Energy seal for high frequency energy apparatus

Abstract

A high frequency oven having a door sealed to the oven by a seal which prevents the escape of high frequency energy between the door and the oven by acting as a choke to energy attempting to pass across the seal in which excitation of energy modes in a band of frequencies including the desired operating frequency range of the oven is controlled peripherally along the seal. An energy absorbing gasket surrounds the seal to absorb any energy passing outwardly from the energy seal. The questions raised in reexamination request No. 90/000,945, filed Jan. 29, 1986, have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e).

We claim: .[. 
     
       1.  Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency;   said enclosure comprising at least a wall member having an access opening and a closure member for said access opening; and   an energy seal comprising at least portions of said wall and closure members to define an elongated energy mode supporting structure;   said mode supporting structure comprising means for substantially inhibiting the propagation of energy at said frequency in one direction and substantially providing for propagation of said energy in a different direction..]. .[.2. The apparatus according to claim 1 wherein said propagating inhibiting and provision means comprise structural variations to provide points of maximum and adjacent points of minimum variation in the energy propagating characteristics along at least a portion of said   
     
     
        mode supporting structure..]. .[.3.  The apparatus according to claim 2 wherein the distance between points of maximum variation and adjacent points of minimum variation are less than one effective electrical wavelength of said frequency of energy within said enclosure..]. .[.4. The apparatus according to claim 2 wherein at least some of said structural 
     
     
        variations are periodic..]. 5. .[.The apparatus according to claim 2 wherein at least some of said structural variations are aperiodic.]. .Iadd.Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency and a plurality of modes;   said enclosure comprising at least a wall member having an access opening and a door for said access opening;   an energy seal comprising at least portions of said wall and door to define an elongated energy mode supporting structure;   said mode supporting structure comprising means for directing substantially all energy propagation entering said seal in a first direction outwardly across said mode supporting structure and means for substantially inhibiting the propagation of said energy at said frequency in directions perpendicular and oblique to said first direction; and   said propagation inhibiting and directing means comprising aperiodic structural variations along at least a portion of said mode supporting   
     
     
        structure.Iaddend.. .[.6.  The apparatus according to claim 2 wherein said structural variations are produced by means comprising slots..]. .[.7. The apparatus according to claim 2 wherein said structural have a major dimension extending normal to the direction of energy propagating along 
     
     
        said structure..]. 8. .[.The heating apparatus according to claim 6 wherein.]. .Iadd.Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency;   said enclosure comprising at least a wall member having an access opening and door for said access opening;   an energy seal comprising at least portions of said wall and door to define an elongated energy mode supporting structure;   said mode supporting structure comprising means for directing substantially all energy propagation entering said seal in a first direction outwardly across said mode supporting structure and means for substantially inhibiting the propagation of energy at said frequency in directions perpendicular and oblique to said first direction;   said propagation inhibiting and directing means comprising structural variations along at least a portion of said mode supporting structure;   said structural variations being produced by means comprising slots; and .Iaddend.   at least some of said slots have a different length. .[.9. The apparatus according to claim 2 wherein one of said energy seal wall members is movable..]. .[.10. The apparatus according to claim 1 and means coupled to said mode supporting structure for dissipating energy transmitted therethrough..]. .[.11. Heating apparatus comprising:   an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency;   means for producing a plurality of energy modes within said enclosure in a cyclically varying manner;   said enclosure comprising at least a wall member having an access opening and a closure member for said access opening; and   an energy seal comprising at least portions of said wall and closure members to define an elongated energy mode supporting structure;   said mode supporting structure comprising means for substantially inhibiting the propagation of energy at said frequency in one direction and substantially providing for propagation of said energy in a different   
     
     
        direction..]. .[.12.  The apparatus according to claim 11 wherein said propagation inhibiting and provision means comprise structural variations to provide points of maximum and adjacent points of minimum variation in the energy propagation characteristics along at least a portion of said mode supporting structure..]. .[.13. The apparatus according to claim 12 wherein the distance between points of maximum variation and adjacent points of minimum variation are less than one effective electrical wavelength of said frequency within said enclosure..]. .[.14. The apparatus according to claim 11 wherein at least some of said structural variations are periodic..]. .[.15. The apparatus according to claim 11 wherein at least some of said structural variations are aperiodic..]. 
     
     
        .[.  .  The apparatus according to claim 11 wherein said structural variations are produced by means comprising slots..]. .[.17. The apparatus according to claim 11 wherein said structural variations have a major dimension extending normal to the direction of energy propagating along said mode supporting structure..]. .[.18. The apparatus according to claim 16 wherein at least some of said slots have a different length..]. .[.19. The apparatus according to claim 11 wherein one of said energy seal wall members is movable..]. .[.20. The apparatus according to claim 11 and means coupled to said mode supporting structure for dissipating energy transmitted therethrough..]. .[.21. In combination: a cavity;   means for supplying said cavity with electromagnetic wave energy in a frequency range where the dimensions of said cavity are substantially greater than a free space wavelength at said frequency;   access means to said cavity comprising a door for closing an opening in a wall of said cavity; and   means for providing an energy seal between said door and said cavity wall comprising an elongated energy mode supporting structure;   said mode supporting structure comprising means for substantially inhibiting the excitation of predetermined modes of electromagnetic energy at said frequency peripherally along said structure and substantially providing for the propagation of predetermined modes of said energy across said structure..]. .[.22. The combination in accordance with claim 2 wherein said excitation inhibiting and provision means comprise structural variations to provide alternately a maximum and a minimum point in the energy propagating characteristics of said structure..]. .[.23. The combination in accordance with claim 22 wherein the distance between points of maximum variation and adjacent points of minimum variation are less than one effective electrical wavelength of said frequency..]. .[.24. The combination in accordance with claim 23 wherein said structure   
     
     
        comprises a dielectric medium..]. .[.25.  The combination in accordance with claim 24 wherein said structure comprises metallic bounding surfaces..]. .[.26. The combination in accordance with claim 25 wherein said bounding surfaces defining said mode supporting structure are separated by said dielectric medium..]. .[.27. The combination in accordance with claim 26 wherein a medium is provided adjacent said opening for dissipating radiated energy escaping across said structure..]. .[.28. Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having a predetermined frequency;   said enclosure having an access opening;   a member for closing said opening; and   elongated energy mode supporting structure comprising a choke disposed adjacent to at least one peripheral wall of said opening;   said mode supporting structure comprising structural variations to yield predetermined maximum and minimum points to control the energy propagating characteristics in predetermined directions within said structure..].   
     
     
        .[.  .  The apparatus according to claim 28 wherein said choke and mode supporting structure are filled with a dielectric medium..]. .[.30. The apparatus according to claim 28 wherein said choke is disposed along at least portions of the peripheral edges of said closure member..]. .[.31. The apparatus according to claim 28 wherein said choke is disposed within at least portions of one peripheral wall of said opening..]. .[.32. The apparatus according to claim 28 wherein at least some of said structural variations are periodic..]. .[.33. The apparatus according to claim 28 wherein at least some of said structural variations are aperiodic..]. .[.34. The apparatus according to claim 28 wherein the distance between points of maximum variation and adjacent points of minimum variation are less than one effective electrical wavelength of said frequency of energy 
     
     
        within said enclosure..]. .[.35.  The apparatus according to claim 28 and means for producing a plurality of modes within said enclosure in a cyclically varying manner..]. .[.36. The apparatus according to claim 28 and means coupled to said mode supporting structure for dissipating energy escaping from said line..]. .[.37. Heating apparatus comprising: a source of microwave energy;   means for concentrating energy from said source in a restricted region of space comprising a wall member having an access opening;   the maximum linear dimension of said space being at least a plurality or free space wavelengths of the predominant frequency band of said energy and the periphery of said access opening being greater than a plurality of free space wavelengths of said energy;   means for substantially preventing the escape of said energy from said region through said opening comprising means for producing substantially standing waves from any portions of said energy which pass through said opening and a plurality of frequency responsive means spaced around at least a major portion of said opening for providing impedance variations to transmission of said energy around the periphery of said opening;   the average spacing between the maxima and/or minima of said impedance variations at said frequency being less than one-half of a free space   
     
     
        wavelength of said frequency..]. .[.38.  The apparatus according to claim 37 wherein said means for preventing the loss of said energy through said opening comprises a member for closing said opening..]. .[.39. The apparatus according to claim 37 and secondary means for preventing the escape of said energy comprising a lossy energy absorbing material disposed adjacent to said opening..]. .[.40. The apparatus according to claim 37 wherein said means for providing impedance variations comprises spaced impedance discontinuities..]. .[.41. the apparatus according to claim 40 wherein said impedance discontinuities comprise spaced slots extending in a direction substantially perpendicular to the periphery of said opening..]. .[.42. The apparatus according to claim 40 wherein said impedance discontinuities comprise spaced slots extending obliquely to the 
     
     
        periphery of said opening..]. .[.43.  The apparatus according to claim 40 wherein said impedance discontinuities extend in a direction perpendicular to the periphery of said opening for a distance substantially equal to a quarter wavelength of said standing waves..]. .[.44. The apparatus according to claim 37 wherein said means for producing said standing waves comprises a substantially short circuit electrically spaced from said wall member by a distance substantially equal to one or more half wavelengths of said standing waves..]. .[.45. The apparatus according to claim 38 wherein said means for providing said standing waves comprises a mode supporting structure made up at least in part of portions of said wall member and portions of said closure member..]. .[.46. The apparatus according to claim 45 wherein said impedance variations extend around at least a major portion of at least one peripheral wall of said mode supporting structure..]. .[.47. The apparatus according to claim 45 wherein said mode supporting structure comprises an input section communicating with said restricted region and having said means for producing said impedance variations and a section outside said input section for reflecting an impedance which is substantially less than the average characteristic impedance of said input section..]. .[.48. The apparatus according to claim 37 wherein said wall member is a portion of a conductive enclosure surrounding said region and said means for preventing the escape of said energy through said opening comprises a conductive closure member covering said opening and spaced from said wall member by a dielectric medium forming a mode supporting structure having at least an input section and a choke section and said means for providing impedance variations comprise a plurality of impedance discontinuities in the input section of said mode supporting structure spaced along a major portion of the periphery of said opening with the average of said spacing being less 
     
     
        than one-half of a free space wavelength of said frequency..]. 49. .[.The apparatus according to claim 48.]. .Iadd.Heating apparatus comprising: a source of microwave energy;   means for concentrating energy from said source in a restricted region of space comprising a wall member having an access opening;   the maximum linear dimension of said space being at least a plurality of free space wavelengths of the predominant frequency band of said energy and the periphery of said access opening being greater than a plurality of free space wavelengths of said energy;   means for substantially preventing the escape of said energy from said region through said opening comprising means for producing substantially standing waves from any portions of said energy which pass through said opening and a plurality of frequency responsive means spaced around at least a major portion of said opening for providing impedance variations to transmission of said energy around the periphery of said opening;   the average spacing between the maxima and/or minima of said impedance variations at said frequency being less than one-half of a free space wavelength of said frequency;   said wall member being a portion of a conductive enclosure surrounding said region and said means for preventing the escape of said energy through said opening comprises a conductive closure member covering said opening and spaced from said wall member by a dielectric medium forming a mode supporting structure having at least an input section and a choke section and said means for providing impedance variations comprising a plurality of impedance discontinuities in the input section of said mode supporting structure spaced along a major portion of the periphery of said opening with the average of said spacing being less than one-half of a free space wavelength of said frequency; and, .Iaddend.   wherein said input and choke sections are separated by a common wall and said spaced impedance discontinuities are disposed in said common wall. .[.50. The apparatus according to claim 48 and secondary means for preventing the escape of said energy comprising a lossy energy absorbing material coupled to the output portion of said mode supporting structure..]. .[.51. Heating apparatus comprising:   an enclosure;   means for energizing said enclosure with energy having a predetermined frequency;   said enclosure comprising a wall member having an access opening and a closure member for said access opening; and   an energy seal comprising at least portions of said wall and closure members spaced from one another by a dielectric medium;   said energy seal further comprising a plurality of spaced slots extending in a direction substantially perpendicular to the periphery of said opening and defining therebetween conductive elements;   the average spacing between said slots being less than one-half of a free   
     
     
        space wavelength of said frequency..]. .[.52.  The apparatus according to claim 51 wherein said spaced slots are disposed along at least portions of the peripheral edges of said closure member..]. .[.53. The apparatus according to claim 51 wherein said spaced slots are disposed along at least portions of one peripheral wall of said opening..]. .[.54. Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having a predetermined frequency;   said enclosure comprising a wall member having an access opening and a closure member for said opening; and   an energy seal comprising an input section and a choke section made up of at least portions of said wall and closure members spaced from one another by a dielectric medium;   said energy seal further comprising a plurality of spaced slots extending in a direction substantially perpendicular to the periphery of said opening and defining therebetween conductive elements;   said elements all having one end interconnected and the other ends terminating in a dielectric medium;   the average spacing between said slots being less than one-half a free   
     
     
        space wavelength of said frequency..]. 55. .[.The apparatus according to claim 54.]. .Iadd.Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having a predetermined frequency;   said enclosure comprising a wall member having an access opening and a closure member for said opening;   an energy seal comprising an input section and a choke section made up of at least portions of said wall and closure members spaced from one another by a dielectric medium;   said energy seal further comprising a plurality of spaced slots extending in a direction substantially perpendicular to the periphery of said opening and defining therebetween conductive elements;   said elements all having one end interconnected and the other ends terminating in a dielectric medium;   the average spacing between said slots being less than one-half of a free space wavelength of said frequency; and .Iaddend.   wherein said input and choke sections are separated by a common wall and   
     
     
        said spaced slots are disposed in said common wall. 56. The apparatus according to claim .[.54.]. .Iadd.55 .Iaddend.wherein said choke section is disposed along at least portions of one peripheral wall of said 
     
     
        opening. 57. The apparatus according to claim .[.54.]. .Iadd.55 .Iaddend.wherein said choke section is disposed along at least portions of one peripheral wall of said closure member. .Iadd.58. Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having a frequency in a predominant frequency band;   the sum of the linear dimensions of said enclosure being at least a plurality of free space wavelengths of said frequency;   an access aperture in a wall of said enclosure;   a door for closing said access aperture;   a microwave energy seal having conductive portions of said wall and said door forming an elongated energy mode supporting structure comprising a reentrant choke structure having a common wall with an input transmission line structure, said common wall being substantially less than a quarter wavelength in thickness at said predetermined frequency; and   said common wall containing slots which inhibit the propagation of said energy in directions in said seal perpendicular and oblique to an outward direction and direct the propagation of said energy from the interior of said enclosure in said outward direction to said reentrant choke structure substantially only through said input transmission line structure.   
     
     
        .Iaddend. .Iadd.59.  Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency and a plurality of modes;   said enclosure comprising at least a wall member having an access opening and a door for said access opening; and   an energy seal comprising at least portions of said wall and door to define an elongated energy mode supporting structure;   said mode supporting structure comprising means for directing substantially all energy propagation entering said seal in a first direction outwardly across said mode supporting structure and means for substantially inhibiting the propagation of energy at said frequency in directions perpendicular and oblique to said first direction;   said propagation inhibiting and directing means comprising slots in said mode supporting structure, said slots being arrayed in said perpendicular direction and extending in said first direction. .Iaddend. .Iadd.60. Heating apparatus comprising:   an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency and a plurality of modes;   said enclosure comprising at least a wall member having an access opening and a door for said access opening;   an energy seal comprising at least portions of said wall and door to define an elongated energy mode supporting structure;   said mode supporting structure comprising means for directing substantially all energy propagation entering said seal in a first direction outwardly across said mode supporting structure and means for substantially inhibiting the propagation of said energy at said frequency in directions perpendicular and oblique to said first direction; and   said structural variations are produced by means comprising spaced slots extending obliquely to said perpendicular direction. .Iaddend. .Iadd.61. A microwave oven comprising:   a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying microwave energy predominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the linear dimensions of said enclosure being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of a wall of said conductive enclosure and said door;   said seal comprising an input transmission line section disposed between the interior of said enclosure and a choke section with means comprising slots in a conductive wall of said input transmission line section for directing substantially all of said energy propagation in a single direction outwardly toward said choke section which reflects said energy back through said input section into said enclosure and for inhibiting the propagation of energy in said frequency band in directions perpendicular and oblique to said single direction; and   means for providing that all energy entering said seal enters through said input transmission line section. .Iaddend. .Iadd.62. A microwave oven comprising:   a conductive enclosure supplied with microwave energy predominantly in a predetermined band;   said enclosure having an access aperture whose linear dimensions are substantially greater than the free space wavelength of said energy;   a door for closing said access aperture;   means for cyclically varying the mode pattern within said enclosure;   a microwave seal comprising conductive portions of said enclosure and said door;   said seal comprising an input transmission line section interconnecting the interior of said enclosure and a choke section; and   means comprising slots in a conductive wall of said choke section for restricting propagation in said choke section to a TEM-like mode.   
     
     
        .Iaddend. .Iadd.63.  A microwave oven comprising: a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying said enclosure with microwave energy predominantly in a predetermined frequency band;   means for cyclically varying the mode pattern within said enclosure;   the linear dimensions of said enclosure being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of a wall of said conductive enclosure and said door; and   said seal comprising an input transmission line section coupling the interior of said enclosure with a choke section with means comprising slots in a conductive wall of said input transmission line section for directing substantially all of said energy propagation in a single direction outwardly toward said choke section which reflects said energy back through said input section into said enclosure and for inhibiting the propagation of energy in said frequency band in directions perpendicular and oblique to said direction, the input transmission line section comprising portions of said wall and said door which form parallel elongated planar structures and which limit energy propagation to said choke section to the space between said planar structures. .Iaddend. .Iadd.64. A microwave oven comprising:   a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying microwave energy perdominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the sum of the linear dimensions of said enclosure and said aperture being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of a wall of said conductive enclosure and said door extending around the periphery of said access aperture;   said seal comprising an input transmission line section coupled between the interior of said enclosure and a choke section;   means for providing that all energy entering said seal enters through said input transmission line section; and   means comprising a slotted common wall of said input transmission line section and said choke section for coupling to said choke section substantially all of said energy in said input transmission line section directed generally orthogonally to the periphery of said access aperture while inhibiting the propagation of said energy in the peripheral and   
     
     
        oblique directions of said access aperture. .Iaddend. .Iadd.65.  A microwave oven comprising: a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying said enclosure with microwave energy predominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the linear dimensions of said enclosure being substantially greater than the free space wavelength of said energy;   a microwave seal including portions of a wall of said conductive enclosure and said door;   said seal comprising an input transmission line section disposed between the interior of said enclosure and a choke section with means comprising slots in a conductive wall of said input transmission line section for substantially restricting energy propagation in the input transmission line section to a TEM-like mode directed toward said choke section whereby said energy propagation is blocked by said choke section; and   means for providing that all energy entering said seal enters through said input transmission line section. .Iaddend. .Iadd.66. Heating apparatus comprising:   an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency and a plurality of modes;   said enclosure comprising at least a wall member having an access opening and a door for said access opening; and   an energy seal comprising at least portions of said wall and door to define an elongated energy mode supporting structure;   said mode supporting structure comprising means for directing substantially all energy propagation entering said energy seal in a first direction outwardly across said mode supporting structure and for substantially inhibiting the propagation of said energy at said frequency in directions perpendicular and oblique to said first direction. .Iaddend. .Iadd.67. The apparatus according to claim 66 wherein said propagation directing and inhibiting means comprises structural variations to provide points of maximum and adjacent points of minimum variation in the energy propagating characteristics along at least a portion of said mode supporting   
     
     
        structure. .Iaddend. .Iadd.68.  The apparatus according to claim 67 wherein the distance between points of maximum variation and adjacent points of minimum variation are less than one effective electrical wavelength of said frequency of energy within said enclosure. .Iaddend. .Iadd.69. The apparatus according to claim 67 wherein at least some of said structural variations are periodic. .Iaddend. .Iadd.70. The apparatus according to claim 67 wherein said structural variations are produced by means comprising slots. .Iaddend. .Iadd.71. The apparatus according to claim 67 wherein said structural variations have a major dimension extending normal to the direction of energy propagating along said structure. .Iaddend. .Iadd.72. The apparatus according to claim 67 wherein one of said energy seal wall members is movable. .Iaddend. .Iadd.73. The apparatus according to claim 66 and means coupled to said mode supporting structure for dissipating energy transmitted therethrough. .Iaddend. .Iadd.74. The apparatus according to claim 66 wherein said plurality of energy modes are produced in a cyclically varying manner. .Iaddend. .Iadd.75. Heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having a predetermined frequency and a plurality of modes;   said enclosure having an access opening;   a door for closing said opening; and   elongated energy mode supporting structure comprising an elongated choke disposed adjacent to at least one peripheral wall of said opening;   said mode supporting structure comprising means for directing substantially all energy propagation outwardly in a first direction to the mouth of said choke and for substantially inhibiting the propagation of energy at said frequency in directions perpendicular and oblique to said first direction, said propagation inhibiting and directing means comprising structural variations arranged in a direction perpendicular to said first direction.   
     
     
        .Iaddend. .Iadd.76.  The apparatus according to claim 75 wherein said choke and mode supporting structure are filled with a dielectric medium. .Iaddend. .Iadd.77. The apparatus according to claim 75 wherein said choke is disposed along at least portions of the peripheral edges of said 
     
     
        closure member. .Iaddend. .Iadd.78.  The apparatus according to claim 75 wherein said choke is disposed within at least portions of one peripheral wall of said opening. .Iaddend. .Iadd.79. The apparatus according to claim 75 wherein at least some of said structural variations are periodic. .Iaddend. .Iadd.80. The apparatus according to claim 75 and means coupled to said mode supporting structure for dissipating energy escaping across said structure. .Iaddend. .Iadd.81. A microwave oven comprising: a conductive enclosure having an access aperture;   a door for closing and opening said access aperture;   means for supplying microwave energy predominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the sum of the linear dimensions of said enclosure being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of a wall of said conductive enclosure and said door;   said seal comprising an input transmission line section coupled between the interior of said enclosure and a choke section; and   means in a wall common to said input transmission line section and said choke section for directing the propagation of substantially all of said energy in said frequency band entering said seal in a single direction across said choke section and for inhibiting the propagation of energy entering said seal in directions perpendicular and oblique to said single   
     
     
        direction. .Iaddend. .Iadd.82.  An oven comprising: an enclosure;   means for energizing said enclosure with energy having a frequency in a predominant frequency band;   the sum of the maximum linear dimensions of said enclosure being at least a plurality of free space wavelengths of said frequency;   an access aperture in a wall of said enclosure;   a door for closing said access aperture and forming a microwave energy seal with said wall at said frequency band around the periphery of said aperture;   said seal comprising an input transmission line section coupled between the interior of said enclosure and a reentrant choke section which provides for the propagation of substantially all of said energy in said frequency band in a direction generally orthogonal to said periphery from the interior of said enclosure substantially only through said transmission line structure to said reentrant choke structure while inhibiting the propagation of waves of said energy in said frequency band in directions perpendicular and oblique to said orthogonal direction. .Iaddend. .Iadd.83. A microwave oven comprising:   a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying microwave energy predominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the sum of the linear dimensions of said enclosure being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of the wall of said conductive enclosure around said aperture and conductive portions of said door; and   said seal comprising an input transmission line section, a choke section and an output transmission line section connected at a common junction;   said common junction being coupled to the interior of said enclosure substantially only through said input transmission line section; and   said seal comprising means in a thin conductive wall common to said input and choke sections for permitting the propagation of waves of said energy entering said seal in an outward direction toward said choke section and for inhibiting the propagation of waves of said energy in said frequency band in directions perpendicular and oblique to said outward direction. .Iaddend. .Iadd.84. A microwave oven comprising:   a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying microwave energy predominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the sum of the linear dimensions of said enclosure and said aperture being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of a wall of said conductive enclosure and said door around the periphery of said access aperture;   said seal comprising an input transmission line section coupled between the interior of said enclosure and a choke section;   means for providing that all energy entering said seal enters through said input transmission line section; and   means comprising an apertured common wall of said input transmission line section and said choke section for coupling to said choke section substantially all of said energy in said input transmission line section directed generally orthogonally to the periphery of said access aperture while inhibiting the propagation of said energy in the peripheral and   
     
     
        oblique directions. .Iaddend. .Iadd.85.  Microwave heating apparatus comprising: an enclosure;   means for energizing said enclosure with energy having a frequency in a predominant frequency band;   an access aperture in a wall of said enclosure;   the sum of the linear dimensions of said enclosure and said aperture being at least a plurality of free space wavelengths at said frequency;   a door for closing said access aperture;   a microwave energy seal between said wall and door comprising adjacent conductive portions of said wall and closure members;   said seal comprising a choke section and an input transmission line section having a thin conductive wall which is common to both sections and which contains means for providing for the coupling of energy entering said seal from the interior of said enclosure in an outward direction toward said choke section through said input transmission line structure while inhibiting the propagation of said energy in directions perpendicular and oblique to said outward direction, said adjacent conductive portions forming parallel elongated planar structures with means limiting access to said choke section to the space between said planar structures. .Iaddend.   
     
     
        .Iadd.86.  A microwave oven comprising: a conductive enclosure supplied with microwave energy predominantly in a predetermined band;   said enclosure having an access aperture whose linear dimensions are substantially greater than the free space wavelength of said energy;   a door for closing said access aperture;   means for cyclically varying the mode pattern within said enclosure;   a microwave seal comprising conductive portions of said enclosure and said door;   said seal comprising an input transmission line section interconnecting the interior of said enclosure and a choke section; and   means in a conductive wall of said choke section for restricting propagation in said choke section to a TEM-like mode and thereby inhibiting the propagation of other modes having propagation components around the periphery of said access aperture. .Iaddend. .Iadd.87. A microwave oven comprising:   a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying microwave energy predominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the linear dimensions of said enclosure being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of a wall of said conductive enclosure and said door;   said seal comprising an input transmission line section disposed between the interior of said enclosure and a choke section with means in a conductive wall of said input transmission line section for substantially restricting said energy propagation to a TEM-like mode directed toward said choke section whereby said energy propagation is blocked by said choke section; and   means for providing that all energy entering said seal enters through said input transmission line section. .Iaddend. .Iadd.88. Heating apparatus comprising:   an enclosure;   means for energizing said enclosure with energy having a frequency in a predominant frequency band;   the sum of the linear dimensions of said enclosure being at least a plurality of free space wavelengths of said frequency;   an access aperture in a wall of said enclosure;   a door for closing said access aperture;   a microwave energy seal having conductive portions of said wall and said door forming an elongated energy mode supporting structure comprising a reentrant choke structure having a common wall with an input transmission line structure, said common wall being substantially less than a quarter wavelength in thickness at said predetermined frequency; and   said common wall containing slots oriented in an outward-pointing direction and spaced from each other in a direction perpendicular to the outward-pointing direction. .Iaddend. .Iadd.89. Heating apparatus comprising:   an enclosure;   means for energizing said enclosure with energy having at least a predetermined frequency and a plurality of modes;   said enclosure comprising at least a wall member having an access opening and a door for said access opening;   an energy seal comprising at least portions of said wall and door to define an elongated energy mode supporting structure; and   said mode supporting structure comprising slots in at least one of said wall and said door, the slots being arrayed in a peripheral direction around the access opening and extending in the outward-pointing direction, the extent of the slots in the direction perpendicular to both the peripheral direction and the outward-pointing direction being substantially less than a quarter wavelength at said predetermined   
     
     
        frequency. .Iaddend. .Iadd.90.  A microwave oven comprising: a conductive enclosure supplied with microwave energy predominantly in a predetermined band;   said enclosure having an access aperture whose linear dimensions are substantially greater than the free space wavelength of said energy;   a door for closing said access aperture;   means for cyclically varying the mode pattern within said enclosure;   a microwave seal comprising conductive portions of said enclosure and said door;   said seal comprising an input transmission line section interconnecting the interior of said enclosure and a choke section at least in part bounded by a conductive wall, said conductive wall being substantially less than a quarter wavelength in thickness at said predetermined frequency; and   a plurality of slots in said conductive wall of said choke section, the slots being arrayed in a peripheral direction around the access opening and extending in the outward-pointing direction. .Iaddend. .Iadd.91. A microwave oven comprising:   a conductive enclosure having an access aperture;   a door for closing said access aperture;   means for supplying with microwave energy predominantly in a predetermined band to said enclosure;   means for cyclically varying the mode pattern within said enclosure;   the linear dimensions of said enclosure being substantially greater than the free space wavelength of said energy;   a microwave seal comprising portions of a wall of said conductive enclosure and said door; and   said seal comprising an input transmission line section disposed between the interior of said enclosure and a choke section, with a plurality of slots in a conductive wall of said input transmission line section, said conductive wall being substantially less than a quarter wavelength in thickness at said predetermined frequency, and the slots being arrayed in a peripheral direction around the access opening and extending in the outward-pointing direction. .Iaddend. .Iadd.92. Heating apparatus comprising:   an enclosure;   means for energizing said enclosure with energy having a frequency in a predominant frequency band;   the sum of the linear dimensions of said enclosure being at least a plurality of free space wavelengths of said frequency;   an access aperture in a wall of said enclosure;   a door for closing said access aperture;   a microwave energy seal having conductive portions of said wall and said door forming an elongated energy mode supporting structure comprising an input transmission line structure and a reentrant choke structure, the input transmission line structure and the choke structure sharing a conductive wall in common, said conductive wall being substantially less than a quarter wavelength in thickness at said predetermined frequency; and   said common wall containing a plurality of slots arrayed in spaced apart relationship in the peripheral direction around the access opening and extending in the outward-pointing direction. .Iaddend.