EP0605046B1 - Microwave device comprising at least one transition between a transmission line integrated on a substrate and a waveguide - Google Patents

Description

The invention relates to a microwave device comprising at least one transition between a line of transmission integrated on a substrate, arranged in a said first microwave cavity, and a waveguide formed of this second microwave cavity, this transition comprising an open end of the integrated line forming probe inserted into the guide cavity, at a distance of one short circuit closing the end of the guide, this transition further comprising an impedance adapter system.

The invention finds its application in microwave devices which include on the one hand integrated circuits and secondly waveguides, which must be connected to each other. The invention finds therefore its application in the field of antennas television, and in the field of radars for automobiles, among others.

A transition between a waveguide and a line microstrip is already known from the publication in "1988 IEEE MTT-S Digest, P.4, pp.473-474 ", entitled" Waveguide-To-Microstrip Transitions FOR MILLIMETER-WAVE Applications "by Yi-Chi SHIH, Thuy-Nhung TON, and Long Q.BUI, belonging to Hughes Aircraft Company, Microwave Products Division, TORRANCE, California, USA.

This publication describes a transition between a microwave line of the microstrip type, disposed in a first microwave cavity, and a waveguide formed of a second microwave cavity. This transition includes an open end of the integrated line which is introduced into the waveguide, perpendicular to its axis of propagation, through an opening made in a wall of the waveguide. In this way, the electric field propagation plans E of the probe and the guide coincide. This transition further comprises an impedance adapter system applied to the integrated line which consists of a narrowing over a certain length of the microstrip at the surface of the substrate. This length is intended to form a quarter-wave adapter so as to tune the input impedance of the probe to 50 Ω. The end of the short-circuit waveguide is located at a distance L from the microstrip conductor and the probe-forming end of the latter enters the guide to a depth D. By carefully adjusting these dimensions, the known device can be broadband in the K frequency band (18-26 GHz).

However, to date, in the field of telecommunications, we are using more and more circuits planar integrated operating at very high frequencies between 40 GHz and 100 GHz. These integrated circuits include general of planar transmission lines, for example from type called microstrip, and are connected to each other, or connected to antenna elements, by means of waveguides.

These planar integrated circuits, operating at these frequencies so high, require appropriate boxes able to preserve their performance. They require plus devices capable of transitioning between their input / output pads and the waveguides of connection.

Regarding the boxes, they must have very high microwave qualities, which are specific to the working frequency of the circuits. Focus must be put particularly on the perfection of the contacts of mass, and on that of the microwave links between the I / O pads for integrated circuits and components external, connections which must be carried out by means of wires conductors, for example in gold, very short and very thin, subject to the various studs by means of micro-welds, performed for example by thermocompression. The focus should be also put on the mechanical resistance and the tightness of boxes which must preserve the integrated circuits of dust and corrosion liable to deteriorate their electrical qualities; indeed, many circuits microwave frequencies used in telecommunications are positioned on antenna mounts or on vehicles and undergo therefore bad weather.

With regard to the devices carrying out a waveguide / transmission line transition, they must be both compatible with standard waveguides, and with the integrated circuit microwave inputs / outputs. In in addition, these devices must have all the qualities mechanical and electrical defined above for enclosures. In particular, these devices must be waterproof and not not cause leaks between the guides wave and integrated circuits. Electrical connections between this kind of transition device and a circuit integrated given must meet more defined conditions high relative to perfection of microwave contacts and ground contacts.

In addition, these transitional arrangements must show good adaptation, in a wide band of frequencies, and at frequencies as high as 40 GHz at 100 GHz.

• qui permette de raccorder un guide d'onde à un circuit intégré d'une manière étanche,
• qui permette de réaliser industriellement des connexions hyperfréquences avec un circuit intégré avec la perfection requise,
• qui présente une adaptation facile à réaliser industriellement, aux hyperfréquences envisagées.

The device known from the cited document does not provide a waveguide / transmission line transition:

• which allows a waveguide to be connected to an integrated circuit in a sealed manner,
• which enables microwave connections to be made industrially with an integrated circuit with the required perfection,
• which presents an adaptation easy to carry out industrially, to the microwaves envisaged.

First of all, the known device of waveguide / transmission line transition does not allow to obtain the non-rupture of the seal which is required for the microstrip line. The latter is carried out on a substrate by an integrated circuit technique. The cavity which receives must therefore, for the reasons explained above, be waterproof against the waveguide. Now, the planar substrate which supports the probe end inserted in the guide wave does not close the guide cavity, since the dimension transverse of the substrate is less than the magnitude "a" of the straight section of the guide.

Then the realization of the electrical adaptation is delicate. To make the transition, you have to do penetrate the line from a distance D, less than the dimension "b" of the guide, in the cavity of the guide. The end of the line therefore forms an open circuit which radiates. You must then place judiciously at a distance L = λ / 4 from said line, a plane metal forming a short circuit for the guide, which closes this guide perpendicular to the direction of propagation, so as to ensure maximum power propagation radiated in this transition. The radiation is therefore tunable by the distance L of the short circuit which is fixed. This transition then requires an impedance transformer which consists of a narrowing of the microstrip conductor to proximity to the probe. This kind of technology is difficult to industrially implement when the designer of microwave devices is facing the problem of realize consumer devices as is the case in television or automotive. Then that the performances obtained are not sensitive to manufacturing tolerances; however, in the case of this narrowing of the conductor, they are.

In addition, the substrate used to achieve the known device, is made of a flexible material (Duroid) which has several special features. In the known device this flexible substrate is used for two reasons: the first reason is that the transverse dimensions of the substrate are necessarily, for reasons of adaptation, very small, and that only a flexible substrate can support such small dimensions: the second reason is that flexible substrates have a low permeability of the order of 2, while the hard substrates, such as alumina, have good permeability higher, of the order of 8 to 10, much further from the air permeability (1). It turns out that this flexible substrate is a disadvantage for making electrical connections microwave using very fine gold wires because of its flexibility, the technology of fixing the wires by thermocompression cannot be used. The realization of interconnections between a flexible substrate and "a chip" or integrated circuit hard substrate is a problem that the man of the profession does not know how to solve well to date. So this kind interconnection should be avoided, so that the designer of microwave devices can count on good performance industrial manufacturing.

Consider the dimensions involved in this state of the art. With reference to FIG. 1a of document cited, the large dimension "a" of the guide is 3.8 mm. The substrate that is introduced into the guide is much less wide: its width is approximately half of "a" or 1.9 mm. The distance between the two waveguides in the double assembly transition, also described in the cited publication, is 18 mm. In this known device, the dimensions of the substrate are so finally 1.9 mm x 18 mm. These dimensions make the very fragile substrate. this is why, in the known assembly, the substrate cannot be made of a material other than flexible.

An object of the invention is therefore to avoid these disadvantages, and in particular to provide a device for transition between a guide and a transmission line, capable to house an integrated circuit with the required performance for a box: able to allow a connection between the line of transmission and the microwave pad of the case which is easy to carry out industrially, and reliable; and who ensures tightness of both the transmission line and the circuit integrated and the connection between these two elements.

This goal is achieved by the defined device in the preamble and further characterized in that, first, the substrate is made of a permeability material of the order of 8 to 10, and in this that, next, the impedance adapter system includes apart from a restriction of the dimension of said first cavity microwave perpendicular to the direction of propagation, over a length parallel to the direction of propagation in the integrated line, and also includes a restriction on dimensions of the cross section of the waveguide in the region between the plane of the probe and the short-circuit plane.

• les moyens d'adaptation qui sont appliqués à la fois à la cavité du guide et à la cavité de la ligne permettent d'utiliser un substrat de dimension transversale environ double de celui de l'état de la technique, d'où il résulte que ce substrat peut être dur ;
• le substrat de permitivité élevée pourra être un matériau dur qui permet d'effectuer des soudures par thermocompression sur le conducteur de la ligne et donc d'obtenir de bons contacts hyperfréquences ;
• le substrat étant à la fois dur et plus large que le substrat connu est apte à s'étendre transversalement sur toute la section droite du guide pour la fermer et ainsi rendre étanche la cavité de la ligne, cette fermeture étant d'autant plus facile que la cavité du guide à des dimensions restreintes dans cette région.

This device shows several advantages which interact with each other:

• the adaptation means which are applied both to the cavity of the guide and to the cavity of the line make it possible to use a substrate with a transverse dimension approximately twice that of the prior art, from which it follows that this substrate can be hard;
• the substrate of high permissibility could be a hard material which makes it possible to perform thermocompression welding on the conductor of the line and therefore to obtain good microwave contacts;
• the substrate being both hard and wider than the known substrate is able to extend transversely over the entire cross section of the guide to close it and thus seal the line cavity, this closing being all the easier as the cavity of the guide to restricted dimensions in this region.

In one implementation, this device is characterized in that in the region of the probe, this substrate covers the entire cross section of the waveguide, to produce the sealing of the line cavity.

• la cavité de la ligne étant étanche peut recevoir un circuit intégré ;
• ce circuit intégré aura une liaison hyperfréquences de très bonne qualité avec la ligne, du fait du substrat dur ;
• le système d'adaptation de ce dispositif de transition est meilleur que l'adaptateur connu ;
• la bande de fréquence de fonctionnement de ce dispositif de transition peut aussi être notablement étendue.

The advantages are that:

• the cavity of the line being sealed can receive an integrated circuit;
• this integrated circuit will have a very good microwave link with the line, due to the hard substrate;
• the adaptation system of this transition device is better than the known adapter;
• the operating frequency band of this transition device can also be significantly extended.

• la FIG.1A représente le substrat avec le conducteur de la ligne de transmission, et en pointillé la projection de la partie de cavité hyperfréquences, côté conducteur de la ligne, vu du dessus ;
• la FIG.1B représente le substrat avec le conducteur de la ligne de transmission, et en pointillé la projection de la cavité du guide d'onde, côté face du substrat opposée à celle qui reçoit le conducteur vu du dessus ;
• la FIG.1C représente en coupe le dispositif de transition entre un guide d'onde et une ligne de transmission du type microruban selon les FIG.1A et 1B ;
• la FIG.2A représente en vue plane, la lame métallique supérieure avec le court-circuit du guide et le logement pour un circuit intégré ;
• la FIG.2B représente en vue plane, une lame métallique intermédiaire entre le substrat côté conducteur de la ligne, et la lame métallique supérieure, cette lame intermédiaire ayant les découpes pour les systèmes adaptateurs et la découpe pour le logement d'un circuit intégré ;
• la FIG.2C représente en vue plane, une lame métallique qui support directement le substrat côté plan de masse ;
• la FIG.2D représente en vue plane une lame métallique dite inférieure avec un entonnoir entre la partie adaptateur du guide d'onde et le guide d'onde lui-même ;

d'une manière générale les FIG.2 représentent des lames métalliques assemblables pour réaliser une double transition ligne de transmission/guide d'onde.The invention is described below in detail, with reference to the appended schematic figures including:

• FIG.1A shows the substrate with the conductor of the transmission line, and in dotted line the projection of the microwave cavity part, driver side of the line, seen from above;
• FIG.1B represents the substrate with the conductor of the transmission line, and in dotted line the projection of the cavity of the waveguide, side face of the substrate opposite to that which receives the conductor seen from above;
• FIG.1C shows in section the transition device between a waveguide and a microstrip type transmission line according to FIG.1A and 1B;
• FIG.2A shows in plan view, the upper metal strip with the short-circuit of the guide and the housing for an integrated circuit;
• FIG.2B shows in plan view, an intermediate metal strip between the substrate on the conductor side of the line, and the upper metal strip, this intermediate strip having the cutouts for the adapter systems and the cutout for housing an integrated circuit;
• FIG.2C shows in plan view, a metal strip which directly supports the substrate on the ground plane side;
• FIG.2D shows in plan view a so-called lower metal blade with a funnel between the adapter part of the waveguide and the waveguide itself;

in general, FIG. 2 represents metal blades which can be assembled to make a double transition between the transmission line and the waveguide.

FIG.1C shows in section a waveguide / transmission line transition device. The waveguide itself is constituted by the hollow metallic piece 100 which has a rectangular cross section: the short side of dimension b1 is in the plane of FIG.1C, and the long side of dimension a1 is perpendicular in the plan of FIG.1C. The electric field E symbolized by an arrow, is parallel to the short side b1 and propagates in the rectangular cavity 102a.

The transition includes a blade-shaped part said base, or lower blade 1, metallic, attached by fixing means, not shown, for example screws, of a part to guide 100, and secondly to support 2 of substrate 23 of the transmission line. The lower blade 1 has a opening 12a in the extension of opening 102a of the guide wave; and the metal support 2 has an opening 22a in the extension of the opening 12a in the lower part.

In addition the transition includes a shaped part metal blade 3 called upper intermediate which is positioned and fixed above the support 2, the substrate 23 being itself disposed in its support with the conductor 24 of the transmission line on its upper face. This blade upper intermediate 3 includes an opening 32a in the extension of the openings 102a, 12a, 22a of the underlying parts.

The transition adapter system includes a narrowing of the waveguide dimensions in the section located between the transmission line and the short circuit plane. To this end, the opening 22a of the support blade 2, and the opening 32a of the upper intermediate blade 3, are rectangular, with the short side of the dimension rectangle b2 <b1 and parallel to b1 and the short side of the opening 102a of the guide: and with the long side of the dimension rectangle a2 <a1, and parallel to a1 the long side of the opening 102a of the guide. The transition between the guide itself 102a, from dimensions a1 x b1, and the narrowed upper part formed by openings 22a, 32a, of dimensions a2 x b2 is made by the opening 12a of the lower blade 1, this opening 12a having a funnel shape, with a smaller dimension of opening equal to a1 x b1 of the guide, and a dimension upper opening equal to a2 x b2 of the upper part shrinking. We will call hereafter the narrowed parts 22a, 32a undersized guide parts.

FIG. 1A and 1B represent the substrate 23 seen from face. The transmission line is made using so-called technology microstrip which comprises a substrate 23, a line conductor formed of the microstrip 24 deposited on the upper face of the substrate 23 and a ground plane formed on the opposite face.

The waveguide / transmission line transition is done by introducing the end 25a of the conductor 24, of a length ℓ in the cavity of the guide formed by the openings 102a, 12a, 22a, 32a. In this cavity, the maximum power is transmitted between the guide and the line, because the short circuit 42a is arranged at a distance D from the end 25a of the probe line. This distance D is created by the thickness of the upper intermediate piece 3.

In FIG. 1A, the dotted line shows the projection of the cavity 32a, 33a and 41 made in the blade intermediate 3 for the microwave line formed from the substrate 23 and conductor 24. So that the narrowed cavity 32a is rectangular or nearly rectangular so that produce the desired adaptation, the cavity 31 of the line has a narrowing 33a over a certain length L parallel to the line conductor 24. The dimension L on which is practiced the narrowing, and the dimension of the narrowing itself in part 33a is not critical.

The substrate 23 is arranged in a groove 26 practiced in the support 2, to its dimensions. As shown on FIG. 1A and 1B, this substrate is rectangular, and its width is roughly equal to the large dimension a1 of the waveguide himself.

In FIG. 1B, the dotted line shows the projection of the cavities 22a and 32a of dimensions a2 x b2 and the projection of cavity 102a from the guide dimension a1 x b1.

The substrate 23 for making the line of microstrip transmission is chosen from a hard material, by example of quartz or alumina or a ceramic. Of a generally the permissiveness of hard materials for microwave substrates is in the range of 8 to 10, i.e. much larger than that of flexible materials which is around 2: the air permissiveness being 1.

This results in a big change in the functioning in microwave.

In the embodiment of the guide transition wave / line described with reference to FIG.1, the substrate hard 23 is chosen of appropriate dimensions to close the cavity 102a, 12a, 22a of the waveguide in the upper part of opening 22a. This is possible because the dimensions of this substrate are greater than those of this opening.

• l'adaptation peut être obtenue avec un substrat dur de grande dimension a1, à peu près double de ce qui était connu de l'état de la technique, donc suffisamment grande pour que ce substrat soit réalisable industriellement ;
• ce substrat dur a alors les dimensions nécessaires à la fermeture du guide, c'est-à-dire à la création d'une étanchéité pour la ligne ;
• l'adaptation est obtenue par la réalisation d'un étrécissement de la partie supérieure du guide, facile à réaliser, et favorable à l'étanchéité ; l'autre rétrécissement 33a n'étant pas critique du fait qu'il ne sert qu'à permettre à la cavité 32a d'être rectangulaire ;
• l'utilisation du substrat dur permet non seulement l'étanchéité de la cavité de ligne, mais encore de pouvoir réaliser de bons contacts par thermo-compression, sur le conducteur de ligne ;
• enfin la partie 41 de la partie supérieure 1, qui se trouve dans la zone étanche de la cavité 31 de ligne, peut recevoir sans encombre un circuit intégré bien protégé. La partie 41 est un agrandissement vers le haut de la cavité hyperfréquences 31 de la ligne.

It appears that the choice of a hard substrate produces a favorable change in microwave operation for several reasons:

• the adaptation can be obtained with a large hard substrate a1, roughly double what was known in the state of the art, therefore large enough for this substrate to be industrially feasible;
• this hard substrate then has the dimensions necessary for closing the guide, that is to say for creating a seal for the line;
• the adaptation is obtained by making a narrowing of the upper part of the guide, easy to produce, and favorable to sealing; the other narrowing 33a is not critical in that it only serves to allow the cavity 32a to be rectangular;
• the use of the hard substrate not only makes it possible to seal the line cavity, but also to be able to make good contacts by thermo-compression, on the line conductor;
• finally the part 41 of the upper part 1, which is in the sealed zone of the line cavity 31, can safely receive an integrated circuit that is well protected. Part 41 is an upward enlargement of the microwave cavity 31 of the line.

The problem that arises when adopting a substrate with a permitivity as high as that of a hard substrate (about 8 to 10) is that the line cavity, and the cavity at the line / guide transition must be fine studied because excitement of higher modes occurs there which are centered on frequencies relatively close to those of the operating band and which constitute a phenomenon which renders the action of the adaptation system ineffective known. The problem is therefore to move the frequencies away from these higher modes.

This problem is solved by practicing the narrowing of the upper part of the guide materialized by parts 22a, 32a. At the same time, this solution allows obtain a frequency band widened towards the frequencies high. Thus, this new means of adaptation makes it possible to obtain a better adaptation of the order of 22 dB at 70 GHz instead of the known 15 dB, the possibility of working up to frequencies of the order of 100 GHz, and further better sealing the transition.

Indeed, the person skilled in the art will choose to carry out with the parts 22a, 32a, an undersized guide which allows to reject the appearance of modes higher than frequencies very high, much higher than the frequencies at which currently wish to work in the field of telecommunications: for example higher than 110 GHz. In this indeed the skilled person will choose an undersized guide structure 22a, 32a having a fair cutoff frequency higher than the frequency at which he wishes to work, then it will adjust the distance D from the short circuit plane to optimize the coupling between probe 25a at the end of the microstrip line, and the waveguide.

So, in this device, instead of oversizing the waveguide opposite the line like this was known from the state of the art, the problem is solved by undersizing the guide with respect to the line. The adoption of a hard substrate in this device creates a disturbance which is used to carry out the adaptation of the line guide. The undersizing of the guide allows position the useful frequency band. The higher the frequency the higher the guide, the smaller the guide will be.

Examples of dimensions will be given below. appropriate to perform the different parts of the transition, depending on the frequency sought.

FIG. 2 represent in plan view the different parts of the transition as shown in section in FIG. 1C. The elements represented in FIGS. 2A to 2A also allow for a double transition, that is to say a transition per transmission line of the type microstrip between two waveguides having cavities respectively 102a, 102b of dimensions a1 x a2. The different parts 1, 2, 3, 4 are metal blades or metallic.

FIG.2D represents the lower blade 1 of the device, or base, which shows the trace of two openings in shape of truncated pyramids 12a, 12b respectively corresponding to the funnel-shaped transition between the waveguide cavities having the dimensions a1 x b1, and those of undersized guides in the region included between probe ends 25a, 25b and short circuits 42a, 42b.

FIG. 2C represents the support plate 2 of the substrate 23. This support blade has a groove 26 of just dimensions higher than those of the substrate, rectangular, with enlargements 21 on the long sides of the substrate, the small ones sides of the substrate being substantially equal to the large dimension a1 of the guides, and the large dimension of the substrate being suitable for receiving a connection line between two waveguides, that is to say at least 18 mm; the substrate is intended to be glued in the bottom 27 of the groove 26, which must therefore have a depth at least equal or substantially equal to the thickness of the substrate. When gluing, the back side of the substrate is applied by gluing in the bottom 27 of the groove 26 and the excess glue comes out through the enlargements 21. The substrate 23 may have a ground plane on its rear face, in the part in contact with the bottom of the groove, or we use the bottom of this groove as ground plane, the glue being chosen to be conductive. There is also a realization of transmission line, called coplanar, where the ground plane is made on the same face of the substrate as the Line driver.

The ends of the conductor 24, produced at the upper part of the substrate, arrive substantially in the center openings 22a, 32a, the trace of which is shown in dotted on FIG. 2C.

FIG. 2B represents the intermediate blade upper 3 with cutouts 32a, 32b to form the guides narrowed (or undersized) narrowing 33a, 33b forming the microwave cavities of the line of transmission, and the cavity 31 to receive an integrated circuit to connect with the transmission line. The trace of the substrate 23 is shown in dotted lines in this FIG. 2B. Thickness of this blade 3 is D.

FIG. 2A represents the upper blade 4 called cover that closes the microwave cavity of the line and constitutes the short-circuit plans 42a, 42b. This blade upper 4 is also thick enough to present a recess 41 suitable for containing the integrated circuit at connect to the transmission line.

The different blades 1, 2, 3, 4 and the waveguides 100 (not shown in FIG.2) are subject to each other for example by screws, after mounting of the substrate 23 and connections with the integrated circuit (which is also not shown), which is positioned in cavity 41.

Example of realization

The dimensions of the parts of the transition device described above are given by way of non-limiting example in order to obtain operation in the frequency band.
50 to 90 GHz.
These dimensions are given for a double transition, of the type represented in FIG. 2:
a1 = 3.8 mm b1 = 1.9 mm
a2 = 3.1 mm b2 = 1.5 mm
L = 4 mm
ℓ = (b2 / 2) + (b2 / 10)
D = 1.8 to 2.4 mm for a frequency 55 GHZ.
Substrate material = Alumina (Al ₂ O ₃ )
Permitivity of the alumina material ε = 9.6
Alumina substrate thickness = 0.127 mm
Microstrip conductor width = 0.127 mm
Total length of the substrate = 18 mm
Total substrate width = 4 mm
Transverse dimension of the line cavity restriction (33a, 33b) = 1 mm
Losses by unbalance for the 2 transitions and the 18 mm line: 20 to 25 dB (better than the state of the art which obtains 15 dB)
Insertion losses ≃ 2.3 dB equivalent to the state of the art.

Claims (11)

1. Microwave device comprising at least one transition between a transmission line (24) integrated on a substrate (23), disposed in a first microwave frequency cavity (31), and a waveguide (100) formed by a second microwave frequency cavity (102a, 102b), this transition comprising an open end (25a, 25b) of the integrated line which end forms a probe inserted into the cavity of the waveguide, at a distance from a short-circuit (42a, 42b) which closes off the end of the waveguide, this transition further comprising an impedance adapting system, characterized in that first the substrate (23) is of a material having a dielectric constant of the order from 8 to 10 and in that secondly the impedance adapting system comprises a dimensional restriction (33a, 33b) of said first microwave frequency cavity which is perpendicular to the direction of propagation over a length parallel with the direction of propagation in the integrated line (24), and also comprises a restriction of the dimensions of the cross section of the waveguide in the area (22a, 32a; 22b, 32b) between the probe (25a, 25b) and the short-circuit plane (32a, 42b), forming in this area a part of the waveguide called undersized waveguide.
2. Device as claimed in Claim 1, characterized in that in the area of the probe the substrate (23) covers the whole cross section of the waveguide so as to seal the line.
3. Device as claimed in Claim 2, characterized in that the integrated line (24) is a microstrip line formed by a microwave frequency conductor in the form of a strip realised on a surface of the hard substrate (23) whose other surface carries a ground plane disposed in contact with a groove (27) of said first cavity of said first microwave frequency cavity (31) or formed by said groove (27).
4. Device as claimed in Claim 3, characterized in that the cavity (31) of the transmission line (23, 24) comprises a seaied housing (41) for an integrated circuit to 'oe connected to this line.
5. Device as claimed in one of the Claims 1 to 4, characterized in that it comprises various parts (1, 2, 3, 4) which are metallic or metal plated and have the form of sheets, having grooves for forming cavities for the waveguide(s) and a cavity for the microwave line, these sheets (1, 2, 3, 4) being superimposed by their opposite recessed parts and their grooves interconnected to form uninterrupted microwave frequency cavities.
6. Device as claimed in Claim 5, characterized in that said metallic or metal plated sheets form a first part called lower part (1, 2) which accommodates the substrate (23) of the integrated line in a recess (26) whose bottom (27) is in contact with or forms the ground plane of the line, which has a cavity (22a, 22b) of an undersized waveguide disposed in the extension of a waveguide (102a, 102b), and which has a waveguide transition (12a, 12b) to change dimensions of the waveguide to the dimensions of the undersized waveguide (22a, 22b), the dimensions of the substrate (28) in the area of the probe being provided to cover the whole cross section of the undersized waveguide (22a, 22b) so as to close off the cavity (31) of the transmission line with respect to the waveguide, and in that said metallic or metal plated sheets form a second part called upper part (3, 4) to hermetically seal the line cavity (31) which comprises a cavity (32a, 32b) of the undersized waveguide disposed in the extension of the undersized waveguide of the lower part (1, 2), closed off by a plane (42a, 42b) that forms the short-circuit of the waveguide, which comprises a cavity (31) for the transmission line and which comprises a narrowing (33a, 33b) of this cavity, to form, together with the undersized waveguide (22a, 32a; 22b, 32b) the impedance adapter.
7. Device as claimed in Claim 6, characterized in that the second part called upper part is itself formed by two sheets (3 and 4), one upper intermediate metallic or metal plated sheet (3) including a recessed part (31) for forming the cavity of the line, ending up on either one of the two sides of the sheet (3), this cavity (31) having the narrowing (33a, 33b) and this sheet (3) including the cavity of the undersized waveguide (32a, 32b) provided between the probe and the short-circuit of the waveguide, to realise the impedance adapter, and a sheet called lid (4) to close off the first microwave frequency cavity (31) and to form (a) short-circuit plane(s) (42a, 42b) for the waveguide(s).
8. Device as claimed in Claim 7, characterized in that the sheet called lid (4) has a cavity (41) in the area that does not coincide with the narrowing (33a, 33b) for accommodating accessory microwave devices.
9. Device as claimed in one of the Claims 7 or 8, characterized in that the upper intermediate sheet (3) defines by its thickness (D) the distance between the probe (25a, 25b) and the respective short-circuit planes (42a, 42b) of the waveguides.
10. Device as claimed in one of the Claims, 7 or 8, characterized in that the first part called lower part is formed itself by two sheets (1 and 2), one sheet called base sheet (1) having an opening (12a, 12b) in the form of a funnel to form the transition between the waveguide (102a, 102b) and the undersized waveguide (22a, 22b), and a sheet called support sheet (2) to be disposed between the base (1) and the upper intermediate sheet (3), comprising part of the undersized waveguide (22a, 22b), and having a recess (26) for accommodating the substrate (23) which stretches out across the undersized opening (22a, 22b), the substrate (23) comprising the microstrip conductor (24) on its surface opposite to the surface contacting the flat bottom (27) of the groove (26).
11. Device as claimed in one of the Claims 1 to 10, characterized in that it comprises two transitions disposed each on one of the ends of the integrated transmission line, with an impedance adapter associated with each of these transitions, in that an integrated circuit is arranged in a cavity (41) and connected to the transmission line, and in that the waveguides (102a, 102b), the parts of the undersized waveguides (22a, 32a, 22b, 32b) and the transitions between waveguides and undersized waveguides (12, 12b) have rectangular cross sections.

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