EP0718907A1 - Phased array antenna and method of its manufacturing - Google Patents

Abstract

The antenna has an antenna surface with a number of transmitter/receiver elements arranged in a matrix, each associated with a respective transmitter/receiver module (TR1,...TR4) positioned beneath the antenna surface. A reception frame (TP) supports a number of transmitter/receiver modules and has at least 2 heat sinks (KU) through which a cooling medium is circulated, with a clamp for pressing the modules into contact with the heat sinks. Pref. the clamping device uses at least 2 rod-shaped clamping elements (SPE1,SPE2) secured together via a clamp screw and a clamp spring.

Description

The invention is based on a phase-controlled antenna according to the preamble of patent claim 1 and a method for its production according to the preamble of patent claim 5.

The invention relates in particular to a phase-controlled antenna for a radar system, a large number of radiating elements, for example dipole radiators, being arranged in a matrix in one plane, for example in rows and columns arranged at right angles to one another. It is advantageous if both the rows and the columns are at the same distance. Also orders from Radiator elements in a triangular grid are used. With such an arrangement of radiator elements, a large number of transmission and / or reception directional diagrams can be produced. For this purpose, it is necessary to establish an amplitude and / or phase relationship that can be determined as precisely as possible between the transmit and / or receive signals to be assigned to each radiator element. This should be able to be changed as quickly as possible, so that a large number of operating modes, for example an electronically carried out pivoting process and / or a shaping of the directional diagram of the antenna, can be carried out. To carry out such operating modes, it is expedient to directly connect a separate transmit and / or receive module (T / R module) to each transmit and / or receive radiator element. Each T / R module contains all of the transmit and / or receive modules that are customary in radar technology, for example transmit and receive amplifiers, transmit / receive switches and phase and amplitude adjusters. The continuously evolving electronics make it possible to reduce these assemblies more and more and to design them for ever increasing transmission and / or reception frequencies, for example the GHz range. For special applications, it is possible, for example, to feed each T / R module only an analog LO signal ( L ocal- O scillator) that is generated by a single (common) LO generator. All other signals required in radar technology, for example IF signals and control and / or switching signals, can be supplied to the T / R modules in digital form, for example via a so-called digital bus.

Such an overall arrangement, which is also referred to as an active front end, of T / R modules and radiator elements has the particular advantage that a control and / or evaluation device coupled to the front end can also be largely constructed using digital modules and that between the front end and the control and / or evaluation unit only a few analog and digital connecting lines are required.

Such a front end has the particular disadvantage that, due to the low efficiency of the T / R modules, in particular with high transmission power, a high power loss (heat) arises in each T / R module, which must be dissipated. This requires a cooling system that takes up a lot of space, thereby determining the minimum distance that can be achieved between the radiator elements (T / R modules).

The invention is therefore based on the object of specifying a generic antenna which, with a small (grid) spacing between the T / R modules, enables high power dissipation, which is easy to maintain and which is inexpensive to manufacture.

The invention is also based on the object of specifying a method for producing such an antenna.

This object is achieved by the features specified in the characterizing parts of claims 1 and 5. Advantageous refinements and / or further developments can be found in the further claims.

A first advantage of the invention is that several T / R modules can be combined electrically and mechanically to form a macro module and this macro module can be arranged in a macro housing.

A second advantage is that each macro housing is only attached to a frame by means of a single fastening screw, which can accommodate a large number of macro housings, depending on the antenna configuration required. This makes it possible to replace a macro housing at low cost.

A third advantage is that after mounting, all macro housings rest against air or liquid-cooled heat sinks, which enable the power loss that is produced to be transported effectively.

A fourth advantage is that there is no need to interrupt the cooling circuit while replacing a macro housing.

A fifth advantage is that the mechanical and electrical structure of a macro housing are largely independent of one another, so that, in particular, effective routing of electrical conductor tracks is possible.

A sixth advantage is that very inexpensive tests of individual components and / or assemblies can be carried out during the manufacture of a front end, so that possible errors can be recognized and eliminated at an early stage. This can include data showing the differences between the individual properties of the T / R module considered to form a reference or ideal T / R module, are stored in a module-internal memory. This makes it possible to exchange T / R modules in the HF front end of a radar system without having to change other modules with regard to the individual properties of the respective module.

Further advantages result from the following description of an exemplary embodiment. This is explained in more detail with the aid of schematically represented figures.

Show it

• FIG. 1 shows a top view of an opened macro housing.
• FIG. 2A, FIG. 2B shows a top view and a section of a receiving frame for receiving macro housings.
• FIG. 3 shows a section through two attached macro housings.

FIG. 1 and FIG. 3 shown to scale, in the sense that the proportions can be removed.

The exemplary embodiment described below relates to a phase-controlled antenna (active front end), in which a multiplicity of transmitting and / or receiving radiator elements, for example dipole radiators, are arranged in one plane, for example in the form of a planar rectangular matrix with a grid dimension ( Row and column spacing) of approximately 13.6 mm. This level, which is also called the antenna level below, has one Area normal FN, which is shown in the figures as an arrow. The tip of the arrow points in the "up" direction (header of the drawing level). T / R modules are located below the antenna level, with a T / R module being assigned to each transmitting and / or receiving radiator element. This means that the T / R modules are also arranged in the grid dimension of the radiator elements. In a plane parallel to the antenna level, the T / R modules therefore also have the exemplary selected grid dimension of approximately 13.6 mm. For example, four such adjacent T / R modules are now combined to form a macro module. The latter is arranged in a macro housing.

FIG. 1 shows a top view of an opened macro housing MG. This is rectangular in plan view, a connector and / or connecting strip AS, VS being provided on each of the two narrow sides. The aforementioned radiator elements of the antenna level can be connected to the plug and / or connecting strip AS. The connecting lines required for operating the macromodule can be connected to the opposite plug and / or connecting strip VS, preferably by plug connections, which will be explained in more detail below.

In the macro housing MG there is a carrier plate TP, the one shown in FIG. 1 visible top side is advantageously fully usable for the assembly of electronic components and / or assemblies. The carrier plate TP has, for example, a length l = 120 mm, a width b = 52 mm, a thickness d = 1.5 mm and consists of one material with predefinable thermal properties, for example a molybdenum-copper alloy, which is currently commercially available under the name Mo30Cu. The mounting plate TP is attached to the macro housing MG by means of fastening screws TBS, which are screwed from the underside of the macro housing MG (FIG. 3) and do not protrude beyond the top of the mounting plate TP. The upper side is therefore advantageously a level which can therefore be used completely for the construction of electronic circuits, that is to say that no mechanical design features, for example openings, have to be taken into account in the circuits.

In this exemplary embodiment, the circuits for four T / R modules TR1 to TR4 are attached to the surface of the carrier plate TP, preferably by means of electrically conductive adhesive connections. Each T / R module contains three circuit parts. These can advantageously first be checked and / or adjusted independently of one another and can then be attached in strips in the manner shown by adhesive and bonded connections to the carrier plate TP. A circuit arrangement GS common to all T / R modules is also attached to the carrier plate TP. The type (layout) of the circuits is not described in detail since they are not relevant for the understanding of this patent application. All circuits can be implemented, for example, as printed circuits on currently commercially available ceramic substrates. A logic circuit LS which is common to all T / R modules and is shown in dashed lines is also attached to the underside of the carrier plate TP, for example also by gluing.

It can be seen that such a carrier plate TP can itself be produced in a cost-effective manner on the one hand and can be equipped and tested with circuits (substrates) in a cost-effective manner on the other hand. Only then is it installed in the macro housing MG and the required connections, e.g. by soldering and / or bonding, to plug connections AS, VS.

The electrical and / or electromagnetic shields required for the operation of such a macromodule, in particular between the T / R modules TR1 to TR4, can be produced by attaching corresponding metallic (shielding) webs to the housing cover MD (FIG. 3) . These are then arranged with the housing cover MD closed between the T / R modules.

FIG. 2A shows a schematically illustrated receiving frame for accommodating a plurality, e.g. a few hundred such macromodules according to FIG. 1.

FIG. 2B shows a schematically illustrated section of the receiving frame along the line AA (FIG. 2A).

According to FIG. 2A, the receiving frame essentially consists of a predeterminable number of heat sinks KU arranged parallel to one another, through which a cooling liquid, for example water, can flow. The heat sinks KU are attached at their ends to an annular holding frame HR and have a rectangular cross section, the dimensions of which can be seen in FIG. 3 result. According to FIG. 2B also has a rectangular cross section and also serves as a distribution line for the incoming and outgoing coolant, which flows through all heat sinks KU in parallel, for example in the direction of arrow F. Below the heat sink KU (based on the surface normal FN) is shown in FIG. 2B attached a connector socket and distribution circuit VSB and fastened to the holding frame HR by means of struts STR.

All macro modules M, of which in FIG. 2A, 2B only two pieces are shown, are now inserted against the direction of the surface normal FN between the heat sink KU and plugged into the distributor circuit VSB with the plugs VS (FIG. 1, 2B). In this way, all electrical connections are made both between the macromodules M and from these to a control and / or evaluation unit (not shown). This is because it has line connections LB to the distributor circuit VSB, for example. The macro modules M are now by means of a clamping device SP, which is based on FIG. 3 is explained in more detail, pressed against the heat sink KU, so that there is both a mechanically stable connection and excellent thermal contact.

FIG. 3 shows a section through two macro modules according to FIG. 1. The macro modules are designed so that in a region BE on the connector strip AS, the antenna side, the carrier plate TP is directly (flat) on the macro housing MG. As a result, there is particularly good electrical and heat-conducting contact between the carrier plate TP and the macro housing MG in this area. This contact can be improved by using a thermal paste. In this area BE are those electrical components, for example Power amplifier PA, which generate a large power loss. In this area BE, the side of the macro housing MG facing the heat sink KU is designed in such a way that there is good thermal contact, that is to say a good interlocking connection is present, which can be increased by an optional application of a thermal paste (thermal compound). This thermal contact is essentially constant over a wide, predefinable temperature range, for example from -50 ° C to + 50 ° C. This is achieved by a resilient tensioning device SP (FIG. 2A, 2B). This consists of a first tensioning element SPE1, a second tensioning element SPE2, a tensioning screw SPS, a tensioning spring SPF and an area (chamfer) of the housing cover MD adapted to the tensioning elements SPE1, SPE2. The tensioning elements SPE1, SPE2 have, for example, a cross section of approximately 6 mm × 6 mm and, in the manner shown, a bevel (bevel), for example of 45 °, on the mutually facing edges. The same bevels (chamfers) are present on the housing cover MD. If the clamping screw SPS, for example a so-called Allen screw, is now tightened, preferably by means of a torque wrench, the housing cover MD and thus the macro housing MG are pressed apart, perpendicular to the surface normal FN, but in the plane of the drawing, and thus pressed against the heat sink KU . The set contact pressure is essentially independent of temperature fluctuations due to the tension spring SPF. A disruptive bending of the housing cover MD, which is possible per se, is avoided by the shielding webs already mentioned, which are supported on the macro housing MG and thus bring about mechanical stabilization.

It can be seen that the clamping device SP described causes a good mechanical three-dimensional attachment (clamping connection) of the macro housing to the heat sinks KU by the pressing process. For particularly high mechanical loads (vibrations), this attachment can be reinforced by elevations and depressions, which are attached to the macro housing MG and the heat sink KU, and each engage in a form-fitting manner. Alternatively or in addition, it is possible to attach the macro housing MG to the heat sink KU by means of fastening screws BF.

From FIG. 1 it can be seen that the clamping elements SPE1, SPE2 (as well as the associated objects on the housing cover MD) are arranged approximately in the middle of the macro housing and have a length (perpendicular to the plane of the drawing in FIG. 3) which is less than or equal to half the width (approximately b / 2) of the macro housing MG. As a result, it is advantageously possible to mount and dismantle all macro modules independently of one another in the mounting frame (FIG. 2A, 2B). The following example explains this. It is believed that according to FIG. 2A there is a maximum possible number of macromodules M that touch each other between the heat sinks KU. If a specific macro module is to be replaced as part of maintenance, it is only necessary to loosen the associated clamping screw SPS (FIG. 3) and move it, including the clamping elements SPE1, SPE2, along the heat sinks (by the length of the clamping elements). Then you can use SPE1, SPE2 clamping elements, SPS clamping screw and SPF clamping spring be removed as a whole unit in the direction of the surface normal FN. This means that two macro modules can be removed. In particular according to FIG. 3, the dimensioning of all mechanical components is now selected so that a specific macro module, for example the one shown in FIG. 3 shown on the left, can be removed from the mounting frame in the direction of the surface normal FN. A replacement macro module is then inserted in the reverse order.

Thereby, it is for example possible to repair an in use (operation) befindliches active front end, which has a so-called BITE device (B uild I n T est E quipment), Current. It is not necessary to move the front end to a special maintenance workshop. A defective macro module can be determined by the BITE device. After removing the associated radiator element, this can be replaced in the manner described. This exchange is advantageously possible without cooling liquid having to be removed from the heat sinks and then topped up again. It is therefore not necessary to vent the cooling system.

The invention is not limited to the examples described, but can be applied analogously to others. For example, it is possible to arrange more than four T / R modules in a common module housing or, alternatively, to mount each T / R module individually in one housing. Furthermore, macro modules with different numbers of T / R modules can be used in the mounting frame. This makes it possible to use the device shown in FIG. 2A shown circular shape to be largely approximated by T / R modules and radiator elements. It also follows from this that other antenna shapes, for example elliptical or rectangular shapes, can also be implemented.

Furthermore, it is not necessary that the surface of the heat sink KU facing the radiator elements forms a plane (straight line in FIG. 2B). Rather, it is also possible to bend the surface, e.g. to be concave. As a result, a specific directional diagram can be generated solely by the mechanical structure.

Claims (6)

Phase controlled antenna, at least consisting of an antenna surface in which a plurality of transmitting / receiving radiating elements are arranged in a matrix, - An associated T / R module is available for each transmitting / receiving radiator element
and the T / R modules are arranged below the antenna normal with respect to the surface normal thereof,
characterized by - that a mounting frame is available for fastening several T / R modules (M), - That the receiving frame contains at least two rows of heat sinks (KU), - That the heat sinks (KU) have inlet and outlet connections for a cooling medium at their ends, a common feed line (HR) for supplying the cooling medium is connected at least to the inflow connections, - That a distribution circuit (VSB) is arranged below the heat sink (KU), which has electrical plug connections for the electrical coupling of the modules (M)
and - That a clamping device (SP) is available for pressing at least two modules (M), which are in a row formed by two heat sinks (KU), to the associated heat sinks (KU). Phase-controlled antenna according to Claim 1, characterized in that the tensioning device (SP) consists of at least two rod-shaped tensioning elements (SPE1, SPE2) which can be resiliently tensioned against one another by means of a tensioning screw (SPS) and a tensioning spring (SPF). Phase-controlled antenna according to Claim 1 or Claim 2, characterized in that the tensioning elements (SPE1, SPE2) have a length less than or equal to half the width of a module housing (MG). Phase-controlled antenna according to one of the preceding claims, characterized in that that several T / R modules (TR1 to TR4) are arranged in a macro housing (MG) on an essentially flat carrier plate (TP), - that the carrier plate (TP) is fastened to the macro housing (MG) by fastening screws (TBS), - that a housing cover (MD) is provided for the macro housing (MG), - That at least one shielding web is attached to the housing cover (MD) for electrical and / or electromagnetic shielding of the electrical components and / or assemblies arranged on the carrier plate (TP)
and - That on the side facing away from the shielding web of the housing cover (MD) there is a thickening with bevels (AB) which complement the clamping device (SP). Method for producing a phase-controlled antenna according to one of the preceding claims, characterized in that that electrical components required for T / R modules are attached to a surface of a substrate suitable for electronic circuits, - That the substrate is attached to a carrier plate (TP) by means of an adhesive connection, - That the carrier plate (TP) is fastened within a macro housing (MG) by means of several fastening screws (TBS) taking into account a predeterminable torque and - That two macro housing (MG) are attached to a heat sink (KU) of a mounting frame by means of a common clamping device (SP). A method according to claim 5, characterized in that an electrically conductive adhesive connection is selected.

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