Patent Publication Number: US-10326191-B2

Title: Spatial power combiner

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119 to French Patent Application No. 1561267, filed Nov. 23, 2015, the entire content of which is hereby incorporated by reference 
     TECHNICAL FIELD 
     The present invention concerns a spatial power combiner including several inputs and one output. 
     BACKGROUND 
     A power combiner is a device enabling the power from several inputs to be combined into a single output. 
     The generation of high power is necessary in certain applications, for example in radar systems in order to emit a high power signal or communication systems in order to deliver a high power signal to a communication channel. 
     As the level of power output of a single power amplifier is often insufficient, a power combiner is necessary to add or combine power outputs from several power amplifiers. 
     Thus, power combiners are often used with a set of power amplifiers, each power amplifier amplifying an input signal and supplying an output signal. The power combiner combines the power of the output signals from the power amplifiers and generates a total output power. 
     Numerous architectures for power combiners exist. A spatial power combiner is one type of power combiner constituted by a cavity supplied by signals coming respectively from a set of input transmission lines. The power coming from each line is combined and collected into a central output transmission line. 
     In the current spatial power combiners, the inputs of the power combiner are not isolated from each other. Thus, as each input of the combiner influences the other inputs, a failure at one input or at components linked to that input is able to be propagated to the other inputs. 
     Furthermore, a fault of a single power amplifier may lead to a large degradation in the performance of the power combiner, which may lead to a fault in the operation of the device in which the power combiner is used. 
     SUMMARY 
     An object of the present invention is to overcome at least one of the aforesaid drawbacks and to provide a spatial power combiner in which the reliability is improved. 
     To that end, according to a first aspect the present invention provides a spatial power combiner comprising several inputs to which are respectively linked a set of transmission lines, and an output. 
     The spatial power combiner further comprises a body forming a cavity, the set of transmission lines passing longitudinally through said cavity and being disposed around an absorbent member extending longitudinally in said cavity. 
     The absorbent member makes it possible to isolate the transmission lines from each other, the signals carried by the transmission lines thus not influencing each other. 
     Furthermore, in case of a fault in a transmission line, that transmission line has no effect on the other transmission lines of the set and the power combiner still delivers an adequate output signal, in the worst of cases it being possible that the power at the output is reduced. 
     In an embodiment, the length of the absorbent member is equal to the length of the transmission lines in the spatial power combiner. 
     Thus, the absorbent member extends longitudinally over the entirety of the length of the transmission lines, which improves the isolation between the inputs and may facilitate the assembly of the power combiner at the time of its manufacture. 
     In another embodiment, the length of the absorbent member is less than the length of the transmission lines in the spatial power combiner. 
     By virtue of the reduction in the length of the absorbent member relative to the length of the transmission lines, the magnetic and dielectric losses due to the absorbent are reduced. 
     In a particular case, the absorbent member extends starting from the input of said spatial power combiner. 
     By virtue of this provision of the absorbent member, the evacuation of the energy dissipated in the form of heat in the power combiner is improved due to the fact that the heat travels a shorter distance. 
     In another particular case, the absorbent member extends starting from the output of said spatial power combiner. 
     In an embodiment, the spatial power combiner further comprises heat dissipation means extending longitudinally in the cavity, the absorbent member surrounding the dissipation means. 
     According to a feature, the heat dissipation means comprise a metal rod. 
     In particular, in the case in which the absorbent member extends starting from the input and the absorbent member is shorter than the length of the transmission lines, the distance traveled by the heat along the metal rod is reduced. 
     According to a feature, the transmission lines are microstrip transmission lines. 
     Thus, the connection of the input transmission lines to electronic circuits is facilitated. 
     Furthermore, no transition to another type of transmission line is necessary, avoiding losses linked to the transitions between different types of transmission lines. 
     According to another feature, the inputs of the spatial power combiner have a low impedance. 
     The connection of the inputs of the combiner to electronic circuits or components having low impedance outputs is thus facilitated. As a matter of fact, when the impedance values are close, implementing the adaptation of impedances is simplified. 
     According to another feature, the spatial power combiner comprises a heat evacuation module. 
     This heat evacuation module assists in the heat dissipation of the spatial power combiner. 
     According to an embodiment, the spatial power combiner comprises an impedance preadaptation module disposed at the input of the spatial power combiner, the impedance preadaptation module comprising first parts of the transmission lines of the set of transmission lines. 
     In an embodiment, each first part of the transmission lines comprises a set of layers, the set of layers comprising:
         1) at least one first conductive layer transporting a signal and having a width reducing along that first part of the transmission line, and   2) at least one second conductive layer serving as a reference for potential and comprising an opening having a width increasing along the first part of said transmission line.       

     Thus, on account of the variations in the width of the first conductive layer and of the opening of the second conductive layer, the impedance value of the transmission line varies along the transmission line. 
     In particular, the impedance increases along the transmission line. 
     Therefore, the impedance value of a transmission line at the input of the spatial power combiner is less than the impedance value of the transmission line at the output of the combiner. 
     In a variant of this embodiment, the set of layers comprises a third conductive layer serving as a reference for potential. 
     In another variant of this embodiment, the impedance preadaptation module comprises a support on which are disposed the first parts of the transmission lines, the support comprising a set of hollows, each first part of the transmission lines of the set of transmission lines being respectively disposed on a hollow of the set of hollows. 
     Thus, the second conductive layer of each set of layers of each transmission line is in contact with each hollow of the support. 
     According to a second aspect, the present invention concerns a power amplification set formed by a spatial power combiner in accordance with the invention and an amplification structure disposed at the input of said spatial power combiner, the amplification structure comprising a set of inputs and a set of outputs, the outputs being respectively linked to the inputs of the spatial power combiner. 
     Therefore, the transmission lines of the spatial power combiner are connected to the outputs of the amplification structure. 
     Thus, the spatial power combiner combines the powers respectively present at the outputs of the amplification structure. 
     Furthermore, the transmission lines at the input of the spatial power combiner respectively correspond to the transmission lines at the output of the amplification structure. 
     According to a feature, the amplification structure comprises a set of power amplifiers, each power amplifier being linked to each output of the amplification structure. 
     Thus, the signals at the input of the power combination set are first amplified and then their power is combined, by the spatial power combiner, as a single output. 
     According to a feature, the outputs from the power amplifiers have a low impedance. 
     Thus, the impedance adaptation between the amplification structure and the power combiner is easily carried out. 
     The power amplification set has features and advantages that are similar to those described above in relation to the spatial power combiner. 
     Still other particularities and advantages of the invention will appear in the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       In the accompanying drawings, given by way of non-limiting example: 
         FIG. 1 a    represents a perspective view with partial cutting away of a power amplification set according to an embodiment of the invention comprising a spatial power combiner according to a first embodiment of the invention. 
         FIG. 1 b    represents an exploded perspective view of the power amplification set of  FIG. 1   a.    
         FIG. 2  represents a perspective view with partial cutting away of the power combiner according to a second embodiment of the invention; 
         FIG. 3  represents a perspective view with partial cutting away of the power combiner according to a third embodiment of the invention; and 
         FIGS. 4 a  and 4 b    represent an exploded view of a first part of a transmission line of the power combiner represented in  FIGS. 2 and 3  according to two embodiments; 
     
    
    
     DETAILED DESCRIPTION 
     A power amplification set in accordance with the invention will be described with reference to  FIGS. 1 a    and  1   b.    
       FIG. 1 a    represents a power amplification set  100  comprising a spatial power combiner  10  and an amplification structure  20 . 
     An exploded view of the power amplification set is represented in  FIG. 1   b.    
     The spatial power combiner  10  is disposed at the output of the amplification structure  20 . 
     The amplification structure  20  comprises a set of inputs  21   a ,  21   b ,  21   c , . . . and a set of outputs  22   a ,  22   b ,  22   c , . . . , the number of inputs and outputs of the sets being identical. 
     It will be noted that below in this document, the inputs of the amplification structure  20  are referenced  21  and the outputs  22 . 
     The amplification structure  20  further comprises a set of power amplifiers  23 , each power amplifier  23  being linked to an input  21  of the amplification structure  20  and to an output  22  of the amplification structure  20 . 
     Input transmission lines a 1 , b 1 , c 1  . . . respectively link the inputs  21  of the amplification structure  20  and the power amplifiers  23 . Output transmission lines a 2 , b 2 , c 2  . . . respectively link the power amplifiers  23  and the outputs  22  of the amplification structure  20 . 
     Thus, the power amplifiers  23  respectively amplify the signals at the inputs  21  of the amplification structure  20  and generate amplified signals at the outputs  22 . 
     The amplification structure  20  comprises a body  24  enclosing the power amplifiers  23  and the input transmission lines a 1 , b 1 , c 1  . . . and output transmission lines a 2 , b 2 , c 2  . . . . 
     In the embodiment represented in  FIGS. 1 a  and 1 b   , the body  24  is of octagonal shape, and the amplification structures comprise eight inputs  21 , eight outputs  22 , as well as eight power amplifiers  23 . Each set formed by a power amplifier  23 , an input transmission line a 1 , b 1 , c 1  . . . and an output transmission line a 2 , b 2 , c 2  . . . is disposed on a face of the body  24  of octagonal shape. 
     Of course, the body of the amplification structure may have different geometric shapes, and the number of inputs, power amplification outputs and transmission lines may be different. 
     It will be noted that in this partial view with partial cutting away represented in  FIG. 1 a   , only three of the aforementioned sets are visible. 
     As the power amplifiers  23  are known to the person skilled in the art, they will not be described in more detail in this document. 
     In the represented embodiment, the amplification structure  20  comprises cooling means  25  disposed on the periphery of the body  24  in order to dissipate the heat produced by the power components, in particular by the power amplifiers  23 . 
     The spatial power combiner  10  is disposed at the output of the amplification structure  20 . 
     The outputs  22  of the amplification structure  20  are linked to inputs  11   a ,  11   b ,  11   c , . . . (designated  11  below in this document) of the spatial power combiner  10 . The powers of the signals at the output of the amplification structure  20  are thus combined by the spatial power combiner  10  into a single output power of the spatial power combiner  10 . 
     Thus, the spatial power combiner  10  of the transmission lines a, b, c, . . . are respectively linked to the inputs  11   a ,  11   b ,  11   c , . . . of the spatial power combiner  10 . 
     It will be noted that the transmission lines a, b, c, . . . of the spatial power combiner  10  are a continuation of the output transmission lines a 2 , b 2 , c 2  . . . of the amplification structure  20 . 
     The spatial power combiner  10  further comprises an output  12  on which a combined power is generated. 
     On this output  12 , a combined output signal is thus generated, having a power corresponding to the combined powers of the input signals  11  of the spatial power combiner  10 . Therefore, at the output  12 , there is generated a combined output signal having a power corresponding to the combined powers of the output signals of the amplification structure  20 . 
     Electronic equipment may be linked to the output  12  of the spatial power combiner  10  in order to use this combined power. 
     It will be noted that in the example embodiment described, the output  12  has high impedance, having, as an example that is in no way limiting, 50 Ohms. 
     The signal at the output  12  of the spatial power combiner  10  may thus be used, for example in an antenna or as input to a device serving as a transition for a wave guide to a coaxial line, without requirement for impedance transformation, or with an impedance transformation that is easy to carry out. 
     The spatial power combiner  10  comprises a cylindrical body  13  forming a cavity  14 . 
     The transmission lines a, b, c, . . . comprise a first part corresponding to the portion of line between the input  11  and the cavity  14  of the spatial power combiner  10 . 
     Below in this document, the part of the spatial power combiner at the location of the cavity  14  will be named core  101  of the combiner. The first part of a transmission line a, b, c, . . . is also named access line aa, ba, ca, . . . . 
     Each input line a, b, c, . . . further comprises a second part ab, bb, cb, corresponding to the portion of line between the access line aa, ba, ca . . . and the output  12  of the combiner. The second parts of the transmission lines ab, bb, cb, . . . pass longitudinally through the cavity  14  starting from the input  11  of the spatial power combiner  10  and extending to the output  12  of the spatial power combiner  10 . 
     In the described embodiment, the input transmission lines a, b, c . . . are microstrip transmission lines. 
     Thus, provided that the power amplifiers  23  deliver output signals to microstrip lines, the connection between the amplification structure  20  and the spatial power combiner  10  may be made directly and without requiring conversions between different types of lines. 
     Losses due to the transformation of the signals between lines of different types are thus avoided. 
     The spatial power combiner  10  comprises an absorbent member  15  extending longitudinally in the cavity  14 . 
     The absorbent member  15  is placed between the input transmission lines a, b, c, . . . in particular between the second parts of the transmission lines ab, bb, cb, . . . in the core  101  of the combiner. 
     More particularly, the second parts of input transmission lines ab, bb, cb, . . . are disposed around the absorbent member  15 . 
     In the embodiment represented in  FIG. 1 , the absorbent member  15  extends over the whole length of the second parts of transmission lines ab, bb, cb, . . . that is to say that it extends over the entirety of the cavity  14  between the input  11  and the output  12  of the spatial power combiner  10 , more particularly over the entirety of the core  101  of the spatial power combiner. 
     Therefore, in this embodiment, the length of the absorbent member  15  is equal to the length of the second parts of the transmission lines ab, bb, cb, . . . in the spatial power combiner  10 . 
     In other embodiments, such as the embodiment represented in  FIGS. 2 and 3 , the length of the absorbent member  15  is less than the length of the second parts of the transmission lines ab, bb, cb, . . . in the spatial power combiner  10 . 
       FIG. 2  represents a spatial power combiner  10 ′ according to a second embodiment of the invention. It will be noted that the cavity is not represented in this  FIG. 2 . 
     In this embodiment, the transmission lines a′, b′, c′, . . . and in particular the second parts of the transmission lines ab′, bb′, cb′, . . . are disposed around the absorbent member  15 ′, the absorbent member  15 ′ extending longitudinally in a part of the cavity (not shown in the  FIG. 2 ). 
     In this embodiment, the absorbent member  15 ′ extends starting from the outlet  12 ′ of the spatial power combiner  10 ′ over a predetermined length. 
     By way of example that is in no way limiting, the predetermined length may be 50 mm. 
     Naturally, the value of this predetermined length may be different, this value varying for example according to the nature of the absorbent member  15 ′ used. 
     In an embodiment, the absorbent member  15  comprises an absorbent material, such as an epoxy resin with a filler of particles of a magnetic absorbent material, for example ferrite particles. 
     In this embodiment, the spatial power combiner  10 ′ further comprises a plastic member  16 ′ extending longitudinally in the cavity, as an extension to the absorbent member  15 ′. 
     The plastic member  16 ′ has a mechanical function, enabling the transmission lines a′, b′, c′, . . . to be held in place. 
     In this embodiment, the absorbent member  15 ′ and the plastic member  16 ′ are fastened together by means of a threaded rod disposed in a recess  18 ′ formed in the absorbent member  15 ′ and the plastic member  16 ′. 
     Thus, the absorbent member  15 ′ and the plastic member  16 ′ are fastened together by screwing. 
     In particular, a first part of the recess  18   a ′, corresponding to the recess formed in the plastic member  16 ′, is a tapped longitudinal recess, the walls of the recess  18 ′ thus forming a screw thread. A second part of recess  18   b ′, corresponding to the recess formed in the absorbent member  15 ′, is a recess of which the walls are smooth. 
     Of course, the fastening of the absorbent member  15 ′ and of the plastic member  16 ′ may be carried out by different means. 
       FIG. 3  represents a third embodiment of the spatial power combiner  10 ″. 
     In this embodiment, the absorbent member  15 ″ extends longitudinally in the cavity (not shown in this  FIG. 3 ) starting from the input  11 ″ of the spatial power combiner  10 ″, over a predetermined length. 
     By way of example that is in no way limiting, the spatial power combiner may have a length of 300 mm, and the absorbent member 50 mm. 
     According to another example, for a spatial power combiner with low losses, the length of the absorbent member may be 20 mm. 
     Of course, the values of the lengths of the spatial power combiner and of the absorbent member may be different. 
     In this embodiment, the spatial power combiner  10 ″ comprises heat dissipation means  17 ″ extending longitudinally in the cavity. 
     The heat dissipation means  17 ″ comprise a metal rod in an embodiment. 
     This embodiment is particularly advantageous since the metal rod enables efficient dissipation of the thermal energy in the form of heat produced in the spatial power combiner  10 ″. 
     In this embodiment, the absorbent member  15 ″ is disposed such that it surrounds the dissipation means  17 ″ over the predetermined length. 
     Thus, the heat dissipation means  17 ″ extend longitudinally within the whole of the cavity. The absorbent member  15 ″ extends over a predetermined length starting from the input  11 ″ of the spatial power combiner  10 ″. The heat dissipation means  17 ″ are thus surrounded by the absorbent member  15 ″ over the predetermined length. 
     In an embodiment, the spatial power combiner  10  (see  FIG. 1 ) further comprises a heat evacuation module  18 . 
     This heat evacuation module  18  may be used with different structures of spatial power combiners  10 ,  10 ′,  10 ″ in particular with the structures represented in  FIGS. 2 and 3 . 
     This thermal evacuation module  18  makes it possible to dissipate more of the heat produced in the spatial power combiner  10 . 
     The heat evacuation module  18  is a conventional module known to the person skilled in the art and does not require to be described in detail here. 
     In the embodiments described, the outputs of the power amplifiers  23  (or outputs  21  of the amplification structure  20 ) have low impedance. 
     Furthermore, the inputs  11  of the spatial power combiner  10  also have low impedance. 
     Furthermore, even though the inputs of the spatial power combiner have low impedance, the output of the combiner has a high impedance. 
     In an embodiment such as that represented in  FIGS. 1 a  and 1 b    the spatial power combiner  10  further comprises an impedance preadaptation module  102 . This impedance preadaptation module  102  modifies the value of the impedance present at the input  11  of the spatial power combiner  10 . 
     The impedance preadaptation module comprises the first parts of the transmission lines aa, ba, ca . . . or access lines. Each access line aa, ba, ca . . . comprises a printed circuit comprising at least two conductive layers, one conductive layer transporting the signal and one conductive layer serving as a reference for potential. 
     Two embodiments of a printed circuit forming the access lines aa, ba, ca are represented by  FIGS. 4 a    and  4   b.    
       FIG. 4 a    is a simplified illustration of an exploded view of a printed circuit forming the first part of a transmission line or access line aa of the spatial power combiner  10  according to an embodiment. 
     Each access line aa, ba, ca, . . . comprises a set of layers superposed relative to each other. 
     In the embodiment represented in  FIG. 4 a   , the set of layers comprises a first conductive layer  200 , a second conductive layer  400 , as well as a third conductive layer  700 . 
     In this embodiment, the first conductive layer  200  transports a signal, and the second  400  and third  700  conductive layers serve as references for potential. 
     The set of layers further comprises a first isolating layer  300 , a second isolating layer  600  and an adhesive layer  500 . 
     In an embodiment, one of the conductive layers, here being the third conductive layer  700 , comprises pins  800  disposed on the edges along the length of the layer. 
     In this embodiment, each of the other layers ( 200 - 600 ) comprises openings  900  disposed on the edge along the length of the layer, an opening having a complementary shape to that of a pin  800  of the third conductive layer  700  and being situated such that a pin  800  can be inserted into an opening  900  of each layer of the set of layers forming the access line aa. 
     The set formed by the pins  800  and by the openings  900  forms means for holding or fastening the layers of the set of layers together. 
     Of course, other manners of fastening or holding may be employed in other embodiments. 
     Furthermore, the number of layers may be different. 
     The first conductive layer  200  comprises a central part  201  and two lateral parts  202 . 
     The central part  201  of the first conductive layer  200  transports the signal transported by a transmission line a, of which the power will be combined with that of the other signals transported by the other transmission lines b, c, . . . . 
     The lateral parts  202  of the first conductive layer  200 , the second conductive layer  400  and the third conductive layer  700  serve as reference for potential. The lateral parts  202  of the first conductive layer  200 , the second  400  and third  700  conductive layers are linked together by the pins  800 , these pins being for example of metal. 
     A first isolating layer  300  is disposed between the first  200  and the second  400  conductive layer in order to isolate these latter two from each other. 
     Similarly, the second isolating layer  600  is disposed between the second  400  and the third  700  conductive layers. 
     In this embodiment, an adhesive layer  500  is disposed between the second conductive layer  400  and the second isolating layer  600 . 
     It will be noted that in the described example, the first conductive layer  200 , the second conductive layer  400  and the first isolating layer  300  form a first set, and the third conductive layer  700  and the second isolating layer  600  form a second set, the first and second sets being held together by means of the adhesive layer  500 . 
     Of course, other conductive, isolating and adhesive layers may be added and the order of the layers may be different. 
     The variation of impedance is provided by the first conductive layer  200  and the second conductive layer  400 . 
     In the example represented, the width of the first conductive layer  200  reduces along the first part of the transmission line aa. The width of the first conductive layer  200  here thus has a smaller value at the output of the impedance preadaptation module  102 ,  102 ′ (or at the input of the core  101 ,  101 ′ of the combiner) than at the input of this module  102 ,  102 ′ (or at the input of the spatial power combiner  10 ). 
     The second conductive layer  400  comprises an opening  401 . This opening  401 , or the width of the opening  401 , increases along the first part of the transmission line aa. The opening  401  of the conductive layer  400  is thus greater at the output of the impedance preadaptation module  102 ,  102 ′ (or at the input of the core  101 ,  101 ′ of the combiner) than at the input of this module  102 ,  102 ′ (or at the input of the spatial power combiner  10 ). 
       FIG. 4 b    is a simplified illustration of an exploded view of a printed circuit forming the first part of a transmission line or access line as a′ of the spatial power combiner  10  according to a second embodiment. 
     In this embodiment, the set of layers forming the access line aa′ comprises a first conductive layer  200 ′, a second conductive layer  400 ′ and an isolating layer  300 ′. 
     The assembly formed by these three layers forms the access line aa. This access line aa′ is disposed on a support or foot  1000 ′, the second conductive layer  200 ′ being in contact with the hollow  1001 ′. 
     In particular, the support  1000 ′ comprises a set of hollows  1001 ′, each hollow  1001 ′ having a suitable shape for receiving the printed circuit forming the access line aa′. 
     Thus, in the embodiment described the number of hollows is equal to the number of access lines aa′, ba′, ca′, . . . . 
     Of course, the support  1000 ′ may be in one piece or be formed by a set of supports, each support being associated with an access line aa′, ba′, ca′, . . . . 
     In this embodiment, the support  1000 ′ further comprises a second hollow  1002 ′ formed in the first hollow  1001 ′, the second hollow  1002 ′ receiving a second isolating layer  600 ′. 
     The second isolating layer  600 ′ and the second hollow  1002 ′ thus have complementary shapes. 
     The second isolating layer  600 ′ disposed in the second hollow  1002 ′ of the support  1000 ′ assists in holding the printed circuit forming the access line aa′ disposed in the first hollow  1001 ′ of the support  1000 ′. 
     In the described embodiment, the support  1000 ′ is produced from metal. 
     The first conductive layer  200 ′ transports the signal transported by a transmission line a′, of which the power will be combined with that of the other signals transported by the other transmission lines b′, c′, . . . . 
     The second conductive layer  400 ′, as well as the metal support  1000 ′ serve as references for potential. 
     It will be noted that when the printed circuit is inserted into the first hollow  1001 ′ of the support  1000 ′, the second conductive layer  400 ′ is in contact with the support  1000 ′. 
     The isolating layer  300 ′ is disposed between the first conductive layer  200 ′ and the second conductive layer  400 ′ in order to isolate them from each other. 
     As for  FIG. 4 a   , other metallization and isolating layers may be added to the set of layers. 
     Furthermore, the width of the first conductive layer  200 ′ reduces along the first part of the transmission line aa′. The width of the first conductive layer  200  here has a smaller value at the output of the impedance preadaptation module  102 ,  102 ′ (or at the input of the core  101 ,  101 ′ of the combiner) than at the input of this module  102 ,  102 ′ (or at the input of the spatial power combiner  10 ′). 
     The second conductive layer  400 ′ comprises an opening  401 ′. This opening  401 ′, or the width of the opening  400 ′, increases along the first part of the transmission line aa′. The opening  401 ′ of the conductive layer  400 ′ is thus greater at the output of the impedance preadaptation module  102 ,  102 ′ (or at the input of the core  101 ,  101 ′ of the combiner) than at the input of this module  102 ,  102 ′ (or at the input of the spatial power combiner  10 ′). 
     In embodiments in which the spatial power combiner does not comprise an impedance preadaptation module  101 ,  101 ′, the impedance variation between the input and the output of the spatial power combiner is provided only by the coaxial structure of the combiner core  101 ,  101 ′. 
     In all the embodiments, the common-mode impedance of the transmission lines of the coaxial structure of the power combiner increases along the coaxial structure of the combiner core  101 ,  101 ′. This increase is made by a reduction in the ratio between the diameter formed by the set of the transmission lines situated within the cylindrical body  13  and the inside diameter of the cylindrical body  13  of the core of the spatial power combiner  10 . 
     It will be noted that the disposition of the lines within the cylindrical body  13  and the actual cylindrical body  13  form a coaxial structure.