Microwave oven door seal

Claim 1

In a microwave oven comprising a source of microwave energy having a predetermined frequency and wavelength, an enclosure having located therein a cooking cavity for receiving items to be heated by the microwave energy, the cooking cavity having an access opening, a door for opening and closing the access opening, the door and enclosure defining therebetween a door gap, a door seal arrangement for inhibiting the leakage of microwave energy through the door gap, said door seal arrangement comprising: one of the door and the enclosure defining an electrically conductive planar surface generally parallel to the plane of the door in its closed position; the other of the door and enclosure having an electrically conductive channel member defining a recessed channel, said planar surface and said channel member each extending in juxtaposition with each other with the door in its closed position about the periphery of the access opening; microwave pervious electrical insulation means interposed between said channel member and said planar surface, said insulation means and said channel member cooperating with said planar surface to define a first transmission path for microwave energy propagating through the door gap; a transmission member disposed within said recessed channel and extending along the length thereof, said transmission member and said channel member establishing a second transmission path for microwave energy propagating through the door gap, said second path intersecting said first path at an inner intersection relatively near the cavity and at an outer intersection relatively remote from the cavity; said first and second paths being configured proximate said inner intersection to split therebetween energy propagating through the door gap from the cavity and to recombine energy propagating along said second path with energy propagating along said first path proximate said outer intersection, the effective electrical length between said inner and outer intersections measured along said second path differing from the distance between said intersections measured along said first path such that proximate said outer intersection, energy from one of said paths differs in phase relative to that from the other path by approximately a half wavelength whereby upon recombination, energy from one of said paths substantially cancels energy from the other one of said paths, effectively inhibiting energy leakage beyond the door gap.