TWO-WAY HYPERFREQUENCY COUPLER INCLUDING TWO PARALLEL, DOUBLE-RIBBED WAVE GUIDES

The present invention relates to a bidirectional microwave coupler comprising two parallel waveguides, double rib.

In most microwave devices, it is necessary to be able to take a determined part of the signal produced, in order to measure the various parameters defining this microwave signal and, optionally, to correct them according to the conditions of use. This operation is carried out using devices known under the name of couplers, which take a determined percentage of the power conveyed.

The microwave emission sources often delivering high powers, the most suitable means of propagation are the waveguides.

Very wide band directional couplers are known, typically from 1 GHz to 100 GHz, produced in the form of hole couplers, the holes serving to achieve the coupling between the two waveguides.

[0005] An exemplary embodiment of such a hole coupler is illustrated in FIG. 1, from the book “Microwave Engineering”, p. 339, by David M. Pozar, 4ed, Wiley, 2012.

[0006] In FIG. 1 is shown a bidirectional microwave coupler with holes comprising two superimposed parallel waveguides, respectively forming a main path VP and a coupling path VC. The coupler comprises N + 1 holes indexed from n = 0 to n = N.

[0007] Such a multi-hole coupler makes it possible to act on the directivity, as a function of the frequency. Indeed, all the diameters of the holes are as many parameters of an associated function and which make it possible to obtain, for example, a response of the Chebyshev type, or even a response of the binomial type, among the most conventional.

Considering the general case of the multi-hole coupler of FIG. 1, comprising N + 1 equidistant holes coupling the two parallel waveguides, the amplitude of the incident wave in the main path guide VP is A. At each opening, a small fraction of this wave is transmitted to the coupled channel generating on this channel a positively directed wave of amplitude A * Fn and a negatively directed wave of amplitude A * Bn. Fn and Bn are respectively the

Coupling coefficients of the positive wave and the negative wave. The holes are equidistant from a distance d, in m.

[0009] For example, a 20 dB coupler has a power coupling factor of 10 20/1 ° = 0.01, so that the power transmitted by the waveguide is 1 - 0.01 = 0, 99 of the incident power (1% coupled to the upper guide). The voltage (or field) drop in the main path waveguide VP is equal to V0.99 = 0.995, or 0.5%. Thus, the amplitude of the incident field is identical to each hole, but the phase changes from one opening to another.

Also an opening or hole generally excites the opposing traveling waves with different amplitudes. Also, by naming F n the coupling coefficient of the n th hole in the forward direction, and naming B n the coupling coefficient of the n th hole in the back direction, the amplitude of the wave in the forward direction can be written:

[001 1] F = A e ~ jl3Ncl ån = o Fr because all the components travel on a path of the same length.

The amplitude of the wave in the rear direction can be written:

B = A
because the length of the path of the n ' th component is 2 bhά.

[0014] b represents the propagation constant, in rad / m.

The phase reference is taken at the first hole of index 0.

The coupling C and the directivity D can be calculated by the following relationships:

[0018] D = -20 log | £ | = -20 log | ¾ ^ dB

An object of the invention is to reduce the length that is significant for a given directivity.

It is proposed, according to one aspect of the invention, a bidirectional microwave coupler comprising two parallel double-rib waveguides, having two respective faces arranged vis-à-vis and mechanically connected by a metal layer, and comprising antenna assemblies connecting the respective interiors of solid parts outside the ribs of the two waveguides, an assembly

antenna comprising an antenna fixedly mounted in a dielectric insert fixedly mounted in said metal layer.

Thus, the length of such a coupler is reduced compared to a hole coupler of the state of the art, because it allows, compared to the circular openings to obtain a stronger coupling between the main path and the coupled path.

[0022] The length is thus shortened by approximately 30% to 70% compared with a hole coupler. For example, a 100 mm coupler has thus been produced in the 6 to 18 GHz band while retaining good directivity, ie directivity greater than 17 dB.

The spacing between the antennas according to the invention can be significantly less than that necessary for an equivalent coupler with holes, which, if it were of the same length, for example 100 mm, would have a directivity significantly less than 17 dB , of the order of 10 dB.

In one embodiment, a dielectric insert comprises an outer shoulder and an inner shoulder.

The outer shoulder keeps the insert fixed in the metal layer between the two waveguides, and the inner shoulder keeps the antenna fixed in the insert, in a simple manner achieve, and at reduced cost.

In one embodiment, a dielectric insert fixedly mounted in said metal layer has no portion inside the two waveguides.

[0027] Thus, no insert part is found inside the two waveguides, which simplifies the design of the coupler, and facilitates heat exchange.

According to one embodiment, an antenna is cylindrical in shape and provided with a collar intended to be mounted in abutment on the internal shoulder of an insert.

The cylindrical shapes are easy to achieve for the stops, as well as for the shoulders.

In one embodiment, a dielectric insert comprises a fluoropolymer, such as polytetrafluoroethylene (acronym PTFE) which is a fluoropolymer derived from tetrafluoroethylene.

[0031] According to one embodiment, an antenna comprises aluminum and / or copper.

In one embodiment, the metal layer comprises copper and / or aluminum.

The invention will be better understood by studying a few embodiments described by way of non-limiting examples and illustrated by the appended drawings in which:

FIG. 1 schematically illustrates a bidirectional microwave coupler with holes, according to the state of the art;

FIG. 2 schematically illustrates a bidirectional microwave coupler, in perspective, according to one aspect of the invention;

Figure 3 schematically illustrates the bidirectional microwave coupler of Figure 1, in sectional view, according to one aspect of the invention;

FIG. 4 schematically illustrates an antenna assembly, according to one aspect of the invention; and

Figure 5 schematically illustrates a plurality of antenna assembly, in sectional view, according to one aspect of the invention.

In all of the figures, the elements having identical references are similar.

In the present description, the embodiments described are not limiting, and the characteristics and functions well known to those skilled in the art are not described in detail.

Figure 2 schematically shows a bidirectional microwave coupler, in sectional view, according to one aspect of the invention, comprising two parallel waveguides VP, VC, double rib NVP, Nvc, having two respective faces arranged in vis-à-vis and mechanically connected by a metal layer CM.

The two waveguides VP and VC have two respective faces arranged vis-à-vis (vi their large side) and mechanically connected by the metal layer CM, and include EA antenna assemblies connecting the respective interiors of parts solid except ribs Nvc , NVP, of the two waveguides VP, VC.

As shown in Figures 4 and 5, an EA antenna assembly comprises an antenna Ant fixedly mounted in a dielectric insert Ins fixedly mounted in the metal layer CM.

[0044] Thus the coupling is made by the Ant antennas and not by holes as in the state of the art.

The dielectric insert Ins serves both as an electrical insulator and as a support. The insert Ins comprises an EPI internal shoulder and an EPE external shoulder. The EPE external shoulder makes it possible to keep the insert Ins fixed in the metal layer CM between the two waveguides VP, VC, and the EPI internal shoulder makes it possible to keep the antenna Ant fixed in the insert Ins, and this, in a way that is simple to achieve, and at reduced cost.

A dielectric insert Ins can remain external to the two waveguides VP, VC, so no insert part is found inside the two waveguides, which simplifies the design of the coupler and facilitates heat exchanges.

These Ant antennas can vary in diameter and height after optimization, making it possible to obtain better performance in terms of directivity and to reduce the total length of the coupler.

An antenna Ant can be of cylindrical shape and provided with a collar collar mounted in abutment on the internal shoulder of the insert Ins.

The choice of dielectric is made according to the needs of use, taking into account the temperature and the power.

Figure 3 is a sectional view in the longitudinal direction of the coupler of Figure 2.

CLAIMS

1. Bidirectional microwave coupler comprising two parallel waveguides (VP, VC), double rib (NVP, NVC), having two respective faces arranged opposite and mechanically connected by a metal layer (CM), and comprising antenna assemblies (EA) connecting the respective interiors of solid parts except ribs of the two waveguides (VP, VC), an antenna assembly (EA) comprising an antenna (Ant) fixedly mounted in a dielectric insert (Ins) mounted fixed in said metallic layer (CM).

2. Coupler according to claim 1, wherein a dielectric insert (Ins) comprises an outer shoulder (EPE) and an inner shoulder (EPI).

3. Coupler according to one of the preceding claims, wherein a dielectric insert (Ins) fixedly mounted in said metal layer (CM) has no portion inside the two waveguides (VP, VC).

4. Coupler according to one of the preceding claims, wherein an antenna (Ant) is cylindrical in shape and provided with a collar (Col) intended to be mounted in abutment on the internal shoulder (EPI) of an insert ( Ins).

5. Coupler according to one of the preceding claims, wherein a dielectric insert (Ins) comprises a fluoropolymer.

6. Coupler according to one of the preceding claims, wherein an antenna (Ant) comprises aluminum and / or copper.

7. Coupler according to one of the preceding claims, wherein the metal layer (CM) comprises copper and / or aluminum.