DE2018069A1 - Device for transmitting microwave energy to materials or workpieces - Google Patents

Description

Herne, 8000 Munich 23,

Freillgrathstrasse 19. ., -,., -,. Eisenacher Strasse 17

P.O. Box 140 Dipl.-Ing. RH Bahr Pai.-Anw.Betzier

Pt app. Herrmann-Trentepohl Oinl Phil «FH U ^ rH Rpt 7 IP r Telephone: 39 8011

Telephone: 51013 Uipi.-rnyS. CQUaTd ΡβΙΖΙβΓ 398012

⁵ "°; ^{4 Dipl.-Ing.W.} Herrmann-Trentepohl _{Tl 398013}

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ßahrpatente Herne PATENTANWÄLTE Babetzpat Mönchen

Telex 08 229 853 *} Π1 O Π PQ Telex 05 245 62

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Bayrische Vereinsbanfc Munich 952287 Dresdner Bank AG; Herne 202 436

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Ref .: M 02 201 Lev / Sz

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Gryodry Corporation, San Eamon, California, USA

Device for transmitting microwave energy Materials or work pieces

The invention relates to an apparatus for heating, cooking \ or drying material by microwave energy. In particular, the invention is concerned with a device for heating by means of microwave energy "wherein the applicator in which the material is treated is a waveguide or hollow conductor.

An early development in the field of cooking means Microwave energy or electronic energy consisted in the Construction of a box which formed a cavity of substantially rectangular shape and was designed for heating food. The relative dimensions of

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The wavelength and cavity at a given frequency are such that the cavity is several wavelengths on one side. Food is placed in the cavity, the door is closed and the oven is switched on. The furnace is equipped with mode stirrers and reflectors such that the heat generated in the furnace is generally independent of the position of the heated material. This type of furnace is sometimes referred to ¹¹ oven as "batches, as the material is heated in a mass or in a batch or is cooked} of the furnace must often be parked to the food in the oven to introduce or to take out therefrom. Sometimes these ovens are also referred to as multi-wave type cavities because they are designed to excite many different modes or types of microwave energy within the cavity, and the reflectors and mixers (stirrers) are usually provided to evenly handle the multi-wave type cavities. Distribute microwave energy (multimode).

A continuous type microwave oven has been developed which gives microwave power in an elongated tunnel through a series of slot openings that are longitudinally spaced to the tunnel. These tunnels serve the same purpose Function like the multi-weave type cavities as a number different wave types are excited when the microwave energy enters the tunnel. A continuous one Belt conveys the material to be heated through tunnel j and Energy-absorbing devices (in the form of sinks or traps cooled by circulating liquid) are on each end of the tunnel near the entry and exit openings is provided to prevent excessive escape of radiation to prevent and to prevent abundant microwave energy to absorb such that damage to the microwave system is prevented. The openings for coupling the from the Source-derived microwave energy to the interior of the cavity cause higher losses and lower the Q value

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(i.e. the ratio of stored energy to released energy) of the cavity. These energy losses cannot to be recovered.

Another development used a waveguide or waveguide, which was laid in a serpentine arrangement (sometimes referred to as a meander system) and arranged in such a way that the Product has been fed through aligned slots in a number of such serpentine turns. Energy is in a Pumped to the end of the waveguide} the energy level decreases along the length of the waveguide and eventually ends in a Water load. f

This decrease in performance along the direction of power flow is particularly noticeable for lossy products. - ■■ ■ The size of the power decrease with respect to ζ (this is the direction of power flow through a waveguide) is defined as the attenuation constant a waveguide applicator.

A waveguide or waveguide is understood to mean a hollow tube or a line with an essentially closed cross section in order to allow electromagnetic energy to propagate or to guide in the micro-wave range. As used herein, the term waveguide λ is of a general nature in that it encompasses both the conduit which couples power from the source to the applicator and the applicator itself which forms the "fireplace" or "treatment zone" as he is sometimes called. The direction in which the energy travels is referred to as the "z" direction. A "rectangular waveguide" is a waveguide of substantially rectangular cross-section, although it need not necessarily be a proper rectangle. The lowest mode (ie, TE ^ Q mode) of propagation of microwave energy through a waveguide is characterized by the fact that the electric field lines between two opposite

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the wall surfaces (sometimes also called the "wide walls"), and that these field lines are generally parallel to one another and perpendicular to the flow of microwave energy (or power). The ^W y "coordinate lies in the direction along which these field lines run; and the" x "coordinate lies perpendicular to the y direction and to the power flow. Thus the x and y coordinates are orthogonal to one another and form a plane perpendicular to the power flow through a waveguide.

If the cross section of the waveguide is rectangular, the distance separating the wide walls (ie along the y coordinates) is "b" j and the distance separating the other side walls (that is, the width of the wide walls and along the x coordinates) is the same "a ^M.

TE mode operations refer to transverse electrical Field vectorsj and QM mode types refer to transversal magnetic field vectors.

The TE mode describes the electric field within the waveguide, with (a) no component whatsoever of the electric field in the z-direction is present | (b) there are ^ "m" nodes (minima or maxima) in the electric field strength profile present along the x-direction and (c) there are "n" nodes in the electric field strength profile along the y-rich · * · tion available.

The TE _- .Q mode operating mode in a waveguide thus relates to a state where the electric field vector is perpendicular between the wide walls (in the y direction) and there is essentially no electric field in the z or x direction. It should be pointed out that the above explanations, which have only been given for the purpose of explanation, are "theoretical". Working

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wise or view result. The Freiraiimwellenlange the excitation frequency λ ₀ is the length of one period of the frequency Erregerfre _r, as it would exist if the wave would propagate through free space. The "b" dimension can be kept at a vert less than half the free space wavelength of the excitation frequency to allow the propagation of all TM modes and. to suppress all IE -Mo de art en where η is an integer greater than zero. Furthermore, the "a" dimension can be kept greater than half the free space wavelength and less than a free space wavelength to suppress the TE mode types where m is greater than one.

In the EELq mode, the intensity of the electric field varies along a sine function from a minimum on one side of the treatment zone through a maximum at the transverse center of the broad wall (ie χ * a / 2), and back to a minimum on the opposite side of the Treatment. Zone. For a given input power, the electric field strength is at a maximum at the transverse center of the treatment zone. In the previously described meander system, the treated material is applied through the waveguide. guided a slot which is formed at this center point and is elongated in the direction of the power flow. As will be explained in more detail below, the electric field λ strength at the location of the slot is reduced by increasing one of the dimensions, either '&"or ^ir b". A lower limit of the electric field strength is limited by the TE ".Q ~ mode restrictions at" a ^M and "b".

If the damping constant is very high and if the area of application is, for example, the drying of blackboards with a substantial width in the direction of power flow, then "there will be a great deal more power at the input end of each of the serpentine Laid sections of the applicator discharged or consumed than is consumed at the output end. Under these Under certain circumstances, only one edge of the material would be sufficiently treated

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delt. That is, considering only a pair of on facing wide walls centered slots, which are designed so that they carry out the wall board allow, the slots are elongated in the direction of the power flow (the z-direction) so that the building board is transverse to the z-direction is moved and the power flow from a side Edge of the building board goes to the other. - Because of the high moisture content the building board ensures that it is lossy, a large proportion of power is consumed in the first edge part of the material, which leads to the second edge part. uneven drying occurs. Indeed this one will P undesirable effect somewhat compensated for in a meander system with a number of turns, since the first pass the Current moves in one direction across the material or parallel to it} in the second pass the current moves in the opposite direction. For lossy material however, this compensation is not very effective! and a non-uniform one Heating of this material does occur.

There are many advantages in terms of design and efficiency given when a waveguide is used as a heat applicator over multiple wells en type cavities is used. With a waveguide applicator, in which a traveling wave is excited or excited and a current or power through the applicator flows, the stimulus and propagation modes are in controllable in the sense that a system can be designed in such a way that that only the modes species that are desired will breed. This leads to the possibility of pre-determining the energy consumption in the treated material and an interpretation against that Creation of escape of radiant energy for the operating modes alone.

On the other hand, from the practical point of view, most sources of microwave power are magnetron tubes designed to generate microwave energy over a very narrow frequency band | and although the

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Frequency of the magnetron can vary slightly, its Output power drop noticeably for such frequency changes. There is a complicated correlation between the oscillation frequency of a magnetron and the load | which is fed. So if the load is even slightly varies, the oscillation frequency of a magnetron can be shifted and its output power can be made more remarkable Way vary. Does an applicator have a high Q value? (which is desirable to increase performance) then the load occurring on the magnetron should be kept essentially constant, although the proportion of the treated Ma- I terials can vary considerably. The maintenance a constant load - seen from the magnetron the working of the magnetron within a very narrow frequency band - and thus maintains its service life due to the low reflected power a way of working with a significantly higher degree of efficiency.

Because the transverse width of the wide load is excessive is made big, the profile of the high-performing person will continue spread out and the power density decreases for a fixed · put down input power. Furthermore, the damping constant and the heating rate are reduced, whereby a l more uniform heating of the material along the. Direction of the ™ Power flow is caused. The term "oversize" as used here is intended to mean that the width the wide walls is greater than the free space wave length of the Excitation frequency.

This result is -'obviously beneficial not only for Applications where the material is conveyed through central slots in the wide wall, but also for applications cases where the material between the wide walls along the Sifting through the flow of services and not through them. Furthermore, this is necessary for a batch or stacking pan to

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Relclmng more uniform heating is desirable.

In, use cases where a supported wide screen is desirable is the waveguide coupling line from source to Applicator symmetrical about a plane passing through the center lines the wide walls runs to the excitation of the

Prevent fashion styles where m is an even integer. For these modes, where m is an odd integer, occurs no excessive radiation through a central slot in the wide walls.

P According to this concept is also an alternative embodiment provided, the wide wall is slotted and tapered, increased uniformity in heating rate or magnitude in the direction of power flow to accomplish. This means that the damping rate is increased by 3 °, while the available power decreases by a more uniform one To create a large amount of energy output at all points in the direction of the power flow.

According to the invention, a microwave heating applicator in the form of a rectangular waveguide with dimensions ^M a "and ^w b ^w transversely to the power flow through the waveguide is proposed. The dimension ^M b ^M is therefore kept smaller than half the free wavelength of the excitation frequency A, and the dimension "a" is increased above \ , thereby decreasing the damping constant for the applicator and the heating rate of the material being treated. The microwave power is transmitted through a treatment zone in a first direction; and the electric field strength varies from a minimum to one across the direction of power flow Side of the treatment zone to a maximum in the middle of the zone and back to a minimum on the other side of the treatment zone. These sides of the treatment ^{zone form the dimension w} a "j and the material is passed through the treatment zone either along the direction of the power flow or perpendicular to the

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Direction of the power flow, depending on the area of application. ■

Exemplary embodiments of the invention will now be based on of the accompanying drawings are explained in more detail in which -

Fig. 1 is a perspective view

a meander waveguide system according to the invention;

ig. Figure 2 is a close-up view of a portion of Figure 2

Apparatus according to Fig. 1, with adjacent sections of the applicator are shown

Fig. 3 is a reduced view of a

typical section of the applicator system according to Fig. 1 j

FIGS. 4-4A show the advantages of the invention in FIG

Use with a waveguide applicator, with the material in between the wide walls treated ™; ■

Fig. 5 is © iß. Diagram and shows the ver

Reduction in the damping constant and the heating rate in the direction of the Power flow according to the invention !, and

Figure 6 is a view of an alternative

Embodiment where the wide wall tapers.

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It can be assumed that the theoretical aspects of the present invention will be better understood if the inventive concept is first discussed with regard to particular applications. Before the theoretical aspects of the invention are discussed, the application of the measure according to the invention to a coiled pipe or meander system should be explained. Referring to Figures 1 and 2, microwave input power is received from a source of microwave energy 10 along an input waveguide 10a which is shown to be in a substantially horizontal arrangement 9k . For reasons that will be explained in more detail later, the waveguide input feed system is symmetrical about a plane parallel to the direction of the power flow that passes through the center lines of opposite broad walls.

All of the waveguide elements described here consist of electrically conductive material, for example aluminum. The input waveguide section 10a can assume a taper or conicity in order to enlarge its cross-sectional area defined by the peripheral flange 11. The flange 11 is connected to a respective peripheral flange 12, which is at the input end of a superiors Wellenleiterkrümmerabsehnittes 13 _Ä see, which is a 90 ° elbow.

The wide walls of the waveguide elements shown in FIGS. 1 and 2 extend in an essentially vertical plane j such a wide wall is denoted by 13a for the input bend 13 shown in FIG. For the same bend, the opposing side walls are denoted by 13b and 13c, respectively. The cross-section of each of the illustrated waveguide elements (that is, in a plane perpendicular to the power _{flow when excited in the TE ^ 0} mode) is essentially rectangular in shape.

Power is supplied from the input manifold 13 to a plurality of waveguide applicator sections given, each with 14, 15,

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16 and 17 are designated. Each applicator section provides a "heating chamber" or "treatment zone ^11. It should be understood that any number of such sections can be arranged through which the treated material can be passed. A coupling section 18 connects the bend 13 to the first applicator section 14; and adjacent applicator sections are connected to one another by means of U-shaped coupling elements designated 19, 20 and 21. Power flows in opposite directions in adjacent applicator sections or turns , which can be led to a subsequent applicator 'section or can be used to couple power with one end, which can be provided with a water load in order to absorb and consume or dissipate the entire remaining energy, unless it is already used Heating the treated material v was consumed.

The treated material is denoted by 24 and at this In the form of the application, it is laid out in the form of a flat sheet lossy material, for example as veneer paneling or building board. The sheet material 24 is passed through the waveguide sections 14-17 guided over slots which are centered in each of the broad walls of these applicator sections j | and run in the direction of the power flow. Like from 3Tig. 2 can be seen, is for adjacent applicator sections 15 and 16 · a slot 26 in a first wide wall 27 of the applicator section 15 molded; and the slot 27 is centered on the horizontal center line in the wide wall 27 and runs in the direction of the power flow. A similar slot (hidden in Pig. 2) is in the opposite wide wall 28 of the applicator section 15 is formed. These slots are aligned horizontally to allow the material 24 to pass completely through the Applicator section 15 transversely to the wide walls 27 and 28 to lead. Similarly, there is a slot JO in a wide wall 31 of the applicator sections 16 and a slot 32 in FIG

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opposite wide wall 33 of this section formed.

The material is driven and supported by a plurality of vertically spaced drive rollers. A first pair of owls is shown generally at 35 in S ¹ Ig. 1 and is arranged in front of the entry of the material into the waveguide applicator section 14. Subsequent pairs of drive rollers are provided between adjacent applicator sections, the pair between applicator sections 15 and 16 comprising an upper roller 37 and a lower roller 38, as can be seen in FIG. Means are provided to adjust the spacing of the rollers and the tension with which the pairs of rollers grip the material being processed. ■

Still referring to Fig. 2, the arrangement is the U-shaped Coupling section 20 shown in dashed lines. Reference should now be made in particular to the applicator section 16 will; the width of the wide wall 31 is indicated by the dimension arrow "a" denotes; and the width of the side walls of the applicator section 16 is indicated by the dimensional arrow "b", as here shown, defined.

According to FIG. 3, the applicator section 16 is now in the front view shown} it can be seen that this peripheral side flanges 40 and 41 to connect to, respectively corresponding flanges on the U-shaped connecting elements 20 and 21. For the sake of simple construction and maintenance as well as cleaning the interior of the Applicator section 16 can be cut in left and right halves be provided with the circumferential view around their Central part are provided, which, however, do not cause any interference in the implementation through the elongated slots 30 and 32.

1-3 show an embodiment according to which the in

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the material located vertically through the with Opened wide walls of each applicator section is guided and wherein the cross-sectional area of the waveguide is held substantially constant; however, the invention is not so limited. However, the invention is special useful for such applications, as detailed below will be discussed, the inventive system includes the installation of elongated slots halfway up the wide walls allows that extend in the direction of the power flow without a substantial radiation through these slots would be done by microwave energy. - ■

According to an alternative embodiment, the treated material can be guided entirely within the wave guide applicator section - in this case the material (if it is a web material) would lie in a plane parallel to the wide walls. According to FIG. 4, the cross section of a rectangular applicator section is shown schematically, the upper and lower wide walls being denoted by 43 and 44 and the opposing side walls being denoted by 45 and 46, respectively. The treated material is denoted by the reference number 47. Again, the transverse width of the wide walls 43 and 44 is indicated by the dimension "a ^M } the transverse width of the side walls 45 and 46 is indicated by the transverse dimension ^w b ^H.

In this embodiment, the material may be along the (i.e. either in or against) the direction of the power flow or it can remain stationary. The same Effects of a more uniform heating amount are achieved.

FIG. 6 is a waveguide section similar to that in FIG. 3 shown where the wide wall with 31 'and the Hittelschlitz is designated with 30 *. It should be noted be that the wide walls of the waveguide according to FIG

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get tapered, and become smaller in width as you move progresses in the direction of the power flow. So takes the Cross-sectional area of the waveguide in the direction in which the power flows, from to be discussed further Establish.

In the slotted waveguide constructions of the type shown in FIGS. 1-3 (that is, the meander or serpentine arrangement) the dimensions ^M a ^w and ^M b ^{w can} be limited so that only the TE ^ Q mode is allowed to propagate. I. E. the dimension "a" (the width of the wide walls) is anywhere between half a \ and a full A ₀ * ^ ⁰ · ^ - & i- ^e dimension

and a full A ₀

^w b ^M is everywhere less than or equal to half a λ _ο · Since the frequencies available for commercial heating by microwaves are limited by government regulations and to a certain extent also by the operating frequencies of the available magnetrons, these limitations in the dimension "a" and ^w b "for a given frequency imposes an upper limit on the size of the waveguide.

The electric field strength for EEU ₀ in a plane transverse to the direction of power flow is a sine function with a value zero on each of the side walls and a maximum value in the center W between the side walls. For example, as shown in FIG. 4, where the dimension ^M b ^{w is} equal to half the free space wavelength of the excitation frequency, the dimension "a" ¹ "(bounded by the vertical dashed lines) forms the upper limit for the transverse width of the The equation for the electric field strength or intensity in the! SLgModeeart is given below as equation (1) The x-direction is the horizontal direction in Fig. 4-, the y-direction is the vertical direction in Figs the z-direction is perpendicular to the plane of the drawing in FIG. 4 (ie in the direction of the power flow).

- E ₀ a {% - £ -) (D-

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The one transmitted by a waveguide of the TE ^^ mode Power is equal to the integral of the scalar product of Poynting's vector and the differential cross-sectional area of the conductor (i.e. a χ b). Theoretically, this results power calculated according to equation (2) ..

■ ■. . , ■ ■ - / ■■■■ -. ■■ - ■ -. ■ _ ■ --.-

where E ₀ equals the electric field strength at χ - a / 2 (ie

the maximum electric field strength), |

X ■ '■' ■: ■ free wavelength (wavelength in free space) ym characteristic impedance of free space.

From equation (2) it follows that for a constant input power (this is the usual case) the maximum electric field strength E_ varies inversely with the transverse area of the waveguide} and for a constant ^w b "dimension and a / X 1 as the maximum elec- tric Λ field strength is greater than about inversely proportional to the square root of the dimension ^M a ^M. In other words, with increasing dimension ⁿ a ^w himmt, the maximum electric "field strength and vice versa.

The power distribution in a plane transverse to the direction of the power flow is proportional to the product E ^ sin (■■). This distribution is schematically represented by 48 in Figure 4A designated curve for the case in which the Ab -. * - measurement "a ¹¹¹ smaller than the free wavelength of the Anregüngsfrequenz is (as in the conventional rectangular waveguides according to the IFFI ^ ^ jModeart are excited or excited).

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The square of the electric field strength in the middle can be re the output power can be normalized according to equation (3).

4- -

Equation (3) can be simplified to E ²

8V

From equation (4) it follows that by increasing the dimension ^M a ⁿ beyond A _Q , the value E _Q becomes smaller and smaller. I. E. the power distribution curve changes from that of representation 48 to that represented by curve 49 in FIG. 4A, while the transverse width of the broad ^{walls changes from dimension w} a lw to dimension ^M a ". Wach FIG. 4 gives the horizontal axis the transverse position along the broad wall (x-direction) and the vertical axis is equal to the power It is seen from Fig. 4A that as the dimension ^w a ^{M increases,} the power on the center line

decreases from Ρ _Λ to the value P ^1,
oo

While the dimension ^w a "is made larger than the free wavelength of the excitation frequency, the square of the normalized electric field strength clearly decreases and also enables propagation of the TE ^ modes, where m is an integer greater than one. These other modes can when they are strongly excited, lead to the appearance of a noticeable radiation from the longitudinal slot according to the embodiment of Fig. 13. It should be noted, however, that the

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Dimension ^M b ^{M is kept} smaller than half the free wavelength of the excitation frequency. As long as the waveguide is also excited symmetrically with respect to a plane parallel to the direction of the power flow, which runs through the longitudinal center line of the broad walls of the applicator sections, the TE modes, where m is an even integer, are not excited. The IE modes, where m is an odd number greater than one, although they can be excited, do not radiate through the longitudinal slot at χ 3 a / 2, since the magnetic 3? Eld in the z-direction, H, at χ «a / 2 * is zero.

So if care is maintained in the excitation of the waveguide with .über- I large at χ - a / 2, the TE _mQ modes, where m is an even integer, will not be excited with a significant amount of energy; the escape of microwave power from the slot is restricted to considerable limits.

The heating rate on the first coil assembly applicator section 14 is reduced compared to the waveguide applicators, where a is less than A ₀ . In addition, however, the change in the heating rate with ζ is also remarkably reduced so that the heating is spread more uniformly while the material is being processed. That is., The heating ä by a hand of the building board to another gleichförmigerj and subsequent sections have a heating rate almost equal to that of the previous section is when the wave guide is of oversize.

This effect of reducing the attenuation constant in the direction of the power flow is considered to be an important advantage of the invention and is illustrated graphically in Fig. 5, where the vertical coordinate is the power density and the horizontal coordinate is the z-direction. Prop. 4 therefore explains the power density distribution in the plane χ <■ a / 2, which extends the length of the power flow direction} which is related to the reference

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The curve denoted by 50 indicates this for a waveguide applicator at a smaller than X. If the dimension "a" rises above the free wavelength of the excitation frequency, the power density distribution curve changes to that indicated by curve 51, from which it can be seen that the initial power density decreases _{from P Q} to P _Q; the attenuation also becomes "more uniform. It should be noted that the attenuation (ie, dP / dz) varies with the first derivative of curves 50 and 5 * 1.

This effect of achieving a more uniform heating rate in the direction of the P power flow is important not only in the serpentine arrangement, where the heating rate for subsequent one of the applicator sections becomes more uniform, but also in that in S ¹ Ig. 4, where the material being treated is conveyed parallel to and between the wide walls. By making the heating rate more uniform in the z-direction, extreme temperatures at the point where the material is introduced into the applicator are avoided. The advantage of having a longitudinal slot which extends in the direction of expansion of the wide wall and is centered around the line χ »a / 2 is also important in applications where a liquid, e.g. B. Fett or Feuchtigfe speed is supplied while the material is being heated. The associated application of the same day (internal file number U 02 202) describes a waveguide applicator for baking or cooking ham, the teachings according to the invention being used to advantage.

Those skilled in the art will understand that the present invention described herein Principles also used in combination with elements of the waveguide applicator system in the above-mentioned application such as the facilities for circulating air through the waveguide, the water load, with which the waveguide ends further in the direction of flow of the power from the applicator sections, or the blocking film

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tern designed in such a way that it can supply energy to the Entry or exit of the material for the designated in Fig. 4 Reject embodiment.

Finally, it can be seen from equation (4) that the normalized electric field strength can be increased in the direction in which the power flows by keeping ^M b "as a constant and by decreasing the width" a "of the wide wall by a taper as shown in Figure 6. This taper increases the field strength at the slot even if the overall power decreases due to attenuation.

Changes and modifications are within the scope of the invention.

Claims;

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Claims (18)

Claims 1. I device for transmitting microwave energy to materials or workpieces, characterized by a microwave _{energy source (10) of wavelength A 0} »waveguide applicator devices (13-17) with transverse dimensions" a "and" b "in a plane perpendicular to the continuous power flow, Where ^w b "is less than about half of λ and" a " λ ^ is; and by means (10a; 11; 12) for Coupling of this source (10) to the applicator devices (13-17) for their excitation. 2. Apparatus according to claim 1, characterized in that this dimension ^M a ^M defines the transverse width of a pair of opposing wide walls (4) in the power flow direction and that at least one of these wide walls defines a slot which is centered around its transverse center
i'st and runs in the direction of the power flow. 3. Apparatus according to claim 1, characterized in that this dimension "a" forms the transverse width of a pair of opposing wide walls which run in the direction of the power flow, each of the wide walls forming a slot which is centered approximately around its transverse center and extends in the direction of the power flow and
further includes facilities that pass the material through them
Move slots across the direction of power flow. 4. Apparatus according to claim 3 »characterized in that the applicator device is designed as a plurality of turns (14-17), each opening or loop representing an applicator section and all of these wide walls
Slits (30; 26 · ..) define ₉ which are roughly centered on the transverse width and in the direction of the power flow
with all of these slots aligned to allow the passage of material therethrough. - 21 - 009885/1410 5. The device according to claim 1, characterized in that the waveguide applicator device is defined by a first pair of opposing wide walls which extend in the direction of the power flow and have a transverse dimension equal to "a", and that a second pair of opposing side walls in the direction of Power flow extends and has a transverse dimension equal to ^M b ⁿ and that this material or workpiece (24-) is arranged between these broad walls over an extensive area. 6. Device for the transfer of "heat to web material, characterized by a source (10) for ¹ generation of microwave energy; waveguide devices that are excited by the source mainly in the TE, * _O -mode and thereby power along of the waveguide device, the waveguide device having a rectangular cross-section which forms a pair of opposed broad walls which are separated by a distance of less than about half the wavelength of the excitation frequency; and by a pair of opposed side walls at a distance greater than the free wavelength , along the center line thereof extend this excitation frequency, wherein the opposing Breitwandungen form a pair of slots in the direction of% Leist Ting flow to the inclusion of this material, and carrying through this material means (57 »38) for its movement through this pair of slots transversely to the river of the Leistu ng through this wave guide device in such a way that the damping constant is reduced by this material in the direction of the power flow. 7. Apparatus according to claim 6, characterized in that the wave guide means a plurality of separate applicator sections forms, with the power flowing in opposite directions in adjacent sections and corresponding ones Wide walls run parallel to one another, the ■ - ■ P? Ö09885 / U10 Walls of each applicator section form a pair of slots that extend along the centerline of the Walls extending in sighting of the power flow, with all of the slots for receiving this material aligned with one another are. 8. Apparatus according to claim 7? characterized by a coupling waveguide device (10a) which receives power from the source (10) and couples it to the waveguide device, the waveguide device being symmetrical about a plane parallel to the direction of the power flow and through w the centers of this pair of slots runs to a stimulus of IE_ ■
is an integer. to prevent excitation of the IE fashions, with m a straight 9 · Device according to claim 7 »characterized in that the transverse width of each pair of opposing broad walls is progressively reduced to taper form, while the separation between these broad walls is less than half a free wavelength of the excitation frequency is held, the taper being symmetrical about a plane parallel to the direction of the power flow and through the Center lines of this pair of slots runs. 10. Microwave heating device, characterized by the combination of a waveguide of rectangular cross-section, the one in the EELß fashion style stimulated and with a couple facing each other Wide walls with a width transversely to the direction of the power flow greater than the free wavelength the excitation frequency is provided and a workpiece or material in this waveguide between the broad walls for consuming or dissipating microwave energy here in. 11. The device according to claim 10, characterized in that the opposite broad walls have parallel sides 009885/1410 --i - these wave guide devices separated by a distance smaller than about half the free wavelength of this excitation frequency "form. 12. A method for heating a material, characterized in that an electric microwave field with a free Wavelength of a certain dimension is generated; this microwave field so crowded in a treatment zone is that essentially the entire electric field vector lines lie in one plane and the intensity of this field Side in this level from a minimum of a first / this zone through a maximum at a central point in this zone and then, to a minimum at a second side of this zone varies; that the power of this field is one-way is transmitted perpendicular to this plane; - that this microwave field to this material in a treatment zone the heating of which is transferred while maintaining the distance between these first and second minimum points, which the sides of the treatment zone are greater than the free wavelength of the microwave field at least over a portion form this treatment zone. 13 · Method according to claim 12, characterized in that the dimensions of this treatment zone transverse to the alignment of the power flow and transversely to the direction of the field lines smaller than half of the free wavelength of these Excitation frequency is maintained. 14-. Method of heating a material, characterized in that that in a first direction through a treatment zone microwave energy is transmitted by an electrical Field-supplied, which at a certain Frequency is excited and whose field lines run essentially in a plane perpendicular to this first direction, wherein the intensity of this field in this plane of one Minimum on a first side of this treatment zone 009885/1410 a maximum at an intermediate point in this treatment zone and then varied to that minimum as a second side of that treatment zone; that this material through this treatment zone moved in a direction perpendicular to that first direction and through the maximum field level intensity is in such a way that the microwave power through this material is transverse to the direction of movement of this material through it Treatment zone is transferred; and that the distance between the first and second sides of this treatment area which this field strength is greater at this minimum than the free wavelength of this excitation frequency over at least part of this treatment zone is held. 15 · "Method according to claim 14, characterized in that this material is essentially planar and that these field lines are essentially parallel to one another in this treatment zone run and that when this material moves through this treatment zone in one direction is guided parallel to these field lines and to the direction of the transmission of microwave power. 16. The method according to claim 14, characterized in that the distance between the first and second sides of this treatment zone converges in the direction of the power flow. 17. The method according to claim 14, characterized in that these field lines transverse to the direction of their course within less than half of the free wavelength of the excitation frequency are squeezed together in this treatment zone. 18. A method for heating a material or workpiece, characterized in that microwave power by a the first treatment zone is transmitted in a first direction, this power or energy is generated by an electric field which is excited at a certain frequency and whose field lines are essentially parallel to each other and 009885 / U10 -25- run within a plane perpendicular to this first direction en, the strength of this field in this plane along a line transverse to these field lines from a minimum a first side of this treatment zone by a maximum an intermediate point in this treatment zone and then to a minimum on a second side of this treatment zone varies; and that this material passes through this treatment zone is moved along this first direction and these first and second sides of this treatment zone at a distance greater than the free wavelength of this excitation frequency are kept over at least a part of this treatment zone. 19- The method according to claim 18, characterized in that the field along the direction of these field lines to less than half a wavelength of the excitation frequency is limited. 009885/1410 Blank page