FR2520160A1 - Homogeneous thermal treatment of materials by microwaves - transmitted by pairs of aerials penetrating the waveguides - Google Patents

Abstract

Appts. for the thermal treatment of material by microwaves consists of an ultra-high frequency generator delivering its energy to the inside of a rectangular metal wave guide with a short-circuit plate at each end. One or more pairs of adjustable aerials traverse one face of the guide to transmit the energy from the interior of the guide in the direction of the material to be irradiated. The electromagnetic energy profile radiated from the guide can be tailored to the dielectric properties of the material being treated and its distribution within the treatment chamber. The treatment field is homogeneous. Energy transfer to the material is good because of the electric field parallel to the largest dimension of the material. There are not dangerous interactions between the emissions of different guides.

Description

 The invention relates to a device for heat treatment of materials using microwaves.

 It is known that the industrial, scientific and medical implementation of microwave frequencies generally combines three subsets: a microwave generator, a waveguide and an applicator that encloses the material to be treated.

 The wave generator generally consists of a klystron or a magnetron that delivers its electromagnetic energy inside a metal waveguide of generally rectangular section, the wave is then guided to the applicator generally consisting of a metal enclosure or cavity, in which is found the material that is to be heated: the electromagnetic energy of the waves is transformed into thermal energy when the material enclosed in the applicator has the required dielectric properties and that the electromagnetic waves are correctly coupled to the material.

 Many applications are known that use guided waves at frequencies greater than 200 megahertz. Such applications often use waveguides opening directly into the metal cavity. Other systems use radiating slot waveguides; in this case, the generally rectangular section waveguide is characterized by slots on at least one of its faces; these slots allow the electromagnetic waves to radiate in the applicator. More elaborate systems may use radiating antennas arranged on one or more faces of the waveguide.

 Known systems have many disadvantages. The electromagnetic field is generally of a very poor homogeneity in the various points of the applicator; the heat treatment of the material then becomes random, since it preferably heats up at the points where the electromagnetic energy density is the most important.

Other defects of the known systems are the existence of standing waves inside the waveguides and dangerous interactions between the radiated waves emanating from several guides.

 The present invention aims to eliminate these disadvantages commonly encountered. The advantages which result from the implementation of the invention can be enumerated thus - Possibility of adjusting the profile of the electromagnetic energy radiated outside a waveguide according to the dielectric characteristics of the materials to be treated and according to the distribution of said materials inside the cavity.

- Regularity and hosogenity of the electromagnetic field in the material to be treated.

- Good transfer of electromagnetic energy to the material through the incident electric field parallel to the largest dimension of said material.

- Absence of dangerous interactions between the transmitter guides, whether the cavity is very damped or when it is almost empty.

 The invention also aims to enable the realization of siwples devices, economic and modular for the treatment of materials regardless of their thickness in static or parade.

 The device according to the invention is characterized in that it comprises alone or in combination - one or more microwave generators delivering energy in one or more waveguides of preferentially rectangular cross section, generally arranged in the same plane end to end and / or side by side.

Each waveguide being terminated at each of its two ends by a short circuit board. Advantageously, each waveguide is supplied at its center or at one of its ends by a single generator.

- One or more pairs of waveguide antennas, electrically isolated from it, drawing the microwave energy inside the waveguide, to re-emit it towards the product to be irradiated. The shapes of said antennas are characterized by the fact that the distance between two antenna sections of the same pair inside the guide is Ag / 4 (Ag being the length of the guided wave for the operating frequency of the antenna). generator and the dimensional characteristics of the waveguide) and that the distance between two antenna emitter sections of the same pair outside said guide is Ro / 4 (Ro being the length of the wave-in the for an operating characteristic of the generator). According to an important characteristic of the invention, the emitting sections of the antennas are parallel to the face of the waveguide traversed by said antennas, according to a complementary characteristic, these emitter sections are parallel. between them and have a length equal to Ro / 2 or a multiple.

A support plane of the products or materials to be irradiated substantially parallel to the plane formed by the waveguides and parallel to the emitting parts of the antennas, characterized in that this support plane does not absorb or reflect the microwave frequencies and that its distance is adjustable relative to the plane formed by the waveguides and the emitting part of the pairs' antennas.

A metal plane parallel to the plane of the waveguides but disposed on the other side of the support plane, characterized in that the distances between this metal plane and the support plane on the one hand, between the metal plane and the
plane waveguides on the other hand, can be adjustable independently
from each other.

There are various embodiments of the invention allowing
to respect a distance Ag / 4 inside the waveguide between two years
of the same pair, as well as the distance Ro / 4 between the emitting sections of the same antennas external to the guide and parallel to each other
1 / The two antennas forming a pair cross a face of the guide along two points located on the median axis xy equidistant from the two faces ad
The two antennas are perpendicular to the face in question and have a very slight curvature either inside the
guide, from the outside so as to respect the distances Ag and Bo for
the two inner and outer sections perpendicular to the face of the guide along the xy axis. The two antennas are then inclined parallel to the
considered face of the guide and preferably oriented on either side of the axis xy and perpendicular to said axis.

20 / The distance Δg inside the waveguide can be made artificially equal to the distance ho by interposing in the guide between these pairs of antennas or between the antennas of the same pair or in combination a ma
material having adequate dielectric characteristics. In this case the antennas can then have an L shape, one branch of which is perpendicular to the face of the guide along the xy axis. The other branch is then parallel to the guide at a distance r E thereof, in an orientation perpendicular to the xy axis.

30 / In a third possible embodiment of the invention, the antennas are also L-shaped. The branch of the L forming the transmitting part is always parallel to the face of the guide from which the receiving part is derived, but the Transmitting parts are preferably oriented parallel and symmetrically with respect to the xy axis, the distance between these emitting parts being Po / 4. The dimension between two sections of the waveguide at the point of passage of the antenna through the relevant waveguide face is Gag / 4.

40 / In a fourth possible embodiment of the invention, it is possible to use the magnetic coupling between the receiving part of the antennas and the guided waves. The outer portion of the antenna pair guide will then preferably have the shape of a T, while the inner portion of the guide will have a loop shape. The distance between centers of the loops will be Agit4 and that between the upper and parallel parts of said T will be Po / 4.

 A complementary feature of the invention is the diposition of the generator relative to the antenna pairs allowing a uniform radiation of the guided energy at each antenna. According to the desired mode of application of the invention, the generator may be arranged in the middle of the waveguide if the number of antenna pairs is an even number or at one end of the waveguide, regardless of the number of pairs of antennas. To ensure this uniform radiation the length r1 of the antenna section internal guide will vary from one antenna to another depending on the arrangement of this antenna relative to the generator. The dimension rI is determined according to the desired coupling with respect to the wave propagated in the guide.

 Other objects, advantages and provisions of the invention will appear more clearly on reading the description of various embodiments of the invention which follows, this description being made in a nonlimiting manner with reference to the drawings below. appended in which - Figure 1 illustrates the perspective view of a waveguide supporting two pairs of antennas according to a first embodiment of the invention.

FIG. 2 illustrates a view of the antennas of FIG. 1 along an Al-Al section of the waveguide.

- Figure 3 illustrates a view of the antennas of Figure 1 according to a section Bj-Bl of the waveguide.

FIG. 4 illustrates the perspective view of a waveguide supporting two pairs of antennas according to a second particular embodiment of the invention.

- Figure 5 illustrates a view of the antennas of Figure 4 in a section Bs-Bs of the waveguide.

FIG. 6 illustrates the perspective view of a waveguide supporting two pairs of antennas according to a third particular embodiment of the invention.

- Figure 7 illustrates a view of the antennas of Figure 6 in a section 4 -A6 of the waveguide.

FIG. 8 illustrates the perspective view of a waveguide supporting two pairs of antennas according to a fourth particular embodiment of the invention. FIG. 9 illustrates the perspective view of a waveguide supporting two pairs of antennas according to a particular fifth embodiment of the invention.

FIG. 10 illustrates the perspective view of a waveguide supporting two pairs of antennas according to a sixth particular embodiment of the invention.

FIG. 11 illustrates the view of an antenna of FIG. 10 in a sectional view
C- C of the waveguide.

FIGS. 12 and 13 illustrate very schematically the complete longitudinal sections of two waveguides, each powered by a generator according to two particular embodiments of the invention.

FIG. 14 very schematically illustrates a particular mode of application of the invention for the irradiation of materials at microwave parade according to a view, in longitudinal section, of several waveguides (sections according to FIG.
EE of Figure 15).

FIG. 15 very schematically illustrates the same embodiment of the invention as FIG. 14 in a side sectional view of a plurality of waveguides (section along D-D of FIG. 14).

FIG. 16 illustrates a particular embodiment of the invention that is particularly advantageous for treating bulk products.

 Antennas 1, 2, 3, 4, of Figure 1 are coupled in pairs (1,2) and (3,4). The internal rectilinear sections I of these antennas shown in FIGS. 2 and 3 are perpendicular to the largest internal width face b of the metal waveguide: 6 of internal section a x b. For the 2450 MHz frequency, it is known that the standardized a and b scores are respectively 43 mu and 86 mu. An insulating washer 5 makes it possible to electrically isolate each antenna from the waveguide. The outer part of the antennas is characterized by the sections E (shown in FIG. 2). These emitting sections E are parallel to the face of the guide from which the antennas emerge and are oriented perpendicularly to the median axis xy of said face; according to Figure 1 these sections E are oriented alternately to the left (antennas 1 and 3) and to the right (antennas 2 and 4) of the xy axis. The curvatures practiced on the sections C make it possible to bring the emitting sections of the same pair of antennas together, as indicated in FIG. 3, these curvatures are practiced outside the waveguide. These antennas can be made of any good electrically conductive metal in the form of a wire diameter of about 2 or 3 mm and can be deformed cold to practice such curvatures.

 The internal distance tI between the inner sections I of the same pair of antennas, for example the antennas 3 and 4 in FIG. 3, has been determined experimentally satisfactorily when tI Xg / 4 and that QE distance between the emitter sections E is equal to Ao / 4 while the length t of the emitter section E is Po / 2. Similarly, it has been possible to determine experimentally the distance r E of FIG. 2 (distance between the emitter section E and the face of the guide) as satisfactory when r E is substantially equal to Po / 4. In the foregoing length of the guided wave according to the frequency of the generator and according to the dimension b of the waveguide.

 = 341On the wave in the air according to the same frequency of the generator.

In the particular case of a frequency of 2450 MHz and a dimension b = 86 me we will have respectively Ag = 172 mm and Bo = 124 mm so t 3 43 mm = 31 mm t = 62 mm r ~ 31 mm
Such an arrangement of the antenna pairs makes it possible, on the one hand, to nullify the existence of standing waves inside the guide and, on the other hand, an excellent coupling between the guided waves and the antennas while keeping at these antennas a very small apparent surface.

Furthermore, the maximum coupling between the antennas and the space to be irradiated is achieved by means of the reflector formed by the face of the guide parallel to the emitting part, further propagation is normal to this face of the guide. To obtain a uniform radiated field, the coupling of each antenna is variable according to the rank of this antenna with respect to the generator. We can define the coupling of the antenna number "n" as
n N-n + l
n = sequence number of the antenna with respect to the generator
N = total number of antennas on one side of the generator
The coupling "C" of each antenna with respect to the guided wave at the latter is a function of the rI dimension. The r1 dimension is the length of each rectilinear section I internal to the waveguide and perpendicular to the face. crossing the guide (Figures 2 and 3).

 The function between coupling "C" and rI is complex. Although this function is calculable by known formulas, each application will be the subject of an empirical adjustment of this dimension rI by sliding according to any known mechanical process of the antennas in the insulating washers 5.

 Thus, the adjustment of each dimension rI allows either an identical energy density radiation at each antenna or an adaptation of the energy density profile according to the dielectric and / or geometric characteristics of the product to be treated.

By way of illustration, the value of the rI values set experimentally in the case of a waveguide on which 11 pairs of antennas made according to FIG. 1 have been adapted will be indicated below. In this case, the values densities of the radiated energy represent differences of less than 20 X in resonance and large surge between the maxima and
a minima according to points located on / line parallel to the guide at a distance of 250 ws thereof.The frequency of the generator being 2450 MHz for a standard waveguide.

<tb> N <SEP> of <SEP> the <SEP> antenna <SEP> pair <SEP> 1 <SEP> 2 <SEP> 3 <SEP> 4 <SEP> 5 <SEP> 6 <SEP> 7 <SEP> 8 <SEP> 9 <SEP> 10 <SEP> 11
<tb> by <SEP> report <SEP> at <SEP> generator
<tb> Quote <SEP> rI <SEP> in <SEP> mu <SEP> for <SEP>
<tb> 1st <SEP> antenna <SEP> of <SEP> the <SEP> pair <SEP> 12.5 <SEP> 13 <SEP> 13.5 <SEP> 14 <SEP> 14.5 <SEP> 15 <SEP> 16 <SEP> 17 <SEP> 18 <SEP> 19 <SEP> 22.5
<tb> by <SEP> report <SEP> at <SEP> generator
<tb> Rating <SEP> rI <SEP> mu <SEP> for <SEP><SEP> 13 <SEP> 14 <SEP> 14.5 <SEP><SEP> 15 <SEP> 16, <SEP> 18 <SEP><SEP> 19, <SEP> 21 <SEP> 22 <SEP> 40
<tb> 2nd <SEP> antenna <SEP> of <SEP> the <SEP> pair
<Tb>

 The embodiment according to FIGS. 4 and 5 has the same characteristics as the embodiment according to FIGS. 1, 2 and 3. The only difference is the position of the curvatures making it possible to respect the dimensions t E = Ao / 4 and t = Ag / 4 between the antennas 7 and 8 and between the antennas 9 and 10. As shown in Figure 5, these curvatures are performed in this case inside the waveguide. The dimensions t, r E and rI remain identical to the previous embodiment.

 The embodiment of the invention according to FIGS. 6, 7 and 8 uses the known physical principle-that the length of the propagated wave varies as a function of the dielectric characteristics of the material in which this wave propagates.

So for a material located inside the waveguide Àgm =
Agm = length of the guided wave inside the material 'P dielectric characteristic of the material
To simplify the embodiment of the invention, it may be advantageous to make the physical distances equal between the antenna sections internal to the guide and between the outer sections for two antennas of the same pair.

à 2450 MHZ pour un Ac
Dans la mise en oeuvre pratique de l'invention on choisit un matériau ayant une constante diélectrique un peu plus élevée que la valeur théorique ' définie ci-dessus et on adapte les formes géométriques dudit matériau.If the guide was filled with a dielectric material this simplification would be realized when #gm = A0 is when

at 2450 MHZ for an Ac
In the practical implementation of the invention, a material having a dielectric constant a little higher than the theoretical value defined above is chosen and the geometrical shapes of said material are adapted.

According to FIGS. 6 and 7, the distances t between the antennas (10 and 11) and between the antennas (12 and 13) are identified both inside and outside the guide, this distance is: # = # 0 . The antennas 10, 11, 12, 13
4 have the shape of the letter L. Parts 14, 15, 16, 17 of cylindrical shapes of heights equal to a, of suitable diameter, respectively surround the antenna sections 10, 11, 12, 13 internal to the guide 18, while electrically isolating these antennas from the guide.

 According to FIG. 8, a piece 19-of rectangular section exa is disposed inside the guide 20 by means of a slit of width e made along the guide in the middle of one of the large sides thereof. other of the median axis xy.

 As previously antennas 21, 22, 23, 24 have the shape of the letter L. They slide inside the room 19, which isolates them from the guide 20 through holes t = ΔT practiced in this room 19 perpendicular to the slotted face of the guide. The thickness e of the piece 19 is empirically adapted.

 Obviously in the embodiments according to FIGS. 6, 7 and 8, the dimensions rg, rI and t remain identical to the previous embodiments.

 The embodiment according to Figure 9 also uses antennas 24, 25, 26, 27 having the shape of the letter L, grouped in pairs (24,25) and (26,27), isolated from the metal guide 28 by parts insulators 29, 30, 31, 32.

The particularity of this embodiment of the invention is the orientation of the emitting parts of the antennas in a direction parallel to the x, y axis. The two antennas (24,25) or (26,27) of the same pair are oriented in the opposite direction.

 The distance t = gag / 4 is given by the distance between two lateral sections of the guide at the points where the antennas 24 and 25 pass through the face B.

The distance tE is determined by the distance between the two transmitting parts of the antennas. The dimensions t, d, and rI remain those indicated in the foregoing.

The embodiment illustrated in FIGS. 10 and 11 shows a possibility of magnetic coupling between the guided wave and the antennas. In this case the antennas 30, 31, 32, 33 grouped in pairs (30,31) and (32,33) preferentially pass through a small internal dimension face a of the waveguide along the median axis zz '. This setting of the coupling of the loops in the guide is obtained by directing these loops more or less in the field, this by rotation of the workpiece 35. The washer 5 is an insulating material. When this loop is positioned, the transmitting parts are oriented parallel to each other.
on rotation / the outer vertex of the loop. These parts. The metal part 35 is then fixed by welding or screwing on the waveguide 29. The height r E remains equal to Po / 4. The distance between 2 antennas is 0/4; the distance Ag / 4. is much less critical than in the case of the electrical coupling, and to bring this dimension closer, the dissymmetry of the loop is sufficient.

 As illustrated in FIGS. 12 'and 13, each waveguide provided with antenna pairs may form a microwave irradiation unit.

The characteristics of each emitter guide are determined by the desired applications, in particular by the power density required for the treatment envisaged near the sample or inside it.

 An elementary irradiator shown in Figure 12 comprises a generator 37, a waveguide 38 shown in longitudinal section. Each end of the waveguide is terminated by short-circuit metal plates 39 and 40. Microwave generator 37 delivers its energy inside the waveguide via its transmitting antenna -A The distance from the antenna A to the short-circuit plate 39 enables the reflection of the waves by this short-circuit board, and an optimum transmission of the energy to the antennas 41, 42, 43, 44, 45, 46 , n -1, n, grouped in pairs (41,42), (43,44), (45,46), (nl, n). Said pairs of antennas are in any of the embodiments described above, the adaptation of the internal rI rating allows each antenna to draw an equal amount of energy within the guide whatever the rank of this The energy density along a line parallel to the waveguide at any distance from it can be very homogeneous, the application of this form of irradiator is particularly advantageous for the treatment of thick products constant. When the product to be treated is not of constant thickness, it is possible to adapt the dimensions rI by simple adjustments to obtain the desired distribution of the energy density in the space.

 An elementary irradiator according to FIG. 13 comprises a generator 47 whose transmitting antenna 48 is situated equidistant from the short circuit plates 49 and 50. The waveguide 51 supports an even number of antenna pairs. Half of these pairs of antennas are located to the right of the generator, the other half to the left, by symmetry. The homogeneity of the radiated electromagnetic field is as previously ensured by the adaptation of the rI dimensions.

The rI dimension of the inner section of an antenna to the left of the generator is the same as that of the symmetrical antenna to the right of the generator.

The antennas 52, 53, 54, 55 grouped in pairs (52,53) and (54,55) respectively have dimensions r1 of rI 52 rI 53 r1 54 tu.55 respectively equal to the dimensions r1 56 rI 57> r1 58 rI 59 antennas 56, 57, 58, 59 grouped in pairs (56,57) and (58,59).

 The advantage of the elementary irradiations according to FIGS. 12 and 13, apart from the possibility of controlling the distribution of the radiated energy, is to allow flexible and very modular implementations, making it possible to solve many problems posed by industrial applications. and scientists of microwaves.

 Thus, modules according to FIG. 12 may be placed end to end, that is to say the short-circuit plate 39 against the short circuit board 40 of the following module. Similarly, these modules can be placed side by side in the same plane, but provided that the antennas of a guide are staggered with respect to the next guide, which will lead to an improvement in the homogeneous distribution of the density. of energy if that's the goal. The number of elementary modules will determine the total power of the irradiator, the proximity of these modules will determine the average energy density of the level of the surface of the material to be treated.

 Figures 14 and 15 illustrate a particular embodiment of modular irradiators for the treatment of material parade.

 FIG. 14 is a sectional view of the irradiating assembly in longitudinal section of the radiating waveguides arranged end to end (section E-E of FIG. 15). Fig. 15 is a cross-sectional view of the irradiating assembly in a lateral section of the irradiating waveguides arranged side by side (D-D section of Fig. 14).

 the irradiating waveguides 38 and 51 of FIG. 14 are identical to those shown in FIGS. 12 and 13. They are terminated by the short-circuit plates 39, 40 and 49, 50. The guides 51 are identical to the guides 61, 62 , 63, 64 shown in cross sections in Figure 15. The set of waveguides is supported by a metal plane 60 which emerge the antenna pairs 67, 68, 69, 70, 71, 72, 73 .. As previously described, the transmitting portions of these pairs of antennas are parallel to the plane 60. The length of the guides 38, 51 as well as the distances between each line of guides 61, 62, 63, 64, will determine the total power of the installation as well as the energy density at the material to be treated 65 disposed on a support plane 66.This support plane 66 is made of a non-metallic material that does not absorb microwaves.

 In order to obtain an optimum coupling between the waves emitted by the emitting parts of the antenna pairs 67, 68, 69, 70, 71, 72, 73, etc., and the product to be treated 65, the distance n between the plane 60 and the support plane 66 is mechanically adjustable, the plane 60 of the waveguides is naturally parallel to the support plane 66. A metal reflecting surface 74 is, on the other hand, positioned parallel to the plane 66 but on the other side thereof relative to in the plane 60. The distance in between the planes 74 and 66 is also adjustable mechanically. The adjustment of the distances m and n makes it possible to obtain on one hand the resonance, on the other hand the optimum coupling between the waves and the material 65.

 According to a particular embodiment of the invention, the support plane 66 may be a part of a treadmill or conveyor belt whose entry inside the applicator will be at 75 and the exit at 76. The inputs and outputs 75 and 76 are provided with known protection devices which prevent the propagation of electromagnetic waves to the outside of the applicator. The applicator is in a closed metal box formed by the metal plates 74, 60, 77, 78, 79, 80, 81, 82.Thus, thanks to the orientation of the emitting part of the antenna pairs according to a parallel direction to the largest dimension of the material to be treated 65 and thanks to the optimization of the coupling between the waves and the material by the plates 60 and 74, it is possible to treat with an excellent yield in the same applicator very different products in their dimension, in their dielectric constant to the atmosphere and temperature, in their mass, etc.

 FIG. 16 illustrates a particular mode of application of the invention that is advantageously adapted to the treatment of products presenting themselves as enmasse.

The product to be treated 83 is supported for example by a circular plate 84 in mechanical rotation about the axis 85. The applicator is constituted by a metal box formed by the plates 86, 87 and the plans 88 and 89 on which are arranged the waveguides. The sample is introduced into the cavity through the door 90. The radiating waveguides 91 and 92 are of the type shown respectively in FIGS. 12 and 13. Such a configuration makes it possible to treat bulk products with a relatively wide distribution. homogeneous energy density.

Claims (12)

 1 - Microwave irradiation device formed by a microwave generator delivering its energy inside a rectangular waveguide terminated at each end by a short-circuit plate, a face of the guide being crossed one or more pairs of electrically isolated antennas thereof, characterized in that  the distance inside the guide between the internal sections of two antennas forming a pair is Gag / 4.  the distance outside the guide between the emitting sections of two antennas forming a pair is Tao / 4.  - the antenna transmitting sections located outside. of the guide are parallel to each other and parallel to the face of the guide whose antennas emerge at a distance substantially equal to axis / 4 of said face.  the lengths of the emitter sections of the antennas are X02 (or a multiple of this length).  Àg: is the length of the guided wave for the operating frequency of the generator and for the geometrical shape of the waveguide.  Ao: is the length of the wave in the air for the same operating frequency of the generator.  2 - irradiating waveguide according to claim 1 characterized in that. that the antennas emerge from the waveguide at points located on the median axis xy of the considered face of the guide, the distances Tao / 4 between the emitting sections and Gag / 4 between the internal sections of two antennas forming a pair obtained by a curvature made either inside the guide or outside near the point of isolation, the inner sections being rectilinear, the emitting sections being oriented in a direction perpendicular to xy but alternately in opposite directions.  3 - irradiating wave uptake according to claim 1 characterized in that the geometric distances between the inner antenna sections of the guide and the outer sections of antennas forming a pair are identical thanks to a material of adequate dielectric characteristics and shapes defined geometries interposed in the guide between the inner sections of antennas so as to modify the length of the guided wave and to make it equal to Ao, the internal antenna sections being rectilinear.  4 - irradiating waveguide according to claim 1 characterized in that the antennas have the shape of the letter L, a branch of the L forming, the emitting part, a part of the other branch forming the inner part of the guide, the internal distances Gag / 4 and the external distances Ao / 4 being determined by the mean paths of the waves  the points of passage of the antennas through the face of the guide are  located at distances of Ao / 8 on both sides of the xy axis.  the distance between two sections of the guide in two planes perpendicular to xy at the two points of passage of the antennas of the same tap is Gag / 4 of the emitting parts are oriented parallel to xy but alternately in the opposite direction.  5 - irradiating waveguide according to claim 1 characterized in that the antenna sections located inside the guide have a loop shape and the outer sections the shape of the letter T, the upper part of the T forming the transmitter section oriented perpendicular to the edges of the guide.  6 - Irradiating waveguide according to any one of the preceding claims, characterized in that the geometric dimensions or the orientations of the antenna sections internal to the waveguide are variable from one antenna to another in proportion to the energy flow. the electromagnetic level of the antenna considered so that the energy drawn inside the guide is identical for each antenna or possibly that the profile of the energy emitted outside the guide is adapted to the distribution of the densityd energy sought according to the physical characteristics of the product to be treated.  7 - Microwave irradiation device composed of irradiating waveguides according to any preceding claim characterized in that the irradiating waveguides can be placed end to end or face to face to form a plane of irradiation of dimensions and adjustable powers.  8 - Microwave material processing device according to claim 7 characterized in that the materials to be treated are arranged on a microwave-insensitive support plane substantially parallel to the irradiation plane and parallel to a reflective metal plane disposed of the other side of the support plane with respect to the irradiation plane, the irradiation plane and said metal plane constituting a metal cavity closed around the product to be treated.  9 - Microwave material processing device according to claim 8 characterized in that the distances between the support plane and the irradiation plane on the one hand, and between the support plane and the reflector plane on the other hand are adjustable independently of one another.  10 - Devices for processing microwave parcel materials according to claims 8 and 9 characterized in that the support plane of the material is a part of a conveyor belt which passes through the metal cavity.  11 - Microwave irradiation device according to any one of claims 1 to 7 characterized in that the irradiating waveguides can 8tre-arranged in different planes according to the physical characteristics of the material to be treated especially when it is present in a mass form.  12 - Any product having during its manufacturing phase underwent microwave treatment for heating, polymerization, dehydration, physical change of state using a device according to any one of the preceding claims.