MXPA00000470A - Circuit and method for receiving or transmitting microwaves - Google Patents

Abstract

The invention concerns a circuit for receiving (or transmitting) microwaves comprising radiating means (144) for receiving (or transmitting), filtering means for eliminating microwaves received (or transmitted) at different frequencies, by the radiating means, and means for amplifying received (or transmitted) waves. The circuit comprises a first (or last) stage (150, 152;182, 184) connected to the radiating means including a planar filter (150;182) whereof the transmission (or reception) rejection rate is limited to a fraction, preferably a very small part, of the total rejection required for eliminating the transmitting (or receiving) frequencies and an amplifier (152;184) whereof the gain is likewise a fraction of the circuit total gain. Preferably, the first (or last) stage planar filter is directly connected to the radiating element. The noise viewed by the radiating means is minimised.

Description

CIRCUIT AND PROCEDURE FOR RECEIVING OR ISSUING MICBOONDAS The invention relates to a circuit and a method for receiving and / or emitting microwave or microwave waves.

Transmission and reception circuits are commonly used in telecommunications systems. These circuits are usually destined to emit important powers and to receive weak powers. Thus, for example, in telecommunications systems in which the signals are surveyed by geostationary satellites.

In these systems, the emission frequencies and the reception frequencies are different to prevent the reception signals from being disturbed by the emission signals. It is also necessary to provide filtering means so that, in each way, the desired frequency can be received or emitted and the frequency of the other channel eliminated. The separation between the signals must be particularly careful when the emission and the reception are simultaneous.

REF. 32362 In these systems, a waveguide source and a high rejection duplicator in the respective emission and reception bands, as well as waveguide circuits, are most often envisaged. They therefore have a significant saturation that can not be suitable for all applications, particularly for telecommunication system terminals in which each subscriber must have an emitter and a receiver.

In particular, the circuits of emission and reception of microwave frequencies can be used in a common way, for both domestic and professional uses, in satellite telecommunication systems.

For example, telecommunication systems of this type are developed for applications called "multimedia". In these systems, a constellation of satellites in low orbits, of altitude between 800 and 1500 km, or medium, of altitude between 6000 and 12000 km is expected. The orbits are called "low or medium" as opposed to geostationary satellites whose altitude is 36000 km. The satellites aim to ensure communication between land users. The communications thus transmitted are of a multimedia nature, that is, they concern television signals, audio signals, video, numerical data of all kinds, programs, telephone or telecopy signals. In relation to communications rejected by geostationary satellites, the low altitude of the satellites reduces the communication distance and then the delays due to propagation, which facilitates the interactivity of these systems. In addition, with constellations, coverage can be optimized, for example, by privileging areas of high population density, even when a geostationary orbit privileges the areas near the equator.

A terrestrial user can not communicate with a satellite other than during the time during which that satellite is "in view" of the user; this duration is generally of the order of twenty minutes. It is therefore necessary that, on the one hand, the user's antenna can follow the satellite over its trajectory and, on the other hand, the user can instantly switch over the communication on the next satellite, which enters its field of vision, even when the previous satellite He is moving away from his field of vision. The instantaneous switching is especially necessary for interactive communications for which a service interruption, also of short duration, is not contemplated. To solve this problem, a device for transmitting and receiving two antennas is generally envisaged, one of which is moved to follow the satellite with which the user communicates and the other is on hold and pointed towards the beginning of the vision of the next satellite.

The transmitting and receiving devices, and particularly their antennas and the associated circuits, intended for such telecommunication systems must be particularly light and of reduced dimensions to facilitate the movement and installation on the roof of a building (particularly an individual house). and, thus, take care of aesthetics.

In addition, it may be advantageous to associate the two transmitting and receiving devices and circuits associated with a common focusing lens. In that case, these two devices and their circuits must coexist in a limited space, which reinforces the need for slight saturation and light weight of these devices and circuits.

Under these conditions, it is hardly contemplated to mention the technology of waveguides that is heavy and saturating. It is thus made mention of a planetary technology of which the most common is called "micro tape". But with this technology, the known solutions to the problem of isolation between the emission and the reception drag important losses that degrade the quality of union or force to surpass the antenna. Such is the case in the device described in EP 0 744 831. 0, it is necessary to foresee a strong filtering Rate of attenuation (or strong rejection) for, in the reception band, eliminate the emission frequencies, and analogously in the emission band, eliminate the reception frequencies. But, filters of a high rejection index and slight interference are difficult to perform in planar technology.

The invention remedies this drawback.

It allows a simple and slight interference of emission and / or reception circuits with high frequencies in planar technology, with an excellent isolation between the emission and reception circuits.

The circuit of emission and reception of microwave waves according to the invention is characterized in that the reception circuit contains at least two stages of filtering and amplification connected to the radiant medium and comprising respectively, on the one hand, a flat filter whose rejection of the emission frequencies is limited to a fraction, preferably a slight part, of the total rejection necessary to eliminate the emission frequencies, and on the other hand, an amplifier whose advantage is also a fraction of the total circuit advantage, said Filtering and amplification stages allow progressive filtering and amplification.

The rejection rate of the filter of this stage is preferably selected in such a way that the amplifier is not misaligned by the residual emission signals.

The rejection complement is provided by at least one other planar filter and amplifier stage.

At the level of the radiant device, the interference provided by the filtering is mainly a function of the interference carried by the first filter connected to this radiating device, the interference provided by the other filter (s) being in practice negligible. , since it decreases n proportion of the advantage of the amplifiers that separate this other filter from the radiant device.

Thus, the rejection rate of the first filter being moderate, the interference is equally moderate.

A moderate Rejection Index filter can be performed more simply and less expensively than a filter with a high rejection rate.

In particular, mention may be made of low-cost substrates such as matrix substrates in flexible organic material such as PTFE, since filters with a high rejection index generally require substrates in aluminum.

It is preferable that the transmission circuit is carried out analogously, that is to say with at least two stages connected to the radiating device, which respectively comprises, on the one hand, a planar filter whose rejection rate of the reception frequencies is equal to a fraction ( preferably a slight part) of the rejection rate necessary to eliminate the reception frequencies and, on the other hand, an amplifier whose advantage does not represent more than a fraction (preferably a slight part) of the total circuit advantage.

It will be noted here that "planar technology" means a technology by which the elements are made in the flat form. The technique called "micro tape" will be used in particular. In this case, a substrate with a thickness of 0.5 to 2 mm is mentioned, whose lower mass plane is stuck on the bottom of a metal case. It is also possible to mention the technique called "suspended triplaca". In this case, a substrate with a thickness of 0.15 to 0.5 mm is used, the underside of which is not metallized and pressed between two metal shells. With this technique, the hyperfrequency energy propagates mostly in the air above and below the substrate, which induces lighter losses than in the case of the micro-tape technique. On the contrary, the dimensions of the circuits are more important.

For the realization of circuits, these two techniques are practically identical, only the dielectric constant effective e ^ that can be different. From which it follows that the wavelength may also be different, given that this wavelength is related to the effective dielectric constant e_ by the following formula: ? = c / [f (v'e_)], formula in which c is the speed of light, f is the frequency.

Other features and advantages of the invention will appear with the description of certain of its embodiments, which are carried out referring to the drawings annexed to the present on which: Figure 1 is a diagram showing the use of an emission and reception device according to the invention in a satellite telecommunication system in the path, Figure 2 is a diagram of an antenna comprising two transmitting and receiving devices according to the invention, this antenna which is also used in a satellite telecommunication system, Figure 3 is a diagram of a part of emission and reception device according to the invention, Figures 3a and 3b are schemes analogous to that of Figure 3, but for two variants, Figure 4 is a block diagram of an emission and reception device and circuit according to the invention, Figure 5 is a diagram of the emission and recovery circuits according to the invention, and Figure 6 represents an exemplary embodiment of reception circuits.

In the telecommunication system represented on FIG. 1, a set of satellites 10, 12 circulates on an orbit 14 at an altitude of approximately 1000 to 1500 km above the surface 16 of the earth. Each satellite contains means of transmitting and receiving to reject a communication between terrestrial users and access stations to "specific services, such as data banks." There is thus represented on FIG. 1 a user terminal 18 that establishes an interactive communication with another user or a land station (not represented) by the satellite's intemediary 12. The interactive character of communication is symbolized by a double arrow 20 on the path of the electromagnetic waves between the antenna 22 of the satellite 12 and the antenna 24 of the subscriber 18 .

The antenna 24 is, for example, arranged on the roof of a single house. It contains a focusing surface 26, for example spherical, as shown on FIG. 2, and two mobile radiating elements 28 and 30 on the focal surface 26 of the antenna 24.

The radiating element 28 is programmed to follow the satellite 12 with which the user is in view, while the radiating element 30 is in the waiting position. The latter remains pointed towards the zone of appearance of the next satellite. In effect, when the satellite 12 leaves the field of view of the antenna and that the next satellite enters the field of view, the radiant element 30 replaces the element 28 used to effect the communication. The switching of the element 28 with the element 30 can be carried out instantaneously.

In the example represented on FIG. 1, the user 18 is provided with a device 32 that allows the satellites to be followed ", to program the emission and reception of the signals and, if necessary, to describe these signals. Information is recorded in relation to the positions of the satellites, so that at each instant the motors that ensure the movement of the radiating elements 28 and 30 can be programmed so that they are pointed precisely towards the satellites.

If a micrc-computer is used, it can also be used to receive or broadcast programs.

In this example of multimedia application, it is also provided to connect, by means of a connector or distributor 36, a telephone or telecopy line 38 and a receiver 40 for television or radio broadcasts.

A more detailed example of antenna 24 with radiating elements 28 and 30 is shown on FIG. 2.

In this embodiment, a fixed lens 42 is provided which allows to receive a hyperfrequency beam over a solid angle of sufficient value to collect the signals of the satellites in the path in the user's vision area.

This lens focuses the received rays on a spherical surface on which the radiating elements "28 and 30 move. This lens 42 is supported by two uprights of which only one of reference 44 is visible on Figure 2.

The radiating elements 28 and 30 are movable on the spherical focusing surface 26. For this purpose, two motors and two arms are provided for each of these elements. For simplicity, only the motors and arms of the radiating element 28 will be described.

To displace the radiating element 28, a first motor 46 integral with a lower support 48 is provided and whose shaft allows an arm 50 to rotate at the end of which is the second motor 52 which itself carries a forearm 54 at the end of the arm. which is the radiant element 28. To ensure the displacement of the radiating element 28, the motors 46 and 52 are directed by information provided by the microcomputer 34 or similar.

Each radiating element 28, .30 are associated with an emitting circuit and a receiving circuit which will be described later in connection with FIG. 5.

The terminals 18, which are widely diffused apparatuses, are essential to be of light saturation, of light weight and of a minimized cost. The need for a light saturation and a light weight is reinforced by the fact that the emission and reception devices are mobile and are associated in a small volume, that of the antenna 24.

This minimization of saturation, weight and price must be compatible with high performances needed by, particularly the high flow of information and the simultaneity of the emission and reception. From this point of view, the isolation between the emission and reception signals presents a difficult problem to solve, especially in the context, mentioned above, of slight saturation and low price.

In the example, the reception band Rx is from 11.7 to 12.45 Ghz (being able to extend to 12.55 GHz), while the emission band T .. is from 14 to 14.3 GHz. The emission power is of some watts, of the order from 2 to 3.

The radiant element according to the invention is of the planar type. It comprises, in the example shown on the fogura 3, a tablet or "patch" 60 (FIG. 3) having the shape of a circle truncated by parallel semi-biceps 62 and 64. Two accesses 66 and 68 are associated with this tablet 60. in micro ribbon lines that form a 90 ° angle. These two accesses 66 and 68 are excited by two signals 90 ° out of phase. The access 66 corresponds to the reception and is therefore related, in particular, to an amplifier 70 of slight interference, while the access 68 corresponds to the emission and is therefore related, among others, to a power amplifier 72.

The excitation of lines 66 and 68 by 90 ° offset signals allows to obtain emission and reception signals that are in circular polarizations in inverse directions. The orthogonal polarizations of the emission and reception signals, added to the frequency bands other than these signals, allow an isolation of the order of 20 dB between these signals. The planar technology used to make the radiating element minimizes its cost, its saturation and its weight. In addition, the realization of two shortcuts "minimizes the number of components and allows to pass from hybrid coupler of wide band or of circulator eats in the variants represented" on figure 3a [Utl. : ac? on of m; irculator) and on figure 3b use of a hybrid coupler) In the example shown on FIG. 3a, there is provided a truncated circular flat tablet 74 having an access connected to the output of the power amplifier 72: (emission circuit) through a circulator 76.

The access 78 is also connected to the reception path, ie to a light interference amplifier 70, by means of the same circulator 76. Although this embodiment is less advantageous on the plane of saturation and cost, it has the advantage of be simple to perform.

In the example of figure 3b, there is provided a planar radiating element 80 of non-truncated circular shape having two orthogonal accesses 82 and 84 connected to two terminals, respectively 86 and 88, of a hybrid coupler 90 containing two other terminals, respectively 92 and 94. the terminal 92 is connected to the input of a light interference amplifier 70., and the terminal 94 is connected to the output of the power amplifier 72. The 90 ° hybrid coupler allows to transform orthogonal linear polarizations, on its terminals 92 and 94, in circular polarizations in opposite directions on its terminals 86 and 88. Thus, on the accesses 82 and 84, the signals have circular polarizations of inverse directions. The hybrid coupler 90 is preferably of the wide band tip. For this purpose, one or several supplementary branches 9c are provided in icrocinta.

Although, in relation to the embodiment shown on FIG. 3, this variant implies a larger volume, it nevertheless has the advantage of allowing a safe operation and a very satisfactory isolation between the emission and recitation signals.

An embodiment of the device for transmitting and receiving a planar tablet that can be used preferably with the embodiment of FIG. 3 will now be described in relation to FIG. 4. It can also be used with the variants of the Figures 3a and 3b.

In this example, two superposed planar tablets are contemplated, respectively 98 and IO'O. Each of these tablets has a shape corresponding to that shown on FIG. 3, that is to say the shape of a semi-beveled circle. However, the dimensions of these pills are different. One of them, the lower tablet 98, presents diomensiones corresponding to a resonance in the reception band and the upper tablet has lighter dimensions that correspond to a resonance in the emission band (the highest frequencies).

The two pads have a relative arrangement such that they have the same central axis (perpendicular to their planes) and that their semi-bevels are parallel.

The accesses 102 are arranged under the lower tablet 98. On the figure 4 a single access is visible.

These accesses are aligned in micro tape or triplaca suspended. They are connected to the filtering circuits and light or power interference amplifiers by means of micro tape or triplet lines. In the example, the filtering and adaptation means are also in line of micro tape or triplaca.

The pads as well as the accesses arranged in a cylindrical cavity 110 open towards the top and having a bottom 112.

This cavity 110 limits the cone of emission and reception of the hyper-redundancy waves in order that this cone is relatively narrow, directed towards the satellite 12.

The bottom of the cavity is connected to a channel 114 of perpendicular axis 116 of the cylindrical cavity 110. In that channel there is a substrate 118 which contains, on the one hand, the access lines 102 and on the other hand, filtering and adaptation in micro tape or ttriplate lines 120. The substrate also contains, at the end of the channel 114 opposite the cavity 110, active elements such as transistors 122 of amplifier (s). The end part of the channel 114 that contains the transistors 122 in planar micro tape technique is separated from the circuits-120, preferably in triple planar suspended technique, by means of a sealing wall 124.

The end of the channel 114 comprises a terminal 128 for the reception signals and a terminal 130 for the emission signals.

The upper opening of the cavity 110 is closed by a protective cappuccino 134 of plastic material such as "Teflon" or ABS.

In variant (not shown), the accesses are on tablets, by reference axis 98.

It is also possible to provide a single tablet with accesses on this pad or at a distance from the latter.

A filter and amplification circuit according to the invention is now described in relation to FIG. 5, which makes it possible to minimize the interference, particularly that generated by filtering, at the same time, making it possible to reduce the cost of realizing the circuits. In addition, the losses are minimized.

The emission and reception that are carried out simultaneously, the elimination, by filtering, of the emission frequencies in the reception circuits as well as the elimination, by filtering, of the reception frequencies, in the emission circuits must be particularly effective.

For this purpose, according to the invention, in each circuit, planar filters and an amplification and filtering in several stages are foreseen. The attenuation, or rejection, of the filter that is closest to the radiating element has a value that is a fraction of the attenuation necessary to eliminate the frequencies to be suppressed. In one example, the total rejection rate necessary to eliminate the emission (or reception) frequencies is of the order of 50 dB and the rejection of the filter of the first (or last) stage is no more than of the order of 14 dB. This last value is calculated as a function of the compression point of the first transistor (amplifier) in reception (or of the interference factor of the last transistor, amplifier, in emission), of the power to be emitted, or of the isolation between the two ports of the source (radiant element; The amplification provided by the first stage of the amplification also represents a fraction of the advantage In this way, the interference seen by the radiating element is minimized. Indeed, this interference depends above all on the interference provided by the amplification stage and the filter closest to this element. On the contrary, the interference provided in the radiating element by the furthest, amplification and filtering stages only intervene in an attenuated manner, since this interference is diminished in proportion to the advantage of the intermediate amplification stages that are found between the radiating element and the interference generating filter.

In addition, the planar filters of moderate rejection can be carried out easily, at a moderate cost, since the ubstratos used can be of a low recovery price. It is known, in fact, that filtering in a planar micro tape technique (or suspended triplaca) requires, for high rejection rates, relatively expensive aluminum substrates, while for lighter rejection rates, cheaper substrates can be used, for example. example based on PTFE, as will be seen later.

In the example shown in Figure 5, the receiving circuit comprises a first part 140 disposed between the access 142 of the chip 144 of the radiating element and an end of a cable 146. A second part 148 is disposed between the other end of the cable 146 and the demodulator (not shown) of the reception circuit.

The access 142 is directly connected to the input of a first filter 150 of the bandpass type for the reception frequencies and the band-cut type for the emission frequencies. For these emission frequencies, it has a relatively moderate rejection characteristic, 14 dB. For the reception frequency, the attenuation (or loss) is of a light value, of the order of 0.2 dB. This last filter 150 is connected to the input of a first amplifier 152, to a scio transistor in the example.

This amplifier 152 has an advantage of 8 dB in the example. It should be noted that this 8 dB advantage is not the maximum advantage that could be obtained with a transistor. But, in the example, the interference is minimized to a slight detriment "of the advantage, as will be seen later in relation to Figure 6.

This first part 140 of the reception circuit also contains a second amplifier filter stage pair, namely a filter 154 whose input is connected to the output of the first amplifier 152 and a second amplifier 156 also constituted, in the example, by a single transistor. The filter 154 has a rejection of 10 dB for the emission frequencies and a slight rejection, 0.2 dB, for the reception frequencies. Amplification stage 156 has an advantage of 10 dB.

In this example, the parasitic mission signal at the output of stage 156 is less than 10 dB.

The cable 146 - which, in the example, introduces an attenuation of 1.5 dB - is connected to the second filtering and amplification part 148 which comprises a third pair of filters 156 - amplifiers 160. The filter 158 receives the signal provided by the cable 146 and releases a signal to the third amplifier 160. The attenuation of the filter 158 for the emission frequencies is 26.5 dB and the attenuation for the reception frequencies of 1.8 dB. The amplification stage 160 has two transistors and its advantage is 18 dB.

At the output of step 160, a completely filtered signal is obtained from the parasitic emission signals. This output is connected, in a conventional manner, to a mixer 162 which receives on an other input an iocaai oscillator signal of 10.75 GHz. The output of the mixer 162 is connected to a reception demodulator by means of a low pass filter 166.

The attenuation of the parasitic frequencies that is effected by each of the filters is in accordance with the advantage of the associated amplifier in such a way that this attenuation is sufficient to prevent misalignment, or saturation (or compression), of the transistor (s) of the amplifier by the parasitic emission signal. It is therefore necessary that each filter is arranged towards the entrance of the associated amplifier. By "towards the entrance" it is meant here that the filter must be closer to the radiating element than the amplifier of the same pair.

The overall interference factor of the reception circuit is, essentially, that of the first filtering stage 150 and amplification 152.

The coaxial cable 146, as well as the corresponding coaxial cables 170 and 172 for the transmission circuit, forms in the example a deviation around the motors that can be wound or left loose according to the displacement of the arm.

The second part 148 of the reception circuit (as well as the corresponding part of the transmission circuit) is stuck, in the example, at the base of the antenna, that is to say in proximity to the base 48 (FIG. 2).

The first part 142 of the reception circuit is realized in technology called "hybrid without regulation", that is to say that active elements such as transistors are arranged directly on a substrate, without a case, and that the substrate has planar conductors, for example made by gravure. This embodiment allows the interference factor to be further minimized, ie to maximize the signal to interference ratio. The weight and saturation are also minimized.

On the other hand, the part of the circuit 148 located at the foot of the antenna, which is the furthest away from the radiating element, can be realized in a more classical way in integrated technology such as the technology called "MMIC" ("Integrated circuit monolithic microwave ", that is to say integrated monolithic circuit hyper frequencies). Indeed, as indicated, the interference introduced by this stage 148 intervenes little in the overall interference factor. Likewise, the losses of the highest reject index filter 158 (26.5 dB in the example), which avoids the compression or the matching of the transistors of step 160, also intervene less critically than for part 140.

In part 140, the substrates are, for example, substrates RO 3006 or RO 4003 distributed by the "Societe Rogers Corporation. "They are staffed by a flexible organic matrix such as PTFE. (polytetrafluoroethylene) reinforced by glass microfibers and in which ceramic particles are trapped to increase the dielectric constant and then reduce the size of the circuits. This substrate is covered, on the one hand, by a layer of copper that constitutes the mass, while on the other hand it is also coated with photoremovable copper to make the circuits.

The emission circuit is analogous to the reception circuit. The transmitting access 180 of the chips 144 is connected to the output of a first filter 182 whose input is connected to the output of an amplification stage 184. The attenuation of the filter 182 is 14 dB for the reception and 0.2 frequencies. dB for the emission frequencies. The advantage of amplifier 184 is 8 dB.

The input of the amplifier 184 is connected to the output of a filter 186 that receives the output signal from an amplification stage 188. The attenuation of the filter 186 is 10 dB for the reception frequencies and 0.2 dB for the emission frequencies. . The advantage of the amplification stage 188 is 8 dB.

The other part of the emission circuit is also at the foot of the antenna, in the vicinity of the support 48 (FIG. 2) and contains a filter 190 connected to the cable 170 or 172 by means of a switch 173. the filter 190 receives the output signal of a four-transistor 192 amplification stage. The attenuation of the filter 190 is 30 dB for the reception frequencies and 1.8 dB for the emission frequencies. The advantage of the amplifier 192 is 32 dB.

The input of the amplifier 192 is connected to the output of a mixer 194 by means of a filter 196. The • Mixer has two inputs that, in a classical way, are connected on the one hand to the emission modulator (not shown), and on the other hand, to a local emission oscillator at 13.05 GHz.

For this emission circuit, the advantage of splitting in stages is that the last stage, directly connected to port 180, presents slight losses from the fact that the light index was rejected from filter 182 and from the relatively slight advantage of stage 184.

The cable 172 is connected to the circuits associated with the second radiating element (not shown). In other words, the part, from the emission circuit to the switch 173, filter 190, amplifier 192, filter 196 and mixer 194 is common to the radiating elements. On the contrary, the other parts of the circuit are - individual in each radiant element.

An example of a particularly simple and efficient embodiment of the first receiving circuit part 140 is shown in FIG. 6. The first part (182, 184, 186, 188) of the transmission circuit can be carried out analogously; it will not be described in detail.

An important feature of this embodiment is that of filters 150 and 154.

It is known that these filters must have characteristics of bandpass to slight loss for the reception frequencies, and bandpass of strong attenuation for the emission frequencies.

Each of these filters comprises at least one planar conducting element, formed by an engraving which, in the example, is transverse to the recording 200 of propagation of the current. It is thus seen that the filter 150 contains a first elongate rectangular metal engraving 202 perpendicular to the metal engraving 200, and is terminated in a classical open circuit. The filter 150 also contains a second engraving 204 or branch in line on the line 200. This end 204 is terminated by a "pseudo-short circuit", this short circuit that is simulated by a wide capacitive piece 206. In the latter case , thus avoiding a connection with the dough per metallized hole (s).

The end 202 that is terminated in open circuit must have a length 1 such that it has, at its junction with the main line 200, an open circuit for the emission frequencies and a short circuit for the reception frequencies.

This length i must be a multiple of? / 2 for the wavelengths? corresponding to the reception frequencies and a multiple of? / 4 for the wavelengths corresponding to the emission frequencies.

To achieve this goal, the length I is selected at a value of?., / 4,? being a wavelength corresponding to a frequency f- equal to the difference f- - f. between two frequencies f- and f., f-, being a frequency of the emission band and fr / a frequency of the reception band. The frequencies fa, f- and f¿ are also selected to satisfy the following relationships: F- = / 2m ^ l) f: F = 2mf In these formulas, m is a positive integer.

In this way, the length 1 is a multiple of? / 4 for the emission frequencies and is a multiple of? / 2 for the reception frequencies. Under these conditions, the element 202 constitutes a short circuit for the reception frequencies and an open circuit for the emission frequencies.

The end 204, terminated by the large capacitive piece 206 which simulates a short circuit in the joint 204-206, must have a length 1 ', selected in such a way that the element constitutes a short-circuit for the emission frequencies and an open circuit for the reception frequencies A length 1 'of? d / 4', d which corresponds to a frequency fd = ft - fr, will be selected, with: = 2 mf ~, and ! 2m -i; Whatever the embodiment, the desired result is obtained, namely the strong attenuation of the emission frequencies and the undisturbed transmission of the reception frequencies.

In the example for which the R band is 11.7 a 12. 45 GHz and the Tx band is from 14 to J. i. j GHz, in the case of end 204 terminated by a pseudo-short circuit, the frequencies fr, ft and fd can be selected from the following values: F. = 11.75 GH: - 14. 1 GHz - f. = 2.35 GHz fr = 5f ,, and f: 6 f- For the element 202 terminated in open circuit, on the other hand, frequencies f: -, fr and fa such that f will be selected; is a pair multiple of fa and f- an odd multiple of f3.

It is to be noted that either a filter element 202 alone can be used, without the filter element 204-206, either the filtering element 204-206 alone, without the element 202, or finally, as depicted, the two filtering elements simultaneously.

The amplifier stage 152 contains a transistor 208 as well as recorded for the adaptation of the impedance and the polarization of the electrodes. The transistor 208 is, in the example, a transistor of type FHX13X of the Fujitsu brand. Its grid is connected to the line 200 by means of a rectangular engraving 210. The polarizations are applied to engravings of square shapes, 212 for the grid polarization and 214 for the polarization of waste.

The stage 152 is connected to the filtrate stage 154 by means of a capacitor 216 for adaptation and decoupling between the bias voltages on the contacts 212 and 214.

The source of the transistor 208 is connected to the ground by means of an inductance 220, which performs the role of a counter-reaction and is constituted by a ribbon or wiring or connection wire. The value of this inductance 220 is optimized in order to minimize the interference. It has been found that this minimization of interference can lead to a decrease in the advantage; but this decrease is slight and does not alter the amplification performances.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Having described the invention as above, it is claimed as property in the following:

Claims (19)

1. A circuit for receiving (or transmitting) microwave or microwave waves, comprising a radiant medium for the reception (or emission) of the filtering means to eliminate high-frequency waves emitted (or received) at different frequencies, by the radiant medium , and wave amplification means received (or emitted), characterized in that it contains at least two stages of filtering and amplification connected to the radiant medium and comprising, on the one hand, on the one hand, a planar filter whose rejection rate of the emission frequencies ( or reception) is limited to a fraction, preferably a slight part, of the total rejection necessary to eliminate the emission (or reception) frequencies, and on the other hand, an amplifier of the total advantage of the circuit, the aforementioned stages of filtering and amplification to allow progressive filtering and amplification.

2. Circuit according to claim 1, characterized in that the planar filter of the first (or the last) stage is directly connected to the radiating medium.

3. Circuit according to claim 1 or 2, characterized in that the filter attenuation index of the first (or last) stage and the amplifier advantage of this stage have values such that the amplifier is not misaligned. residual (or reception) residuals not eliminated by the associated filter.

4. Circuit according to any one of claims 1 to 3, characterized in that the total rejection index necessary to eliminate the emission (or reception) frequencies being of the order of 50 dB, the rejection of the filter of the first (or of the last) stage is of the order of 1 dB.

5. Circuit according to any one of the preceding claims, characterized in that the amplifier of the first (or last) stage comprising at least one transistor, this stage is in the hybrid form, the transistor comprising a conductive chip devoid of a case and arranged on the substrate on which the planaric filter is made.

6. Circuit according to claim 5, characterized in that the stage, which is furthest away from the radiating means, is made under the form of an integrated circuit, for example in MMIC technology.

7. Circuit according to claim 6, characterized in that the radiant means being mobile, the first (or last) stage is equally mobile and the stage carried out in the form of an integrated circuit is immobile.

8. Circuit according to any one of the preceding claims, characterized in that the substrate for the planar filter of the first (or the last) stage has a matrix in flexible organic matter such as PTFE.

9. Circuit according to claim 8, characterized in that the substrate contains mechanical reinforcing glass fibers and a dielectric filler such as ceramic.

10. Circuit according to any one of the preceding claims, characterized in that it contains three stages of filtering and amplification, the filter attenuation index furthest from the radiant medium having a higher value than the filter attenuation index of the filter. the other two stages.

11. Circuit according to claims 5 and 1G, characterized in that the intermediate stage of filtering and amplification is under the hybrid transistor form comprising a semi-conductive chip devoid of a case disposed on the substrate on which the planar filter is made.

12. Circuit according to claim 11, characterized in that the intermediate stage and the first (or the last) stage are carried out on the same substrate.

13. Circuit according to any one of the preceding claims, characterized in that the amplifier of the first step of the last step contains a transistor for field effect and because a connection wire with the source forms a counter-reaction inductance with a selected value for minimize the interference

14. Circuit according to any one of the preceding claims, characterized in that the reception frequencies are in the range of 11.7 to 12.55 GHz and the emission frequencies in the band 14 to 14.3 GHz.

The circuit is a fourth of the previous claims, which is characterized in that the emission and reception waves are in orthogonal polarizations, particularly in circular polarizations in inverse directions.

16. Circuit according to any one of the preceding claims, which is characterized in that the planar filter is made in micro-tape technique or in suspended triple technique.

17. Application of the circuit according to any one of the preceding claims to a terminal of a telecommunications system in which the terminal is terrestrial and comprises an emission and reception circuit destined to communicate with another terrestrial terminal, or an arrangement that provides services, by means of of a satellite in trajectory.

18. Procedure for reception (or emission) of hyperfrequency waves by a radiant medium, in which hyperfrequency waves emitted (or received) are filtered out at different frequencies by the radiant medium and the received (or emit) waves are amplified, which is characterized in that the filtering and amplification is carried out progressively, the first (or last) filtering carried out from the radiant medium which uses a planar filter that provides a limited rejection of a light part of that necessary to eliminate the length of the corresponding chain, the frequencies of emission (or reception), and because the advantage of amplification in this stage is "also a slight part of the total advantage needed.

19. The method according to claim 18, characterized in that the rejection of the first (or the last filtering) is determined as a function of the compression point of the amplifier of the first stage (or of the interference factor of the last amplification stage), of the power to emit and the insulation between the two ports of the radiant medium.