave energy from said coupler.

Claim 3

A system as in claim 1 in which said microwave absorber includes means forming a plurality of channels, tubes for carrying a dielectric coolant therethrough, portions of said channels being formed of a lossy dielectric material having a dielectric constant intermediate that of said lossy liquid and free space, said lossy dielectric material portions of said coil being arranged immediately Adjacent that side of said directional coupler on the outside of said conductive walls.

Claim 4

A system as in claim 2, in which said channels are spaced one-quarter wavelength apart.

Claim 5

A system as in claim 2, in which the portion of said channel adjacent said directional coupler includes a tubing made of dielectric material having high loss at microwave frequencies.

Claim 6

A system as in claim 4, wherein said lossy material is a silicon rubber loaded with carbon particles.

Claim 7

A system as in claim 5, wherein said channel further includes a tubular section made of material transparent to microwaves and surrounding said lossy tubing to support the same.

Claim 8

In a microwave system for the treatment of materials by the application of microwave electromagnetic fields, a microwave oven, means forming access port to said oven including, an access tunnel and attenuator for use therewith comprising means forming a plurality of conductive walls constructed and arranged to couple to said port and to provide an access tunnel thereto, means associated with one of the walls of said tunnel for forming a multi mode directional coupler for transferring microwave energy from the interior of said tunnel to the exterior thereof, said coupler means being formed by a plurality of slots formed in at least one wall of said tunnel, and arranged at an angle of about 45* to axis of said tunnel, a microwave absorber positioned outside of said conductive tunnel walls to receive microwave energy from said coupler.

Claim 9

In a microwave system for the treatment of materials by the application of microwave electromagnetic fields, a microwave oven, means forming access port to said oven including, an access tunnel and attenuator for use therewith comprising means forming a plurality of conductive walls constructed and arranged to couple to said port and to provide an access tunnel thereto, means associated with one of the walls of said tunnel for forming a multi mode directional coupler for transferring microwave energy from the interior of said tunnel to the exterior thereof, said coupler means being formed by a plurality of slots formed in at least one wall of said tunnel, and arranged at an angle of about 45* to axis of said tunnel, a microwave absorber positioned outside of said conductive tunnel walls to receive microwave energy from said coupler.

Claim 10

A microwave system as in claim 7, in which said slots are spaced apart approximately one-quarter wavelength.

Claim 11

In a microwave system for the treatment of materials by application of microwave electromagnetic field, a microwave oven, means forming access port to said oven, and access tunnel and attenuator for use therewith comprising means forming a plurality of conductive walls constructed and arranged to couple to said port and to provide an access tunnel thereto, a conveyor disposed through said tunnel and oven for passing material to be treated through said oven, means associated with one of the walls of said tunnel for forming a multi mode directional coupler for transferring microwave energy from the interior of said tunnel to the exterior thereof, said coupler means being located throughout at least said one wall of said tunnel, microwave absorber means positioned outside of said conductive tunnel walls to receive microwave energy from said coupler.

Claim 12

In a microwave system for the treatment of materials by application of microwave electromagnetic field, a microwave oven, means forming access port to said oven, and access tunnel and attenuator for use therewith comprising means forming a plurality of conductive walls constructed and arranged to couple to said port and to provide an access tunnel thereto, a conveyor disposed through said tunnel and oven for passing material to be treated through said oven, means associated with one of the walls of said tunnel for forming a multi mode directional coupler for transferring microwave energy from the interior of said tunnel to the exterior thereof, said coupler means being located throughout at least said one wall of said tunnel, microwave absorber means positioned outside of said conductive tunnel walls to receive microwave energy from said coupler.