The present invention relates to a transition arrangement for providing at least one transition between a planar transmission line and a waveguide having the features of the first part of claim 1. The invention also relates to a transition structure comprising such a transition having the features of the pre-characterizing part of claim 14.
The invention also relates to an integrated packaging structure comprising a circuit arrangement and an antenna arrangement having the features of the first part of claim 29.
The use of high frequencies, in the millimetre-wave and sub-millimetre-wave frequency bands, is receiving more and more attention for many different applications, for example high data rate communication links and automotive radar applications. It is attractive to be able to use these frequency regions due to the availability of larger frequency bandwidths. Therefore transitions, or interconnects, between transmission lines, circuits and waveguides or antennas are needed for many different purposes and applications. However, several problems are associated with the provisioning of such transitions or interfaces and, e.g. in particular for antenna and passive and active components integration. A good electrical performance, mechanical reliability and low costs are crucial for high frequency applications, as well as compactness.
In U.S. Pat. No. 8,680,936 a surface mountable transition block for perpendicular transitions between a microstrip or stripline and a waveguide is proposed. A disadvantage of this transition arrangement is that it is not as compact as would be needed for several applications, such as for a steerable beam array antenna with several connected antennas and Tx/Rx blocks. Furthermore, the structure is relatively complex and a very good electrical contact is required by means of via holes for connection with metal planes.
U.S. Pat. No. 7,486,156 discloses a microstrip-waveguide transition arrangement which is fed from the side. Also, this arrangement has a complex structure and is not as compact as would be desired.
In Seo, K., “Planar microstrip-to-waveguide transition in millimetre-wave band”, http://dx.doi.org/10.5772/54662, Advancement in Microstrip Antennas with Recent Applications, Chapter: Chapter 11, Publisher: INTECH, Editors: Ahmed Kishk, pp. 249-277, 2013-03-06 different types of transitions between waveguides and microstrip lines are discussed, such as a probe transition with a back-short, planar proximity coupling transition, a broadband technique of the proximity coupling type transition and a narrow-wall-connected microstrip-to-waveguide transition.
However, all these transitions leave a lot to desire as far as simplicity in structure and compactness etc. is concerned, and several problems associated with the provisioning of a transition between a transmission line and a waveguide remain to be solved, and, so far, no solutions which are entirely satisfactory have been suggested, and all so far proposed transitions between transmission lines and waveguides suffer from disadvantages limiting their use.
Furthermore, for a transition between a waveguide and a circuit at high frequencies, a separate E-plane probe transition is used to provide the interface between the waveguide and the circuit. The E-plane probe transition converts the waveguide TE10 mode to a microstrip or coplanar mode, and a separate transition requires a bond-wire or a flip-chip connection.
The use of separate E-plane probe transitions further complicates any packaging process since they require back-shorts and further steps associated with mounting and accurate alignment of the transition circuit with respect to e.g. a circuit, such as for example an RFIC (Radio Frequency Integrated Circuit) or an MIMIC (Monolithic Microwave Integrated Circuit).
Attempts to integrate waveguide transitions onto a circuit (e.g. an MMIC) for a steerable beam array antenna where many antenna elements need to connect to a separate RF chain generally have not been successful. The main reason is that the width of whole the waveguide transition is way more than λ/2 while the antenna element spacing needs to be below λ/2 to avoid high grating lobes.
In A. U. Zaman, M. Alexanderson, T. Vukusic and P. S. Kildal, “Gap Waveguide PMC Packaging for Improved Isolation of Circuit Components in High-Frequency Microwave Modules,” in IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 4, no. 1, pp. 16-25, January 2014, is disclosed that the use of gap waveguide technology is an effective packaging technique for mm Wave systems that exhibits a lower insertion loss compared to conventional packaging techniques. The circuits are packaged with a pin metal lid, or bed of nails, which works as a high impedance surface or an AMC (Artificial Magnetic Conductive) surface in a wide frequency range. The resulting PEC-PMC (Perfect Electric Conductor-Perfect Magnetic Conductor) parallel-plate waveguide creates a cut-off for the electromagnetic waves, in such a way that the unwanted packaging problems due to substrate modes and cavity resonances are suppressed.
It is therefore an object, in the most general aspect of the present invention, to provide a transition arrangement as initially referred to which can be used e.g. for interconnection of any planar transmission line, e.g. a microstrip line, a stripline or a coplanar transmission line, with a second transmission line, e.g. a waveguide, through which one or more of the above mentioned problems are overcome.
Particularly it is an object of the present invention to provide a transition arrangement, most particularly a high frequency transition arrangement, which is compact.
It is a particular object to provide a transition arrangement, even more particularly a high frequency transition arrangement, which has a simple structure, which is cheap and easy to fabricate, particularly suitable for mass fabrication, and which is easy to assemble.
Particularly it is also an object to provide a transition arrangement, most particularly a high frequency transition arrangement, with a good electrical performance and which has a good mechanical reliability.
Another particular object is to provide a transition arrangement, most particularly a high frequency transition arrangement, which is frequency scalable, and particularly which can be used for different frequencies, from very low frequencies up to very high frequencies, or for microwaves up to sub-millimetre waves.
Further yet it is a particular object to provide a high frequency transition arrangement which can be used for high frequencies, e.g. above 67 GHz or considerably higher, but also a transition arrangement suitable for lower frequencies.
Therefore a transition arrangement as initially referred to is provided which has the characterizing features of claim 1.
It is also an object is to provide a transition structure comprising a transition between a planar transmission line and a second transmission line comprising a waveguide as initially referred to through which one or more of the aforementioned problems can be solved, and which particularly is compact and easy to assemble.
Therefore a transition structure as initially referred to is provided which has the characterizing features of claim 14.
It is also an object of the present invention to provide an integrated packaged or packaging structure comprising an antenna having the features of the first part of claim 29 with one or more transition arrangements or transition structures as referred to above which is easy to fabricate, which is compact and which allows assembly in a fast and easy manner, and which particularly also can be disassembled.
It is also an object to provide a packaged structure, or a packaging structure, comprising one or more such transitions which has low insertion losses, low or substantially no leakage, and is flexible in use.
Further a particular object is to provide a highly integrated structure comprising one or more such transitions which is easy to fabricate, to mount or assemble and which can find a wide-spread use for interconnection of active or passive components and antennas.
Yet another object to is provide a packaged structure, or a packaging structure, comprising one or more such transitions between antennas and active and/or passive components which has a high efficiency and performance, a high gain despite a narrow bandwidth.
Particularly it is an object to provide a packaged structure, or a packaging structure, comprising an antenna arrangement with a good electrical performance and which has a good mechanical reliability.
It is also a particular object to provide a high frequency integrated packaged structure, or packaging structure, which can be used for high frequencies, e.g. above 67 GHz or considerably higher, but also for lower frequencies without leakage of undesired waveguide modes into one or more circuit arrangement arranged on a chip, e.g. an RFIC or an MMIC and between planar transmission lines and waveguides, and which allows a very good coupling of energy to one or more antennas of the packaging structure antenna.
It is also an object to provide a packaging structure with a transition arrangement which is reliable and precise in operation.
Still further a particular object is to provide a packaging structure comprising one or more transitions or interconnects between active and/or passive components, or a circuit arrangement, e.g. one or more RFICs, MMICs, and an antenna arrangement comprising one or more radiating elements through which one or more of the above mentioned problems can be overcome, and which is among other things is easy to fabricate, easy to assemble, preferably also to disassemble, and which is compact, is wideband, has a high performance and low losses.
It is also an object is to provide an integrated packaged structure comprising an antenna arrangement which is steerable, with a steerable beam, particularly with a high gain and a narrow beam, and which is compact.
Therefore an integrated packaged or packaging structure as initially referred to is provided which has the characterizing features of claim 29.
Advantageous embodiments are given by the respective appended dependent claims.
It is an advantage that a packaging structure is provided which has a simple structure and which can be used for many different applications and purposes.
It is an advantage of the invention that a (high) frequency transition arrangement which is compact is provided without the need of having electrical contact between waveguide part and planar transmission line, e.g. a microstrip line.
It is an advantage of the invention that a (high) frequency transition arrangement which is compact is provided which has a wide bandwidth without the need of having a back-short, still having a wide frequency response.
It is also an advantage that a transition arrangement which has a simple structure is provided, which is cheap and easy to fabricate, suitable for mass fabrication, and which is easy to assemble, particularly since no electrical contact is required.
A particular advantage of the invention is that a compact transition arrangement is provided which has a simple structure wherein electrical and galvanic contact between waveguide and e.g. RF board is not needed and which can be widely used.
It is also an advantage that a transition structure is provided which is compact, contactless, and which does not require any back-short. It is also an advantage that a structure is provided which is a multilayer structure. Another advantage is that an integrated and packaged structure is provided which is compact, which can comprise a large number of radiating elements, has low losses, a high yield, is frequency scalable, and is easy to assemble.
It is further an advantage that an integrated packaged structure comprising an antenna arrangement is provided which is easy to fabricate, which is compact and which allows assembly in a fast and easy manner, without any electrical contact requirement between the building blocks, and which particularly also can be disassembled.
It is an advantage of the inventive concept that interconnection problems associated with interconnection of planar transmission lines and waveguides, circuit arrangements and other circuit arrangements and with interconnection with e.g. antennas are overcome.
The invention will in the following be further described in a non-limiting manner, and with reference to the accompanying drawings, in which:
In advantageous embodiments the periodic structure is etched in the substrate 11, and it here comprises a plurality of mushrooms 15,15 . . . arranged in transversal and longitudinal rows disposed perpendicularly to and in parallel with the microstrip 2 and disposed on three sides of the coupling section 3 and along part of the two length sides of the microstrip line 2. For definition, some of the mushrooms can be said to form part of both a transversal and of a longitudinal row.
The substrate layer 11 is disposed on a conducting layer 12 forming a ground plane. Through the use of the periodic structure, here formed by the mushrooms, the transition is allowed to be contactless since the periodic structure stops waves propagating in non-desired directions. Since there will be a strong coupling between the coupling section 3 of the microstrip line 2 and the mushrooms 15, the need for any backshort is avoided which is extremely advantageous. Via the coupling section 3 the EM (electro-magnetic) field from the microstrip line 2 via the mushrooms 15 can be coupled to a second transmission line e.g. a waveguide (see for example the transition structures in
Through the use of e.g. an EBG structure leakage can be avoided completely or to a large extent without there being any contact, and no back-short is needed as mentioned above while there is still a wide band frequency response, and, in addition, an easy assembly of a transition structure providing a transition to a waveguide, waveguides of different types, can be provided. The substrate may also comprise a high impedance surface of any other kind or e.g. an AMC surface, e.g. comprising a periodic or a quasi-periodic structure.
The structure is planar and contactless which is extremely advantageous, allowing the forming of multilayer structures.
In the shown embodiment there are two transversal rows of each four mushrooms 15, . . . which are disposed beyond the coupling section 3 and two longitudinal rows, one on either side of the microstrip 2, each longitudinal row with four mushrooms (two of which also forming part of the two transversal rows disposed beyond the coupling section 3). In the shown embodiment the mushrooms 15 are square shaped with small vias 16 for connection with the ground plane 12. It should however be clear that the mushrooms may have any appropriate shape, circular, rectangular, oval etc., or even in some embodiments they may comprise ridges or similar, or more generally that any other appropriate periodic or quasi-periodic, preferably etched, structure may be used. Also the number of mushrooms, their disposition in regular or partially irregular patterns may vary.
The perpendicular distance between the coupling section 3 of the microstrip line 2 and the first transversal row of mushrooms 15 depends on the used operating frequency, or the wavelength, but is for example about 500 μm, and the distance between adjacent mushrooms is about 700 μm for an operating frequency of about 30 GHz. It should be clear that these figures are by no means to be taken in a limitative sense, but the distances are frequency/wavelength dependent, and can also be different for a given frequency/wavelength in different implementations. Thus, the transition is scalable, and the distances may be larger as well as smaller. For example to operate at 60 GHz, the dimensions and distances of the structure, or the structure, can be scaled by factor of 0.5. the scalability for the dimensions of the structure is substantially linear. If all dimensions and distances are scaled by a factor two, or doubled, the operation frequency band, or the frequencies thereof, will be halved.
The transition arrangement technically can be used for substantially any operation frequency, e.g. from about 1, 2 or 3 GHz up to e.g. 300 GHz, within microwave and millimetre frequency bands.
The disposition and the number of e.g. rows of, here, mushrooms depend on to what type of waveguide there should be a transition. In particular, the second row in the longitudinal direction of the microstrip line 2 distant from the coupling section 3 might be disposed of, particularly, but not exclusively, for perpendicular transitions to waveguides with a relatively narrow aperture, such as a double ridged waveguide. Such additional distant rows assist in providing a better performance.
For example, for a transition to a rectangular waveguide it is advantageous if there are more mushrooms, or protruding elements or similar, since the opening aperture is larger. Particularly there may be three or more rows on either side along the microstrip line for a transition to a rectangular waveguide.
Alignment means (not shown) of any desired type may be used for assuring an appropriate alignment between the waveguide part 20 and the transition arrangement 10.
The transition structure 101 is similar to the transition structure 100 described with reference to
The waveguide block 20F is disposed on the transition arrangement 10F such that the rectangular waveguide 21F will be located above the coupling section 3F. In the shown embodiment the waveguide block 20f covers the mushrooms 15F, . . . except for two mushrooms 15F located in each a longitudinal row and which are most distant with respect to the coupling section (not visible in
Each waveguide 21G1,21G2 will be located above a respective coupling section 3G1,3G2 and such that there is slight a gap there between, the width of the gap being approximately between 0 to 0.03λ (0-300 μm at 30 GHz). In this embodiment the waveguide block 20G covers a transition part 10G comprising a substrate disposed on a conducting layer as discussed above, and comprising the two transition arrangements comprising a common microstrip 2G at the opposite ends of which a respective coupling section 3G1,3G2 is provided, each surrounded by mushrooms 15G1,15G2 disposed in as discussed above with respect to the respective coupling section and the microstrip 2G. In other respects the respective elements are disposed and serve corresponding purposes as already discussed above with respect to the other exemplified transition structures 100-102.
Alignment means (not shown) for introduction into alignment holes 27G,17G of any desired type may be used for assuring an appropriate alignment between the waveguide part 20G and the transition part 10G with the two transition arrangements.
The top slot layer 501 is disposed on a second layer comprising a ridge gap waveguide feeding layer 502, here provided with a respective pin structure 525′, 525″ on the upper and lower sides respectively, which is advantageous for assembly and packaging purposes e.g. as described in WO2010/003808, “Waveguides and transmission lines in gaps between parallel conducting surfaces”, by the same applicant as the present application, designed for stopping or preventing propagation of waves between the metal layers in other directions than along the waveguiding direction. The dimensions of, and the spacing between the pins, or more generally a periodic or quasi-periodic pattern, depend on for which frequency band the integrated packaged structure is designed. It is e.g. possible to use full height pins or similar on one surface of two opposing surfaces, or half-height pins on two opposing one another facing surfaces such that the total pin height is such as to form a desired stop band.
It should be clear that an antenna arrangement comprising a plurality of contactless microstrip to waveguide transitions according to the inventive concept also is applicable for other antenna and packaging techniques, but then absorbers or similar will be needed and the packaging structure will not be so compact, the compactness of an arrangement as shown in e.g.
Alignment means (not shown) of any desired type may be used for assuring an appropriate alignment of the different layers with respect to one another when assembled.
It should also be clear that the use of other types of antennas also is possible, such as SIW antennas and microstrip antennas, and such implementations are also covered by the inventive concept.
The high impedance surface in one embodiment comprises pins 525′ with a cross section e.g. having the dimensions of about 0.1λ-0.2λ, in advantageous embodiments about 0.15λ×0.15λ, and a height of 0.15λ-0.3λ, e.g. about 0.2λ. Preferably the pin period is smaller than λ/3, although it may be smaller and larger as well. As an example the pins may have a width of about 1.5 mm, the distance between pins may be about 1.5 mm, and the periodicity may be about 3 mm at 30 GHz. It should be clear that these figures are merely given for illustrative purposes, the figures may be larger as well as smaller, and also the relationships between the dimensions may be different.
It should be clear that the invention is not limited to any particular number or number of rows of pins; it can be more as well as fewer rows, and the high impedance surface can be provided for in many different manners, comprising different number of protrusions with different periodicity and dimensions etc. as also discussed above, and also depending on the frequency band of interest.
The gap between the high impedance surface of the feeding layer 502 and the slot layer 501 e.g. is in the order of size of 250 μm at 30 GHz. It should be clear that also this figure merely is given for illustrative and by no means limitative purposes.
The high impedance surface or the AMC surface which here comprises a periodic or a quasi-periodic pin structure with a plurality of pins 525′ of metal which are arranged to form a bed of pins, is located at a slight distance, a gap, which is smaller, or much smaller, than λg/4, from the antenna layer, e.g. at a distance of approximately λg/10. The pins of the periodic or quasi-periodic structure have dimensions and are arranged such as to be adapted for a specific, selected, frequency band, and to block all other waveguide modes.
The non-propagating or non-leaking characteristics between two surfaces of which one is provided with a periodic texture (structure), are e.g. described in P.-S. Kildal, E. Alfonso, A. Valero-Nogueira, E. Rajo-Iglesias, “Local metamaterial-based waveguides in gaps between parallel metal plates”, IEEE Antennas and Wireless Propagation letters (AWPL), Volume 8, pp. 84-87, 2009 and several later publications by these authors. The non-propagating characteristic appears within a specific frequency band, referred to as a stopband. Therefore, the periodic texture must be designed to give a stopband that covers with the operating frequency band. It is also known that such stopbands can be provided by other types of periodic structures, as described in E. Rajo-Iglesias, P.-S. Kildal, “Numerical studies of bandwidth of parallel plate cut-off realized by bed of nails, corrugations and mushroom-type EBG for use in gap waveguides”, IET Microwaves, Antennas & Propagation, Vol. 5, No pp. 282-289, March 2011. According to this document the layers must not be separated more than a quarter of a wavelength of a transmitted signal, or rather have to be separated less than a quarter wavelength. These stopband characteristics are also used to form so called gap waveguides as described in “Waveguides and transmission lines in gaps between parallel conducting surfaces”, PCT/EP2009/057743 by the same applicant as the present invention.
The high impedance surface, e.g. the periodic or quasi-periodic structure comprising pins 525′ may be provided for in many different manners. In one embodiment pins are glued onto the feeding layer. Alternatively pins may be soldered onto the feeding layer. Still further a high impedance surface may be provided through milling and comprise pins, ridges, corrugations or other similar elements forming a periodic or quasi-periodic structure. The pins or similar may of course also have other cross-sectional shapes than square shaped; rectangular, circular etc. The width, or cross-sectional dimension/the height of the pins, corrugations or other elements of any appropriate kind, is determined by the desired operating frequency band.
When the second, here bottom, side 502″ of the feeding layer 502 is disposed on the substrate layer 503 comprising a plurality of transition arrangements 510, contactless, perpendicular microstrip to double ridged waveguides 521 transitions will be provided, each corresponding to a transition structure as described with reference to
The bottom side 502″ of the feeding layer 502 can be used for thermal cooling of active components, such as PAs (power amplifier), which may be mounted on the circuit layer 503.
Through the transition arrangements forming perpendicular transitions to, here, double ridge waveguides, according to the present invention it becomes possible to arrange microstrips, and antenna elements, with element spacing about λ/2, wherein λ is the operating frequency, which is extremely advantageous.
Through the present invention a package comprising an antenna arrangement and a number of active components and with a steerable beam capability is provided which is extremely advantageous.
It is also an advantage that an extremely compact arrangement is provided which, in addition, is extremely easy to assemble, requiring no post processing, and to fabricate, and which preferably can be disassembled.
It is also an advantage that a very compact multiport antenna arrangement can be provided which has a good steerability and which at the same time has a high gain also with a narrow beam with an efficient coupling of energy to the antenna elements via the feeding layer.
As opposed to known antenna arrangements using patches as radiating elements, integrated in a PCB, and comprising but one layer with high losses from the substrate, in media and conductive lines, with a low efficiency, or if a SIW (Surface Integrated Waveguides) are used, still involving losses in the substrate, through the inventive concept, a low loss multilayer structure is provided which has considerably lower losses, with a high efficiency, higher gain and a narrower, steerable beam. Since known arrangements require a distance close to one X. (corresponding to the operating frequency) between adjacent antenna elements, those solutions are not suitable for steering the beam due to high grating lobes, whereas through the inventive concept a distance of about λ/2, e.g. 0.5-0.6λ, or even less or somewhat longer can be used and hence a good steerability is enabled, e.g. up to +/−50°. With the structure according to the invention, it is possible to have many transitions and antennas arranged closely, and a multilayer structure is provided. The arrangement also has a narrow beam and a high gain; in known arrangements a narrow beam leads to a drastic loss in gain. The arrangement further is frequency scalable and can be used for different frequency bands.
It is also an advantage that an arrangement is provided which can be disassembled, reassembled, tested and parts, circuits or layers be exchanged. Through the invention transitions from a circuit arrangement, e.g. an RFIC can be provided to a transmitting part, and also to a receiving part.
The height of a packaging arrangement as described above is less than 7 mm at 30 GHz, and the height of a transition arrangement as in
It should be clear that also antenna elements comprising horns, patches, etc. can be used with the inventive concept, but it is less advantageous, active antenna elements comprising slots in a metal layer being preferred.
For performance measurements a back-to-back structure with two waveguide ports similar to the structure described with reference to
The inventive concept can be implemented for many different applications within wireless communication, e.g. for radar sensors in vehicles, automotive radar, cars, air planes satellites, WiGig (Wireless Gigabit), Wi-Fi, and transition arrangements, transition structures and packaging structures based on the inventive concept are suitable for mass production, and can be used within the microwave and millimeter wave frequency bands, e.g. for operation frequencies from 1 or 3 GHz to about 300 GHz.
It should be clear that the invention is not limited to the specifically illustrated embodiments, but that it can be varied in a number of ways within the scope of the appended claims. The invention is also not limited to any specific circuitry, and supporting electronics is not shown for reasons of clarity and since it does not form part of the main inventive concept.
Filing Document | Filing Date | Country | Kind |
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PCT/SE2017/050793 | 7/25/2017 | WO | 00 |