NL1026104C2 - Multi-layer PWB radiant circuit and phase-controlled antenna system in which it is used. - Google Patents

Description

Multi-layer PWB radiant circuit and phase-controlled antenna system in which it is used

This invention relates to a multi-layer PWB (Printed 5 Wiring Board, print panel) radiating circuit. In particular, the invention relates to phase-controlled antenna systems based on such a technology.

The multitude of functionalities of APAR (Acttve Phased Array 10 Radar, active phase-controlled radar) antennas are currently difficult to implement within a given small volume and limited acceptable weight while maintaining high performance and high reliability at acceptable costs, in particular at high operating frequencies (> 10 6Hz). These antennas have to become even more compact because of the requirements that are present for, for example, planar and sunken systems.

APAR antennas are usually characterized by a wide variety of materials. A large number of stand-alone, separately fabricated radiators (for example gotf conductors or Vivaldl-type radiators) must be assembled from separate parts where tight assembly tolerances are required and many complex couplings and connections must be made. Consequently, the production and assembly costs are high and are high the possibilities for further miniaturization are limited 25

Traditionally, various manufacturing and assembly technologies are used, for example for heaters, power supplies and through-connections.

3 © Patent application EP 1 071 161 relates to such an antenna. The radiator construction consists of a stack of disks or patches, comprising a lower active straier on a "dieleetry puck" (diometric filler), fed by a set of "probes" (sew-like feeding lines, in principle a number of "via" connections) and a secondary straier Separated from the active straier by dielectric material, the antenna is therefore not optimized and has the aforementioned disadvantages known in the art.

Moreover, with this antenna, the dielectric pucks containing the lower active emitters must each be placed in a surrounding recess formed in an upper dielectric layer of a different material. This is a rather complicated construction that requires assembly steps subject to strict torture conditions. A modem X-band antenna system for redart applications can be an assembly of thousands of separately fabricated sub-assemblies, each comprising, for example, a radiator and a number of impedance adjustment components, a connector assembly, etc. Each part must be manufactured and assembled, which requires a considerable effort and great precision. It will be clear that the costs involved are high. For example, a radar system of this type can include significantly more than 3000 T / R (Transmit / Receive) module channels per antenna system.

This invention eliminates the aforementioned disadvantages by using a PWB radiating unit which, at least in the utilization of the available volume, is highly optimized, by creating the possibility that at least some emitters do not have to be aligned with their respective Input / output connectors. The resulting system construction is therefore less complex and requires less stringent assembly tolerances.

An object of this invention is a multi-layer PWB beam circuit, comprising: - an RF (Radio Frequency, high-frequency) power supply layer with the power supplies; and - a radiator layer coupled to the first face of the RF feed layer, which radiator layer comprises a system of radiator elements (e.g. microstrip "patch" radiator elements), 1026104 3 input Mgang connectors for connecting T / R modules to the corresponding radiator elements, and - an offset layer for correcting the position shift due to non-alignment of a radiator with the corresponding Ingange / output connector, which offset layer is directly or indirectly coupled to the second plane of the RF supply layer.

Another object of the invention is a phase-controlled antenna system which comprises the above-described multi-layer PWB radiating circuit and at least one T / R module connected to the input / output connector corresponding to the radiator element to be activated.

Further features and advantageous features of the invention 16 will become apparent from the following description of examples of embodiments of the invention, with reference to the illustrations showing specific features of the invention, and from the claims. The separate® properties can be realized separately, all or in any desired combination in one of the possible embodiments of the invention.

- Figure 1, impression of a part of a PWB radiating circuit according to the invention, - Figure 2, cross section through a PWB radiating circuit according to the invention, - Figure 3, example of an off-layer according to the invention, - Figures 4a and 4b, implementation of my PWB carving © circuit according to the invention with T / R modules; Figure 4a is a magnification of a part of Figure 4b and shows the link between the T / R modules and the rays, = Figure 5, example of a calibration layer according to the invention.

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Figure 1 gives an impression of the layered structure (partially shown and not to scale) of an antenna PWB.

The PWB comprises dielectric laminates in a number of strip slits 11 = 14 coupled by adhesive 19. Each radiator can be surrounded by metallized gutters 18, on the sides of which a metal lining is applied, to create a "box-0 structure." Snplaat® of d® gutters can also be fitted with a pattern of densely placed metallized holes (blind® flaps).

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Figure 2 shows the cross section of a characteristic antenna PWB.

The PWB radiating circuit 1 integrates rays 143, offset circuits 11 corresponding in phase 15, feeder circuits 13 including their respective microwave passages, embedded in one multi-layer PWB 1, and optionally calibration networks 12.

The functional design employs a two-layer dielectrically charged stripline structure, wherein the feed circuit is included in the stripline RF feed layer 13 and an offset circuit in the stripline offset layer 11. The offset circuit, for example, a phase-matched offset circuitry is used to avoid a planar offset between the position of radiator 143 and the associated power supply connector 111 at the rear of the assembly. Power connector 111 may be an RF coaxial input / output.

The whole can be supplemented with a stripline layer 12, which includes a test pulse distribution network for antenna calibration and 3 © which uses links for each channel, as shown in Figure 5.

The circuitry of the stripline RF power supply layer 13 is slot (141) coupled (non-galvanically) to a system of randomly formed microstrip patch emitters 143. The transfer can take place within a dielectric hotte to allow RF coupling within the structure. Reduce.

Spotlight 143 is surrounded by a conductive "box" 142.18 to eliminate surface poison coupling phenomena. Spotlight 143 itself may consist of a randomly formed patch metallization 142 surrounded by machined gutters 18, on the sides of which a metallization is arranged around said surface. In essence, this box is a metallized structure, which is also realized through the application of advanced PWB technology.

The emitters 143 can also be given a different 3D shape, using the same PWB technology. A radiator 143 may, for example, be composed of one or more stacked patches, with or without the metallized box structure, for example by surrounding the patches by metallized gutters 18. The stripline RF power supply layer 13 may also be galvanically connected to the (lower) patch by by means of a metallized hole (a via). The box structure can also serve as a dielectrically charged wave-cell radiator and the patch metallization 142 can be made suitable for an iris-type aperture.

The multiple continuous metallic earth layers 18 and 20 present within laminate 1 generate a shield with a very large EMI (ElectroMagnetic Interference) effectiveness

An option is a further integration with a radome 16 and a 2§ FSS (Frequency Selective Screen), the latter serving to reduce the RCS (Radar Cross-Section, radar return) of the antenna. |

The basic configuration of the multi-layer PWB radiating circuit can thus comprise a total of 10 individual dielectric layers, with the possibility of adding specific layers, for example in the case that integrated filtering is required. The versatility of machined gutters (or vias) can undermine the mechanical stability of the laminate and to eliminate this problem a dielectric auxiliary layer 1 S is applied which must ensure that the structural integrity is maintained during | 1026104 β the entire manufacturing process. This auxiliary layer is later used as a cut-off edge for a radome 16 / FSS structure 161.

An optional feature may be a built-in RF filter that uses, for example, a photonic bandafiststrual duration within one of the present stripline layers or an additional target-specific® layer (not shown).

The applied multi-layer PWB technology is an enabling technology, whereby all the required properties can be achieved in a batch process with the organic, controlled dielectric laminates A through J and pattern metallizations 18. As a result, the number of individual parts and assembly steps usually associated with phase-controlled antenna systems can be considerably reduced. This also makes a more flexible, compact and highly integrated design possible, which is also less sensitive to assembly tolerances. Furthermore, this technology facilitates the realization of good structural integrity, scalability, integrated calibration, large bandwidth, good scanning performance, excellent EMI protection and low RCS.

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Because the external radiator system 143 is no more than a plenary structure, the system can be considered as a flat plate and the multi-layer PWB radiating circuit therefore has a low RCS.

Moreover, an RF via Z-axis layer-to-layer interconnection can be implemented via offset layer 11 and, if necessary, calibration layer 12 to the RF feed layer 13, to bypass layers 11 and 12.

In general, multi-layer PWB technology is based on a laminated structure consisting of selectively metallized dielectric layers, which together form one circuit, thanks to post-machining and post-metallization. The combination of basic techniques involved, i.e. photochemical etching, laminating, machining and galvanic technologies, enables an experienced designer to create more unconventional RF structures, such as radiant elements and 3D

1026104 7 transitions, embedded in and functionally linked to the existing RF circuits, all in one product. This can be achieved by considering the 3D RF structures as a stack of 2D substructures, which can be fused together into one total structure after execution of a sophisticated series of process steps. Each PWB can contain hundreds or even thousands of identical RF structures. Moreover, this makes further integration of additional functionality possible

Thanks to the mechanical simplicity of the technology of 10 multi-layer PWB radiating circuits, it is relatively easy to tune them so that one can work with a large bandwidth

Furthermore, with a working frequency of up to 12 GHz, the high integration level made possible by this technology ensures that the emitters 143 are well within half a wavelength apart! can be placed. As a result, extreme scanning angles (beam mobility) are possible without bending loops.

Moreover, since there is a metallic cavity 18 behind patch radiator 142, it has a much better directing effect than what can usually be achieved by patch radiators, while surface waves are suppressed. This helps ensure that a good scanning performance is achieved. The stripline power supply circuit 13 is slot-connected (non-galvanic) to each of the patch emitters 142.

Figure 3 shows the offset layer in greater detail. In this example, offset layer 11 is made suitable for a system of 256 channels. For X-band, the basic dimension of the beam grid is approximately 15 mm x 15 mm.

Thanks to offset layer 11, it is not necessary for T / R modules 2 to be aligned on the street grid, so that space is created where, for example, supporting structures, cabling, coolant manifolds, etc. can be fitted.

The purpose of offset layer 11 is therefore: to allow more flexibility in the mechanical design, because T / R modules 2 no longer have to be aligned with the corresponding radiators 143, which must be positioned in a fixed grid. For this purpose, which can be summarized as correcting the alignment deviation, off-layer layer (11) introduces a phase-matched offset on each channel that contains a radiator element 143 and the associated input / output output connector 111 such that d® is in phase corresponding offset disconnect the gratings from beam element 143 and associated® external active module 2.

Images 4a and 4b demonstrate the advantage of the offset layer. namely that this leaves room behind the antenna system for 10 auxiliary functions.

The image only shows the vertical offset. but the advantage also applies to a horizontal offset 1 § Figure 4b shows an antenna multilayer (multi-layer PWB) 1.

connected to T / R modules 2 and arranged in racks between structural supports 3 which, if desired, include a cow spider, cabling or printed wiring. The structural support is thus made suitable for the placement of T / R modules 2. the latter 20 not having to be aligned with the associated antenna radiator 1. Moreover, the available space behind the control system can be utilized with maximum efficiency.

This is made possible by the specific structure of the antenna multilayer 1 of the present invention, as indicated in Figure 4b, wherein radiators 143 do not have to be aligned with power connectors 111 due to the position-deviation function of offset layer 11 within the multi-layer antenna 1.

In this way OffseMaag 11 facilitates the interconnection between T / R channels 2 and the associated radiators, which do not have to be aligned. This gives more design freedom. The required distance between individual radiators no longer determines the physical layout of the main electronic components immediately after the radiant system.

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This considerably increases the freedom of the antenna system architect and can, for example, result in improved modularity and scalability.

Figure 5 shows in greater detail the calibration layer that includes a test pulse distribution network and links for each of the 768 channels in this example. The test pulse signal is injected into the channels via the couplings. This is an easy and inexpensive way to ensure that the antenna is calibrated at all times.

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Integrated calibration is rarely used in the radar industry due to manufacturing problems. In wave-gel technology, for example, integrated calibration means that a complete test pulse distribution circuit must be interwoven with all active 1s emitter channels (at least a few thousand), requiring much more parts and making assembly much more complex with an ever-increasing level of accuracy required.

Most systems rely on a separate external system for calibration. This is very simple, but it has a major drawback: calibration must take place periodically to ensure continuous, stable operation. In the case of an external system, this means that the system must be positioned very precisely in front of the antenna and then quickly removed again in order to block the field of view as shortly as possible. This is a very difficult procedure that, moreover, cannot be carried out at any time, particularly in bad weather and in particular in maritime applications.

An integrated calibration layer 12, on the other hand, can be used very frequently and under all circumstances, so that antenna 1 can remain calibrated at all times for maximum performance.

The assembly is entirely based on known production processes, adapted to obtain the required structures and properties for this application. The assembly process consists of a sequence of photolthographic, 3D machining, galvanic and laminating processes to create the desired multi-layer PWB radiating circuits. The order in which these process steps are carried out is a factor of decisive significance, the value of the design's feasibility depends on

With design of this multi-layer PWB radiant circuit has an inherent structural integrity. From a mechanical point of view, a multi-layer PWB is a laminated panel based on a polymer composite. The thickness of a panel as described is more than about 10 mm. It is therefore very rigid and usually no additional structural support needs to be provided, which benefits the simplicity of the mechanical design of the radiant circuit. 1§ The use of such a multi-layer PWB radiant circuit in active phase-controlled antenna systems is interesting because it facilitates connection to any type of T / R module, as indicated in Figures 4a and 4b.

2® The application area is mainly radar, but can also extend to wireless telecommunications applications. With regard to radar, the invention can be applied, for example, in S-band and X-band systems, but also in a wide range of other frequency bands. In general, the higher frequency bands will benefit more from the invention, thanks to smaller dimensions, which are proportional to the wavelength.

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Claims (9)

A multi-layer PWB (Printed Wiring Board, print panel) radiating circuit, comprising: - an RF (Radio Frequency, high-frequency) supply layer (13) with the supply circuits; and - a radiator layer (14) coupled to the first face of the RF supply layer, which radiator layer comprises a system of patch B radiator elements (143), - input / output connectors (111) for connecting external active modules (2) to the respective radiator elements (143), characterized in that said multi-layer PWB radiating circuit also comprises an offset layer (11), for correcting the non-alignment of a radiator (143) and the corresponding input / output connector (111) caused by position deviation, which offset layer (11) is directly or indirectly coupled to the second surface of the RF feed layer (13). Multi-layer PWB radiating circuit according to the preceding claim, characterized in that the offset layer (11) for correcting the alignment deviation introduces a phase-matched offset on each channel 20 that has a radiator element (143) and the corresponding input / output output connector (111), so that the phase-matched offset disconnects the grid from the emitter element (143) and the grid from the corresponding external T / R (Transmlt / Receive) modules (2) from each other Multi-layer PWB radiating circuit according to claim 1 or 2, characterized in that the radiator element (143) comprises a dielectrically charged waveguide radiator (142), the patch metallization being made suitable for an irls-type aperture. 30 Multi-layer PWB radiating circuit according to one of the preceding claims, characterized in that the radiator element (143) comprises one or more stacked patch metallization devices (142) that serve as the aperture and are coupled to a stripline power supply (17), which patchss (142) surround! 1026104 are through metallized gutters (18). Multilayer PWB radiating circuit according to one of the preceding claims, characterized in that it comprises a layer dielectric auxiliary layer (15) which is attached to the strater layer. Multi-layer PWB radiating circuit according to one of the preceding claims, characterized in that it comprises a radome layer (18) which is directly or indirectly coupled to the radiator layer (14). 10 The multi-layer PWB radiating circuit according to the preceding claim, characterized in that it comprises a frequency-selective screen structure (161) on the inner surface of the radome layer (16). Multi-layer PWB radiating circuit according to the preceding claim, characterized in that it comprises an RF filter within one of the Days present, or an additional layer specially adapted for filtering Multilayer PWB radiating circuit according to the preceding claim, characterized in that it comprises a calibration layer (12) provided with a test pulse distribution network, which makes it possible for the circuit to be calibrated at any time. A phase-controlled antenna system comprising the multi-layer PWB radiating circuit (1) according to one of the preceding claims and furthermore at least one T / R module (2) connected to the input coupled to the radiator element (143) to be activated. output terminal (111). 1026104