The invention relates to waveguide structures formed by interconnected multiple waveguide sections. These waveguide structures may be used for guiding electromagnetic waves specifically in rotating contactless data links. These waveguide structures include a layer of dielectric material further having at one side a ground layer and opposing thereto a conductor structure of electrically conductive material. The conductor structure may be a uniform line having a predetermined characteristic impedance or a structured pattern which may have a filtering characteristic.
In rotating contactless data links, waveguide structures are used for guiding RF signals. These waveguide structures may include striplines, microstrips or similar structures for guiding electromagnetic waves. They include a dielectric material further having at one side a conductive ground layer and opposing thereto a conductor structure of electrically conductive material, mostly a thin copper layer, which may be galvanized. The waveguide structures are like elongate PCBs (Printed Circuit Boards) and are often manufactured as such. The conductor structure may be a uniform line having a predetermined characteristic impedance or a structured pattern line which may have a filtering characteristic.
A microstrip conductor is disclosed in U.S. Pat. No. 5,530,422 A. A meander shaped conductor structure which offers better coupling and RF noise suppression is disclosed in EP 1 012 899 B1. The structured pattern line disclosed therein has a constant characteristic impedance for lower frequencies e.g., less than 5 GHz and a high suppression of higher frequencies.
In large devices like CT (Computed Tomography) scanners, a waveguide structure may have a total length up to 5 m adapted to the outer circumference of the rotating part of the gantry. Normal PCBs are comparatively small and manufacturing waveguide structures with a length of up to 5 m needs special manufacturing processes which are extremely expensive.
Starting from normal PCBs, the manufacturing machines may be increased in size. Further, it may be possible to wind up the PCBs and materials as they are long but comparatively narrow and must have some flexibility to form a circle in the later application.
The problem to be solved by the invention is to provide larger waveguide structures for lower costs while maintaining good RF characteristics.
Solutions of the problem are described in the independent claims. The dependent claims relate to further improvements of the invention.
In an embodiment, multiple waveguide sections are joined together to form a larger waveguide structure by at least one fixed connector. Although it may be more straightforward to use standard PCB connectors, which may be connected and disconnected, fixed connectors, which e.g., may be soldered, welded, have a conductive adhesive, or a galvanized contact, between the PCBs have shown to offer significant advantages. Connecting waveguide sections by such connectors allows to manufacture the waveguide portions like PCBs by normal manufacturing machines and processes. Special interconnections between the waveguide sections are provided to maintain the RF characteristics of the waveguide portions throughout the waveguide structure. The interconnections are designed such, that they do not extend over the surface of the waveguide sections to avoid collision with a receiving pickup passing the waveguide structure at a close distance. Further, the interconnections may provide reinforcement to increase the mechanical stability, e.g., to prevent damages during transport and during assembly into a larger slipring body. Such a reinforcement may still have some degree of flexibility and/or be limited in size to give the overall waveguide structure a flexibility to be adapted to a circular body.
The waveguide sections include at least one layer of a dielectric material (an insulating material). They may also include a plurality of dielectric layers. They may be printed circuit boards. There may be conductive layers or layers with conductive structures between the dielectric layers. The waveguide sections may have at one side, here called the bottom side, of a layer of a dielectric material a conductive ground layer and opposing thereto, here called the top side, a conductor structure of electrically conductive material. Herein the terms top side and bottom side are only used for simplifying reference. The embodiments may also be reversed with the bottom side on top or in any other orientation.
The ground layer and/or the conductor structure may include a thin copper layer, which may be galvanized with a high conductivity material like silver or gold.
The conductor structure may include at least one or a pair of elongate conductors, which may be parallel and spaced with a first distance. The conductor structure may be a uniform line or a pair of uniform lines having a predetermined characteristic impedance or a single or a pair of structured pattern lines which may have a filtering characteristic. The predetermined characteristic impedance may be essentially constant over the length of the conductor structure. The characteristic impedance may be a constant value between 1 Ohm and 200 Ohm or between 10 Ohm and 100 Ohm. There may be a single line or a pair of lines, which may be operated differentially. For a larger number of signals, a larger number of lines may be provided. The ground layer and/or the conductor structure may be at outer sides of the dielectric material or embedded into the dielectric material. They have at least to be separated by dielectric material. The conductor structures normally are not connected to the ground layer.
The waveguide sections may have the shape of a rectangular plate or arc shaped plate with a thickness of less than 3 mm, 2 mm or 1 mm, depending on the specific implementation They have two opposing ends and two opposing longitudinal sides between the ends. They may also have the shape of a flexible PCB with a thickness of less than 1 mm, 0.5 mm, 0.2 mm, or 0.1 mm. The minimum thickness may be 0.1 mm, 0.2 mm, or 0.25 mm, depending on the specific implementation. The lines may have a linear (straight) shape and in the case of two or more lines, they may be parallel to each other.
The waveguide sections may include an interface section at at least one of the two opposing ends. The interface sections may include an intermediate conductor from each of the elongate conductors at the top side to the bottom side of the at least one layer of a dielectric material.
Two elongate or elongated and parallel to one another conductors may be separated by a distance (at the interface sections) that is larger than the first distance. The first distance is the distance the conductors have over their length and distant from the interface sections. To the two elongate conductors two intermediate conductors may be connected, which have a distance larger than the first distance.
An x-axis (the longitudinal axis of a waveguide section) is defined along the length of the lines and at the center of the lines in the plane of a waveguide section. A first end and a second end of a waveguide section are spaced in direction of the x-axis.
A y-axis (the transverse axis) is substantially orthogonal (under a 90° angle) to the x-axis in the plane of the waveguide section. A z-axis is orthogonal to the x- and y-axis and protrudes from the plane of the lines to the space above the lines. A first end and a second side of a waveguide section are spaced in direction of the y-axis.
The waveguide sections may have a length (in direction of the longitudinal axis) of less than 100 cm, 80 cm, 50 cm, or 30 cm and a width, which may be smaller than the length of less than 10 cm, 5 cm, 3 cm, 2 cm or 1 cm, depending on the specific implementation. The width may be more than 3 mm or 5 mm. The waveguide sections may be cut from shorter panels which may have lengths of 24″, 48″, 54″, 72″ or 84″. For all sizes there may be clippings (border areas) of 1″ at each side of the panel of usable (printable) size. It may also be possible to use maximum available panel lengths of typically 102″ as waveguide section. Depending on the requirement of the design lengths may be up to 2540 mm, 2080 mm, 1770 mm or up to 1320 mm, 1160 mm and 550 mm can be realized or any length below, in practice longer than 300 mm.
The waveguide sections may be either flat or arc-shaped around an axis parallel to the y-axis or the z-axis.
At least one fixed connector may be provided to connect two waveguide sections. Such a fixed connector may be a printed circuit board and includes at least one layer of a dielectric material having a top side, a bottom side and two opposing ends. It may further include at least one contact pad of electrically conductive material on the top side, and a connector ground layer of electrically conductive material on the top side and insulated from the at least one contact pad.
The fixed connector as a printed circuit board may have a length of 7 mm to 18 mm, a width similar in value to the width of the waveguide sections.
The at least one fixed connector may be is attached by its top side to the bottom side of the interface section of a first end of at least one first waveguide and to the bottom side of the interface section of a second end of at least one second waveguide. Further, each of the intermediate conductors of interface sections of the waveguide sections may be connected to a contact pad and are insulated from the ground layer. Consequently, they are also insulated from the connector ground layer. The waveguide sections may be opposing each other and at least one intermediate conductor of a first waveguide section is connected to an opposing intermediate conductor of a second waveguide section by at least one contact pad.
In an embodiment, a waveguide structure may include at least one first waveguide section mechanically and electrically connected by at least one fixed connector to at least one second waveguide section,
each of the at least one first and the at least one second waveguide sections may include at least one of:
the at least one fixed connector may include at least one of:
the at least one fixed connector may be attached by its top side
and the interface sections may include an intermediate conductor from each of the elongate conductors at the top side to the bottom side of the at least one layer of a dielectric material,
each of the intermediate conductors being connected to a contact pad and insulated from the ground layer,
the at least one first and the at least one second waveguide sections are opposing each other and at least one intermediate conductor of a first waveguide section is connected to an opposing intermediate conductor of a second waveguide section by at the at least one contact pad.
In another embodiment, a waveguide structure may include at least one first waveguide section mechanically and electrically connect-ed by at least one fixed connector to at least one second waveguide section,
each of the at least one first and the at least one second waveguide sections may include at least one of:
the at least one fixed connector may include at least one of:
and
the at least one fixed connector may be attached by its top side
and
the interface sections may be connected by a pair of conductive pads, where each of the conductive pads connects each of a pair of elongate conductors of the at least one first waveguide section to each of the corresponding of the elongate conductors of the at least one second waveguide section.
Conductive pads may include at least one of copper, brass, tin, silver or gold. They me be a thin film or layer of such conductive material. The conductive pads may form a corrugation between the waveguide sections. The interface sections may be straight cut ends of the waveguide sections.
In an embodiment, at least one electrical contact is formed by soldering connections, welding connections, conductive adhesive, or galvanized contact.
In the following the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment with reference to the drawings. Reference is made to the list of reference numerals below which identifies the components in the figures.
In
The waveguide structure as shown may be mounted to the circumference of a slipring module by adhesives, a layer of adhesive tape or mounting brackets or a combination those.
In
Further, the first interface section 218 includes a first intermediate conductor 215 which extends from the first elongate conductor 212 down to the bottom side of the first layer of dielectric material. There may be a first contact pad 214 at the bottom of the first layer of dielectric material 211 to simplify contacting with a fixed connector 250. The first contact pad 214 may be connected to the first intermediate conductor 215.
Further, the second interface section 228 includes a second intermediate conductor 225 which extends from the second elongate conductor 222 down to the bottom side of the second layer of dielectric material. There may be a second contact pad 224 at the bottom of the second layer of dielectric material 221 to simplify contacting with a fixed connector. The second contact pad 224 may be connected to the second intermediate conductor 225.
A fixed connector 250 includes a fixed connector dielectric layer 251 which has a connector ground layer 255, 256. The sections of the connector ground layer 255, 256 are electrically connected, for example by a connector ground base layer 252 at the bottom side of the fixed connector dielectric layer and by additional vias or through-holes 257. Further, the fixed connector further includes at least one contact pad 253 on its top side which is electrically insulated from the ground layer. The fixed connector may have the same width as the first and second waveguide sections, but may be much shorter, e.g., up to 5 cm or up to 10 cm.The thickness of the fixed connector and/or of the waveguide sections may be more than 0.5 mm and up to 2 mm, 3 mm or 5 mm. The fixed connector and/or f the waveguide sections may include a fiber reinforced polymer for increased mechanical stability and may be a PCB.
To provide an electrical connection between the first waveguide section 210 and the second waveguide section 220, the fixed connector 250 is soldered to these waveguide sections. For ground connection, the connector ground layer 255, 256 is soldered to the ground layers 216, 226 of first and second waveguide sections. Further, the contact pad 253 is soldered to the first and second intermediate conductors 215, 225, and/or to first and second contact pads 214, 224. The contact pads provide a better soldering over a larger surface, but they may also be omitted, if the intermediate conductors reach close to the contact pad. Instead of soldering, the contact may be established by welding, conductive adhesive or anodizing, or a combination thereof. In addition, there may be rivets and/or screws for mechanical fixation of at least one waveguide section to a fixed connector.
In
In
To provide an electrical connection between the first waveguide section 210 and the second waveguide section 220, the fixed connector 350 may be soldered to these waveguide sections. For ground connection, the connector ground layers 355, 356 which are connected by at least on via 357 to the fixed connector ground base layer 352 being below the dielectric layer 351, are soldered to the ground layers 216, 226 of first and second waveguide sections. Further, the contact pad 353 is soldered to the first and second intermediate conductors 215, 225, and/or to first and second contact pads 214, 224.
In the previous embodiment, there is a significant distance between the interface sections of the waveguide sections, whereas in this embodiment, the interface sections of the waveguide sections are directly connected together. This distance has an immediate influence on the characteristic impedance of the interface sections. The characteristic impedance of the interface sections may normally match to the characteristic impedance of the elongate conductors to avoid reflections and therefore signal distortions. Therefore, the distance between the interface sections may be selected such that the characteristic impedance of the connection between the interface sections matches to the characteristic impedance of the waveguide sections.
Alternatively, the holes 259 may be used to enforce the mounting of a waveguide section to the fixed connector 250 by inserting and compressing rivets.
All embodiments of lines, waveguides, waveguide sections and fixed connectors may be combined.
100 waveguide structure
110 waveguide section
111 layer of dielectric material
112, 113 elongate conductors
114, 115 elongate conductors as microstrip conductors
116 ground layer
117 waveguide section
118, 119 layer of dielectric material
120 waveguide section
130 waveguide section
131 waveguide section
132 waveguide section
133 distance between elongate conductors at end section
134 first distance between elongate conductors
140 waveguide section
141 first end section
142 second end section
151 radius in x-z plane
152 radius in x-y plane
200 waveguide structure section
210 first waveguide section
211 first layer of dielectric material
212, 213 first elongate conductors
214 first contact pad
215 first intermediate conductor
216 first ground layer
218 first interface section
220 second waveguide section
221 second layer of dielectric material
222, 223 second elongate conductors
224 second contact pad
225 second intermediate conductor
226 second ground layer
228 second interface section
250 fixed connector
251 fixed connector dielectric layer
252 connector ground base layer
253, 254 contact pads
255, 256 connector ground layer
257 via, trough hole
258 solder spots
259 screw holes
300 further waveguide structure section
310 first waveguide section
315 shortened first intermediate conductor
320 second waveguide section
325 shortened second intermediate conductor
350 modified fixed connector
351 fixed connector dielectric layer
352 connector ground base layer
353 contact pad
355, 356 connector ground layer
357 via, trough hole
358 solder spots
359 protrusion
360 waveguide structure section
400 waveguide structure section
410 first waveguide section
412 first elongate conductors
415 first intermediate conductor
420 second waveguide section
422 second elongate conductors
425 second intermediate conductor
450 fixed connector
451 fixed connector dielectric layer
452 connector ground base layer
462 solder
500 waveguide structure section
510 first conductor element section
511 first layer of dielectric material
520 second conductor element section
521 second layer of dielectric material
550 fixed connector
560 waveguide structure section
561 first conductor element section
562 first layer of dielectric material
563 second conductor element section
564 second layer of dielectric material
565 first ground layer
566 second ground layer
600 glued waveguide structure section
601 waveguide structure section with conductive pad
602 waveguide structure section with connecting pad
603 waveguide structure section with flexible conductive pad
610 first waveguide section
611 first layer of dielectric material
612, 613 first elongate conductors
616 first ground layer
618 first interface section
620 second waveguide section
621 second layer of dielectric material
622, 623 second elongate conductors
626 second ground layer
628 second interface section
663 conductive glue
665 conductive pad
670 connecting pad
675, 676 conductive pads
677 base
685, 686 flexible conductive pads
687 solder
688 corrugation
710, 720, 730, 740, 750 waveguide sections
715, 725, 735, 745 fixed connectors
761, 762 terminations
765 signal connector
Number | Date | Country | Kind |
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20162482.2 | Mar 2020 | EP | regional |
Number | Date | Country | |
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Parent | PCT/EP2021/056243 | Mar 2021 | US |
Child | 17897537 | US |