EP0205212B1 - Modular microwave antenna units and antenna composed of such units - Google Patents

Description

The invention relates to a microwave antenna for reception on emission of a rectilinearly polarized wave, comprising at least one unit module comprising four radiating elements in the form of horns whose openings form a two-dimensional pattern in a plane parallel to a plane of reference P, and comprising a supply network composed of rectangular section waveguides connected on the one hand to the horns and on the other hand between them so that for each horn the total length of the feed path is the same , the section of the waveguides being of dimensions a and b defined by the relations a> b, and the small dimension b being placed parallel to the reference plane P in the planar network so that the latter is able to propagate the mode TEoi, this supply network being of the so-called "planar" type because it is distributed in a single plane parallel to the reference plane P, and of the so-called "arborized" type because that the horns are supplied in phase using power dividers.

The invention finds its application, for example in the production of flat antennas for the reception of television broadcasts retransmitted by artificial satellites.

• Le réseau d'alimentation en guide d'onde est du type dit "planaire" du fait qu'il est distribué dans un seul plan parallèle au plan des ouvertures, et est du type dit "arborisé" du fait que les cornets sont alimentés en phase à l'aide de diviseurs de puissance. La section des guides d'onde est de dimensions a et b définies par la relation b > a, la petite dimension a étant placée parallèlement au plan du réseau planaire en sorte que ce dernier est apte à propager le mode TEo selon lequel le vecteur champ électrique É se propage parallèlement au plan de ce réseau d'alimentation. Les branches des diviseurs de puissance sont telles qu'elles permettent la propagation du vecteur champ électrique É perpendiculairement à leurs parois perpendiculaires au plan du réseau. Cependant, ce dispositif comporte des portions de guides d'onde de forme hélicoïdale. De ce fait, il est réalisé au moyen de tronçons de tubes métalliques de section rectangulaire auxquels on donne la forme souhaitée pour le réseau d'alimentation.

It is already known from US-A-2,540,839, with reference to FIG. 22 of this document, a unitary microwave antenna module for the reception or emission of a rectilinearly polarized wave comprising radiating elements in the form horns and a supply network composed of rectangular section waveguides connected on the one hand to the horns and on the other hand between them. For each horn the total length of the feeding path is the same, the horns being four in number and their openings forming a two-dimensional network.

• The waveguide supply network is of the so-called "planar" type because it is distributed in a single plane parallel to the plane of the openings, and is of the so-called "arborized" type because the horns are supplied with phase using power dividers. The section of the waveguides is of dimensions a and b defined by the relation b> a, the small dimension a being placed parallel to the plane of the planar network so that the latter is able to propagate the TEo mode according to which the vector field electric É is propagated parallel to the plan of this supply network. The branches of the power dividers are such that they allow the propagation of the electric field vector E perpendicular to their walls perpendicular to the plane of the network. However, this device includes portions of helical waveguides. As a result, it is produced by means of sections of metal tubes of rectangular section to which the desired shape is given for the supply network.

An antenna comprising radiating elements in the form of horns supplied by waveguides is also known from patent DE 2641711. This document describes a linear antenna module, consisting of a row of horns machined from a fiber block. glass with metallic surfaces. This row of horns is supplied on the one hand by a main line and on the other hand by individual lines connected to the main line. The main line is of rectangular section, machined in aluminum and can be filled with a dielectric material. It is carried out so as to form in the plane of the electric field E a stepped power divider making it possible to supply at equal power the waveguides which ensure the individual connection of the horns with the main line. Each of these waveguides, of rectangular section, is formed by a laminated structure comprising a dielectric material interposed between two layers of copper, the edges of this structure being metallized. The length of the individual feed guides, as well as their connection point to the main line, are chosen so that for each horn, the length of the feed path composed of the main line and the individual feed line, is the same. Such a structure is provided to allow phase differences in the feeding of the horns to be corrected by shortening some of the individual feeding lines.

However, such an antenna has many drawbacks. First of all, it necessarily has very high losses because the propagation of the waves in a dielectric medium such as that which constitutes the layered structure of the individual supply lines of the horns is always subject to high losses even if the dielectric is very good quality. The introduction of an identical dielectric material in the main line further increases the losses. Added to this is the fact that the price of a good quality dielectric material is always very high and considerably increases the cost of the antenna.

Then, the antenna module described in the cited document is of linear form, with series supply, which makes it very difficult to feed the horns exactly in phase and therefore it is essential to carry out a adjustment of the length of the individual supply lines to improve this result. However, it remains difficult to supply all the horns exactly in phase if a wide operating frequency band is required. In addition, the solution proposed by the cited document to solve this problem, leads to a complex antenna shape, as well as an assembly and a adjustment too delicate to be carried out for example during a mass production.

This is why the present invention proposes a new microwave antenna module which is free from these drawbacks.

According to the present invention, these problems are solved by a microwave antenna as described in the preamble, characterized in that, in this module, the power dividers are T-shaped whose branches are symmetrical, in that the openings of the horns are square and form in a plane parallel to the reference plane P, a two-dimensional network of square shape obtained by the fact that the openings of the horns are deduced from each other by translations of the same pitch along axes parallel to their sides, in that that the large dimension a of the waveguides is a = ÀJ2 where À _c is the cut-off wavelength of the guides, in that each internal horn mouthpiece of cross section equal to that of the waveguides is individually connected to a waveguide of the grating by an elbow whose angle is in a plane parallel to a plane Q, this plane Q being defined as perpendicular to the reference plane P and parallel to one of he sides of the square opening of the horn as well as to the large dimension a of the internal mouth of the latter, in that each individual feeding guide is linear and connected to one of the symmetrical linear branches of a first T-shaped power divider by an elbow whose angle is located in the plane of the network, the main branch of this power divider being curved, in that each group of two horns thus formed is connected to one symmetrical curved branches of a second T-shaped power divider, the main branch of which is also curved, so that the two groups of two horns thus formed are fed symmetrically with respect to a plane Q ', this plane being defined as perpendicular both to the reference plane P and to the plane Q and so that the curvature of the branches of the two power dividers allows the propagation of the mode T _oi , this antenna being made up of two plates , the surfaces of which are electrically conductive, the horns being formed in the thickness of the first plate, the openings of the horns opening onto the first face of this plate and the mouths on the second face, the guide supply network being formed by grooves made on the first face of the second plate, these grooves constituting three of the four faces of the guides and the application of the second face of the first plate on the first face of the second plate forming the fourth face of the guides and the connections with cones.

The present invention also provides a microwave antenna as described in the preamble, characterized in that, in this module the power dividers are T-shaped whose branches are symmetrical, in that the openings of the horns are square and form in a plane parallel to the reference plane P, a two-dimensional network of square shape obtained by the fact that the openings of the horns are deduced from each other by translations of the same pitch along axes parallel to their sides, in that the large dimension has waveguides is a = À _c / 2 À _c is the cut-off wavelength of the guides, in that each internal horn mouthpiece of cross section equal to that of the waveguides is individually connected to a guide d grid wave by an elbow whose angle is in a plane parallel to a plane Q, this plane Q being defined as perpendicular to the reference plane P and parallel to one of the sides of the open square urea of the horn as well as to the large dimension a of the internal mouth of the latter, in that each individual feeding guide is linear and connected to one of the symmetrical linear branches of a first power divider in T shape by an elbow whose angle is located in the plane of the network, the main branch of this power divider being curved, in that each group of two horns thus formed is connected to one of the symmetrical curved branches d 'a second T-shaped power divider, the main branch of which is also curved, so that the two groups of two horns thus formed are fed symmetrically with respect to a plane Q', this plane being defined as perpendicular to both to the reference plane P and to the plane Q and so that the curvature of the branches of the two power dividers allows the propagation of the Toi mode, this antenna consisting of two plates, the surfaces of which are electrically conductive, the horns being formed in the thickness of the first plate, the openings of the horns opening on the first face of this plate and the mouths on the second face, the guide supply network being formed by hollow grooves formed on this second face, and constituting three of the four faces of the guides, the second plate having a first planar face and the application of the second face of the first plate on the first face of the second plate forming the fourth face of the guides and the connections with the horns.

The antenna produced according to the present invention offers numerous advantages. First of all, it has losses as low as possible because it is entirely supplied by waveguides excluding any dielectric other than air.

Then, due to the tree-shaped form of the power supply network, all the horns are supplied in phase, and this over a wide frequency band, without the need for any adjustments.

In addition, due to the planar shape of the feed network, the antenna can be produced using only two plates, metallic or even only metallized, by a very simple manufacturing process.

In addition, the antenna thus produced has excellent mechanical qualities. It is particularly solid, resistant to weathering and aging.

Finally, this antenna has great technical qualities. It can operate in the microwave domain, for example 12 GHz and over a very wide frequency band. Its directivity and gain performance can even be adapted to the application of reception of television programs relayed by satellites by appropriately calculating the dimensions of the horns and guides.

This antenna fulfills one of the essential conditions required for this application: it does not have any secondary lobes of the network. Being an inexpensive flat antenna, it is well suited for consumer applications, and it is easy to install.

• - la figure 1 qui montre en perspective un élément rayonnant d'un module unitaire selon l'invention ;
• - la figure 2a qui montre en perspective un module unitaire selon l'invention ;
• - la figure 2b qui montre en perspective le réseau d'alimentation de ce module ;
• - la figure 3 qui représente, en coupe parallèle au plan de référence P, le réseau d'alimentation de ce module ;
• - la figure 4 qui représente les positions respectives du plan de référence P et des plans de symétrie Q et Q' du réseau d'alimentation ;
• - les figures 5a et 5b qui représentent en coupe respectivement parallèlement au plan Q' et parallèlement au plan Q, un élément rayonnant du module unitaire ;
• - les figures 6a et 6b qui représentent des portions des deux plaques constituant une antenne selon l'invention, dans une mise en oeuvre ;
• - la figure 7 qui représente un élément rayonnant de l'antenne dans une autre mise en oeuvre ;
• - la figure 8 qui représente les coordonnées angulaires d'un point M de l'espace par rapport au plan de référence P ;
• - la figure 9 qui représente l'enveloppe Ci du diagramme de rayonnement de l'antenne imposée par les normes CCIR dans l'application de l'antenne à la réception d'émissions de télévision relayées par satellites et l'enveloppe C₂ du diagramme de polarisation croisée.

The invention will be better understood using the following description, illustrated by the appended figures, of which:

• - Figure 1 which shows in perspective a radiating element of a unit module according to the invention;
• - Figure 2a which shows in perspective a unit module according to the invention;
• - Figure 2b which shows in perspective the supply network of this module;
• - Figure 3 which shows, in section parallel to the reference plane P, the supply network of this module;
• - Figure 4 which shows the respective positions of the reference plane P and the symmetry planes Q and Q 'of the supply network;
• - Figures 5a and 5b which show in section respectively parallel to the plane Q 'and parallel to the plane Q, a radiating element of the unitary module;
• - Figures 6a and 6b which show portions of the two plates constituting an antenna according to the invention, in one implementation;
• - Figure 7 which shows a radiating element of the antenna in another implementation;
• - Figure 8 which shows the angular coordinates of a point M in space with respect to the reference plane P;
• - Figure 9 which represents the envelope Ci of the antenna radiation diagram imposed by CCIR standards in the application of the antenna to the reception of television programs relayed by satellites and the envelope C ₂ of the diagram of cross polarization.

The antenna module according to the invention consists of four horns, the openings of which form a pattern repeated by simple translation, along two axes parallel to the sides, with the same pitch, in a plane parallel to the reference plane P, as it is shown in Figure 2a, in perspective, seen from above. This module is therefore square in shape in this plane.

The supply network of these four horns is shown in perspective in Figure 2b. This network is said to be "planar" because it is distributed in a single plane parallel to the reference plane P. All the waveguides connecting the guides 3 of individual feed of the horns to each other are of the same type as the guides 3, ie "plan É.

The planar supply network is therefore called "plan É.

In addition, to allow the supply of the four cones in phase, this network is of the so-called "tree" type. Indeed, the horns are fed by two symmetrically with respect to a plane parallel to the plane Q, to form two groups of two identical radiating elements. Then the two groups thus formed are supplied symmetrically, with respect to a plane parallel to a plane Q ', this plane Q' being defined as perpendicular both to the reference plane P and to the plane Q as shown in FIG. 4 In the environment outside the antenna in operation, the plane Q 'is defined by the electric field E and the perpendicular oz to the plane P.

As shown in Figure 2b in perspective and Figure 3 in section parallel to the plane P, the supply symmetry of two horns can be obtained by a planar network such as elbows 5 whose angle is located in the plane of the network connect the individual feed guides 3 of these horns to a power divider 6 in the shape of a T in the same plane. The plane of symmetry of the system formed by the two horns, the two elbows 2, the two individual guides 3, the two elbows 5 and the upper bar of the power divider 6, is a plane parallel to Q, the trace of which is I "in Figure 3.

The supply symmetry of the two groups of two horns thus formed is obtained by connecting the waveguides 8 from the power dividers 6 by a T-shaped power divider 7 located in the plane of the network. The upper bar of this power divider 7, of output 9, and the guide sections 8 admit as plane of symmetry a plane parallel to Q 'whose trace is J'J "in FIG. 3.

Thus for each horn, the length of the feeding path is exactly the same and the horns are fed perfectly in phase.

The waveguide sections 8, the upper bar of the T forming the power divider 7, and the waveguide section 9 output from this divider, are provided curved, as shown in FIGS. 2b and 3 , so that the electric field vector remains perpendicular to the walls of the guides during the propagation of the TEoi mode.

A microwave antenna can be formed from a multiple of four of such unit modules supplied to each other by a planar arborized network of the same type as the network distributed inside each module and in the same plane as the latter. In this way the antenna can include the number of radiating elements necessary to obtain the desired gain for the antenna and all the radiating elements of the antenna are however supplied in phase.

Because the waveguide supply network is designed in a plane parallel to the plane of the cone openings, it is possible to make the entire antenna in the form of a planar antenna using only two plates . These plates can be metallic and machined, or even molded plastic whose surfaces are metallized.

According to a first embodiment illustrated in Figures 6a and 6b, the antenna consists of two plates 100 and 110, the main faces 101 and 102 for the plate 100, and the main faces 103 and 104 for the plate 110 are parallel to the reference plane. The plate 100 comprises a multiple number of four of unit modules of four horns placed in an adjacent manner, so that all the horns are deduced from each other by a translation of the same pitch in the two directions parallel to the sides of the square openings . The horns are shaped in the thickness of the plate 100 so that the openings are flush with the face 101 and so that the mouths 4 are flush with the face 102, the thickness of the plate 100 being provided equal to the height h of the cones (see Figures 5a and 5b). The plate 110 comprises the elbows 2 and the planar feed network of the antenna formed by grooves made in the hollow on the face 103 of this plate. The grooves have a width b and a depth a and constitute three of the faces of the network waveguides. The application of the face 103 of the plate 110 on the face 102 of the plate 100 forms the fourth face of the rectangular section waveguides of the supply network and connects the horns to the network thus formed. It will be noted that the plate 110 must have a thickness slightly greater than the magnitude a, which gives for the total thickness of the planar antenna thus formed a value slightly greater than the magnitude of a + h.

According to a second embodiment, illustrated in FIG. 7, the antenna consists of two plates 200 and 210, the main faces 201 and 202 for the plate 200, and the main faces 203 and 204 for the plate 210 are parallel to the reference plane P. The plate 200 comprises the unit modules placed adjacent to each other, as in the embodiment described above. The horns are shaped in the thickness of the plate 200 so that the openings are flush with the face 201 and so that the mouths are in the thickness of the material forming the plate 200. The latter is provided with a thickness equal to the height h of the horns increased by the value of the dimension has guides. The antenna feed network is formed on the face 202 of the plate 200 in the form of hollow grooves of width b and depth a, and of elbows 2 making it possible to connect the mouths of the horns to the grooves. The plate 210 is a simple blade with parallel faces. The application of the face 203 of the plate 210 on the face 202 of the plate 200 forms the fourth face of the waveguides of the supply network.

The antenna used according to one of the embodiments described above is therefore particularly simple and inexpensive to manufacture. It can be made in large series. It has great mechanical strength and does not require adjustment during assembly. To further facilitate the positioning of the plates 100 and 110, or 200 and 210 one on the other, there may be provided on these plates positioning pins or any other well-known identification and fixing system of the skilled in the art. For example, the plates can also be held opposite one another by screws.

As this antenna does not include a dielectric, the losses are as low as possible, and on the other hand it is extremely resistant to aging.

In addition, this antenna is of low volume and low weight. It is therefore particularly easy to set up and its support is then inexpensive.

Such an antenna is therefore extremely well suited to general public use for the reception of television broadcasts transmitted by satellites. Indeed in such a reception system the antenna is an important element for two reasons: firstly the quality of reception depends directly on the characteristics of the antenna and secondly, the cost of the antenna and its support as well as the cost of installation and pointing to the satellite largely define the final cost of the reception system.

The following example is given to show that the antenna according to the invention can also have technical characteristics appropriate for the reception of television broadcasts relayed by artificial satellite.

Example of realization

It is recalled that an antenna intended for the reception of television programs relayed by satellite must be able to receive a circular polarization, right or left according to the transmitting satellite.

We know that the polarization of an electromagnetic wave is defined by the direction of the electric field E in space. If at a point in space, the electric field vector É remains parallel to a straight line, necessarily perpendicular to the direction of propagation of the wave, this wave is polarized rectilinearly.

On the other hand, the wave is circularly polarized if the end of the electric field vector E describes a circle in the plane perpendicular to the direction of propagation. The polarization is right circular when E turns clockwise for an observer looking in the direction of propagation. The polarization is left circular in the other case.

A circularly polarized wave can be broken down into two linearly polarized waves, perpendicular to each other and phase shifted by ± ₇ r / 2.

The antenna intended for the envisaged application can therefore be produced according to the following principle: the two perpendicular components, due to the emission by the satellite of a circularly polarized wave, are picked up and then composed with the appropriate phase shift (± π / 2 depending on whether we are dealing with a circular polarization doirte or left).

The implementation of this principle supposes the use in front of the antenna of a depolarizing radome. This radome is designed in such a way that it delays one of the components of the circularly polarized wave, thus causing the necessary phase shift. The two linear polarization waves are thus in phase and their vector composition gives a linearly polarized wave which can be received by an antenna with a single linear polarization such as the antenna according to the present invention. The depolarizing radome is not described here as not being strictly part of the invention.

• - la bande de fréquence doit se situer entre 11,7 et 12,5 GHz ;
• - le diagramme de rayonnement de l'antenne doit être enveloppé sous le gabarit représenté par la courbe Ci montrée sur la figure 9, selon lequel une atténuation de 3 dB du lobe principal correspond à une ouverture 8 du faisceau de 2°, exprimée par la relation :
  • e -3dB = 2° qui est l'ouverture du faisceau à mi-puissance ; et selon lequel les lobes secondaires sont atténués de 30 dB à 12^. _;
• - la polarisation croisée doit être enveloppée sous le gabarit représenté par la courbe C₂ sur la figure 9.
• - le rapport entre gain de l'antenne G et la température de bruit T en degré Kelvin doit être :
  

It should also be remembered that, for the application envisaged, the antenna must meet the standards formulated by the CCIR (International Radiocommunication Committee). These conditions are as follows:

• - the frequency band must be between 11.7 and 12.5 GHz;
• - the antenna radiation diagram must be wrapped under the template represented by the curve Ci shown in FIG. 9, according to which an attenuation of 3 dB of the main lobe corresponds to an opening 8 of the beam of 2 °, expressed by the relationship :
  • e -3dB = 2 ° which is the beam opening at half power; and that the side lobes are attenuated from 30 dB to 12 ^. _;
• - the cross polarization must be wrapped under the template shown by curve C ₂ in Figure 9.
• - the ratio between gain of the antenna G and the noise temperature T in degrees Kelvin must be:
  

où λ_c est la longueur d'onde de coupure du guide. En effet si la dimension a est trop faible alors la longueur d'onde guidée varie trop en fonction de la fréquence. Et inversement si la dimension a est trop grande, alors le guide propage plusieurs modes à la fois.As shown in FIG. 2b, the supply network of the unitary antenna module allows the propagation of the TEoi mode. So that this mode can propagate it is necessary that the large dimension has waveguides which is perpendicular to the electric field É checks the relation (1):

where λ _c is the cut-off wavelength of the guide. Indeed if the dimension a is too small then the guided wavelength varies too much as a function of the frequency. And conversely if the dimension a is too large, then the guide propagates several modes at the same time.

correspondant à une longueur d'onde de coupure

et doncFor the frequency band 11.7 - 12.5 GHz. a cut-off frequency can be adopted

corresponding to a cut-off wavelength

and so

• a = 15 mm is a good compromise.

dans laquelle

• F, = facteur de réseau
• F = facteur de correction pour un élément.

The problem which also arises particularly is that of the network lobes. Indeed, the total gain of the antenna 6 is linked to the gain of a radiating element G _e by the relation (2)

in which

• F, = network factor
• F = correction factor for an element.

The lattice factor F _r is a function of the angle e of radiation, the latter being defined as shown in FIG. 10, by the angle between the normal oz to the plane xoy containing the plane P of the antenna, and the direction OM of the radiation. The network factor F _r checks the relation (3)

dans laquelle n est le nombre d'éléments rayonnants formant l'antenne et

où d est la distance entre éléments rayonnants et λ la longueur de l'onde propagée.

in which n is the number of radiating elements forming the antenna and

where d is the distance between radiating elements and λ the length of the propagated wave.

• F_{r =} 1

The relation (2) shows that one obtains a maximum radiation when the network fector:

• F _{r =} 1

For the lobes of the network to be completely avoided, it is necessary that the function F _r has only one maximum corresponding to the main lobe, that is to say that the term Sinu takes the value 0 only one time. This condition is met if:

This relation establishes that for the lobes of network to be completely avoided it is necessary that the distance d between the radiating elements is lower than the wavelength λ propagated in the guide. Otherwise, network lobes appear. We will choose for example d = 22 mm.

où δ est l'épaisseur minimale de matériau séparant deux guides Avec δ = 0,5 mm, il vient alors : b = ₃ mm.The dimension b is given by (see Figure 3):

where δ is the minimum thickness of material separating two guides With δ = 0.5 mm, it then comes: b = ₃ mm.

According to the present invention, this condition can easily be fulfilled with the dimensions and characteristics of the radiating elements and the waveguides given in Table I.

This table is completed by FIGS. 5a and 5b which respectively represent a section of a radiating element parallel to the plane Q therefore to the "plane H", and parallel to the plane Q 'therefore to the "plane E".

The gain G _e of such a radiating element can be calculated using the relationships given in the work published by Nha-BUI-NA in MASSON editions, entitled "Microwave antennas".

This gain achieved for the chosen dimensions a value of the order of G _e = 9.5 dB.

• n = 512 éléments rayonnants
• ou à l'aide
• N = 128 modules unitaires selon l'invention présente alors, en présumant des pertes de 0,5dB dans les lignes, un gain total
• G = 36,1 dB

An antenna made using

• n = 512 radiating elements
• or using
• N = 128 unit modules according to the invention then presents, assuming losses of 0.5dB in the lines, a total gain
• G = 36.1 dB

The coupling between element can be considered negligible. Adaptations may be provided at the elbows or power dividers to improve these results.

However as is, this antenna perfectly meets CCIR standards. In particular, the radiation diagram obtained perfectly meets the conditions of FIG. 9, both for the envelope Ci and for the envelope C ₂ of the cross-polarization diagram.

Indeed, from the value imposed for the ratio between the gain of the antenna and the noise temperature, the antenna must have a gain of at least 34 dB.

The value reached here of more than 36 dB is perfectly suitable and the fact that the antenna does not have any secondary network lobes is one of its most interesting characteristics for this application.

Finally, the possibility of making such an antenna in two plates as described has made it a perfect device for this general public application.

Claims (5)

1. High-frequency antenna for receiving or transmitting a rectilinearly polarized wave, comprising at least one antenna unit module which comprises four radiating elements having the form of horns (1) whose openings form a two-dimensional pattern in a plane parallel to a reference plane P, and a power supply array (6, 7, 8, 9) assembled from waveguides of rectangular cross-section (8, 9) connected to the horns (1) and also interconnected so that for each horn (1) the overall length of the supply path is the same, the cross-section of the waveguides (8, 9) having dimensions a and b defined by the relation a > b, and the small dimension b being placed parallel to the reference plane P in the planar array so that the latter is suitable for propagating the TE_oi, mode, this supply array (6, 7, 8, 9) being of the "planar" type because it is distributed in a single plane parallel to the reference plane P, and of the "tree-structure" type because the horns (1) are fed in-phase by means of power dividers (6, 7), characterized in that the power dividers (6, 7) in this module have the form of a T with symmetrical branches, in that the apertures of the horns (1) have a square cross-section and in that they form in a plane parallel to the reference plane P a two-dimensional square array obtained because the horn apertures are derived one from the other by translations of the same step size along axes which extend parallel to their sides, in that the large waveguide dimension (8, 9) is a = ÀJ2 where À_c is the cut-off wavelength of the waveguides, in that each internal entrance (4) having a cross-section identical with that of the waveguides is individually connected to a waveguide of the array (3) by an elbow (2) having a bend located in a plane parallel to a plane Q, this plane Q being defined as perpendicular to the reference plane P and parallel to one of the sides of the square aperture of the horn (1) and also to the large dimension a of the latter's internal entrance, in that each individual feeding waveguide is linear and connected to one of the symmetrical linear branches of a first power divider (6) having the form of a T by an elbow (2) having a bend located in the plane of the array, the main branch of this power divider being incurved, in that each group of two horns thus formed is connected to one of the symmetrical incurved branches (8) of a second power divider (7) having the form of a T whose main branch (9) is also incurved, so that the two groups of two horns thus formed are fed symmetrically relative to a plane Q', this plane being defined as perpendicular to both the reference plane P and plane Q so that the curve of the branches of the power dividers (6, 7) permits propagation of the T₀₁ mode, this antenna comprising two plates (100, 110) whose surfaces are electrically conductive, the horns (1) being formed in the thickness direction of the first plate (100), the apertures of the horns opening on the first surface (101) of this plate and the entrances (4) on the second surface (102), the waveguide feeding array (3) being formed by slots realised in the first surface (103) of the second plate (110), these slots constituting three of the four waveguide surfaces and the application of the second surface (102) of the first plate (100) on the first surface (103) of the second plate (110) forming the fourth surface of the waveguides (3) and the connections to the horns (1).

2. High-frequency antenna for receiving or transmitting a rectilinearly polarized wave, comprising at least one antenna unit module which comprises four radiating elements having the form of horns (1) whose openings form a two-dimensional pattern in a plane parallel to a reference plane P, and a power supply array (6, 7, 8, 9) assembled from waveguides of rectangular cross-section (8, 9) connected to the horns (1) and also interconnected so that for each horn (1) the overall length of the supply path is the same, the cross-section of the waveguides (8, 9) having dimensions a and b defined by the relation a > b, and the small dimension b being placed parallel to the reference plane P in the planar array so that the latter is suitable for propagating the TEo₁ mode, this supply array (6, 7, 8, 9) being of the "planar" type because it is distributed in a single plane parallel to the reference plane P, and of the "tree-structure" type because the horns (1) are fed in-phase by means of power dividers (6, 7), characterized in that the power dividers (6, 7) in this module have the form of a T with symmetrical branches, in that the apertures of the horns (1) have a square cross-section and form in a plane parallel to the reference plane P a two-dimensional square array obtained because the horn apertures are derived one from the other by translations of the same step size along axes which extend parallel to their sides, in that the large waveguide dimension (8, 9) is a = Xd2 where À_c is the cut-off wavelength of the waveguides, in that each internal entrance (4) having a cross-section identical with that of the waveguides is individually connected to a waveguide of the array (3) by an elbow (2) having a bend located in a plane parallel to a plane Q, this plane Q being defined as perpendicular to the reference plane P and parallel to one of the sides of the square aperture of the horn (1) and also to the large dimension a of the latter's internal entrance, in that each individual feeding waveguide is linear and connected to one of the symmetrical linear branches of a first power divider (6) having the form of a T by an elbow (2) having a bend located in the plane of the array, the main branch of this power divider being incurved, in that each group of two horns thus formed is connected to one of the symmetrical incurved branches (8) of a second power divider (7) having the form of a T whose main branch (9) is also incurved, so that the two groups of two horns thus formed are fed symmetrically relative to a plane Q', this plane being defined as perpendicular to both the reference plane P and plane Q so that the curve of the branches of the power dividers (6, 7) permits propagation of the T₀₁ mode, this antenna comprising two plates (200, 210) whose surfaces are electrically conductive, the horns being formed in the thickness direction of the first plate (200), the apertures of the horns opening on the first surface (201) of this plate and the entrances on the second surface (202), the waveguide feeding array (3) being formed by slots realised in said second surface (202) and constituting three of the four waveguides surfaces, the second plate (210) having a first planar surface (203) and the application of the second surface of the first plate (202) on the first surface (203) of the second plate (210) forming the fourth surface of the waveguides (2) and the connections to the horns (1).

3. High-frequency antenna as claimed in one of the Claims 1 or 2, characterized in that it comprises a number of unit modules which is a multiple of four, fed by means of a tree-structure planar array of the same type as the array distributed within each module (6, 7, 8, 9) and in the same plane as the latter, in such a way that all the horns (1) of the antenna are fed in-phase.

4. Antenna as claimed in one of the Claims 1 to 3, characterized in that the plates (100, 110, 200, 210) are made of an electrically conductive material.

5. Antenna as claimed in one of the Claims 1 to 3, characterized in that the plates (100, 110, 200, 210) are made of a dielectric material whose surfaces are covered with an electrically conductive material.

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