PASSIVE RADIO FREQUENCY DEVICE WITH AXIAL FIXING APERTURES

Abstract

Radio frequency device including at least: a tube through which a channel passes, a front face and/or a rear face forming a bearing surface through which the channel passes, the bearing surface forming an annular frame around one end of the tube and being integral with the tube. The bearing surface includes axial fixing apertures passing through the bearing surface and opening outside the channel in order to allow fixation of the device, and the width of the frame being greater at and in the immediate vicinity of the axial fixing apertures than at a distance from these axial fixing apertures.

Claims

1-13. (canceled)

14. Radio frequency device comprising at least: a tube through which a channel passes, a front face and/or a rear face forming a bearing surface through which the channel passes said bearing surface forming an annular frame around one end of the tube and being integral with the tube, said bearing surface comprising a plurality of axial fixing apertures passing through the bearing surface and opening outside said channel in order to allow fixation of the device, the width of said frame being greater at and in the immediate vicinity of the axial fixing apertures than at a distance from these axial fixing apertures wherein said bearing surface forming a lattice structure, said lattice structure being reinforced around each axial aperture.

15. Radio frequency device of claim 14, said lattice structure being reinforced around each axial aperture by a reinforcing ring.

16. Radio frequency device of claim 14, the bearing surface being planar.

17. Radio frequency device of claim 14, said front face or rear face comprising a recessed central portion delimited by a deep annular groove.

18. Radio frequency device of claim 14, the channel comprising a non-conductive core and a conductive jacket around this core, said core and said conductive jacket extending into said bearing surface.

19. Radio frequency device of claim 18, wherein the core is made by additive manufacturing.

20. Radio frequency device of claim 14, wherein the front and/or rear faces are in a plane perpendicular to the channel axis.

21. Radio frequency device of claim 14, the device being a waveguide.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0068] Examples of the implementation of the invention are shown in the description illustrated by the attached figures in which:

[0069] FIGS. 1a, 1b and 1c illustrate examples of waveguides of the prior art, comprising a flange surrounding the waveguide and allowing two waveguides with compatible flanges to be fixed together;

[0070] FIG. 2 is a perspective view of two parts intended to be joined in a plane perpendicular to the direction of signal propagation to form a longer waveguide;

[0071] FIG. 3 shows an enlarged view of a lug of a variant of the device in which the fixing lugs are made with a lattice structure;

[0072] FIG. 4 illustrates a front view of a front or rear face of a waveguide device forming a bearing surface (flange) provided with an opening corresponding to said channel, said bearing surface being made of a lattice structure and comprising four reinforced axial apertures.

[0073] FIG. 5 shows a cross-sectional view of a device having a core covered with a conductive jacket on the inner and outer walls.

EXAMPLE(S) OF EMBODIMENT OF THE INVENTION

[0074] FIGS. 1a to 1c illustrate examples of flanges belonging to prior art radio frequency devices. These flanges are provided to facilitate the assembly together of several devices, for example several waveguide sections of identical or different shapes. Fixing is achieved by contacting the flanges provided at the ends of the waveguide sections. The flanges have apertures for the insertion of fixing elements such as screws or pins. The known flanges are large and their surface area is significantly larger than the surface area of a waveguide section. The large surface areas provided allow high quality assemblies to be made, with precise alignments, without the risk of impairing the performance of the assembled elements. However, the large surface areas used make the parts considerably heavier, making them unsuitable for certain applications where mass is a critical factor.

[0075] An example of a device according to the invention is illustrated in FIG. 2. As illustrated, the radio frequency device 1, here a passive radio frequency device, for example a waveguide, comprises a tube 2 of elongated shape along a longitudinal axis A-A. A channel 3, for the transmission of the radio frequency signal, is also aligned along the axis A-A, and passes through the tube. In the example shown, the longitudinal opening 3 is rectangular in cross-section and defines a channel for the transmission of the radio frequency signal. Other channel shapes, including round, square, elliptical, semi-circular, semi-elliptical, hexagonal, octagonal, etc., can be used.

[0076] The cross-section of the opening is determined according to the frequency of the electromagnetic signal to be transmitted. The dimensions of this internal channel and its shape are determined according to the operational frequency of the device 1, i.e. the frequency of the electromagnetic signal for which the device is manufactured and for which a stable transmission mode and optionally with minimum attenuation is obtained. The tube 2 may be made of metal, or by metallization of a core 2 of for example polymer, epoxy, ceramic, organic material or metal.

[0077] A front face 4 and/or a rear face 5 define bearing surfaces for connecting two or more devices 1 together along the axis A-A. The bearing surfaces of the front 4 and rear 5 are in a plane perpendicular to the channel axis.

[0078] In order to fix two consecutive adjacent devices together, the front and/or rear faces of the device form an annular surface around the channel 3, this annular surface comprising a plurality of fixing lugs 6. The width of the annular surface is therefore greater at the lugs around the fixing points than between the lugs, thereby strengthening the fixing points. The contact face of each lug is coplanar with the adjacent face 4 or 5 of the channel. Arrangements can be designed to maintain compatibility with existing flanges, whether standardized or not.

[0079] In the illustrated examples, exactly three fixing points are provided, thus enabling isostatic fixing. These three fixing points are provided in three lugs 6 distributed around the opening and thus creating an isostatic fixing plane. The lugs 6 are here distributed with two lugs in the lower corners and one in the middle area of the opposite edge. Other arrangements with lugs 6 in the corners and/or along the edges are possible.

[0080] The lugs have axial apertures 7, which are used to insert fastening elements such as screws, screw/nut assemblies, pins, etc. Other apertures may be provided in the lugs or bearing surfaces to reduce mass. Heat dissipation surfaces may also be provided.

[0081] In order to best meet the desired objectives of reducing mass in relation to the use of flanges, the dimensions of the lugs 6 are greatly reduced in relation to those of the device 1. For example, the lugs 6 are dimensioned so that the total sum of the footprints E is less than one third and more preferably less than one quarter of the external perimeter of the core 2 of the device 1. By footprint is meant the width of the lug at the level of the intersection with the core 2 of the device, as illustrated for example in FIGS. 2 and 4.

[0082] FIG. 3 illustrates an alternative embodiment in which at least one of the lugs 6, and possibly the remainder of the annular surface around the channel, is made of a lattice structure, i.e. comprising beams separated by recesses. Such an architecture further contributes to the objectives of mass reduction, without affecting the rigidity and/or durability of the fixture.

[0083] FIG. 4 illustrates a front view of an all-mesh bearing surface (flange) 4 between the four axial fixing apertures 7. The apertures are reinforced with a reinforcing ring 70 which is denser than the rest of the mesh around each aperture. This design allows the size of the bearing surface 4 to be increased, without significantly increasing its mass, and thus ensures a strictly flat bearing surface even after clamping against the corresponding bearing surface of an adjacent device. The density of the mesh may vary around the periphery of the bearing surface, and may be greater, for example, in the vicinity of the fixing apertures 7 than at a distance from them.

[0084] The tube and its bearing surfaces 6 are preferably produced by additive manufacturing, as described later. This method of manufacturing makes it possible to produce in a simple manner a device provided with bearing surfaces (flanges) of complex shape, for example a tube provided with lugs, and/or a lattice structure.

[0085] FIG. 2 illustrates two aligned devices 1, intended to be fixed together.

[0086] The two devices are intended in this example to be juxtaposed one after the other in the direction of signal transmission, thus forming a continuous elongated longitudinal channel. The bearing surfaces intended to be brought into contact are flat and perpendicular to the direction of transmission of the radio frequency signal.

[0087] The front or rear face of the device may have a central area that is very slightly recessed so that it does not touch the face of the flange of the device or of the connected equipment, but is separated from it by a narrow gap. The recessed area is bounded by a deeper groove in the flange surface. This arrangement allows for short-circuit operation. This central recessed area can also be provided in the case of a lattice flange as described above.

[0088] In the embodiment illustrated in FIG. 5, the inner and outer surface of the core 2 are covered with a conductive metal layer, for example copper, silver, gold, nickel etc, plated by chemical deposition without electrical current. The thickness of this layer is for example between 1 and 20 micrometers, for example between 4 and 10 micrometers. FIG. 5 illustrates the device in which a layer formed by metal deposition forms a conductive coating 8 on the inner surface 9 and on the outer surface of the core 2. The coating may also be a combination of layers, comprising for example a smoothing layer directly on the core, one or more bonding layers, etc.

[0089] In this example, the bearing surfaces (e.g. the lugs 6) also comprise a core covered by the outer conductive layer 8.

[0090] The thickness of this conductive coating 8 or 9 must be sufficient for the surface to be electrically conductive at the chosen radio frequency. This is typically achieved by using a conductive layer with a thickness greater than the skin depth 6.

[0091] This thickness is preferably substantially constant on all internal surfaces in order to achieve a finished part with accurate dimensional tolerances for the channel.

[0092] In one embodiment, the thickness of this layer 8 or 9 is at least five times and preferably at least twenty times greater than the skin depth, in order to improve the structural, mechanical, thermal and chemical properties of the device. The surface currents are thus mainly, if not almost exclusively, concentrated in this layer.

[0093] The application of a metallic coating on the external surfaces does not contribute to the propagation of the radio frequency signal in the channel 3, but does have the advantage of protecting the device from thermal, mechanical or chemical attack. In a non-illustrated embodiment, only the inner surface of the core, around channel 3, is covered with a metal jacket. The outer surfaces are bare, or covered with a different coating.

Additive Manufacturing

[0094] The device 1 is advantageously manufactured by additive manufacturing, preferably by stereolithography, selective laser melting, selective laser sintering (SLS) in order to reduce surface roughness. The core material may be non-conductive or conductive. The wall thickness is for example between 0.5 and 3 mm, preferably between 0.8 and 1.5 mm.

[0095] The shape of the device may be determined by a computer file stored in a computer data medium and used to control an additive manufacturing device.

[0096] The deposition of conductive metal on the inner and possibly outer faces is achieved by immersing the core 2 in a series of successive baths, typically 1 to 15 baths. Each bath involves a fluid with one or more reagents. The deposition does not require the application of a current to the core to be coated.

Reference Numbers Used on Figures

[0097] 1 Passive radio frequency device

[0098] 2 Core

[0099] 3 Channel

[0100] 4 Front side

[0101] 5 Rear side

[0102] 6 Lugs

[0103] 7 Axial fixing aperture

[0104] 70 Reinforcement ring

[0105] 8 Inner conductive coating

[0106] 9 External conductive coating