Waveguide power divider

Abstract

A waveguide power divider (10) comprising an input waveguide (1) extending along an input propagation axis (a1), and which is coupled via a coupling zone (ZC) to two output waveguides (2, 3) extending respectively, from said coupling zone, along a first output propagation axis (a2) and a second output propagation axis (a3); the three propagation axes forming a propagation plane (PP). The coupling zone contains an electrically conductive divider element (4) extending, along a secondary axis orthogonal to the propagation plane, between two walls parallel to the propagation plane, and which is in contact with both of said walls. The divider element is shaped, when microwave power is injected at the input of the waveguide power divider, to: significantly reduce the reflected power; and control the distribution of microwave power in the two output waveguides.Abstract Figure: Figure 1.

Description

Title of the invention: Waveguide power divider Technical field

[0001] The invention relates to a waveguide power divider, the function of which is to divide an electromagnetic power into two fractions.

[0002] It also relates to a microwave installation comprising said waveguide power divider, as well as to a microwave method implemented by said microwave installation.

[0003] The invention finds a preferred, and non-limiting, application in the division of microwave power into two fractions which are transferred to one or more microwave cavities, with the aim of controlling the distribution of microwave energy, for example in an application of heating a product, generating a plasma, deposition or chemical conversion by microwaves. Prior art

[0004] In known manner, waveguide power dividers are waveguide paths that consist of an input waveguide that gradually deforms into at least two output waveguides. They are generally used in microwave installations by having their input waveguide connected to the output of a microwave generator and their output waveguides opening into at least one microwave cavity. When their output waveguides are connected to a microwave cavity, the waveguide power dividers then serve to divide or split the power delivered by the microwave generator in the internal volume of the microwave cavity.

[0005] In waveguide power dividers, it is observed that not all of the power injected into the input of the input waveguide is fully distributed in the output waveguides. Indeed, part of the power injected into the input of the input waveguide is reflected at the coupling zone between the waveguides and is therefore not transmitted into the output waveguides; in other words, this reflected power returns to the microwave generator.

[0006] In order to minimize the reflected power, one solution consists of adding an impedance matching element such as an iris at the input of the waveguide power divider. However, this impedance matching is dependent on the frequency of the electromagnetic waves, in addition to being dependent on the sizing of the impedance matching element. In fact, the powers delivered at the output of the output waveguides vary according to the frequency of the electromagnetic waves, which is not satisfactory when such a frequency varies during use.

[0007] It is also known that the power introduced into the input waveguide is split into the output waveguides equally or unequally depending on the dimensions of all the waveguides. In the conventional case where the waveguides have the same section, then the power introduced into the input waveguide is distributed equally between the output waveguides.

[0008] In other words, this splitting of the powers is fixed and therefore not adaptive. This inability to modify the splitting of power can prove problematic in application contexts for which it would be necessary to vary the distribution of power at the output of the two output waveguides opening into the cavity; for example, in the case where a microwave cavity would be used to process / heat in a chain and in an automated manner products which pass through it over time along its entire length. Summary of the invention

[0009] In order to address these issues, the invention proposes a waveguide power divider comprising: - an input waveguide extending along an input propagation axis and which has, along said input propagation axis, an opposite input end and an opposite output end; - a first output waveguide and a second output waveguide coupled to the output end of the input waveguide and extending respectively along a first output propagation axis and a second output propagation axis, where the input propagation axis, the first output propagation axis and the second output propagation axis define a propagation plane; wherein the first output waveguide and the second output waveguide extend from a coupling region located in line with the output end of the input waveguide; the waveguide power divider being characterized in that it comprises a divider element which: - is electrically conductive; - is arranged inside the coupling zone; - extends along a secondary axis which is orthogonal to the propagation plane, between two walls parallel to the propagation plane; and - is in contact with the two walls.

[0010] Advantageously, the divider element makes it possible to significantly reduce, or even eliminate, the reflected power rate at the input of the waveguide power divider (in other words, to reduce the reflected power towards the input end of the input waveguide) when an electromagnetic wave penetrates inside this one, this over a wide frequency band included in the microwave frequency range. The reflected power rate is moreover no longer or only slightly dependent on the frequency.

[0011] Another advantage of the divider element is that its mechanical production inside the waveguide power divider is easier compared, for example, to the mechanical production of an iris, being in particular less sensitive to deviations in dimensions.

[0012] According to a characteristic of the invention, the dividing element is adjustable in position inside the coupling zone.

[0013] Advantageously, the adjustment in position of the divider element makes it possible to control and drive the splitting of the microwave power between the two output waveguides of the waveguide power divider. Thus, the operation of the waveguide power divider is not limited to a single configuration of splitting the microwave power between the two output waveguides.

[0014] According to one embodiment of the invention, the dividing element is adjustable in position in a discrete manner in a predefined number of positions.

[0015] In other words, in this embodiment, the waveguide power divider is configurable in several microwave power splitting configurations, the number of which is predefined and corresponds to the number of positions in which the divider element can be adjusted.

[0016] By way of illustration, if it is considered that the microwave power is split between a first fraction of the microwave power transmitted in the first output waveguide, and a second fraction of the microwave power transmitted in the second output waveguide, the waveguide power divider can have three splitting configurations such that the ratios between the two fractions correspond to: - 50 / 50, meaning that the first fraction and the second fraction are both equal to 50%, and the microwave power is equally distributed between the two output waveguides; - 10 / 90, meaning that the first fraction is equal to 10% and the second fraction is equal to 90%, meaning that 10% of the microwave power is transmitted in the first output waveguide, and 90% of the microwave power is transmitted in the second output waveguide; and - 90 / 10, i.e. the symmetrical of the previous distribution, in other words the first fraction is equal to 90% and the second fraction is equal to 10%, meaning that 90% of the microwave power is transmitted in the first output waveguide, and 10% of the microwave power is transmitted in the second output waveguide; this therefore for these three discrete positions proposed for illustrative and non-limiting purposes.

[0017] According to one embodiment of the invention, the dividing element is continuously adjustable in position between two extreme positions.

[0018] In other words, in this embodiment, the waveguide power divider is advantageously flexible and modular because the divider element is continuously adjustable in position between two extreme positions; leaving an operator with full control over the splitting of the microwave power between the first output waveguide and the second output waveguide through a multitude of splitting configurations.

[0019] One of the two extreme positions, called the first extreme position, corresponds to a splitting configuration for which a minimum of the first fraction of the microwave power transmitted in the first output waveguide is defined, and a maximum of the second fraction.

[0020] Conversely, the other of the two extreme positions, called the second extreme position, corresponds to a splitting configuration for which a maximum of the first fraction of the microwave power transmitted in the first output waveguide is defined, and a minimum of the second fraction of the microwave power transmitted in the second output waveguide.

[0021] Thus, the operator, by moving the dividing element from one extreme position to the other, varies the first fraction (respectively the second fraction) from its minimum to its maximum (respectively from its maximum to its minimum); or vice versa.

[0022] In one embodiment of the invention, the dividing element is coupled to an actuator adapted to move the dividing element.

[0023] In other words, the dividing element is moved and adjusted in position in an automated manner using an actuator, such as a motorized actuator or a hydraulic or pneumatic actuator.

[0024] In one embodiment of the invention, the dividing element is moved manually by an operator.

[0025] According to a characteristic of the invention, the dividing element is adjustable at least between: - an equilibrium position in which the dividing element is located on the input propagation axis; - at least one first unbalanced position and at least one second unbalanced position in which the dividing element is located respectively on either side of a reference plane defined by the input propagation axis and the secondary axis.

[0026] In other words, in terms of displacement of the dividing element, the equilibrium position is between the at least one first unbalance position and the at least one at least one second unbalance position; meaning that the at least one first unbalance position and the at least one second unbalance position each comprise one of the two extreme positions as defined above.

[0027] In one embodiment of the invention, the equilibrium position corresponds to a configuration of splitting the microwave power such that the latter is equally distributed between the two output waveguides (i.e. the 50 / 50 splitting configuration).

[0028] In one embodiment of the invention, the at least one first unbalanced position and at least one second unbalanced position are located within the coupling zone such that they are symmetrical with respect to the reference plane, such that the microwave power distributions in the two output waveguides for the splitting configurations associated with the at least one first unbalanced position and at least one second unbalanced position are also symmetrical (for example: 10 / 90 for the at least one first unbalanced position, and 90 / 10 for the at least one second unbalanced position).

[0029] According to one embodiment of the invention, the dividing element is adjustable in position at least by translation along one or more directions orthogonal to the secondary axis.

[0030] According to one embodiment of the invention, the dividing element is adjustable in position at least by translation from the equilibrium position in a first direction of translation towards the at least one first unbalanced position, and in a second direction of translation, opposite the first direction of translation, towards the at least one second unbalanced position.

[0031] According to one embodiment of the invention, the dividing element is adjustable in position at least by rotation around a reference axis orthogonal to the propagation plane.

[0032] According to one embodiment of the invention, the dividing element is adjustable in position at least by rotation from the equilibrium position in a first direction of rotation towards the at least one first unbalanced position, and in a second direction of rotation, opposite to the first direction of rotation, towards the at least one second unbalanced position.

[0033] According to one embodiment of the invention, the input waveguide comprises an impedance matching element, such as for example an iris or a stub.

[0034] As previously indicated, the divider element may possibly significantly reduce the reflected power at the input of the waveguide power divider without completely eliminating it, so that there remains a very slight disadvantage. impedance matching. Adding an impedance matching element to the waveguide power divider can advantageously correct this mismatch in this context and eliminate or reduce the remaining reflected power.

[0035] According to one embodiment of the invention, the first output propagation axis and the second output propagation axis are collinear with each other, and are orthogonal to the input propagation axis.

[0036] In other words, the waveguide power divider in this embodiment has the shape of a “T” waveguide power divider.

[0037] According to one embodiment of the invention, the input waveguide, the first output waveguide and the second output waveguide each have a rectangular section.

[0038] According to one embodiment of the invention, the dividing element is formed from a rod, for example of cylindrical section.

[0039] The invention also relates to a microwave installation comprising at least: - at least one microwave cavity; - at least one microwave generator generating microwaves; - at least one waveguide power divider as previously described, such that the input end of the input waveguide of the at least one waveguide power divider is coupled to the at least one microwave generator, and such that the first output waveguide and the second output waveguide of the at least one waveguide power divider are coupled to the at least one microwave cavity for transmitting respectively a first fraction and a second fraction of a microwave power introduced into the input waveguide of the at least one waveguide power divider.

[0040] In other words, in the microwave installation, the microwaves penetrating inside an input waveguide are generated by a microwave generator. The two output waveguides are in turn coupled to a microwave cavity (or to two respective distinct microwave cavities), either directly, or indirectly via guide paths.

[0041] The output waveguides, or guide paths, are shaped to open into the microwave cavity at different locations, or to open into two separate microwave cavities.

[0042] Thus, and advantageously, it is possible, thanks to the divider element, to control the distribution of the microwave power (in other words, to control the values ​​of the first fraction and the second fraction of the microwave power), and consequently to control the microwave energies delivered to two distinct points, way of controlling (in other words, controlling or adjusting) the distribution of the microwave field inside the or each microwave cavity. In a heating application, controlling the distribution of the microwave field makes it possible to control the distribution of the thermal effect. In a plasma generation application, controlling the distribution of the microwave field makes it possible to control the distribution of the plasma energy. In a chemical conversion application, controlling the distribution of the microwave field makes it possible to control the distribution of the conversion rate.

[0043] In one embodiment of the invention, a microwave cavity may have two openings each arranged on at least one of its walls. A microwave installation may also comprise a plurality of microwave cavities coupled / connected to each other via these openings.

[0044] Each of these microwave cavities can also be coupled to at least one microwave generator and one waveguide power divider as described above. In such an embodiment, it is made possible to control the distribution of the microwave field in each of the microwave cavities of the microwave installation. Similarly, since each microwave cavity is coupled to a microwave generator, it is possible to inject power into one or more microwave cavities of the installation, and not into others.

[0045] According to a characteristic of the invention, the at least one waveguide power divider is coupled to an actuator designed to move the divider element, and the microwave installation comprises a control unit connected to the actuator and configured to control the movement of the divider element of the at least one waveguide power divider in order to control values ​​of the first fraction and the second fraction of the microwave power.

[0046] Such a control unit is for example of the type comprising an automaton, a processor, a microcontroller, an electronic card or any other equivalent calculation and processing means.

[0047] In one embodiment of the invention, the microwave installation comprises at least one measuring device capable of measuring at least one parameter representative of a distribution of the microwave field inside the at least one microwave cavity, and in which the control unit is connected to said measuring device and is configured to control the movement of the divider element of the at least one waveguide power divider as a function of the distribution of the microwave field inside the at least one microwave cavity.

[0048] Advantageously, because the measuring device is configured to continuously measure a distribution of the microwave field and communicate the measurement result to the control unit, the latter is capable in real time of adjusting the distribution. of the microwave field throughout the internal volume of the at least one microwave cavity.

[0049] This measuring device may for example be a device for measuring temperature, or for measuring light intensity, or for measuring reflected power.

[0050] In a particular embodiment of the invention, the microwave installation comprises at least one movement system configured to move a product inside the at least one microwave cavity, and in which the control unit is configured to control the movement of the divider element of the at least one waveguide power divider as a function of the movement of the product inside the at least one microwave cavity.

[0051] In different application contexts, the microwave cavity of the microwave installation can be used as an agri-food heating tunnel for heating, tempering or defrosting foodstuffs (for example meat, fish, fruit and vegetables, etc.), or as a pasteurization tunnel for pasteurizing foodstuffs in bulk or contained in hermetically sealed packaging.

[0052] The at least one microwave cavity has two openings (an inlet opening and an outlet opening) and is crossed by at least one movement system (for example a conveyor line) configured to move the foodstuffs inside the at least one microwave cavity.

[0053] In the case of a tempering / heating or pasteurization treatment, since the distribution of the microwave power is controlled inside the microwave cavity by means of the dividing element of the at least one waveguide power divider to which the latter is coupled, said microwave power can be more concentrated where the product being conveyed is located / positioned at a time t. Indeed, considering a single microwave cavity, at the start of treatment, the product will be located at the entrance (near one of the two openings of the microwave cavity), whereas it will tend to be positioned in the center of the microwave cavity in the middle of treatment, and at the exit (near the other of the two openings of the microwave cavity at the end of treatment).Thus, controlling the distribution of microwave power advantageously allows the product to be heated evenly throughout its passage through the microwave cavity.

[0054] The distribution of the microwave field (and therefore of the thermal effect in this heating application) inside the microwave cavity is ensured by the movement of the dividing element as a function, at a time t, of the position of the product inside the enclosure.

[0055] Another advantage of controlling the distribution of microwave power in such a microwave installation is that its energy efficiency is improved.

[0056] The invention finally relates to a microwave method implemented by a microwave installation as described above, said microwave method comprising at least the following steps: - a step of generating microwaves by the at least one microwave generator; - a step of guiding the microwaves to the input end of the input waveguide of the at least one waveguide power divider; - a step of splitting a microwave power introduced into the input waveguide of the at least one waveguide power divider, in order to transmit into the at least one microwave cavity the first fraction and the second fraction of the microwave power coming respectively from the first output waveguide and the second output waveguide of the at least one waveguide power divider.

[0057] As a reminder, during the fractionation step, the first fraction and the second fraction of the microwave power can be transmitted in the same microwave cavity, at two distinct locations in this microwave cavity; or alternatively, during the fractionation step, the first fraction of the microwave power can be transmitted in a first microwave cavity and the second fraction of the microwave power can be transmitted in a second microwave cavity.

[0058] According to a characteristic of the invention, the fractionation step comprises a control sub-step consisting of controlling the movement of the divider element of the at least one waveguide power divider in order to control values ​​of the first fraction and the second fraction of the microwave power.

[0059] According to one embodiment of the invention, the splitting step comprises a measuring sub-step consisting of measuring a distribution of the microwave field inside the at least one microwave cavity, and in which the controlling sub-step consists of controlling the movement of the divider element of the at least one waveguide power divider as a function of the distribution of the microwave field inside the at least one microwave cavity.

[0060] According to one embodiment of the invention, the control sub-step consists of controlling the movement of the divider element of the at least one waveguide power divider to homogenize the distribution of the microwave field inside the at least one microwave cavity (and therefore for example homogenize the thermal effect or the energy of the plasma or the chemical conversion rate).

[0061] According to one embodiment of the invention, the microwave method comprises a displacement step consisting of moving a product inside the at least one microwave cavity, and in which the control sub-step consists of controlling the displacement of the divider element of the at least one waveguide power divider as a function of the displacement of the product inside the at least one cavity. microwave. Brief description of the drawings

[0062] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of non-limiting examples of implementation, made with reference to the appended figures in which:

[0063] [Fig-1] is a schematic perspective view of a waveguide power divider according to a first embodiment of the invention;

[0064] [Fig.2] is a schematic front view of the waveguide power divider of [Fig.l];

[0065] [Fig.3] is a schematic sectional view of the waveguide power divider of [Fig.2] along the axis of this cut BB;

[0066] [Fig.4] is a schematic sectional view of the waveguide power divider of [Fig.3] along the axis of this section DD;

[0067] [Fig.5] is a schematic perspective view of the power divider in guide waves of the invention according to a second embodiment of the invention;

[0068] [Fig.6] is a schematic front view of the waveguide power divider of [Fig.5];

[0069] [Fig.7] is a schematic sectional view of the waveguide power divider of [Fig.6] along the axis of this cut BB;

[0070] [Fig.8] is a schematic sectional view of the waveguide power divider of [Fig.7] along the axis of this section DD;

[0071] [Fig.9] is a schematic top view, for the second embodiment illustrated [Fig.5] to [Fig.8], of several orifices drilled at a wall of the power divider in a sort guide and which comprise a main orifice and secondary orifices such that the main orifice is in an alignment axis with one of the several predefined positions and orthogonal to the output propagation axes along which the two output waveguides extend, the main orifice being shaped so that a conductive rod of the divider element can enter inside the coupling zone (a); of a gripping head coupled to the divider element and used to manipulate / adjust it in one of the several predefined positions inside the coupling zone, the gripping head remaining outside the drilled wall (b); of a metal cap shaped to obstruct a main orifice in the case where the position with which it is associated is not used and thus prevent any microwave leakage (c);the gripping head and the metal cap being screwed to the wall using screws which are inserted into the secondary holes; ;

[0072] [Fig. 10] shows a schematic view of a state-of-the-art "T" waveguide power divider for a given geometry (a); and the evolution, in the microwave frequency range [890 MHz; 940 MHz], reflection coefficient and transmission coefficients for this structure (b);

[0073] [Fig. 11] shows a schematic view of the waveguide power divider of [Fig. 10] but for which an iris has been added forming an impedance matching element (a); and the evolution, in the microwave frequency range [890 MHz; 940 MHz], of the reflection coefficient and the transmission coefficients for this structure (b);

[0074] [Fig. 12] shows a schematic view of a waveguide power divider within the meaning of the invention in which a divider element is integrated in the coupling zone in a position, called the equilibrium position, such that the microwave power arriving from the input waveguide is uniformly distributed between the two output waveguides (a); and the evolution, in the microwave frequency interval [890 MHz; 940 MHz], of the reflection coefficient and the transmission coefficients for this structure (b);

[0075] [Fig. 13] shows a schematic view of a waveguide power divider in an embodiment of the invention in which the divider element is continuously adjustable in rotation on either side of the equilibrium position, which is positioned on an input propagation axis along which the input waveguide extends (a); and the evolution, at a frequency equal to 915 MHz, of the reflected power at the input of the input waveguide and the output powers transmitted at the output of the two output waveguides as a function of the angle formed by the input propagation axis and the position taken by the divider element from the equilibrium position (b);

[0076] [Fig. 14] illustrates the distribution of the electric field in the waveguide power divider of [Fig. 13] when the angle is respectively equal to 10 degrees (a), and 30 degrees (b);

[0077] [Fig. 15] is a schematic view of the waveguide power divider of Figures 13 and 14 when the angle is equal to 30°, and an impedance matching element, here an iris, is added in the input waveguide (a) and the evolution, in the microwave frequency interval [890 MHz; 940 MHz], of the reflection coefficient and the transmission coefficients for this structure (b);

[0078] [Fig. 16] is a schematic perspective view of a microwave installation used in an application context for heating products, which microwave installation comprises a microwave generator (not shown) a microwave cavity crossed laterally by a displacement (or conveying) system shaped to transport the products; and inside which the guide path outlets open at different points, these guide paths being physically connected to the output waveguides of a waveguide power divider according to the first embodiment illustrated in Figures 1 to 4;

[0079] [Fig. 17] is a schematic front view of the microwave installation of [Fig. 16];

[0080] [Fig. 18] is an illustration, in the application context of the microwave installation of Figures 17 and 18, of the control of the distribution of the microwave field inside the microwave cavity via the adjustment in position of the divider element of the waveguide power divider, so that the distribution of the microwave field is adapted to the position of the product to be heated during its conveyance in the microwave cavity (the movement or conveying system not being illustrated here for reasons of clarity); [Fig.l8]-a, [Fig.l8]-b and [Fig.l8]-c showing a theoretical / ideal distribution of the microwave field respectively, at the beginning, in the middle, and at the end of the heating treatment of the product.

[0081] [Detailed description of several embodiments of the invention]

[0082] In this description, it is considered that the waveguide power divider 10 is a planar H waveguide power divider comprising a "T" junction.

[0083] With reference to [Fig.l] to 8, the proposed waveguide power divider 10 firstly comprises an input waveguide 1 which extends along an input propagation axis al and has an input end el, through which microwaves will enter which will propagate inside the input waveguide 1 along the input propagation axis al, and an output end ie opposite.

[0084] It then comprises a first output waveguide 2 and a second output waveguide 3 which extend respectively along a first output propagation axis a2 and a second output propagation axis a3; and each have an input end e2, e3 and an output end s2, s3.

[0085] The input waveguide 1 and the two output waveguides 2, 3 each have a rectangular section.

[0086] The waveguide power divider 10 comprises a coupling zone ZC shaped to couple the output end si of the input waveguide el to the input ends e2, e3 of the two output waveguides 2, 3.

[0087] The input propagation axis al, the first output propagation axis a2 and the second output propagation axis a3 all three define a propagation plane PP.

[0088] Having a "T" junction, the output propagation axes a2, a3 are collinear with each other, and they are also orthogonal to the input propagation axis al.

[0089] Also, the two illustrated waveguide power dividers 10 are H-plane waveguide power dividers, i.e. the "T" profile appears through the long side of the three waveguides 1, 2, 3; and lies in the propagation plane PP which is parallel to the magnetic / microwave field.

[0090] The waveguide power divider 10 is remarkable in that it comprises a divider element 4: - electrically conductive; - which is arranged inside the coupling zone ZC; - which extends along a secondary axis a4 which is orthogonal to the propagation plane PP, between two opposite walls 11, 12 of the waveguide power divider 10 and which are parallel to the propagation plane PP; and - is in contact with the two walls 11, 12.

[0091] The dividing element 4 is in the form of a metal rod 41 (or bar), for example of cylindrical section, and for example solid.

[0092] A first advantage of the divider element 4 is illustrated by means of Figures 10 to 12. In each of these figures a different design of a power divider in a planar H waveguide having a T-junction is considered, and for which the input waveguide 1 and the two output waveguides 2, 3 have a rectangular section and are of the same geometry (in other words, the large sides of the three waveguides 1, 2, 3 are equal, likewise for the small sides). The performances of each of the designs are evaluated by simulation, from the values ​​of dispersion parameters (called S parameters) obtained in a microwave frequency range between 890 MHz and 940 MHz.

[0093] The following are thus evaluated: - the reflection coefficient SI 1, expressed in dB, which corresponds to the microwave power (or power rate) emitted from the input end el of the input waveguide el, and which is reflected towards it; - the transmission coefficient S21, expressed in dB, which corresponds to the microwave power emitted from the input end el of the input waveguide el, and which is transmitted towards the output end s2 of the first output waveguide 2; - the transmission coefficient S31, expressed in dB, which corresponds to the microwave power emitted from the input end el of the input waveguide el; and which is transmitted to the output end s3 of the second output waveguide 3.

[0094] With reference to [Fig. 10], when a state-of-the-art waveguide power divider has such a geometry, one-third of the microwave power entering the input waveguide 1 is reflected toward the input end e1; the remainder of the power is distributed equally between the two output waveguides 2, 3. In other words, nearly one-third (or about 33%) of the microwave power is transmitted toward the output end s2 of the first output waveguide 2, and one-third of the microwave power is transmitted toward the output end s3 of the second output waveguide 3. As illustrated in [Fig.l0]-b, when the frequency is 915 MHz, the values ​​of the coefficients SU, S22, S31 are equal to -4.8 dB. Microwave transmission is disturbed due to the change in the direction of wave propagation (due to the shape of the "T" junction) and the division of a rectangular input waveguide 1 into two rectangular output waveguides 2, 3.

[0095] In the remainder of the description, the terms first fraction F2 and second fraction F3 are used to designate the quantity of microwave power which is transmitted respectively in the first output waveguide 2 and the second output waveguide 3.

[0096] In order to minimize the reflected power Pr at the input of the input waveguide 1, a solution in the state of the art is to add an impedance matching element 13 such as an iris. With reference to [Fig. 11], an iris is added in the input waveguide 1 of the waveguide power divider of [Fig. 10]. As illustrated in [Fig. 11]-b, the reflected power Pr is further minimized with a lower reflection coefficient SI 1 than in the previous design. For example, when the frequency is equal to 915 MHz, the value of the reflection coefficient SI 1 decreases and becomes equal to -24 dB. The fraction of the reflected power Pr at the input of the input waveguide is then of the order of 0.4%; meaning that the first fraction F2 and the second fraction F3 are both equal to 49.8%. In other words, more microwave power is transmitted out of the two output waveguides 2, 3.

[0097] However, such an adaptation, in addition to being dependent on the dimensions of the iris, is frequency dependent. In the example given, the value of the reflection coefficient SI 1 is equal to -11.9 dB and - 19 dB when the frequency is respectively equal to 896 MHz and 922 MHz. The fraction of the reflected power Pr corresponds to 6.5% of the microwave power at 896 MHz, and 1.3% of it at 922 MHz. It also tends towards 10% within the limits of the frequency range considered, that is to say when the frequency is approximately equal to 890 MHz or 940 MHz (the reflection coefficient SI 1 for these two frequencies being approximately equal to -10 dB).

[0098] [Fig. 12] illustrates a waveguide power divider 10 within the meaning of the invention. This design amounts to considering the waveguide power divider of [Fig. 10], but for which the divider element 4 has been added having the characteristics mentioned above.

[0099] As shown in [Fig.l2]-b, the reflection coefficient SI 1 is less than -33 dB over the entire frequency range considered (it even reaches -50 dB at 915 MHz), the fraction of the reflected power Pr at the input of the input waveguide 1 is less than 0.1%.

[0100] Thus, when microwave power enters the input waveguide of the waveguide power divider 10, the divider element 4 allows advantageously to significantly reduce, or even eliminate, the reflected power Pr at the input, this over a wide microwave frequency band. The fraction of the reflected power, as well as the first fraction F2 and the second fraction F3, can be considered as no longer (or almost no longer) dependent on the frequency due to the significant attenuation of the reflection coefficient SI 1. Another advantage of the divider element 4 is that its mechanical production inside the waveguide power divider 10 is easier compared for example to the mechanical production of an impedance matching element 13 of an iris, being in particular less sensitive to coast differences.

[0101] A second advantage of the divider element 4 is that it can be adjustable in position inside the coupling zone ZC, which makes it possible to control and pilot the splitting of the microwave power between the two output waveguides 2, 3, in other words to control the values ​​of the first fraction F2 and of the second fraction F3.

[0102] In an embodiment not illustrated, the dividing element 4 is moved automatically using an actuator.

[0103] In the embodiments described in this part, the divider element 4 is moved manually by an operator by means of a gripping head 40 located at the end of one of the two ends of the divider element 4 and accessible from the outside. One of the two walls 12 of the waveguide power divider parallel to the input propagation axis a1 has at least one opening such that: - the rod 41 of the dividing element 4 can be slid entirely inside the coupling zone ZC and come into contact with the internal face of the other of the two walls H; - the gripping head 40 cannot penetrate inside the coupling zone ZC, and is in contact with the external face of the wall 12.

[0104] The dividing element 4 is adjustable between: - an equilibrium position cp in which the dividing element 4 is located on the input propagation axis al;

[0105] - at least one first imbalance position expl 1, expl2 and at least one second unbalance position exp21, exp22 in which the dividing element 4 is located respectively on either side of a reference plane RP defined by the input propagation axis al and the secondary axis a4.

[0106] The at least one first imbalance position expl 1, expl2 comprises a first extreme position expl 1 such that for this position, the splitting of the microwave power is such that a minimum of the microwave power is transmitted in the first output waveguide 2, and a maximum of the microwave power is transmitted in the second output waveguide. In other words, the first fraction F2 is equal to a minimum value of first fraction, and second fraction F3 is equal to a maximum value of second fraction.

[0107] The at least one second imbalance position expl 1, expl2 comprises a second extreme position exp21 such that for the latter, the fractionation of the microwave power is such that a maximum of the microwave power is transmitted in the first output waveguide 2, and a minimum of the microwave power is transmitted in the second output waveguide 3. In other words, the first fraction F2 is equal to a maximum value of the first fraction, and the second fraction F3 is equal to a minimum value of the second fraction.

[0108] In various embodiments, including those presented, the equilibrium position cp corresponds to a splitting of the power such that the first fraction F2 and the second fraction F3 are equal. In other words, in the equilibrium position cp, the microwave power is equally distributed in the two output waveguides 2, 3.

[0109] With reference to [Fig.l] to [Fig.4], the divider element 4 can be adjusted in position continuously between the two extreme positions expl 1, exp21. For such a design, the waveguide power divider 10 offers great flexibility to an operator in splitting the microwave power between the first output waveguide 2 and the second output waveguide 3, through a plurality of splitting configurations associated with intermediate positions between the extreme positions expll, exp21.

[0110] In other words, the operator has full control over the value of the first fraction F2 (respectively the value of the second fraction F3), which he can continuously change from its minimum (respectively its maximum) to its maximum (respectively its minimum), and vice versa, by moving the dividing element 4 from the first extreme position exp11 to the second extreme position exp21. The intermediate positions therefore include the other unbalance positions exp12, exp22 as well as the equilibrium position cp.

[0111] In the illustrated embodiment, the extreme positions expll, exp21 are lo calibrated in the coupling zone ZC such that they are symmetrical with respect to the reference plane RP which contains the equilibrium position cp (since this is on the input propagation axis al). This means that each unbalance position expll, expl2 (associated with a splitting configuration) located on one side of the reference plane RP has on the other side of said reference plane RP an unbalance position exp21, exp22 (associated with a splitting configuration) which is its symmetrical. For example: - if the values ​​of the first fraction F2 and the second fraction F3 are respectively equal to 10% and 90% for the first extreme position expll (configuration 10 / 90 splitting configuration), then they are respectively equal to 90% and 10% for the second extreme position exp21 (90 / 10 splitting configuration); - if two imbalance positions expl2, exp22 are symmetrical, and for one of them the values ​​of the first fraction F2 and the second fraction F3 are respectively equal to 30% and 70% (fractionation configuration 30 / 70), then these values ​​will be respectively equal to 70% and 30% for the other of the two imbalance positions (fractionation configuration 70 / 30).

[0112] In the embodiment illustrated [Fig.4] to [Fig.8], the divider element 4 is continuously adjustable in position by sliding, being mounted for this purpose on a guide rail 16 integrated here into one of the two walls 12 of the waveguide power divider 10; this guide rail 16 being in the form of a slot made passing through the wall 12. More precisely, the divider element 4 is integrated inside the waveguide power divider 10 such that one of its ends is in direct contact with the wall 11, while its other end, terminated by the gripping head 40, passes through and slides inside the sliding rail 16. Thus, the gripping head 40 slides in the guide rail 16, making it possible to modify the splitting of the microwave power in the two output waveguides 2, 3. The sliding rail is integrated into the wall 12 such that it guarantees its sealing and prevents any microwave leakage.

[0113] In the illustrated example, the guide rail 16 is of rectilinear shape and extends parallel to the output propagation axes a2, a3, so that the dividing element 4 is adjustable in translation. Alternatively, this guide rail 16 may be of curved or incurved shape, and for example of arcuate shape. In the case of such an arcuate shape, the adjustment in position of the dividing element 4 would be equivalent to an adjustment in rotation.

[0114] With reference to Figures 13 and 14, the dividing element 4 is adjustable in position, in another embodiment, by rotation about a reference axis (or pivot axis) orthogonal to the propagation plane PP. The dividing element 4 can then pivot, relative to the reference axis, in a first direction of rotation towards the at least one unbalance position expl 1, expl2, and in a second direction of rotation, opposite to the first direction of rotation, towards the at least one second unbalance position exp21, exp22. In the embodiment presented, the equilibrium position cp is included on the reference axis. Thus, the at least one second unbalance position exp21, exp22 is symmetrical to the at least one first unbalance position expl 1, expl2 relative to the reference axis.

[0115] In this embodiment, the dividing element 4 can pivot in the first direction of rotation considered to be the clockwise direction (respectively in the second direction of rotation considered to be the counterclockwise direction) by an angle a between 0° and 60°. (respectively between 0° and -60°). [Fig.l3]-b shows the evolution of the output power P2 and the output power P3 observed respectively at the output of the output waveguides 2, 3. The frequency considered is 915 MHz.

[0116] When the angle a is zero, the microwave power is equally distributed between the two output waveguides 2, 3. The output powers P2, P3 are both equal to 50% of the input power. When the angle a becomes non-zero and increases, with the divider element 4 tending to move closer to the input e3 of the second output waveguide 3, the output power P2 increases while the output power P3 decreases. Otherwise, with the increase in the value of the angle a, the first output fraction F2 increases and the second output fraction F3 decreases.

[0117] [Fig. 14] shows the distribution of the electric field in the power divider in waveguide 10 when the angle a is equal to 10° (configuration confA) and 30° (configuration confB). It is observable that with the increase in the value of the angle a, the microwave flux tends more and more to propagate from the input el of the input waveguide el towards the output end s2 of the first output waveguide 2, while less and less microwave power propagates towards the output end s3 of the second output waveguide 3.

[0118] When the angle a is equal to 10°, the first fraction F2 is equal to 60% and the second fraction F3 is equal to 40%. All the microwave power is distributed between the two output waveguides 2, 3 and the reflected power Pr at the input el of the input waveguide 1 is zero.

[0119] Nevertheless, depending on the dimensions of the waveguide power divider 10, it is possible, as illustrated [Fig.l3]-b, with the increase of the angle a, that a risk of impedance mismatch may occur, with a small part of the microwave power being reflected towards the input end el of the input waveguide 1. For example, in the configuration confB, the first fraction F2 and the second fraction F3 are respectively equal to 80% and 15%. The fraction of the reflected power Fl represents 5% of the microwave power. The more the angle increases, the more the reflected power is also likely to increase (the fraction of the reflected power Fl reaches approximately 35% when the angle a is equal to 60°).

[0120] In the embodiment shown [Fig.l] to [Fig.4], in order to correct this possible impedance mismatch, an impedance matching element 13, here an iris, can be added in the input waveguide 1. With reference to [Fig. 15] which illustrates the configuration confB when the angle a is equal to 60°, it is observable that at the frequency of 915 MHz, the reflection coefficient SI 1 is largely attenuated by being equal to approximately -45 dB; meaning that the reflected power Pr is zero. The first fraction F2 and the second fraction F3 then become respectively equal, following the addition of the impedance matching element 13 and compared to [Fig.l4]-b, to 89% and 11%. Instead of an iris, it is also possible to use a stub to be placed on the input propagation axis el, upstream of the input end el of the input waveguide; and which extends orthogonally to the propagation plane PP.

[0121] With reference to [Fig.5] to [Fig.8], the dividing element 4 can also be adjusted in position discretely in a predefined number of positions. In the embodiment presented, the dividing element 4 is adjustable in 5 positions: the equilibrium position cp, two first unbalance positions expll, expl2; and two second unbalance positions exp21, exp22. The two first unbalance positions expll, expl2 and the two second unbalance positions exp21, exp22 are positioned in the coupling zone ZC on either side of the reference plane RP, and such that they are symmetrical.

[0122] In this example of [Fig.5] to [Fig.8], the dividing element 4 is considered to be adjustable in rotation, insofar as the discrete positions are distributed on an arc of a circle centered on the reference axis (or pivot axis) previously described, and which, as a reminder, is orthogonal to the propagation plane PP. It would also have been possible for the dividing element 4 to be adjustable in translation with discrete positions distributed on a line.

[0123] Furthermore, each discrete position is defined by a main orifice 01 provided in the wall 12, so that several main orifices 01 are provided (or pierced) on the wall 12. Thus, the dividing element 4 is housed or inserted in one of the several main orifices 01, in order to be in the corresponding position; each position corresponding, as a reminder, to a specific division.

[0124] For example: - the equilibrium position cp corresponds to a 50 / 50 split configuration; - the first extreme position expll and the second extreme position exp21 correspond respectively to 10 / 90 and 90 / 10 splitting configurations; - the other first imbalance position expl2 and the other second imbalance position exp22 correspond respectively to 40 / 60 and 60 / 40 splitting configurations.

[0125] With reference to [Fig.9], in order to manually adjust the dividing element 4, the main orifices 01 are therefore arranged on the wall 12 such that each of the main orifices 01 is in an alignment axis of one of the five positions cp, expll, expl2, exp21, exp22; the five alignment axes being orthogonal to the propagation plane PP and therefore parallel to the reference axis defined above. The radius ROI of each of the main orifices 01 is substantially equal to the radius R4 of the cylindrical rod 41 of the dividing element 4 so that: the rod 41 can penetrate inside the coupling zone ZC until it comes into contact with the wall 11; the gripping head 40 is widened, compared to the rod 41, so that this gripping head grip 40 remains outside the waveguide power divider 10, and is in contact with the outer face of the wall 12.

[0126] It is possible to screw the rod 41 into the main orifices 01, by providing a thread on the rod 41 and tappings in the main orifices 01.

[0127] In the variant illustrated in [Fig.9], the gripping head 40 is screwed onto the wall 12 in order to hold it on said wall 12. For this, secondary orifices 0240 are drilled in the gripping head 40 so that their drilling axes extend parallel to and around the cylindrical rod 41. Each secondary orifice 0240 is shaped to receive a screw 6 with a screw radius R6. Secondary orifices 02 of screw radius R6 are also drilled in the wall 12 around each main orifice 01, and such that the drilling axis of a secondary orifice 02 of the wall 12 is in alignment with the drilling axis of one of the secondary orifices 0240 of the gripping head 40, when the cylindrical rod 41 of the dividing element 4 enters the wall 12 through the main orifice (See [Fig.9]-A).In order to properly screw the gripping head 40 onto the wall 12, the screw length of the screws 6 is at least equal to the sum of the height of the gripping head 40 and the thickness of the wall 12, so that the shanks of the screws 6 pass through the gripping head 40 in the direction of its height, penetrate inside the wall 12 through the secondary orifices 02 thereof, and run along the thickness of the wall 12.

[0128] Once the dividing element 4 is inserted into one of the five main orifices (and therefore adjusted in one of the five positions cp, expll, expl2, exp21, exp22), and in order to prevent any microwave leakage, the other main orifices 01 can be covered or plugged by metal caps 5 as illustrated [Fig.9]-b and screwed onto the wall 12 in the same way as the gripping head 40 of the dividing element 4.

[0129] In one embodiment of the invention, it is conceivable to design a waveguide power divider 10 having a “Y” junction, and in this case the output propagation axes a2 and a3 are not collinear with each other.

[0130] It is also conceivable, in another embodiment, that the waveguide power divider 10 is designed as an E-plane waveguide power divider.

[0131] The waveguide power divider 10 can be used in a plurality of applications, being integrated for example, and not exhaustively, in microwave installations for plasma generation, pasteurization, or heating of products, such as agri-food products.

[0132] With reference to [Fig.16] to [Fig.18], the waveguide power divider is integrated into a microwave installation 100 used for heating products 20, such as agri-food products or foodstuffs, and which implements a microwave process provided for this purpose.

[0133] The installation comprises at least: - a microwave generator 102 and which is shaped to generate the microwaves during a generation step of the microwave process, which is structurally connected to the input end el of the waveguide power divider so that a step of guiding the microwaves towards the input end el of the input waveguide 1 of the waveguide power divider 10 can be implemented; - a microwave cavity 101; - two guide paths 103.

[0134] Each of the guide paths is connected to an output end s2, s3 of one of the two output waveguides 2, 3.

[0135] Thus, during a fractionation step of the microwave process following the guiding step, the microwave power is distributed between the two output waveguides 2, 3 into the first fraction F2 and the second fraction F3 according to the position of the divider element 4 in the coupling zone ZC.

[0136] The first fraction F2 is then transmitted in one of the two guide paths 103, and the second fraction F3 is transmitted in the other of the two guide paths 103. As illustrated [Fig.16] and [Fig.17], the two guide paths 103 have a single path at the output of the output waveguides 2, 3; which then divides into two paths which will open respectively into the microwave cavity 101. The microwave cavity 101 therefore has four microwave power arrivals at four different points.

[0137] The microwave cavity 101 has an opening 22 on each of its side walls 1011, 1012, which allows a movement system 21, such as a conveyor line, to pass through the microwave cavity 101 over its entire length, said movement system serving to move the products 20 to be heated. In the remainder of the description, the movement system 21 is considered to be a conveyor line. As illustrated in the figures, one of the two paths of each of the waveguide paths 103 opens into the microwave cavity 101 via its upper wall, and the other of the two paths opens into the microwave cavity 101 via its lower wall. The microwave radiation therefore propagates inside the microwave cavity 101 above and below the conveyor line 21.

[0138] The outputs of the two guide paths 103 (i.e. the microwave inlets) are provided to be distributed over the entire length of the microwave cavity 101, so that the product 20 can be subjected to microwave radiation coming from at least one of the microwave inlets. Thus, and advantageously, by means of the divider element 4, and by means of the first fraction F2 and the second fraction F3, it is possible to control the distribution of the microwave power, and consequently the thermal effect of the microwave field, inside the cavity microwave 101, in the heating application described.

[0139] The fractionation step comprises a control sub-step consisting of controlling the movement of the divider element 4 of the waveguide power divider 10 in order to control / control values ​​of the first fraction and the second fraction of the microwave power. This control can be carried out automatically (see further) or, as illustrated [Fig. 16] and 17 for which the waveguide power divider 10 corresponds to that presented [Fig. 1] to [Fig. 4], manually by an operator.

[0140] The microwave installation 100 also comprises a control unit (not shown) at least in communication with the microwave generator 102 to control the generation of microwaves at a frequency included in the microwave frequency range (for example 915 MHz), and with the conveyor line 21. In other words, the control unit is shaped to implement at least the generation step and a movement step during which it controls the conveyor line 21 so that it conveys the product 20 inside and outside the microwave cavity 101.

[0141] Inside the microwave cavity 101 is installed a measuring device capable of continuously measuring at least one parameter representative of a distribution of the microwave field (such as for example a temperature or light intensity parameter), during a measurement sub-step included in the fractionation step. The measuring device is in communication with, or physically connected to, the control unit to transmit to it the microwave field distribution measurements.

[0142] The microwave cavity 101 also contains at least one position sensor shaped to continuously provide the position of the product 20 on the conveyor line 21. The at least one sensor is in communication with, or physically connected to, the control unit to transmit to it the position of the product inside the microwave cavity 101. The determination of the position of the product 20 is implemented in parallel with the measurement sub-step.

[0143] Depending on the position of the product 21 and / or the distribution of the microwave field inside the microwave cavity 101 which he detects from the control unit, the operator can modify the position of the dividing element 4 by sliding the gripping head 40 of the latter on the sliding rail 16.

[0144] Thus, and advantageously, the operator can control the distribution of the microwave field (and therefore of the thermal effect) in the microwave cavity 101 and modify it, by moving the dividing element 4 and therefore changing the first fraction F2 and the second fraction F3, depending on the position of the product 20; this with the aim that the product 20 is heated in a homogeneous / uniform manner throughout its conveyance to the interior of the microwave cavity 101.

[0145] Hereinafter, the side walls 1011, 1012 of the microwave cavity 101 are called the inlet wall 1011 and the outlet wall 1012.

[0146] Indeed, with reference to [Fig. 18], at the start of the treatment for its heating, the product 21 is more located near the microwave inlet wall 1011 through which it entered. Thus, to properly heat the product 21, it is preferable to locate the majority of the thermal effect (and therefore the microwave power) near the inlet wall 1011, rather than in the rest of the internal volume of the microwave cavity. In other words, with reference to [Fig.l8]-a, the further one moves away from the inlet wall 1011, the lower the thermal effect (and therefore the microwave power) becomes in the rest of the microwave cavity 101. This amounts to positioning the divider element 4 in the coupling zone ZC of the waveguide power divider so that one of the two fractions (in the diagram, the second fraction F3) is significantly greater than the other of the two fractions (the first fraction F2).This position can for example correspond to the second extreme position exp21. .

[0147] In the middle of the treatment, with reference to [Fig.l8]-b, the product has a greater tendency to be located in the middle of the microwave cavity 101. In this situation, it is preferable for the distribution of the microwave field to be such that the majority of the microwave power (and therefore of the thermal effect) is located in the center of the wave cavity 101. In other words, the dividing element 4 can be positioned in its equilibrium position cp such that the two fractions F2, F3 are equal; or else in a first unbalanced position expl2 or a second unbalanced position exp22 such that the values ​​of the first fraction F2 and the second fraction F3 are sufficiently close.

[0148] Finally, at the end of treatment, and as illustrated [Fig.l8]-c, the product is located close to the outlet wall 1012. To complete its heating, the majority of the microwave power (and therefore the thermal effect) can then be located close to the outlet wall 1012, rather than in the rest of the internal volume of the microwave cavity. In other words, the further one moves away from the outlet wall 1012, the lower the thermal effect (and therefore the microwave power) becomes in the rest of the microwave cavity 101. This amounts to positioning the divider element 4 in the coupling zone ZC of the waveguide power divider 10 so that the first fraction F2 is much greater than the second fraction F3. This position can, for example, correspond to the first extreme position expl 1.

[0149] In the case where the microwave installation 100 described so far comprises a waveguide power divider 10 for which the divider element 4 is adjustable in position in an automated manner by means of an actuator, then said actuator is in communication, in a wired or wireless manner, with the control unit. The control unit control is then configured to continuously implement the control sub-step, by controlling the actuator in order to adjust the position of the divider element 4; this as a function of the microwave field distribution measurements provided by the measuring device, and of the position of the product 20 provided by the at least one position sensor.

[0150] Advantageously, the distribution of the microwave field is controlled automatically, therefore without human intervention, throughout the duration of the heating of the product 20, continuously / in real time by the control unit.

[0151] The waveguide power divider 10 and the microwave installation 100 are described in a microwave frequency range of 890 MHz to 940 MHz. However, the waveguide power divider 10 may be designed for any frequency or frequency range within the microwave frequency band; and integrated into a microwave installation for an application operating at said frequency or frequency range.

[0152] It is also conceivable to temper or heat a product by means of a microwave installation 100 comprising not a microwave cavity 101 as described previously, called a “tunnel”, but a “batch” type microwave cavity into which the product to be tempered is introduced. In other words, the microwave installation 100 does not provide a movement system in this case. In one embodiment of the invention, the product is placed as is in the “batch” type microwave cavity. In another embodiment, the “batch” type microwave cavity comprises a rotating plate on which the product is placed so as to be heated uniformly. In such embodiments, the waveguide power divider makes it possible to control / drive the distribution of the thermal effect inside the batch type microwave cavity.

Claims

Claims

1. Waveguide power divider (10) comprising: - an input waveguide (1) extending along an input propagation axis (al) and which has along said input propagation axis (al) an opposite input end (el) and output end (si); - a first output waveguide (2) and a second output waveguide (3) coupled to the output end (si) of the input waveguide (1) and extending respectively, from a coupling zone (ZC) located in the extension of the output end (si) of the input waveguide (1), along a first output propagation axis (a2) and a second output propagation axis (a3), where the input propagation axis (al), the first output propagation axis (a2) and the second output propagation axis (a3) ​​define a propagation plane (PP);the waveguide power divider (10) being characterized in that it comprises a divider element (4) which: - is electrically conductive; - is arranged inside the coupling zone (ZC); - extends along a secondary axis (a4) which is orthogonal to the propagation plane (PP), between two walls (11, 12) parallel to the propagation plane (PP); and - is in contact with the two walls (11, 12).;

2. A waveguide power divider (10) according to claim 1, wherein the divider element (4) is positionally adjustable within the coupling zone (ZC).

3. A waveguide power divider (10) according to claim 2, wherein the divider element (4) is discretely position adjustable within a predefined number of positions.

4. A waveguide power divider (10) according to claim 2, wherein the divider element (4) is continuously position adjustable between two extreme positions.

5. A waveguide power divider (10) according to any one of claims 2 to 4, wherein the divider element (4) is coupled to an actuator adapted to move the divider element (4).

6. A waveguide power divider (10) according to any one of claims 2 to 5, wherein the divider element (4) is adjustable to the less between: - an equilibrium position (cp) in which the dividing element (4) is located on the input propagation axis (al); - at least a first unbalanced position (expl 1, expl2) and at least a second unbalanced position (exp21, exp22) in which the dividing element (4) is located respectively on either side of a reference plane (RP) defined by the input propagation axis (al) and the secondary axis (a4).

7. A waveguide power divider (10) according to any one of claims 2 to 6, wherein the divider element (4) is adjustable in position at least by translation along one or more directions orthogonal to the secondary axis (a4).

8. A waveguide power divider (10) according to any one of claims 2 to 7, wherein the divider element (4) is adjustable in position at least by rotation about a reference axis orthogonal to the propagation plane (PP).

9. A waveguide power divider (10) according to any preceding claim, wherein the input waveguide (1) comprises an impedance matching element (13), such as an iris or a stub.

10. A waveguide power divider (10) according to any preceding claim, wherein the first output propagation axis (a2) and the second output propagation axis (a3) ​​are collinear with each other, and orthogonal to the input propagation axis (al).

11. A waveguide power divider (10) according to any preceding claim, wherein the input waveguide (1), the first output waveguide (2) and the second output waveguide (3) each have a rectangular cross-section.

12. A waveguide power divider (10) according to any preceding claim, wherein the divider element (4) is formed from a rod (41), for example of cylindrical section.

13. Microwave installation (100) comprising at least: - at least one microwave cavity (101); - at least one microwave generator (102) generating microwaves; - at least one waveguide power divider (10) according to any one of the preceding claims, such that the input end (el) of the input waveguide (1) of the at least one waveguide power divider (10) is coupled to the at least one generator microwave (102), and such that the first output waveguide (2) and the second output waveguide (3) of the at least one waveguide power divider (10) are coupled to the at least one microwave cavity (101) for transmitting respectively a first fraction (F2) and a second fraction (F3) of a microwave power introduced into the input waveguide (1) of the at least one waveguide power divider (10).

14. Microwave installation (100) according to claim 13, wherein the at least one waveguide power divider (10) is according to claim 5 and the microwave installation (100) comprises a control unit connected to the actuator and configured to control the movement of the divider element (4) of the at least one waveguide power divider (10) in order to control values ​​of the first fraction (F2) and the second fraction (F3) of the microwave power.

15. Microwave installation (100) according to claim 14, wherein the microwave installation (100) comprises at least one measuring device capable of measuring at least one parameter representative of a distribution of the microwave field inside the at least one microwave cavity (101), and wherein the control unit is connected to said measuring device and is configured to control the movement of the divider element (4) of the at least one waveguide power divider (10) as a function of the distribution of the microwave field inside the at least one microwave cavity (101).

16. Microwave installation (100) according to claim 14 or 15, wherein the microwave installation (100) comprises at least one movement system (21) configured to move a product (20) inside the at least one microwave cavity (101), and wherein the control unit is configured to control the movement of the divider element (4) of the at least one waveguide power divider (10) as a function of the movement of the product (20) inside the at least one microwave cavity (101).

17. Microwave method implemented by a microwave installation (100) according to any one of claims 13 to 16, comprising at least the following steps: - a step of generating microwaves by the at least one microwave generator (102); - a step of guiding the microwaves to the input end (el) of the input waveguide (1) of the at least one waveguide power divider (10); - a step of splitting a microwave power introduced into the input waveguide (1) of the at least one waveguide power divider (10), in order to transmit into the at least one microwave cavity (101) the first fraction (F2) and the second fraction (F3) of the microwave power coming respectively from the first output waveguide (2) and the second output waveguide (3) of the at least one waveguide power divider (10).

18. A microwave method according to claim 17, wherein the splitting step comprises a driving sub-step of driving the movement of the divider element (4) of the at least one waveguide power divider (10) in order to control values ​​of the first fraction (F2) and the second fraction (F3) of the microwave power.

19. A microwave method according to claim 18, wherein the splitting step comprises a measuring sub-step of measuring a distribution of the microwave field inside the at least one microwave cavity (101), and wherein the driving sub-step comprises driving the movement of the divider element (4) of the at least one waveguide power divider (10) as a function of the distribution of the microwave field inside the at least one microwave cavity (101).

20. Microwave method according to claim 19, in which the driving sub-step consists of driving the movement of the divider element (4) of the at least one waveguide power divider (10) to homogenize the distribution of the microwave field inside the at least one microwave cavity (101).

21. A microwave method according to any one of claims 17 to 20, comprising a moving step of moving a product (20) inside the at least one microwave cavity (101), and wherein the driving sub-step consists of driving the movement of the divider element (4) of the at least one waveguide power divider (10) as a function of the movement of the product (20) inside the at least one microwave cavity (101).

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