Solid-state hyperfrequency amplifier and power combiner comprising four such solid-state amplifiers

Abstract

Disclosed is a solid-state amplifier comprising at least one interconnection, between a microtrack and a linearized impedance transformation waveguide ridge, provided with a clamping device.

Description

DESCRIPTION Title of the invention: Solid-state microwave power amplifier and power combiner comprising four such solid-state amplifiers

[0001] The invention relates to a solid-state power microwave amplifier and power combiner comprising four such solid-state amplifiers.

[0002] The invention lies in the field of solid state power microwave amplifiers or SSPAs, for "Solid State Power Amplifier" in English.

[0003] It is known that amplification systems, such as SSPAs and traveling-wave tubes or TWTAs (Traveling-Wave Tube Amplifier), with spatial or classic combinations, all have major drawbacks.

[0004] Indeed, these amplification systems present problems of compactness, efficiency, repair, maintainability, assembly, assembly cost and evolution, scalability and power limitation.

[0005] This is known from tube amplifiers or traveling wave tubes (TWTAs), which use a heated filament, producing a release of electrons by thermionic emission. These electrons are then accelerated in a vacuum by a high-intensity electric field generated by a very high voltage (THT). Once accelerated, these electrons are focused into a beam that interacts with a microwave. Gradually, the direct current (DC) energy contained in the electron beam is converted into microwave energy as the electrons travel along the interaction line. This energy is then transferred out of the tube, while the residual energy is transferred to the collector and dissipated as heat.

[0006] These amplifiers are very compact and operate at high efficiency, but in an all-or-nothing fashion, and in case of failure, the products are unusable. They require very high voltage, advanced technology, are very expensive to produce, and very difficult to maintain.

[0007] It is also known from monolithic SSPA solid-state amplifiers spatially combined via Vivaldi-type antipodal lines which will then radiate into cavities.

[0008] These cavities form the input points of a conical cavity combiner. This type of amplifier, for example described in US patent 10340574 B2, offers good compactness, relatively low losses, and no interstage interconnection problems. However, its radial configuration makes managing heat dissipation very complex and virtually impossible for optimal operation in pulsed mode, as the energy storage capacitors cannot be placed close to the monolithic microwave integrated circuits (MMICs).

[0009] It is also known as SSPA solid-state amplifiers in hybrid or T-junction combination, in which monolithic microwave integrated circuits (MMICs) are combined via hybrid, Wilkinson, or T-junction couplers.

[0010] Such amplifiers are relatively inexpensive, but nevertheless exhibit relatively high losses, a lack of scalability (power limitation), and very difficult repairability due to the chip and wire type assembly.

[0011] None of the existing solutions mentioned above are satisfactory because they all have major flaws.

[0012] Document EP0074613A1 is also known, which uses a ribbon connection, as illustrated in Figure 1, reference 28. This embodiment uses the ridge feed function, as illustrated in Figure 1, corresponding to Figure 3B of document EP0074613A1, with references 24, 25, 26, and 27. This ribbon connection has the advantage of being flexible but does not allow for simple repair because implementing such a ribbon requires a return to the factory and specific machines.

[0013] One aim of the invention is to overcome the problems mentioned above, and in particular to facilitate repairability, compactness and scalability.

[0014] Also, according to one aspect of the invention, a solid-state power microwave amplifier is proposed, comprising at least one interconnection, between a propagation line and a linearized impedance matching waveguide ridge, or "linearized impedance matching waveguide ridge" in English, equipped with a clamping device ensuring direct contact between the ridge and the propagation line.

[0015] Such a system improves repairability, compactness and scalability.

[0016] According to one embodiment, the clamping device includes at least one pressure screw.

[0017] Thus, tightening this screw makes it possible to constrain the edge of the guide and to keep its end in contact with the propagation line on the printed circuit board, thus offering a flexible and easily repairable connection.

[0018] For example, the pressure screw includes a spherical end or a flat end.

[0019] In one embodiment, the clamping device includes a pressure support stiffener.

[0020] Thus, the stiffener system will give the pressure device an elasticity which will guarantee the absence of deformation and the flat-ended pressure screw will not pierce the material attached to the edge.

[0021] According to another aspect of the invention, a power combiner is also proposed comprising four solid-state power microwave amplifiers according to one of the preceding claims, connected in H by a magic T device.

[0022] Thus, the H-shaped arrangement allows direct interconnection of the amplification modules to the combination system without the need for guided links, thereby limiting losses and improving the distribution of hot spots.

[0023] In one embodiment, the elements of the combiner are mounted flat.

[0024] This allows for easy management of the thermal environment and maintenance, as well as stacking multiple functions.

[0025] According to one embodiment, the magic tee device is monobloc (in the sense that the line-to-guide transitions, the two-to-one elementary magic tees of the magic tee device, the impedance transformation sections and the bi-directional coupler are fused).

[0026] This allows the different elements to be assembled by simply screwing them together without waste, and reduces costs and bulk.

[0027] For example, the one-piece magic tee device includes an S-flange, a bidirectional coupler, three elementary two-to-one magic tees, line-to-guide transitions, and guide-to-coaxial transitions.

[0028] The invention will be better understood upon examination of some embodiments described by way of non-limiting examples and illustrated by the attached drawing in which:

[0029] [Fig.1] schematically illustrates a solid-state microwave power amplifier, according to the state of the art;

[0030] [Fig.2] schematically illustrates a solid-state microwave power amplifier, according to one aspect of the invention;

[0031] [Fig.3] schematically illustrates a solid-state microwave power amplifier, according to one aspect of the invention;

[0032] [Fig.4] schematically illustrates a solid-state microwave power amplifier, according to another aspect of the invention;

[0033] [Fig.5] schematically illustrates a solid-state microwave power amplifier, according to another aspect of the invention;

[0034] [Fig.6] schematically illustrates a solid-state microwave power amplifier, according to another aspect of the invention;

[0035] [Fig.7] schematically illustrates a power combiner, according to another aspect of the invention.

[0036] Across all figures, elements with identical references are similar.

[0037] Figure 2 illustrates, according to one aspect of the invention, a solid-state microwave power amplifier.

[0038] Contrary to the principle of transition between a track acting as a propagation line and the edge of the waveguide described in the state of the art of Figure 1, achieved by a micro-strip link between the edge of the guide and the microtrack, the present invention achieves this transition by a direct contact between the edge and the propagation line ensured by a clamping device, comprising for example at least one pressure screw.

[0039] The solid-state microwave power amplifier includes an upper part 0 of a waveguide, a linearized impedance transformation edge 1, and a lower part 2 of the waveguide, which may, in some cases, also have a linearized impedance transformation edge.

[0040] The solid-state amplifier comprises a printed circuit board 3 with a propagation line or microtrack 6, at least one pressure screw 4, and a pressure support stiffener 5. The amplifier also includes a support base 7 and a waveguide cavity 8. The figures show only a device with one pressure screw 4, but this is not a limitation.

[0041] State-of-the-art solid-state amplifiers all use wired (ribbon link), connectorized (coaxial link) or radiated (antenna) interconnections.

[0042] Figures 3 and 4 show cross-sectional views of a solid-state amplifier according to one aspect of the invention, respectively in front and side view.

[0043] The objective of the solid state amplifier of the invention is to transmit an electromagnetic signal from a propagation line or microtrack 6 to a guide section or section of the guide cavity 8.

[0044] This transmission can be achieved in narrowband using a single edge 1 or "ridge". To extend the bandwidth to 6-18 GHz, a double-edge linearized impedance transformation system 3 is required. 6 as illustrated in figures 3 and 4. For this transmission to be effective, electrical contact must be guaranteed between edge 1 and microtrack 6.

[0045] However, due to the manufacturing and assembly tolerances of the mechanical parts and the printed circuit board 3 mounted on its printed circuit board base 7 (we therefore have a printed circuit board 3 mounted on a metallic base), there remains a thin residual space separating the two transmission lines or edges (edge ​​1 and microtrack 6) which it is necessary to fill.

[0046] In order to ensure electrical contact over the entire temperature range (due to the consideration of expansion effects) and during any intended use (constraints of resistance to vibration and shock), at least one pressure screw 4 is anchored in a pressure support stiffener 5 and deforms the cavity 8 by pressing on the edge 1 while remaining in the elastic domain.

[0047] Pressing on edge 1 allows contact to be made between its lower end and the propagation line or microtrack 6.

[0048] The proper functioning of the amplifier depends on: - the support on edge 1 which must be controlled and the deformation which must be limited so as not to significantly alter the dimensions of cavity 8 (impact on the quality of propagation); - the printed circuit board on which edge 1 comes into contact must be hard and must have a line width or microtrack compatible with the width of the edge at its end; - the type of printed circuit board must be able to pass the expected power (50W CW) over the entire temperature range, from -40° to +85°C; - the operating time of the solid state amplifier must not cause degradation of the printed circuit board, so that it remains in the elastic range; - the connection must be able to be mounted and dismounted without altering performance by simply screwing and unscrewing.

[0049] Preferably, the substrate resists deformation under a minimum pressure of 500 MPa, and is made of Al203 or duroid (registered trademark) of type RO4350 or R04003, and the tightening torque of the screw must not cause irreversible deformation while remaining within the limit of the elastic range.

[0050] In a preferred embodiment, the mechanical and assembly tolerances are compatible with the type of substrate used and therefore with its dielectric permittivity θr. Consequently, the maximum permissible dimension of the gap G1, as illustrated in Figures 5 and 6, is 0.1 mm to ensure that it remains within the elastic range of the clamping device. The tolerances Tx and Tz are then less than 0.1 mm. The architecture illustrated in Figure 7 allows the printed circuit board to be brought against the lower part 2 of the waveguide, resulting in G2 = 0, a crucial element for proper microwave operation. Thus: G1, Tx, Tz, and Ty < 0.1 mm and G2 = 0.

[0051] As shown in Figure 5, the Z-axis alignment tolerance Tz between the lower guide 2 and the support plate 7 remains much smaller than the substrate thickness H H with - r T > 5.

[0052] Similarly, it is important that the bearing area of ​​edge 1 is aligned with the microtrack, as shown in Figure 6. Preferably, the x-alignment tolerance Tx between edge 1 and microtrack 6 should be significantly less than the width Wr of edge 1 at the point of contact with the printed circuit board, or the width Wl of microtrack 6 should be greater than Wr plus the assembly tolerance of 0.1 mm. The simulations therefore imply that it is necessary to have: Wr — < 4 or W > Wr + 0.1mm Tx

[0053] Therefore, the target value 8r of the printed circuit board substrate is given by the following relationship:

[0054] Also, preferably the substrate is low loss, i.e. it should offer the lowest possible tangent delta (tan d) (classically <0.001) to limit heating by linear losses and offer excellent thermal conductivity.

[0055] As illustrated in Figure 7, a power combiner is also proposed comprising four solid-state microwave power amplifiers 10 as previously described, connected in an H configuration by a magic T-connector 11, known as a four-to-one H-topology, which has the particularity that one half is fused with a chassis 12, and the other half is assembled by screwing 13. The combiner includes a bidirectional coupler 14. In addition, the upper part of the combiner device covers both the lower part of the combiner fused with the chassis and the four solid-state microwave amplifier modules.

[0056] The four pressure screws ensure contact between the amplifiers. 10 and the access points of the magic T-shaped 11.

[0057] The combiner's H-shaped configuration optimizes the footprint and hot spot distribution. The four-to-one Magic Tee is a single-piece unit (the S-flange and 14 bidirectional coupler are machined from a single piece) and incorporates microtrack-to-double-edge waveguide transitions with non-standard impedance transformation, enabling optimal compactness without transitions. Losses are therefore minimal and efficiency maximized.

[0058] The 10 high-power microwave amplifiers, the magic T device The components 11 and 14 bidirectional coupler can be assembled and disassembled very easily by simply screwing them together. This greatly simplifies maintenance and repairability.

[0059] The interconnections of the combiner device are not hyperstatic.

[0060] The combiner device also includes a driver module or "driver" in English 18 to pre-amplify the signal.

[0061] The "flat" mounting configuration of the combiner unit's components allows for easy thermal management. The modular design enables cost-effective scalability and easy maintenance.

[0062] The combiner device provides isolation between lanes which allows for the maintenance of performance during mild degradation.

[0063] In this example, the substrate used is an alumina with a thickness H=0.6mm and a line width Wl=0.6mm, resulting in a characteristic impedance of 50 ohms. On the side of the supporting edge, the width is Wr=0.4mm and the overlap length S=0.8mm.

Claims

DEMANDS 1. Solid state microwave power amplifier comprising at least one interconnection, between a propagation line (6) and an edge (1) of a linearized impedance transformation waveguide, provided with a clamping device (4) ensuring direct contact between the edge (1) and the propagation line (6).

2. Solid state microwave power amplifier according to claim 1, wherein the clamping device comprises at least one pressure screw (4).

3. Solid-state microwave power amplifier according to claim 2, wherein the pressure screw (4) comprises a spherical end or a flat end.

4. Solid state microwave power amplifier according to any one of the preceding claims, wherein the clamping device includes a pressure support stiffener (5).

5. Power combiner device comprising four solid-state microwave power amplifiers according to any one of the preceding claims, connected in H by a magic T device (11).

6. Power combining device according to claim 5, in which the elements are mounted flat.

7. Power combining device according to claim 5 or 6, wherein the magic T device (11) is monobloc.

8. Power combiner device according to claim 7, wherein the one-piece magic tee device comprises an S-flange, a bidirectional coupler, three two-to-one elementary magic tees, line-to-guide transitions and guide-to-coaxial link transitions.

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