Enhanced multi-port elemental antenna and associated active electronically scanned array antenna

Abstract

Improved multi-port elementary antenna and associated active electronically scanned array antenna This elementary antenna (5) comprises a radiating element (10), provided with N excitation zones, and a transmission / reception module (20), comprising, for each integer i between 1 and N, an ith chain (21) connected, via an ith feed line (51) to the ith excitation zone (1), the ith chain comprising an ith amplifier (212). The elementary antenna comprises, in the ith chain, an ith robustness phase shifter (213) on a first side of the ith amplifier, between the ith amplifier and the radiating element, and an ith compensation phase shifter (211) on a second side of the ith amplifier, opposite the first side.The sum of the phases introduced by the ith robustness and compensation phase shifters is constant regardless of the chain considered, and the phase introduced by the ith robustness phase shifter is strictly different from the phase introduced by the other robustness phase shifters of the other chains of the elementary antenna. Figure for the abstract: Figure 1.

Description

Title of the invention: Improved multi-port elementary antenna and associated active electronically scanned array antenna

[0001] The invention relates to the field of active electronic scanning array antennas.

[0002] Such a network antenna combines a plurality of elementary antennas, each elementary antenna comprising a transmission / reception module - TRM (for "Transmit Receive Module in English) and a radiating element.

[0003] Document FR 3062523 discloses an array antenna in which each radiating element is connected to the associated TRM by at least two ports. Preferably, each radiating element is connected to the TRM by four ports or eight ports in a differential assembly.

[0004] These different ports constitute, in transmission, as many power injection points so as to increase the total power of the wave emitted by the radiating element.

[0005] These different ports constitute, in reception, as many power collection points so as to distribute the total power of the incident wave on the radiating element.

[0006] Each port is connected to a TRM transmission chain and / or to a TRM reception chain, possibly via a duplexer, such as a circulator or a switch.

[0007] The transmission chain conventionally comprises a controllable phase shifter followed by a power amplifier in order to apply to the corresponding port a transmission signal adjusted in phase and amplitude.

[0008] When designing the antenna, the characteristics of the power amplifier and those of the radiating element are jointly optimized. In particular, the impedance of the load which is connected to the output of the power amplifier, via a transmission line, is optimized according to the characteristics sought for the power amplifier, such as its efficiency, its output power, its linearity, etc. An optimal impedance is thus defined allowing an adaptation of the load connected to the output of the power amplifier so as to allow the power delivered by the power amplifier to be transmitted to the radiating element with high efficiency.

[0009] However, once the elementary antenna is integrated into an array antenna, the electromagnetic couplings between active radiating elements of the different elementary antennas are the cause of an impedance mismatch. In other words, the radiating element connected to the output of the power amplifier of an elementary antenna no longer presents the initial optimal impedance Zopt, but a modified impedance Zo . This is the effect of active load pulling. This load variation can also come from a mismatch of the radiating element due to a modification of its immediate environment, or from an external disturbing signal received by the antenna.

[0010] The consequence of this impedance mismatch is a degradation in the efficiency of the power amplifier. This loss of efficiency typically results in an emitted Fonde attenuation of the order of one decibel.

[0011] The same problem is found on the reception path associated with a port of the radiating element. This comprises a low-noise amplifier to the input of which the received signal, collected by the corresponding port, is applied. However, during the design of the elementary antenna, the low-noise amplifier is sized according to the impedance of the load connected to its input. An optimal impedance Zopt is thus determined. However, electromagnetic couplings between neighboring radiating elements lead to an impedance mismatch. The impedance Zo of the load connected to the input of the low-noise amplifier is different from the optimal impedance Zopt. This impedance mismatch in reception results in a loss of efficiency in the transmission of the power from the radiating device to the low-noise amplifier, and a degradation of the noise figure.

[0012] The aim of the present invention is to solve these problems.

[0013] For this purpose, the invention relates to an elementary antenna comprising a radiating element and a transmission and / or reception module, the radiating device comprising N excitation zones, N being an integer greater than or equal to 2, an excitation zone being a port or a pair of ports, the transmission and / or reception module comprising, for each integer i between 1 and N, an ith chain connected, via an ith feed line to the ith excitation zone of the radiating element, the ith chain comprising an ith amplifier, characterized in that the elementary antenna comprises, for each chain, an ith robustness phase shifter on a first side of the ith amplifier, between the ith amplifier and the radiating element, and an ith compensation phase shifter on a second side of the ith amplifier opposite the first side,and in that the sum of the phases introduced by the ith robustness phase shifter and the ith compensation phase shifter is constant regardless of the chain considered, and the phase introduced by the ith robustness phase shifter is strictly different from the phase introduced by the other robustness phase shifters of the other chains of the elementary antenna.

[0014] According to particular embodiments, the elementary antenna comprises one or more of the following characteristics, taken in isolation or according to all technically possible combinations:

[0015] - each chain is a transmission chain, the amplifier of the ith chain being a power amplifier.

[0016] - each chain is a reception chain, the amplifier of the ith chain being a low noise amplifier.

[0017] - the phases introduced by the robustness phase shifters are distributed uniformly in the interval [0°; 180°[.

[0018] - the radiating element comprising four ports, the phases respectively introduced by the first, second, third, and fourth robustness phase shifters are chosen equal to 0°, 45°, 90°, and 135°.

[0019] - the phases respectively introduced by the first, second, third, and fourth compensation phase shifters are chosen equal to 135°, 90°, 45°, and 0°.

[0020] - the radiating element comprising N pairs of ports, the ith chain comprises a i-th positive amplifier and an i-th positive robustness phase shifter associated with a positive port of the i-th pair of ports, and an i-th negative amplifier and an i-th negative robustness phase shifter associated with a negative port of the i-th pair of ports.

[0021] - the ith robustness phase shifter is constituted by an ith delay line.

[0022] - the ith compensation phase shifter is integrated into an ith controllable phase shifter of the ith chain.

[0023] The invention also relates to an active electronic scanning array antenna comprising a plurality of elementary antennas, characterized in that each elementary antenna is consistent with the previous elementary antenna.

[0024] The invention and its advantages will be better understood on reading the detailed description which follows of a particular embodiment, given solely by way of non-limiting example, this description being made with reference to the appended drawings in which:

[0025] [Fig. 1] [Fig. 1] is a schematic representation of a first embodiment of a multi-port elementary antenna according to the invention;

[0026] [Fig.2] [Fig.2] and a graph representing a Smith chart;

[0027] [Fig.3] [Fig.3] is a schematic representation of a second embodiment of a multi-port elementary antenna according to the invention, in differential assembly; and,

[0028] [Fig.4] [Fig.4] is a schematic representation of a third embodiment of a multi-port elementary antenna according to the invention, in differential assembly.

[0029] [Fig. 1] represents a first embodiment of a multi-port elementary antenna according to the invention.

[0030] The elementary antenna 5 comprises a radiating element 10 and a transmission / reception module, or TRM 20, associated with the radiating element.

[0031] The radiating element 10 comprises a radiating plane, for example metallic and square in shape. Alternatively, the radiating plane may take other shapes, in particular circular.

[0032] The radiating plane of the radiating element 10 is characterized by two directions, orthogonal to each other, each direction passing through the middle of two opposite sides of the radiating element. The first and second directions, D1 and D2, intersect at the center C of the radiating plane.

[0033] In this first embodiment, the total number N of ports is chosen for example to be equal to four.

[0034] According to the first direction D1, the radiating element 10 is provided with a first port 1 and a third port 3, which are arranged on either side of the center C of the radiating element.

[0035] According to the second direction D2, the radiating element 10 is provided with a second port 2 and a fourth port 4, which are arranged on either side of the center C.

[0036] For example, a port is formed by the end of a feed line overlapping a slot provided in a ground plane below the radiating plane. For example, a port is formed by the end of a feed line connected, by a via crossing the ground plane, to the rear of the radiating plane.

[0037] The TRM 20 has four channels, each addressing a particular port of the radiating element.

[0038] Each channel comprises a transmission chain and a reception chain.

[0039] Thus, the TR module 20 comprises a first transmission chain 21 and a first reception chain 31 connected, via a first duplexer 41, to a first feed line 51, the end of which is connected to or forms the first port 1.

[0040] Thus the TRM 20 comprises a second transmission chain 22 and a second reception chain 32 connected, via a second duplexer 42, to a second supply line 52 of the second port 2.

[0041] Thus, the TRM 20 comprises a third transmission chain 23 and a third reception chain 33 connected, via a third duplexer 43, to a third supply line 53, the end of which is connected to the third port 3.

[0042] Thus the TRM 20 comprises a fourth transmission chain 24 and a fourth reception chain 34 connected, via a fourth duplexer 44, to a fourth supply line 54, the end of which is connected to the fourth port 4.

[0043] Furthermore, the TRM 20 comprises an input component 28 for receiving a transmission signal from a transmission electronics (not shown in the figures). SE to be transmitted, and to repeat this input signal on the input of each of the transmission chains 21 to 24 of the TR module 20.

[0044] The TRM 20 comprises an output component 29 making it possible to combine the received signals delivered at the output of each of the reception chains 31 to 34 of the TRM 20, so as to transmit an output signal SS to processing electronics (not shown in the figures).

[0045] For beamforming, conventionally, each transmission chain comprises, in series, a controllable phase shifter and a power amplifier. This beamforming makes it possible to radiate the energy in one or more desired directions, and in a chosen polarization. Depending on the nature of the radiating element, the antenna can allow polarization agility.

[0046] Thus, the first transmission chain 21 comprises a controllable phase shifter 210 and a power amplifier 212, the second transmission chain 22 comprises a controllable phase shifter 220 and a power amplifier 222, the third transmission chain 23 comprises a controllable phase shifter 230 and a power amplifier 232, and the fourth transmission chain 24 comprises a controllable phase shifter 240 and a power amplifier 242.

[0047] According to the invention, each transmission chain is, in addition, provided with a robustness phase shifter and a compensation phase shifter.

[0048] Thus, the first transmission chain 21 comprises a robustness phase shifter 213 and a compensation phase shifter 211, the second transmission chain 22 comprises a robustness phase shifter 223 and a compensation phase shifter 221, the third transmission chain 23 comprises a robustness phase shifter 233 and a compensation phase shifter 231, and the fourth transmission chain 24 comprises a robustness phase shifter 243 and a compensation phase shifter 241.

[0049] A transmission chain can be identified by the integer i of the port to which it is connected.

[0050] In the embodiment of [Fig. 1], the robustness phase shifter of the ith transmission chain is positioned downstream (according to the direction of propagation of the transmission signal) of the power amplifier, i.e. between the output of the power amplifier and the duplexer.

[0051] The compensation phase shifter of the ith transmission chain is, for its part, placed upstream of the power amplifier, that is to say between the output of the controllable phase shifter and the input of the power amplifier.

[0052] The robustness phase shifter of the ith transmission chain introduces a predefined phase (Jx in the transmission signal. This phase is found in the reflection coefficient of the feed line connecting the transmission chain to the radiating element. The variation of the phase of the reflection coefficient results in a variation of the impedance of the load connected to the output of the transmission chain, i.e. the power amplifier.

[0053] The compensation phase shifter of the i-th transmission chain introduces a predefined phase (|)'. into the transmission signal.

[0054] The sum of the phase introduced by the robustness phase shifter of the ith transmission chain and the phase introduced by the compensation phase shifter of the ith transmission chain is a constant Cste, which is common to all the transmission chains of the same elementary antenna 5.

[0055] Thus: Vi, i E {1, 2, ..., N]: ¢. + ([)'= Cste

[0056] This constant may be different from one elementary antenna to another.

[0057] The compensation phase shifter therefore makes it possible to compensate for the phase shift introduced by the robustness phase shifter, and thus guarantee that all the transmission chains introduce the same total phase shift ((^ + (Jf) downstream of the controllable phase shifter.

[0058] The phase introduced by a robustness phase shifter is specific to the ith transmission chain. In other words, two robustness phase shifters of the elementary antenna introduce different phases: V i, V j, i * j : ([>. ± <]>

[0059] Preferably, the phases introduced by the N robustness phase shifters are distributed uniformly in the interval [0°; 180°[, the phases introduced being modulo 1807N.

[0060] With N equal to 4, the phases are then distributed modulo 45°.

[0061] For example, the phases 0°, 45°, 90°, and 135° are chosen as phases respectively introduced by the first, second, third, and fourth robustness phase shifters, 213, 223, 233 and 243.

[0062] And the phases 135°, 90°, 45°, and 0° are chosen as phases respectively introduced by the first, second, third, and fourth compensation phase shifters 211, 221, 231, and 241 so as to guarantee that the total phase introduced by each pair of phase shifters is constant from one transmission chain to the other (downstream of the controllable phase shifters): Cste= 135°.

[0063] In [Fig. 1], the radiating element 10 is consequently excited by four feed lines carrying equiphase-shifted transmission signals by the phase-shifting means presented above.

[0064] [Fig.2] illustrates the effect of implementing robustness phase shifters according to the invention.

[0065] [Fig.2] is a Smith chart, known to those skilled in the art.

[0066] The Smith chart makes it possible to represent reflection coefficients of a load connected by a transmission line at the output of a component, in this case the reflection coefficient F of the radiating element connected to the output of the power amplifier of a transmission chain by a transmission line.

[0067] The impedance of this load is noted Z.

[0068] There is a bijection between the reflection coefficient F and the impedance Z of the load:

[0069] r =

[0070] Z = ^£

[0071] From the point on the Smith chart representing a reflection coefficient F, a first network of circles (Re(z)) allows the real part of a normalized impedance to be read, and a second network of circles (Im(z)) allows the imaginary part of the normalized impedance to be read. The Smith chart in fact represents the normalized impedance, defined as: z — Z., where Zc is a characteristic impedance of the transmission line. The real and imaginary parts of z allow the value of the impedance Z to be calculated, knowing the length of the transmission line and therefore Zc.

[0072] For a given amplifier, an electronic device called a "load pull" is connected to the output of the amplifier and successively presents different values of the reflection coefficient. For each value, characteristic quantities of the amplifier are measured, such as the maximum power or the efficiency. This makes it possible to plot, on the Smith chart, isoperformance curves, for example for the maximum power or for the efficiency.

[0073] At the end of these tests, an optimal reflection coefficient ropt is chosen depending on the application. For example, a value is chosen allowing a certain compromise between maximum power and efficiency for a power amplifier.

[0074] The optimal reflection coefficient TOpt can be fictitiously brought back to the center of the Smith chart (Fopt = 0). Indeed, a power amplifier is generally made up of an amplification stage itself (set of transistors) and an adaptation stage (winding and capacitance). It is the adaptation stage which actually allows the amplification stage to be presented with the optimal reflection coefficient.

[0075] Thus, returning to the presentation of the invention, the optimal reflection coefficient FOpt, corresponding to the optimal impedance Zopt, is chosen to optimize the characteristics of the power amplifier.

[0076] The optimal adaptation coefficient Fopt is obtained at the center of the Smith chart.

[0077] However, due to impedance mismatch, the impedance Zo actually connected at the output of the power amplifier is different from Zopt. It corresponds to the reflection coefficient Fo on the Smith chart.

[0078] As a complex number, this reflection coefficient is written: r^rjexp^' with ITqI the amplitude and (|>0 the phase.

[0079] On the Smith chart of [Fig.2], several isoperformance curves in efficiency of the power amplifier considered have been represented.

[0080] For example, the first curve Eb, the innermost, corresponds to a decrease of one decibel compared to the optimal efficiency obtained for ropt, the second curve E2 corresponds to a decrease of two decibels compared to the optimal efficiency, the third curve E3 corresponds to a decrease of three decibels compared to the optimal efficiency and the fourth curve E4, the outermost, corresponds to a decrease of four decibels compared to the optimal efficiency.

[0081] These curves are not circular around EOpt (i.e. the maximum efficiency obtained for the optimal impedance Zopt ), but have an elliptical shape.

[0082] Since the cause of the impedance mismatch is due to a coupling between the radiating element of the elementary antenna considered and the neighboring radiating elements, the impedance mismatch is a characteristic of the radiating element.

[0083] It is therefore the same for the different power amplifiers addressing the different ports of the same radiating element.

[0084] Consequently, without implementing the invention, the reflection coefficients seen by the different amplifiers of the TRM 20 are equal and are located at the same point, in this case Eo.

[0085] The reflection coefficient Eo is located somewhere on a circle Co with center Eopt and radius ITJ. Its position is not controlled and may in particular correspond to a significant degradation in the performance of the power amplifiers of the same elementary antenna. This is what is represented in Figure 2, where the reflection coefficient Eo is located on the curve E4, i.e. a reduction of four decibels compared to the optimal efficiency according to the example given.

[0086] Since the reflection coefficient Eo is not a priori identical from one elementary antenna to another (which is all the more true for the elementary antennas at the periphery of the network), this leads to a high variability in the performance of the elementary antennas constituting an array antenna.

[0087] On the contrary, by implementing the invention, namely by introducing a characteristic 4>; phase downstream of each power amplifier, the impedance mismatch becomes specific to each transmission chain of the same elementary antenna.

[0088] The reflection coefficient of the ith emission chain then becomes: ri^irjexp(j(0o-2(j).))-

[0089] Thanks to the robustness phase shifter, a rotation around the optimal load point ropt is carried out. This moves the reflection coefficient C of the ith emission chain onto the circle Q.

[0090] The phases <|( being different from one emission chain to another, the reflection coefficients G no longer overlap at the same point, but are distributed over the circle Co. Advantageously, they are distributed uniformly over the circle Co.

[0091] With the previous choice of phases, the first reflection coefficient Tj is not displaced, the second reflection coefficient T2 is displaced by -90°, the third reflection coefficient E3 is displaced by -180°, and the fourth reflection coefficient L4 is displaced by -270° (or +90°).

[0092] As a result, the different reflection coefficients are now on different iso-performance curves. Some reflection coefficients will be on iso-efficiency curves that are better than the original curve or much better than the original curve (E4 in the given example).

[0093] Thus, with the implementation of the invention, the power amplifiers do not undergo the same performance degradation, which means that the overall variation in performance of the elementary antenna varies less than in the state of the art where all the amplifiers can simultaneously undergo a strong degradation. The TRM is therefore made more robust to impedance mismatch.

[0094] As a result, the variability between the elementary antennas of an array antenna is reduced.

[0095] The major advantage of the invention is therefore to guarantee robustness to load variations, and therefore to make the network antenna as a whole more efficient. In addition, polarization agility is maintained.

[0096] The role of the compensation phase shifter is to introduce a phase to compensate for the phase introduced by the robustness phase shifter so that the radiating element is finally correctly excited, i.e. by in-phase signals.

[0097] In practice, the robustness phase shifter can be placed either in the MMIC chip (Monolithic microwave integrated circuit) carrying the power amplification function, or in the receiving printed circuit of the MMIC chip, at the interconnection between the MMIC chip and the port of the radiating element. Alternatively, the robustness phase shifter is produced in a hybrid manner by placing one part in the MMIC chip and the other part in the printed circuit.

[0098] The robustness phase shifter is preferably implemented by a delay line introducing a constant phase shift for a given frequency band.

[0099] As for the compensation phase shifter, its function can be performed by the controllable phase shifter already present to ensure the electronic scanning and polarization agility functions. It must then be controlled appropriately to introduce the required compensation phase. The value of the compensation phase is added to the phase command of a controllable phase shifter. Phase compensation upstream of the power amplifiers can thus be implemented in the depointing control laws without having to implement an additional phase shifter. There is therefore only one phase shifter.

[0100] If the invention has been presented above to remedy the impedance mismatch at the output of the different transmission chains of a TRM, the invention can also be applied, possibly independently, to the impedance mismatch at the input of the different reception chains of a TRM.

[0101] Thus, as shown in [Fig. 1], the ith reception chain integrates a robustness phase shifter, which is positioned upstream (in the direction of propagation of the reception signal) of the low noise amplifier, i.e. between the input of the low noise amplifier and the duplexer. The compensation phase shifter is, for its part, placed downstream of the low noise amplifier, i.e. between the output of the low noise amplifier and the input of the controllable phase shifter.

[0102] Thus, the first reception chain 31 successively comprises a robustness phase shifter 313, an amplifier 312, a compensation phase shifter 311, and a controllable phase shifter 310; the second transmission chain 32 successively comprises a robustness phase shifter 323, an amplifier 322, a compensation phase shifter 321, and a controllable phase shifter 320; the third transmission chain 33 successively comprises a robustness phase shifter 333, an amplifier 332, a compensation phase shifter 331, and a controllable phase shifter 330; and the fourth transmission chain 34 successively comprises a robustness phase shifter 343, an amplifier 342, a compensation phase shifter 341, and a controllable phase shifter 340.

[0103] The robustness phase shifter of the ith reception chain introduces a constant phase into the signal received from the ith port of the radiating element 10.

[0104] The compensation phase shifter of the ith reception chain introduces a constant phase ¢) into the received signal.

[0105] The sum of the phase introduced by the robustness phase shifter of the ith reception chain and the phase (|)'. introduced by the compensation phase shifter of the ith reception chain is a constant Cste, which is common to all the reception chains of the elementary antenna 5.

[0106] Thus: yi, i E {1, 2,... N], ¢. + $'= Cste

[0107] This is so that the different signals received at the output of the reception chains of the same radiating element are equiphase-shifted by the phase-shifting means presented above.

[0108] The phase introduced by a robustness phase shifter is specific to the ith reception chain. In other words, two robustness phase shifters of the elementary antenna introduce different phases.

[0109] This produces a modulation of the load presented at the input of the various low-noise amplifiers of the elementary antenna with the effect of reducing the variability of the signal-to-noise ratio and / or the linearity of the various elementary antennas of the network antenna operating in reception.

[0110] [Fig.3] illustrates a second embodiment. The elementary antenna 1005 includes a TRM 1020 and a radiating element 1010.

[0111] For the sake of clarity, [Fig. 3] has been limited to the transmitting means, but a similar description could be made for the receiving means.

[0112] The radiating element 1010 has four pairs of ports. Each pair of ports has a positive port and a negative port.

[0113] The ports of the same pair of ports are supplied differentially by a suitable transmission chain.

[0114] Thus, a component of the second embodiment identical to a component of the first embodiment is referenced by the same reference number as that used in [Fig.l] to reference the corresponding component. The references of the components of the second embodiment carry an index + or - depending on the positive or negative port of the pair of ports that they address.

[0115] Thus, for the i-th positive transmission chain which is associated with the positive port i+ of the i-th pair of ports, a positive robustness phase shifter is positioned downstream of the positive power amplifier, i.e. between the output of the positive power amplifier and the duplexer, to introduce a positive phase (])+. A positive compensation phase shifter is, for its part, placed upstream of the positive power amplifier, i.e. between the output of the controllable phase shifter and the input of the power amplifier, to introduce a positive phase (j)'*.

[0116] Thus, for the i-th negative transmission chain, which is associated with the negative port i of the i-th pair of ports, a negative robustness phase shifter is positioned downstream of the negative power amplifier, i.e. between the output of the negative power amplifier and the duplexer, to introduce a negative phase ¢. A negative compensation phase shifter is, for its part, placed upstream of the amplifier negative power, i.e. between the output of the controllable phase shifter and the input of the power amplifier, to introduce a negative phase ¢(.

[0117] We keep the constraint:

[0118] vi, i £ {1, 2, ... N}, (|f + ([>^ = ([x + ^ = Cste

[0119] For example, for the embodiment of [Fig.3], with four pairs of ports, the following set of phases is retained:

[0120] $+ = ¢- = o0; (] / = (J)" =135°

[0121] ¢+=^=450.^ = ^-90° 2 2 2

[0122] $+=$ 90o.$'+=^ .go 3 3 3

[0123] ¢+ = A =1350- 4 / = ¢-- = 0 0 4 4 4 4

[0124] Alternatively, it is possible to ensure that the two amplifiers of the same transmission chain are not associated with the same reflection coefficient, by choosing ¢+ different from ¢. This in fact corresponds to considering the radiating element as being powered by eight ports and not four pairs of ports.

[0125] [Fig.4] illustrates a third embodiment. The elementary antenna 2005 comprises a TRM 2020 and a radiating element 1010, which, like the radiating element of the second embodiment, is differentially fed.

[0126] A component of the third embodiment identical to a component of the first embodiment is referenced by the same reference numeral as that used in [Fig.l] to reference the corresponding component.

[0127] In this third embodiment, the ith transmission chain, which is associated with the positive port i+ and the negative port i of the ith pair of ports, comprises a single power amplifier (2212 for the first chain 2021), having one input and two differential outputs.

[0128] A robustness phase shifter (2213 for the first chain 2021), which is positioned between the output of the power amplifier and the duplexer, has two differential inputs and two differential outputs. The robustness phase shifter introduces a robustness phase ([( identical on the two differential links.

[0129] A compensation phase shifter (211 for the first chain 2021) is, for its part, placed upstream of the power amplifier, that is to say between the output of the controllable phase shifter (210 for the first chain 2021) and the input of the power amplifier, to introduce a compensation phase.

[0130] We once again retain the constraint:

[0131] Vi, i E {1, 2, ... N], ¢. + (1 / . = Cste

[0132] We select a set of robustness phases such that: V i and V ji and j £ {1, 2, ... N}, ij

[0133] By implementing the invention in each of the elementary antennas constituting an array antenna, a homogenization of the behavior of the different radiating devices is obtained.

[0134] In an antenna operating in transmission and reception, the invention can be implemented in transmission only, in reception only, or simultaneously in transmission (to remedy the impedance mismatch between the radiating element and the different transmission chains) and in reception (to remedy the impedance mismatch between the radiating element and the different reception chains).

[0135] In the latter case, the phases introduced by the transmission chain and by the reception chain of the same channel may be identical or different.

[0136] If they are identical, the robustness phase shifter is advantageously placed between the duplexer and the radiating element, along the feed line of the corresponding port of the radiating element. A single robustness phase shifter is then placed in common for transmission and reception. For example, phase shifters 213 and 313 are replaced by a common robustness phase shifter implemented on line 51.

[0137] A hybrid solution is conceivable, in which part of the robustness phase shifter is on one side of the duplexer and the other part of the robustness phase shifter is on the other side of the duplexer, on the port feed line.

[0138] In another variant, the invention is implemented in transmission in an antenna operating only in transmission (comprising only transmission chains and therefore not comprising reception chains) or in reception in an antenna operating only in reception (comprising only reception chains and therefore not comprising transmission chains).

[0139] The present invention finds applications in the field of radars, jammers, radios and data links, as well as multifunction systems using active electronically scanned array antennas.

Claims

Claims

1. Elementary antenna (5) comprising a radiating element (10) and a transmission and / or reception module (20), the radiating element comprising N excitation zones, N being an integer greater than or equal to 2, an excitation zone being a port or a pair of ports, the transmission and / or reception module comprising, for each integer i between 1 and N, an ith chain (21, 22, 23, 24) connected, via an ith feed line (51, 52, 53, 54) to the ith excitation zone (1, 2, 3, 4) of the radiating element, the ith chain comprising an ith amplifier (212, 222, 232, 242), characterized in that the elementary antenna comprises, for each chain, an ith robustness phase shifter (213, 223, 233, 243) of a first side of the ith amplifier, between the ith amplifier and the radiating element, and an ith compensation phase shifter (211, 221, 231, 241) on a second side of the ith amplifier opposite the first side,and in that the sum of the phases introduced by the ith robustness phase shifter and the ith compensation phase shifter is constant regardless of the chain considered, and the phase introduced by the ith robustness phase shifter is strictly different from the phase introduced by the other robustness phase shifters of the other chains of the elementary antenna.,

2. Elementary antenna according to claim 1, in which each chain is a transmission chain, the amplifier of the ith chain being a power amplifier.

3. Elementary antenna according to claim 1 or claim 2, in which each chain is a reception chain, the amplifier of the ith chain being a low noise amplifier.

4. Elementary antenna according to any one of the preceding claims, in which the phases introduced by the robustness phase shifters are distributed uniformly in the interval [0°; 180°[.

5. Elementary antenna according to any one of the preceding claims, in which, the radiating element comprising four ports, the phases respectively introduced by the first, second, third, and fourth robustness phase shifters are chosen equal to 0°, 45°, 90°, and 135°.

6. Elementary antenna according to claim 5, in which the phases respectively introduced by the first, second, third, and fourth compensating phase shifters are chosen equal to 135°, 90°, 45°, and 0°.

7. Elementary antenna according to any one of claims 1 to 4, in which the radiating element comprising N pairs of ports, the ith chain comprises an ith positive amplifier and an ith positive robustness phase shifter associated with a positive port of the ith pair of ports, and an ith negative amplifier and an ith negative robustness phase shifter associated with a negative port of the ith pair of ports.

8. Elementary antenna according to any one of the preceding claims, in which the ith robustness phase shifter is constituted by an ith delay line.

9. Elementary antenna according to any one of the preceding claims, in which the ith compensation phase shifter is integrated into an ith controllable phase shifter of the ith chain.

10. Active electronically scanned array antenna comprising a plurality of elementary antennas, characterized in that each elementary antenna conforms to an elementary antenna according to any one of the preceding claims.

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