Multilayer waveguide comprising at least one transition device between layers of this multilayer waveguide

Abstract

The present disclosure relates to a multilayer electromagnetic waveguide that includes a plurality of layers forming guide channels for an electromagnetic wave, and at least one transition device including at least one dielectric layer between two guide channels, referred to as coupled guide channels, extending as an extension. Each transition device includes at least one adaptation channel extending in a longitudinal direction, and each adaptation channel is defined by two electrically conductive walls. At least one wall extends along the dielectric spacer layer from one end of the coupled guide channel, over a length suitable for optimizing the transmission of an electromagnetic wave between the two coupled guide channels.

Claims

1. A multilayer electromagnetic waveguide comprising: several superimposed layers forming guide channels for guiding an electromagnetic wave; and at least one transition device comprising at least one dielectric interlayer between two guide channels, provided as coupled guide channels, extending according to a direction of transmission of the electromagnetic wave between the coupled guide channels via the transition device, wherein each of the at least one transition device comprises at least one adaption channel extending from the coupled guide channels, according to a longitudinal direction secant to the transmission direction, wherein each of the at least one adaptation channel is delimited by at least two electrically-conductive walls, provided as adaptation walls, spaced from each other by the dielectric interlayer of the transition device, wherein each of the adaptation walls extend according to the longitudinal direction along the dielectric interlayer from one end, provided as coupling end, of one of the coupled guide channels, and at least one of the adaptation walls extend according to the longitudinal direction over a length selected between 0.1 and 0.5, to obtain an input impedance of at least substantially zero between the adaptation walls of the adaptation channel at level of the coupling ends of the coupled guide channels to optimize the transmission of the electromagnetic wave between the coupled guide channels.

2. The waveguide according to claim 1, wherein the longitudinal direction of each of the at least one adaptation channel is orthogonal to the transmission direction.

3. The waveguide according to claim 1, wherein at least one of the adaptation walls of the at least one adaptation channel includes a metallic blade.

4. The waveguide according to claim 1, wherein the at least one adaptation wall of the at least one adaptation channel is formed by a plurality of contiguous electrically-conductive vias parallel to each other.

5. The waveguide according to claim 4, wherein the vias extend along the dielectric interlayer from the coupling end.

6. The waveguide according to claim 4, wherein the vias extend along the dielectric interlayer orthogonally to the longitudinal direction of the at least one adaptation channel and to the transmission direction.

7. The waveguide according to claim 1, wherein the dielectric interlayer is interposed between two of the superimposed layers in which extend the coupled guide channels and in that each of the adaptation walls extends between the dielectric interlayer and one of the superimposed layers.

8. The waveguide according to claim 1, wherein each of the coupled guide channels is delimited by the at least two electrically-conductive walls, provided as guide walls, spaced from each other.

9. The waveguide according to claim 1, wherein each of the coupled guide channels is delimited by guide walls parallel in pairs and arranged to form a polygonal cross-section of the coupled guide channel.

10. The waveguide according to claim 1, wherein the at least one transition device comprises two of the at least one adaptation channel extending opposite to each other.

11. An antenna comprising at least one waveguide according to claim 1.

12. A method for manufacturing a multilayer electromagnetic waveguide comprising: superimposing several layers to form guide channels for guiding an electromagnetic wave; and providing at least one transition device comprising at least one dielectric interlayer between two guide channels, provided as coupled guide channels, extending according to a direction of transmission of the electromagnetic wave between the coupled guide channels via the transition device, wherein each of the at least one transition device comprises at least one adaptation channel extending from the coupled guide channels, according to a longitudinal direction secant to the transmission direction, wherein each of the at least one adaptation channel is delimited by at least two electrically-conductive walls, provided as adaptation walls, spaced from each other by the dielectric interlayer of the transition device, wherein each of the adaptation walls extends according to the longitudinal direction along the dielectric interlayer from one end, provided as a coupling end, of one of the coupled guide channels, and at least one of the adaptation walls extends according to the longitudinal direction over a length selected so as to obtain an input impedance of at least substantially zero between the adaptation walls of the adaptation channel at a level of the coupling ends of the coupled guide channels to optimize the transmission of the electromagnetic wave between the coupled guide channels.

Description

DRAWINGS

(1) In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

(2) FIGS. 1 to 5 are schematic perspective views of multilayer waveguides according to five forms of the present disclosure;

(3) FIG. 6 is a schematic longitudinal sectional view of the multilayer waveguide of FIG. 1 whose guide channels are not perfectly aligned;

(4) FIG. 7 is a first diagram of the equivalent circuit of a multilayer waveguide according to the present disclosure comprising two guide channels and an adaptation device;

(5) FIG. 8 is a second diagram of the equivalent circuit of a multilayer waveguide according to the present disclosure comprising two guide channels and an adaptation device;

(6) FIG. 9 is a schematic perspective view of a multilayer waveguide according to a sixth form of the present disclosure;

(7) FIGS. 10 and 11 are schematic longitudinal sectional views of a multilayer waveguide according to different forms having two guide channels extending orthogonally with respect to each other;

(8) FIGS. 12 and 13 are schematic longitudinal sectional views of a multilayer waveguide according to different forms adapted to form a power divider;

(9) FIG. 14 is a schematic longitudinal sectional view of a multilayer waveguide according to form according to the present disclosure comprising five substrate layers forming a multilayer supply network called candlestick network;

(10) FIG. 15 is a schematic sectional view across the thickness of an example of a portion of an antenna structure according to the present disclosure with radiating slots; and

(11) FIG. 16 is a schematic longitudinal sectional view of a multilayer waveguide according to another form according to the present disclosure comprising five substrate layers forming a multilayer supply network called candlestick network.

(12) The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

(13) The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

(14) A multilayer waveguide 20 according to the present disclosure as represented in FIGS. 1 to 6 and 8 comprises at least two guide channels 21.

(15) Each guide channel 21 extends longitudinally according to a transmission direction 22 and is transversely delimited by at least two electrically-conductive walls, called guide walls 23, spaced from each other by a dielectric material 24. Thus, each guide channel 21 allows guiding an electromagnetic wave between its guide walls 23. The guide channels 21 have the same characteristic impedance Z.sub.C1.

(16) Moreover, the guide walls 23 transversely delimiting a guide channel 21 are symmetrical in pairs with respect to a plane, called transmission plane, parallel to these guide walls 23 and equidistant from the guide walls 23, this transmission plane being a midplane of the guide channel 21.

(17) The dielectric material 24 interposed between two guide walls 23 of a guide channel 21 may consist of air or else any other appropriate dielectric solid material. For example, the dielectric element 24 has a relative dielectric permittivity coefficient comprised between 1 and 10, nevertheless there is nothing to prevent from having such a coefficient higher than 10.

(18) In some forms, the guide channels 21 of the multilayer waveguide 20 are integrated into layers 25 of the same solid and rigid dielectric material, called substrate, of the multilayer waveguide 20, superimposed in pairs. The used substrate is selected according to the applications of the multilayer waveguide. In particular, the substrate generally consists of an organic substrate with a low relative dielectric permittivity, that is to say lower than 4. For example, the substrate may consist of a composite material formed of polytetrafluoroethylene and glass fibers such as RT/Duroid 5880 in order to transmit high-frequency electromagnetic waves. The substrate may also consist of a dielectric foam whose relative dielectric permittivity is close to that of air (.sub.r=1).

(19) In particular, in some of these forms, each layer 25 is a plate for manufacturing a printed circuit board (PCB). Each layer 25 then comprises a dielectric material thickness, called substrate, and an electrically-conductive material thickness applied over its two main faces of the substrate.

(20) Each substrate layer 25 has at least one outer face, called coupling face, so that, when the substrate layers 25 are superimposed, a coupling face of a substrate layer 25 faces a coupling face of another superimposed layer. Preferably, the coupling faces of the substrate layers 25 are planar and parallel to each other. Thus, the layers of the waveguide can be superimposed more easily.

(21) A multilayer waveguide according to the forms of the present disclosure represented in FIG. 1, comprises two guide channels 21, called coupled guide channels 21, extending axially but separated from each other so as to have an absence of electrical contact between these two guide channels 21. One end, called coupling end, of a coupled guide channel 21 thus faces a coupling end of another coupled guide channel 21 so that an electromagnetic wave could be transmitted between these two coupled guide channels 21.

(22) In particular, the two coupled guide channels 21 are integrated respectively into two substrate layers 25 separated away from each other. An electromagnetic wave can then be transmitted between these two substrate layers 25 of the multilayer waveguide 20. Thus, the substrate layers 25 of the multilayer waveguide 20 are superimposed so that the coupling ends of the coupled guide channels 21 of two superimposed substrate layers 25 face each other but are away from each other.

(23) Preferably, the transmission direction 22 is orthogonal to the coupling face of each substrate layer 25.

(24) Furthermore, each coupled guide channel 21 is transversely delimited by two guide walls 23. Thus, the guide channel 21 is a parallel-plate waveguide. In particular, each coupled guide channel 21 is delimited by two metallic plates parallel to each other and with the same dimensions.

(25) More particularly, the guide walls 23 delimiting the same side of two coupled guide channels 21 are placed on the same plane so that the two coupled guide channels 21 are perfectly aligned.

(26) The multilayer waveguide 20 comprises, for each pair of coupled guide channels 21, a transition device 28 of the two coupled guide channels 21. This transition device 28 comprises a dielectric interlayer 29 disposed between the two substrate layers 25 comprising the coupled guide channels 21.

(27) In particular, this dielectric interlayer 29 may consist of an adhesive film or a glue layer allowing assembling the substrate layers 25 to each other. For example, the adhesive film may be constituted by a tissue pre-impregnated with resin. For example, the dielectric interlayer 29 has a relative dielectric permittivity coefficient comprised between 2 and 4, more particularly in the range of 2.5. The dielectric interlayer 29 has a smaller thickness than the thickness of each of the two substrate layers 25 connected thereby. In particular, the thickness of the dielectric layer 29 is for example smaller than the wavelength of the electromagnetic wave that propagates in this same dielectric layer 29. For example, in order to transmit a wave between two coupled guide channels at a 30 GHz frequency, the dielectric interlayer 29 has a thickness smaller than /10, preferably smaller than /100.

(28) Alternatively, the dielectric interlayer 29 may be formed by an air layer. This air layer may be unintended, due to manufacturing errors, in particular during the manufacture of hollow waveguides. The substrate layers 25 are then assembled to each other by a mechanical assembly device such as screws or else by pressing for example.

(29) The transition device 28 also comprises at least one adaptation channel 30 extending from the coupled guide channels, each adaptation channel 30 extending according to a longitudinal direction secant to the transmission direction, between the two layers 25 comprising the two coupled guide channels 21. Furthermore, each adaptation channel 30 is delimited by two electrically-conductive walls, called adaptation walls 36, spaced from each other by the dielectric interlayer 29. Each adaptation wall 36 extends between a substrate layer 25 comprising a coupled guide channel 21 and the dielectric interlayer 29. Thus, in some forms of a waveguide according to the present disclosure, at least one transition device comprises one single adaptation channel extending at only one side from the coupled guide channels, according to a longitudinal direction secant to the transmission direction.

(30) Alternatively or in combination, as represented in FIGS. 1 to 6, at least one transition device comprises at least two adaptation channels extending opposite to each other from the coupled guide channels, each adaptation channel extending according to a longitudinal direction secant to the transmission direction.

(31) Each adaptation channel 30 extends according to a longitudinal direction 31, secant to the transmission direction 22, over a predetermined length, called adaptation length l, from the guide walls 23 of the coupled guide channels 21 at the level of the opposing coupling ends of the coupled guide channels 21, and away from these coupled guide channels 21.

(32) In particular, a first adaptation channel 30 of the transition device 28 of two coupled guide channels 21 has a first adaptation wall 36 extending orthogonally to the transmission direction 22 from a first guide wall 23 of a first coupled guide channel 21 at the level of its coupling end. The first adaptation channel 30 also comprises a second adaptation wall 36 extending orthogonally to the transmission direction 22 from a first guide wall 23 of a second coupled guide channel 21 at the level of its coupling end, the first guide wall 23 of the first guide channel 21 and the first guide wall 23 of the second guide channel 21 being placed on the same side of the transmission plane.

(33) A second adaptation channel 30 of the transition device 28 has a first adaptation wall 36 extending orthogonally to the transmission direction 22 from a second guide wall 23 of the first guide channel 21 at the level of its coupling end. The first adaptation channel 30 also comprises a second adaptation wall 36 extending orthogonally to the transmission direction 22 from a second guide wall 23 of the second guide channel 21 at the level of its coupling end.

(34) Each adaptation wall 36 may be formed by an electrically-conductive blade, called adaptation blade 32. Each adaptation blade 32 extends over the adaptation length l from a coupling end of an adaptation guide channel 21 and has a width equal to the width of this coupling end of this guide channel 21. Preferably, an adaptation conductive blade 32 is orthogonal to the transmission direction 22.

(35) The adaptation blades 32 may be disposed against the dielectric substrate layers 25.

(36) In one variant represented in FIG. 2, a coupled guide channel 21 is delimited by two guide walls 23, each guide wall 23 being formed by a row of contiguous vias 27 so as to form a parallel-plate waveguide. Preferably, the vias 27 of the two guide walls 23 are symmetrical to each other with respect to the transmission plane of the guide channel 21. The vias 27 may be oriented according to the transmission direction 22 as represented in FIG. 2 or on the contrary orthogonally to the transmission direction 22 as represented in FIG. 3 depending on the electromagnetic mode that is desired to prevail in the guide channel. The vias 27 of a guide channel 21 are generally integrated into a dielectric substrate layer 25 and throughout the thickness thereof. In particular, when a guide channel is a parallel-plate waveguide, the vias are oriented orthogonally to the direction of a field relating to the electromagnetic mode that is desired to prevail in the guide channel.

(37) The contiguous vias 27 forming a guide wall 23 are spaced from each other by a given distance, for example close to the diameter of the vias, so that a row of vias is similar to a metallic wall with respect to an electromagnetic wave transmission. In particular, the arrangement of the vias 27 of a guide wall 23 is described for example by J. Hirokawa and M. Ando, Single-layer feed waveguide consisting of posts for plane TEM wave excitation in parallel plates, IEEE Trans. Antennas Propag., vol. 46, no. 5, pp. 625-630, May 1998 and by D. Deslandes, K. Wu, Accurate modeling, wave mechanisms, and design considerations of a substrate integrated waveguide. IEEE Trans. on Microwave Theory and Techniques, 2006, vol. 54, no. 6, pp. 2516-2526, or else by F. Foglia Manzillo et al., A Multilayer LTCC Solution for Integrating 5G Access Point Antenna Modules, in IEEE Transactions on Microwave Theory and Techniques, 20 vol. 64, no. 7, pp. 2272-2283, July 2016.

(38) In one variant represented in FIG. 4, the guide channels 21 are delimited by two metallic plates 26 parallel to each other and each adaptation wall 36 of each adaptation channel 30 is formed by a row of contiguous vias 33 parallel to each other and extending according to the longitudinal direction 31 of the adaptation channel 30. More particularly, the vias 33 extend along said dielectric interlayer 29 from a coupling end of a coupled guide channel 21.

(39) In one variant represented in FIG. 5, the guide channels 21 are delimited by two metallic plates 26 parallel to each other and each adaptation wall 36 of each adaptation channel 30 is formed by a row of contiguous vias 33 parallel to each other and extending orthogonally to the longitudinal direction 31 of the adaptation channel 30 and to the transmission direction 22.

(40) More particularly, FIG. 7 represents an equivalent diagram of a multilayer waveguide according to the present disclosure having two guide channels coupled by two adaptation channels.

(41) The formulas given hereinafter are valid for multilayer waveguides having two parallel-plate waveguide type coupled guide channels and when the thickness of the dielectric interlayer is smaller than the wavelength of the electromagnetic waves in the guide channels.

(42) Each adaptation channel 30 has a terminal load with an impedance Z.sub.R, at its end according to said longitudinal direction opposite to the coupled guide channels 21, which has a finite and non-zero value, representative of the phenomena of fringing fields and of radiation effects occurring at the ends of each adaptation channel opposite to the guide channels. This terminal load is equivalent to a resistance in parallel with a capacitor at this end of the adaptation channel. This terminal load implies that each adaptation channel 30 does not terminate neither in a short-circuit nor in an open circuit.

(43) When the relative permittivity .sub.r1 of the layers 25 and the relative permittivity .sub.r2 of the dielectric interlayer 29 are equal to 1, the impedance Z.sub.R of the terminal load may be given by the formula

(44) $Z_R=\frac{1}{G+\mathrm{jB}},\mathrm{where}G=\frac{1}{Z_{c0}}.Math.\frac{t}{2{}_0}\mathrm{and}B=\frac{1}{Z_{c0}}.Math.\frac{t}{{}_0}\ln \left(\frac{2e{}_0}{t}\right),\mathrm{with}{Z}_{c0}=\frac{{}_{0}t}{W},$
.sub.0 being the impedance of an electromagnetic wave in vacuum, e2.718, y1.781, 20 the wavelength of the wave transmitted in vacuum, t being the thickness of the dielectric interlayer 29 and W being the width of the adaptation channel (see N. Marcuvitz, Waveguide Handbook, 3rd ed. New York, N.Y., USA: McGraw-Hill, 1951).

(45) In order to optimize the transmission of the electromagnetic wave between two guide channels, the adaptation length l of each adaptation channel, and therefore of at least one adaptation wall, is selected so as to obtain an input impedance Z.sub.AA, Z.sub.BB of this adaptation channel at least substantially zero. In particular, the input impedance Z.sub.AA, Z.sub.BB of an adaptation channel is the impedance Z.sub.R of the terminal load brought at the input AA, BB of the adaptation channel. The value of the impedance Z.sub.R of this terminal load depends in particular on the thickness and on the permittivity of the dielectric interlayer and on the permittivity of the superimposed layers forming guide channels.

(46) The input impedance Z.sub.AA and Z.sub.BB of each adaptation channel may be defined by the formula

(47) $Z_{{\mathrm{AA}}^{}}=Z_{{\mathrm{BB}}^{}}=Z_{c2}\frac{Z_R+{\mathrm{jZ}}_{c2}\tan \left({}_{2}l\right)}{Z_{c2}+{\mathrm{jZ}}_R\tan \left({}_2,l\right)},$
where .sub.r2 is the characteristic impedance of each adaptation channel, with

(48) $Z_{c2}=\frac{{}_{0}t}{\sqrt{{\mathrm{.Math.}}_{r2}}W},{}_2=\frac{2}{{}_0}\sqrt{{\mathrm{.Math.}}_{r2}},$
and .sub.r2 is the relative permittivity of the dielectric interlayer 29.

(49) The input reflection coefficient S.sub.11 of a first guide channel and the output reflection coefficient S.sub.22 of a second guide channel coupled to the first guide channel may be obtained by the formula:

(50) $S_{11}=S_{22}=\frac{Z_{{\mathrm{AA}}^{}}}{Z_{{\mathrm{AA}}^{}}+Z_{c1}},$
where Z.sub.c1 is the characteristic impedance of each guide channel, with

(51) $Z_{c1}=\frac{{}_{0}t}{\sqrt{{\mathrm{.Math.}}_{r1}}W},$
and .sub.r1 is the relative permittivity of the layers 25.

(52) The adjustment of the adaptation length l of each adaptation channel allows obtaining a low impedance, ideally zero (short-circuit), between the two coupled guide channels so as to improve the transmission of an electromagnetic wave by minimizing or reducing energy losses in particular. In order to obtain a zero input impedance between two parallel-plate waveguide type coupled guide channels, the adaptation length l of each adaptation channel may for example be selected between 0.1 and 0.5, in particular between 0.2 and 0.3. Consequently, the design of a transition device according to the present disclosure is simple and rapid.

(53) The formulas given hereinabove are valid only for some forms of the present disclosure in which one single TEM mode propagates in the guide channels, the substrate layers 25 have the same relative permittivity .sub.r1 and all waves propagate according to the direction of propagation.

(54) FIG. 8 represents another equivalent diagram of a multilayer waveguide according to the present disclosure presenting two guide channels coupled by two adaptation channels 30. This equivalent diagram is valid for any thickness of the dielectric interlayer. Each adaptation channel 30 has a terminal load with an impedance Z.sub.R, at its end according to said longitudinal direction opposite to the coupled guide channels 21, which has a finite and non-zero value, representative of the phenomena of fringing fields and of radiation effects occurring at the ends of each adaptation channel opposite to the guide channels. This terminal load is equivalent to a resistance in parallel with a capacitor at this end of the adaptation channel. Furthermore, the transition region between the adaptation channels and the guide channels is considered as a junction of four 4-port waveguides. The coefficients of a scattering matrix [S] associated to this junction may be obtained by digital simulation. Afterwards, the adaptation length l of each adaptation channel is determined from these coefficients.

(55) The length of each adaptation channel 30 being easily calculable, a transition device 28 may be rapidly and simply designed.

(56) A multilayer waveguide according to the form represented in FIG. 9 comprises two parallelepipedic coupled guide channels 21. In particular, each coupled guide channel 21 is delimited by four guide walls 23 parallel in pairs and orthogonal in pairs. Thus, such guide channels 21 form rectangular waveguides. Each guide wall 23 is formed by a metallic plate 26. The transition device 28 then comprises four adaptation channels 30 between the two guide channels 21. The four adaptation channels 30 are orthogonal in pairs. In particular, each adaptation wall 36 of an adaptation channel 30 is formed by a metallic blade extending from a guide wall 23 of a coupled guide channel 21.

(57) In one variant, when the coupled guide channels 21 form rectangular waveguides, the adaptation walls 36 of the transition device 28 may consist of peripheral walls of the coupling ends of the guide channels.

(58) The adaptation length l of two adaptation walls 36 of a first adaptation channel may be different from that of two adaptation walls 36 of a second adaptation channel orthogonal to the first adaptation channel.

(59) A transition device 28 according to the present disclosure allows improving the transmission of an electromagnetic wave between the coupled guide channels 21 by minimizing or reducing energy losses, as well as the reflection of the electromagnetic waves transmitted between two coupled guide channels 21. In particular, it allows obtaining in the two coupled guide channels 21 separated from each other a transmission of an electromagnetic wave similar to that which would be obtained with a continuous waveguide.

(60) In all of the above-described examples, the frequency of the transmitted electromagnetic wave is 30 GHz. The layers of the compared multilayer waveguides are constituted by a substrate with a relative permittivity equal to 2.2. The results have been obtained by software simulation with an electromagnetic solver 3D simulation software, namely ANSYS HFSS, commercialized by the company ANSYS, Inc., Canonsburg, Pa., USA. Other simulation software such as CST STUDIO SUITE, commercialized by the company CST of America, Inc., Framingham, Mass., USA, or COMSOL Multiphysics, commercialized by the company COMSOL, Inc., Burlington, Mass., USA, or others, may be used.

COMPARATIVE EXAMPLE 1

(61) With a multilayer waveguide not compliant with the present disclosure comprising two superimposed guide channels in electrical contact with each other, we obtain a transmission coefficient in the range of 0.01 dB and a reflection coefficient in the range of 70 dB.

COMPARATIVE EXAMPLE 2

(62) With the case of a multilayer waveguide not compliant with the present disclosure comprising two superimposed guide channels not in electrical contact with each other, comprising a dielectric interlayer constituted by air with a 100 m thickness between two layers of the multilayer waveguide 20 and comprising no transition device 28 according to the present disclosure, we obtain a transmission coefficient in the range of 4 dB and a reflection coefficient in the range of 5 dB.

EXAMPLE 3

(63) With a multilayer waveguide according to the form represented in FIG. 1, comprising a dielectric interlayer 29 constituted by air with a 100 m thickness between two layers of the multilayer waveguide 20, and adaptation blades 32 with an adaptation length l equal to 2 mm, we obtain a transmission coefficient in the range of 0.04 dB and a reflection coefficient in the range of 45 dB.

EXAMPLE 4

(64) With a multilayer waveguide according to the form represented in FIG. 2 and for the same configuration as described for the multilayer waveguide according to the form of Example 3, we obtain a transmission coefficient in the range of 0.05 dB and a reflection coefficient in the range of 44 dB.

EXAMPLE 5

(65) With a multilayer waveguide according to the form in FIG. 1 comprising a 36 m adhesive film and with a 2.6 relative permittivity as a dielectric interlayer 29 of the transition device 28, as well as adaptation blades 32 with an adaptation length l equal to 2 mm, we obtain a transmission coefficient in the range of 0.01 dB and a reflection coefficient in the range of 66 dB.

EXAMPLE 6

(66) In the case of a multilayer waveguide as described in Example 3 and presenting, as represented in FIG. 6, a 0.2 mm misalignment between the two coupled guide channels 21, we obtain a transmission coefficient in the range of 0.05 dB and a reflection coefficient lower than 20 dB.

(67) Hence, a transition device 28 according to the present disclosure is robust with regards to alignment defects of the coupled guide channels 21, which result in a low energy loss.

COMPARATIVE EXAMPLE 7

(68) With a multilayer waveguide not compliant with the present disclosure comprising two superimposed guide channels with a rectangular section in electrical contact, each guide channel being delimited by four guide walls orthogonal in pairs, we obtain a transmission coefficient in the range of 0.03 dB and a reflection coefficient in the range of 85 dB.

COMPARATIVE EXAMPLE 8

(69) With a multilayer waveguide not compliant with the present disclosure comprising two superimposed guide channels with a rectangular section which are not in electrical contact, comprising a dielectric interlayer constituted by air with a 100 m thickness between the two guide channels and comprise no transition device 28 according to the present disclosure, each guide channel being delimited by four guide walls orthogonal in pairs, we obtain a transmission coefficient in the range of 3 dB and a reflection coefficient in the range of 5 dB.

EXAMPLE 9

(70) In the case of a multilayer waveguide according to the form represented in FIG. 8 comprising a 100 m thick air layer as a dielectric interlayer 29 between the two layers 25 of the multilayer waveguide 20, as well as adaptation blades 32 with adaptation lengths l equal to 2.6 mm for two first adaptation channels opposite to each other and 0.25 mm for two other adaptation channels opposite to each other and orthogonal to the two first adaptation channels, we obtain a transmission coefficient in the range of 0.04 dB and a reflection coefficient in the range of 55 dB.

(71) FIGS. 10 to 13 present multilayer waveguides according to the form which may be used as a base block (assembly of coupled guide channels according to a T-like shape, in particular for power dividers, and coupled guide channels perpendicular to each other) for the design of antennas' multilayer waveguides with a more complex structure.

(72) In particular, FIG. 10 presents a multilayer waveguide of the present disclosure comprising two substrate layers 25 including a first substrate layer, called lower substrate layer, comprising a guide channel extending according to a transmission direction and a second substrate layer, called upper substrate layer, comprising a guide channel extending orthogonally to the transmission direction. The transition device 28 comprises two adaptation channels coupling the guide channel of the lower substrate layer to one end of the guide channel of the upper substrate layer. In particular, the adaptation wall of the transition device 28 placed in contact with the coupling face of the upper substrate layer extends along the guide channel of the upper substrate layer so as to delimit it and to enable the guidance of an electromagnetic wave in this guide channel.

(73) FIG. 11 presents a variant of the multilayer waveguide of FIG. 10, the transition device 28 comprising one single adaptation channel. In particular, the multilayer waveguide comprises two substrate layers 25. A first substrate layer, called lower substrate layer, comprises a guide channel extending according to a transmission direction. A second substrate layer, called upper substrate layer, comprises a guide channel extending orthogonally to the transmission direction. The unique adaptation channel, coupling the guide channel of the lower substrate layer at one end of the guide channel of the upper substrate layer, extends orthogonally to the transmission direction opposite to the guide channel of the upper substrate layer. The guide channel of the upper substrate layer is delimited by a metallized wall disposed between the lower substrate layer and the dielectric interlayer extending along the two substrate layers of the multilayer waveguide so as to enable the guidance of an electromagnetic wave in the guide channel of the upper substrate layer while providing the electrical contact with a guide wall of the guide channel of the lower substrate layer. Hence, the guide channel of the upper substrate layer partially comprises the dielectric interlayer.

(74) FIG. 12 presents a multilayer waveguide according to the present disclosure allowing obtaining a power divider with one input and two outputs. In particular, the multilayer waveguide presents four substrate layers 25, a first substrate layer comprising a guide channel extending according to a transmission direction and being connected to a guide channel of a second substrate layer superimposed on the first layer, this last guide channel extending orthogonally to the transmission direction. A third substrate layer superimposed on the second substrate layer also comprises two coupled guide channels extending according to the transmission direction opening onto a coupling face of the third substrate layer. One of the guide channels of the third substrate layer being connected to one end of the guide channel of the second substrate layer, and the other guide channel being connected to another end of this guide channel. A fourth substrate layer 25 comprises two coupled guide channels extending according to the transmission direction, one of these guide channels being positioned opposite a guide channel of the third substrate layer and the other coupled guide channel of the fourth substrate layer facing the other guide channel of the third substrate layer. A first transition device 28 is respectively placed between a first coupled guide channel of the fourth substrate layer and the coupled guide channel facing the latter of the third substrate layer. A second transition device 28 is respectively placed between the other coupled guide channel of the fourth substrate layer and the coupled guide channel facing the latter of the third substrate layer. In particular, the dielectric interlayer 29 is placed between the third substrate layer and the fourth substrate layer. The transition devices 28 comprise two adaptation channels. Furthermore, the adaptation channels are orthogonal to the transmission direction.

(75) FIG. 13 presents a multilayer waveguide according to a variant of FIG. 12. The multilayer waveguide presents two substrate layers 25, a first substrate layer, called lower substrate layer, comprising a first guide channel extending according to a transmission direction and being connected to a second guide channel of the lower substrate layer orthogonal to the transmission direction. A second substrate layer, called upper substrate layer, comprises two guide channels.

(76) A first guide channel of the upper substrate layer is coupled with one end of the second guide channel of the lower substrate layer. The second guide channel is coupled to the other end of the second guide channel of the lower substrate layer. For this purpose, the guide channels of the upper substrate layer are positioned opposite the ends of the second guide channel of the lower substrate layer. A first transition device 28 is placed between the first coupled guide channel of the upper substrate layer and the second guide channel of the lower substrate layer. A second transition device 28 is placed between the second coupled guide channel of the upper substrate layer and the second guide channel of the lower substrate layer. The transition devices 28 comprise two adaptation channels. The two transition devices 28 present a common adaptation wall between the ends of the second guide channel of the lower substrate layer so as to delimit this second guide channel and to enable the guidance of an electromagnetic wave in this second guide channel between its ends. In particular, the common adaptation wall consists of a metallized wall placed over the lower substrate layer.

(77) FIG. 14 presents a multilayer waveguide according to the present disclosure comprising five substrate layers superimposed on each other allowing obtaining a supply network called candlestick network (see for example U.S. Pat. No. 7,432,871). A guide channel, extending according to a transmission direction, of the first substrate layer is coupled by a transition device to a guide channel, extending orthogonally to the transmission direction, from a second substrate layer to the first substrate layer. The transition device between the first and the second substrate layer comprises two adaptation channels. Each of these adaptation channels has an adaptation wall extending along the guide channel of the second substrate layer so as to delimit it. A first end of the guide channel of the second substrate layer is coupled by a transition device to a first guide channel, extending according to the transmission direction, of a third substrate layer. A second end of the guide channel of the second substrate layer is coupled by another transition device to a second guide channel, extending according to the transmission direction, of the third substrate layer. Each of the transition devices between the second and the third substrate layers has two adaptation channels, as represented in FIG. 11. A first guide channel of the third substrate layer is coupled to a first end of a first guide channel, extending orthogonally to the transmission direction, of a fourth substrate layer, as represented in FIG. 12. Similarly, a second guide channel of the third substrate layer is coupled to a first end of a second guide channel, extending orthogonally to the transmission direction, of a fourth substrate layer. A second end of the first guide channel of the fourth substrate layer is coupled by a transition device to a first guide channel, extending according to the transmission direction, of a fifth substrate layer. Furthermore, a second end of the second guide channel of the fourth substrate layer is coupled by a transition device to a second guide channel, extending according to the transmission direction, of the fifth substrate layer. In particular, each transition device between the fourth and the fifth substrate layer comprises two adaptation channels. Each guide channel of the fourth substrate layer is delimited by an adaptation wall of the adaptation channel to which it is associated.

(78) A multilayer waveguide 20 according to the present disclosure may be incorporated into an antenna as represented in FIG. 15. The antenna is made by adding radiating slots on the upper face of the multilayer waveguide 20 represented for example in FIG. 14.

(79) FIG. 16 presents a variant of the multilayer waveguide of FIG. 14. This multilayer waveguide differs from that presented in FIG. 14 in that the transition devices between the first substrate layer and the second substrate layer, between the third substrate layer and the fourth substrate layer and between the fourth substrate layer and the fifth substrate layer comprise one single adaptation channel.

(80) A multilayer waveguide 20 according to the present disclosure whose layers 25 consist of plates for manufacturing a printed circuit board (PCB) may be manufactured by etching the adaptation walls 36 of the adaptation channels 30 across the electrically-conductive material thickness applied over at least one main face of the substrate of each layer 25. Thus, each adaptation wall 36 is formed of the electrically-conductive material of the layers 25. The guide walls 23, formed by vias 27 or metallic plates 26 are manufactured in the layers 25 of the multilayer waveguide by methods known to those skilled in the art. When the manufacture of the adaptation walls 36 and of the guide walls 23 on each layer 25 of the multilayer waveguide 20 is completed, the layers 25 of the multilayer waveguide 20 are assembled by interposing a dielectric interlayer 29 (adhesive film or air layer) between each of them.

(81) A multilayer waveguide 20 according to the present disclosure may also be made by additive manufacturing of layers of polymer material and by deposition of an electrically-conductive material over at least one surface of the layers of polymer material. Afterwards, the adaptation walls 36 of the adaptation channels 30 are etched across the applied electrically-conductive material thickness. Once etched, the layers are then assembled to each other by bonding using an adhesive film.

(82) A multilayer waveguide 20 according to the present disclosure may also be made from metallic parts delimiting the guide channels and the adaptation channels. The space between the metallic parts defining the guide channels or else the adaptation channels may be filled with air or else with a dielectric foam.

(83) Hence, a multilayer waveguide 20 according to the present disclosure may be manufactured with methods known to those skilled in the art. Thus, the manufacture of a multilayer waveguide 20 is simple and rapid to implement.

(84) Moreover, such a manufacturing method may be implemented for a mass production of multilayer waveguides according to the present disclosure.

(85) Furthermore, the tolerance to manufacturing defects of a multilayer waveguide 20 according to the present disclosure allows facilitating the manufacture by providing for a margin for misalignment of the coupled guide channels.

(86) Hence, the present disclosure concerns a multilayer waveguide 20 comprising a transition device 28 with two guide channels 21 extending in a multilayer waveguide 20, each guide channel 21 comprising at least two electrically-conductive walls. The transition device 28 allows improving the transmission of the electromagnetic waves between the guide channels 21, the transition device 28 comprising at least one adaptation channel 30, each adaptation channel 30 being delimited by two electrically-conductive walls.

(87) A multilayer waveguide, a manufacturing method of such a multilayer waveguide and an antenna according to the present disclosure may be the object of numerous variants in connection with the forms represented in the figures.

(88) In particular, each guide wall may be formed by a plurality of contiguous rows of vias. For example, the guide channel 21 may be delimited by four guide walls 23, each guide wall 23 being formed by at least one row, in particular at least two adjacent rows where the vias of one row are shifted according to the transmission direction with respect to the vias of another row of this guide wall 23, for example by three adjacent rows of vias 27 placed in a staggered way.

(89) Furthermore, a multilayer waveguide according to the present disclosure may comprise guide walls formed by at least one row of vias and adaptation walls formed by at least one other row of vias.

(90) A multilayer waveguide 20 according to the present disclosure may be used in order to design radars, satellite systems, circuits and antennas with multilayer waveguides operating up to millimeter-waves. In particular, a multilayer waveguide 20 according to the present disclosure allows making in particular antennas according to a CTS-type structure as represented in FIG. 15.

(91) Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word about or approximately in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, manufacturing technology, and testing capability.

(92) As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean at least one of A, at least one of B, and at least one of C.

(93) The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.