Abstract A resonant cavity in the form of a right circular cylinder is excited in the TM010 mode by a source of microwave energy to generate an electric field with lines extending generally parallel to the axis of the cylindrical sidewall of the cavity. A pair of aligned slots are formed at diametrically opposite locations in the cavity sidewall for passing the web through the applicator in a plane which passes through the axis of the sidewall. The intensity of the electric field within the applicator increases in a radial direction of the cavity from a minimum at the sidewall to a maximum along the axis. Thus, the electric field, at its greatest intensity, extends parallel to the plane of the web for maximum coupling of energy to the web. Air is circulated through the applicator for carrying away moisture and for cooling the sidewalls of the cavity. An adjustable stub, mounted for radial movement in the cavity, tunes the resonant frequency of the cavity to match the frequency of the source.
A system for applying heat to a web or to articles supported by a web comprising: a source of microwave energy, a resonant cavity having a cylindrical conductive sidewall and an axial length less than one-half wavelength of the resonant frequency thereof to suppress the TE11 mode, excitation means receiving microwave energy from said source to excite said cavity in substantially the TM010 mode, said cavity further including means for admitting transportation of said web transverse of the axis of said sidewall wherein the surface of said web extends substantially parallel to the electric field lines within said cavity.
Claim 2
Independent Claim
99 words
A system for applying heat to a web or to articles supported by a web comprising: a source of microwave energy, a resonant cavity having a cylindrical conductive sidewall and an axial length less than one-half wavelength of the resonant frequency thereof to suppress the TE11 mode, excitation means receiving microwave energy from said source to excite said cavity in substantially the TM010 mode, said cavity further including means for admitting transportation of said web transverse of the axis of said sidewall wherein the surface of said web extends substantially parallel to the electric field lines within said cavity.
Claim 3
Dependent Claim
46 words
The system of claim 1 further comprising conduit means for coupling a source of pressurized air into Said cavity means to circulate air therethrough, whereby moist air is purged from the interior of said cavity and the sidewalls of said cavity are maintained in equilibrium temperature.
Claim 4
Dependent Claim
51 words
The system of claim 1 further comprising adjustable screw means threadedly received in the sidewall of said cavity and extending into the interior thereof to a predetermined length for varying the resonant frequency of said cavity to tune said resonant frequency of said cavity to the operating frequency of said source.
Claim 5
Dependent Claim
39 words
The system of claim 3 further comprising probe means extending partially within said cavity to couple power therefrom to monitor the power within said cavity and assist in adjusting the resonant frequency thereof to the frequency of said source.
Claim 6
Dependent Claim
48 words
The system of claim 1 wherein said cavity is further bounded by first and second end plates and wherein said means for admitting transportation of said web comprises a continuous slot formed in diametrically opposite locations of said sidewall and extending through one of said transverse end plates.