CN115207591A - Strong coupling strip line and microwave element containing same - Google Patents
Strong coupling strip line and microwave element containing same Download PDFInfo
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- CN115207591A CN115207591A CN202210794218.3A CN202210794218A CN115207591A CN 115207591 A CN115207591 A CN 115207591A CN 202210794218 A CN202210794218 A CN 202210794218A CN 115207591 A CN115207591 A CN 115207591A
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- dielectric substrate
- strip
- strip conductor
- conductive layer
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
- H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01P5/18—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers
- H01P5/184—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers the guides being strip lines or microstrips
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
- H01Q3/30—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array
- H01Q3/34—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array by electrical means
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Abstract
The present invention provides two coupled striplines, comprising: a first strip conductor disposed on the top surface of the dielectric substrate and a second strip conductor disposed on the bottom surface of the dielectric substrate at an opening of a conductive layer overlying the bottom surface of the dielectric substrate, the conductive layer being separated from the second strip conductor by a gap, wherein at least a portion of the first strip conductor is disposed over a portion of the second strip conductor; at least one additional conductor disposed on the top surface of the dielectric substrate, separated from the first strip conductor by a gap, and connected to the conductive layer by a metal plated hole in the dielectric substrate. The novel strongly coupled stripline provided by the invention is suitable for manufacturing very simple microwave elements only comprising a printed circuit board, overcomes the defects of the known coupled stripline, and provides the strongly coupled stripline formed on two surfaces of a single dielectric substrate by the traditional printed circuit board technology.
Description
Technical Field
The present invention relates to microwave transmission lines and microwave components manufactured using conventional printed circuit board technology.
Background introduction
The modern mobile communication market requires sophisticated antennas, forming narrow beams, operating in multiple frequency bands. The antenna consists of a radiating element and a beam forming network containing a number of passive elements including directional couplers, differential phase shifters and filters. Modern antennas for mobile communications must provide very low levels of passive intermodulation, and therefore the elements of the beam forming network are interconnected by special coaxial cables soldered directly to the passive elements. The size of the passive element must be as small as possible in order to fit it within a confined space within the radome to protect the antenna from adverse weather conditions.
Most broadband and compact directional couplers and phase shifters contain coupled striplines. A directional coupler with a coupling level between 30dB and 10dB comprises two coupled lines arranged on the surface of a dielectric substrate and separated by a gap, but this design cannot produce a coupling between 10dB and 2dB, because the gap between the striplines providing this coupling level must be very narrow and cannot be manufactured by industrial printed circuit board technology. Thus, engineers use another design to increase the coupled signal. Patent US 10833388 B2 describes a circuit comprising several couplers connected together by a power divider to increase the coupled signal. Four couplers connected together can provide up to 3dB coupling levels, but such a circuit is too large and therefore costly to manufacture.
As shown in CN 108110425A, coupled striplines producing coupling levels between 10dB and 2dB must be placed opposite each other on the surface of a thin dielectric substrate. The known circuit comprising a coupler and a differential phase shifter comprises three dielectric substrates arranged on top of each other between two metals, and therefore this design is complicated to manufacture. Furthermore, connecting the coaxial transmission line to the metal plate may produce passive intermodulation products.
Other known couplers Lange comprise several parallel thin strip lines connected by bridges arranged above a dielectric substrate and soldered to the strip lines. Such a design is complex for mass production and is typically applied to a stripline disposed on a substrate made of an expensive ceramic material.
Another directional coupler comprises a substrate comprised of two dielectric layers separated by a conductive layer having a window, two strip lines disposed on the top and bottom surfaces of the dielectric substrate. This design is also complicated for mass production.
Due to the large number of microwave elements used by the modern communications industry, there is a need to simplify the design of coupled lines, providing coupling levels between 10dB and 2dB, suitable for manufacturing directional couplers and other microwave elements including strongly coupled striplines.
Disclosure of Invention
It is an object of the present invention to provide a new type of strongly coupled stripline which is suitable for the manufacture of very simple microwave components comprising only printed circuit boards.
It is a first object of the present invention to overcome the disadvantages of known coupled striplines and to provide strongly coupled striplines formed on both surfaces of a single dielectric substrate by conventional printed circuit board technology.
A second object of the invention is to provide a simple microwave assembly comprising only a single dielectric substrate.
The coupling strip line intended to achieve the object of the present invention comprises a first strip conductor arranged on the top surface of a dielectric substrate and a second strip conductor arranged along the first strip conductor in an opening in a conductive layer covering the bottom surface of the dielectric substrate. The conductive layer covering the bottom surface of the dielectric substrate is separated from the second strip conductor by a gap. Two additional conductors disposed on the top surface of the dielectric substrate are separated from the first strip conductor by a gap and are connected to the conductive layer by metal plated holes in the dielectric substrate. At least a portion of the first strip conductor is disposed over a portion of the second strip conductor.
The even mode of such a strip line has a larger wave impedance Ze than the even mode of a conventional strip line arranged opposite the conductive layer, because the conductive layer is removed from the opening and is arranged only at the opposite edges of the strip conductor. The broad sides of the strip conductors are disposed opposite each other on the top and bottom surfaces of the dielectric substrate, and therefore the wave impedance Zo of the odd mode thereof is smaller than that of a conventional strip line including strip conductors disposed on the top surface of the dielectric substrate and coupled only by their edges. This arrangement of the openings of the conductive layer and the strip conductors increases the coupling between the two strip lines compared to conventional strip lines formed on a single substrate due to the coupling coefficient.
The openings in the conductive layer and the additional conductors disposed on the top surface of the dielectric substrate provide electrical symmetry of the coupled striplines. The gap separating the strip conductor from the conductive layer and the additional conductor has a shape providing equal electrical lengths of the two modes, and therefore it is preferred that the strip line provides directional coupling. The conductive layer and the two additional conductors of the coupling strip line providing a large coupling coefficient K comprise edge notches that are separated from the first and second strip conductor edges by a gap to provide equal electrical lengths of the two modes.
Drawings
Some embodiments of the invention are described by the following figures, in which:
FIGS. 1a, 1b and 1c show the top and bottom surfaces and cross-sections of a dielectric substrate containing the coupling striplines of the present invention, forming a 3dB directional coupler operating in the 690-960MHz band.
Fig. 2a and 2b are measured frequency characteristics of a manufactured sample of the directional coupler shown in fig. 1a-1 c.
Figure 3 shows a perspective view of the bottom surface of a dielectric substrate containing the coupling strip line of the present invention forming a 3dB directional coupler operating in the 1600-2700MHz band and a metal plate disposed adjacent to the dielectric substrate.
Fig. 4a and 4b are measured frequency characteristics of the directional coupler manufacturing sample shown in fig. 3.
Fig. 5a and 5b show top and bottom views, respectively, of a dielectric substrate containing coupled striplines forming phase shifters.
Fig. 6 and table 1 show the simulated frequency characteristics of the phase shifters shown in fig. 5a and 5 b.
Detailed Description
It should be understood that the invention is not intended to be limited to the particular forms disclosed in the above drawings. The intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
The coupled lines must meet the following conditions in order to match the four transmission lines to which they are connected and provide directional coupling. When Z =50Ohm of four transmission lines, the impedances of the even and odd modes of the coupled lines must satisfy the equation Ohm, and the electrical lengths Le and Lo of the even and odd modes thereof must be equal. This means that when the four transmission lines have equal impedances, the two coupled lines must be electrically equal. Placing conventional coupling striplines on the same surface of a dielectric substrate can provide the above conditions and produce directional coupling, but cannot provide strong coupling because conventional printed circuit board technology cannot have a gap at its edge of less than 0.05mm.
The strip conductor of the coupling strip line according to the invention provides a greater wave impedance Ze because the capacitance between the strip conductor and the conductive layer containing the openings arranged opposite the strip conductor is smaller than the capacitance between the strip conductor of a conventional strip line and a conductive layer without openings. The strip conductors of the coupling strip line according to the present invention are disposed opposite to each other on the top and bottom surfaces of the dielectric substrate, providing a smaller odd mode wave impedance than a conventional coupling strip line disposed on one side of the dielectric substrate, which is located on the same surface and coupled only by its edges, because the capacitance between the strip conductors stacked on top of each other is larger than the capacitance between the conventional coupling strip lines. Thus, the coupled striplines of the present invention provide a greater coupling coefficient.
A first embodiment of the invention is shown in fig. 1a-1 c. The strip conductor and the conductive layer forming a 3dB directional coupler operating in the 690-960MHz band are provided on the surface of the dielectric substrate 1. The top surface of the dielectric substrate 1 comprises a first strip conductor 2a and two additional conductors 3a and 3b, the additional conductors 3a and 3b being separated from the first strip conductor 2a by gaps 4a and 4 b. The additional conductors 3a and 3b are connected to a conductive layer 5 provided on the bottom surface of the dielectric substrate 1 through metal plated holes 6. The edges of the additional conductors 3a and 3b contain cut-outs 7, the cut-outs 7 comprising narrow portions 7a and wide portions 7b. The end portions of the strip conductor 2a are connected to the strip conductors 8a, 8 b.
The bottom surface of the dielectric substrate 1 comprises a second strip conductor 2b and a conductive layer 5, the conductive layer 5 being separated from the second strip conductor 2b by a gap 11. The end portions of the strip conductor 2b are connected to the strip conductors 9a, 9b via plated metal holes 10a, 10 b.
The conductive layer 5 comprises a cut 12, the cut 12 comprising a narrow portion 12a and a wide portion 12b. base:Sub>A cross-sectionbase:Sub>A-base:Sub>A of the dielectric substrate across the striplines and the conductive layer is shown in fig. 1 c.
The other ends of the strip conductors 8a, 8b, 9a and 9b are connected to an inner conductor (not shown) of the coaxial cable. The outer conductor of the coaxial cable is connected to conductors 5a-5d arranged near the edge of the dielectric substrate 1 and to the conductive layer 5 via plated metal holes 6.
The odd-mode electromagnetic field of the coupling strip line is concentrated between the coupling lines provided with the dielectric substrate, and therefore, the dielectric substrate can effectively delay the electromagnetic wave. The even mode electromagnetic field of the coupling strip line is concentrated between the edge of the coupling line and the edges of the conductive layer and the additional conductor, and therefore a portion of the electromagnetic wave propagates through the air region adjacent to the dielectric substrate, and therefore the delay of the even mode is smaller than that of the odd mode. The notch 12 significantly increases the even mode wave impedance, but has little effect on the odd mode wave impedance. The cuts 12 form a periodic structure, connecting a plurality of transmission lines having different wave impedances in series. This periodic structure increases the delay of the even mode and allows the electrical lengths of the even and odd modes to be equal.
Thus, the coupling line provides directional coupling and splits the electromagnetic wave exciting the strip line 8a between the strip lines 8b and 9 a. A very small part of the electromagnetic wave exciting the strip line 8a penetrates the strip line 9b. Fig. 2a and 2b depict measured frequency characteristics of a fabricated sample of the directional coupler of fig. 1a-1 c. In fig. 1a strip line 8a corresponds to port 1, strip line 8b corresponds to port 2, strip line 9a corresponds to port 3, and strip line 9b corresponds to port 4. The directional coupler according to the present invention, including the coupling strip line, provides S11 ≦ -31.7dB, S41 ≦ -31dB and coupling-3.4 ± 0.2dB in the 690-960MHz band.
Another embodiment of the present invention is a 3dB directional coupler operating above 1GHz frequency, as shown in figure 3 from a perspective view from the bottom side of the dielectric substrate 13. The metal plate 14, which is arranged opposite to the coupled line 15, is connected to the conductive layer 16 by bent portions 17a-17 d. The metal plate 14 reduces radiation from the coupled line 15, and therefore a directional coupler comprising the metal plate 14 provides less insertion loss than a directional coupler without the metal plate 14.
When the second metal plate is arranged on top of the dielectric substrate 13, the radiation from the coupled lines will be smaller. Fig. 4a and 4b depict measured frequency characteristics of a sample of the directional coupler fabrication shown in fig. 3. A directional coupler comprising a coupled stripline and a metal plate provides S11 ≦ -28.3dB, S41 ≦ -23.2dB, and coupling-3.6 ± 0.2dB in the 1700-2800MHz band.
Another embodiment of the present invention is a phase shifter. Fig. 5a and 5b show top and bottom views, respectively, of a dielectric substrate containing coupled striplines forming phase shifters.
The top surface of the dielectric substrate 18 contains a first strip conductor 19a, and an additional conductor 20 separated from the first strip conductor 19a by a gap 21. The additional conductor 20 is connected to the conductive layer 22 by means of a metal plated hole 23. The edge of the additional conductor 20 located opposite the strip conductor 19a contains a cut 24. The left end of the coupling strip conductor 19a is connected to the strip conductor 25 to form a transmission line connected to the input port of the phase shifter.
The bottom surface of the dielectric substrate 18 includes the conductive layer 22 and the second strip conductor 19b provided in the opening 30. The left end of the strip conductor 19b is connected to the strip conductor 26 through a plated metal hole 27. The strip conductor 26 forms a transmission line connected to an output port of the phase shifter. The right ends of the strip conductors 19a and 19b are connected together by plated metal holes 28a and 28 b. The edge of the conductive layer 22 located opposite the strip conductor 19b contains a cut 29.
The dimensions of the strip conductors 19a and 19b, the additional conductor 20, the gap 21 and the opening 30 are calculated to provide a coupled line matching the transmission line of the strip conductors 25 and 26. Fig. 6 shows a simulation S11 of the phase shifter shown in fig. 5a and 5 b. Table 1 shows the simulated phases of the phase shifters shown in fig. 5a and 5 b. The phase shifter provides S11= -30.76dB and a phase shift of 90+/-2.5 degrees compared to a transmission line having an electrical length of 3/4 wavelength at the intermediate frequency of the 1710-2690MHz operating band.
Table 1
| 1710MHz | 1850MHz | 2000MHz | 2200MHz | 2350MHz | 2500MHz | 2690MHz |
| 90.7° | 92° | 92.3° | 91.4° | 90.6° | 90.3° | 91.5° |
Claims (11)
1. Two coupled striplines, comprising:
a first strip conductor disposed on the top surface of the dielectric substrate and a second strip conductor disposed on the bottom surface of the dielectric substrate at an opening of a conductive layer overlying the bottom surface of the dielectric substrate, the conductive layer being separated from the second strip conductor by a gap, wherein at least a portion of the first strip conductor is disposed over a portion of the second strip conductor;
at least one additional conductor disposed on the top surface of the dielectric substrate, separated from the first strip conductor by a gap, and connected to the conductive layer by a metal plated hole in the dielectric substrate.
2. The two coupled striplines of claim 1, wherein the conductive layer and the two additional conductors comprise cutouts in an edge spaced apart from edges of the first and second strip conductors by a gap.
3. Two coupled striplines according to claim 2, characterised in that at least one of the cuts has a narrow part and a wide part.
4. Two coupled stripline according to any of claims 1 to 3, characterised in that a metal plate is arranged below the dielectric substrate and connected to the conductive layer by means of a metal strip.
5. A directional coupler comprising two coupled striplines according to any one of claims 1 to 3, characterised in that four strip transmission lines are connected to the ends of the first strip conductor and the second strip conductor.
6. A directional coupler comprising two coupled striplines as claimed in any one of claims 1 to 3, characterised in that the third and fourth strip conductors are arranged on the top surface of a dielectric substrate, their ends being connected to the end of the second strip conductor by means of a metallised hole on the dielectric substrate, and their other ends being connected to a coaxial cable or a coaxial connector.
7. A differential phase shifter comprising two coupled striplines as recited in any of claims 1-3, wherein the first end of the first strip conductor and the first end of the second strip conductor are connected to a coaxial cable or coaxial connector, and the other ends of the first and second strip conductors are connected together by a plated metal hole in a dielectric substrate.
8. A differential phase shifter comprising two coupled strip lines according to any of claims 1-3, wherein the third strip conductor is arranged on the top surface of the dielectric substrate, with a first end connected to a first end of the second strip conductor by means of a plated metal hole in the dielectric substrate, and with the other end connected to a coaxial cable or a coaxial connector.
9. A beamforming network comprising two coupled striplines according to any one of claims 1 to 3, forming a directional coupler and a differential phase shifter.
10. The beamforming network of claim 9, comprising a 3dB directional coupler and a 90 degree phase shifter forming a 0/180 degree directional coupler.
11. The beamforming network of claim 9, comprising a 3db directional coupler and a 90 degree phase shifter, and wherein the RF signal is distributed from any one of the two inputs to the three outputs by stripline connections.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210794218.3A CN115207591A (en) | 2022-07-07 | 2022-07-07 | Strong coupling strip line and microwave element containing same |
| PCT/CN2023/092498 WO2024007717A1 (en) | 2022-07-07 | 2023-05-06 | Strong coupling striplines and microwave element comprising same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210794218.3A CN115207591A (en) | 2022-07-07 | 2022-07-07 | Strong coupling strip line and microwave element containing same |
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| Publication Number | Publication Date |
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| CN115207591A true CN115207591A (en) | 2022-10-18 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210794218.3A Pending CN115207591A (en) | 2022-07-07 | 2022-07-07 | Strong coupling strip line and microwave element containing same |
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| WO (1) | WO2024007717A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024007717A1 (en) * | 2022-07-07 | 2024-01-11 | 广州司南技术有限公司 | Strong coupling striplines and microwave element comprising same |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7400214B2 (en) * | 2004-08-30 | 2008-07-15 | Powerwave Technologies, Inc. | Low loss, high power air dielectric stripline edge coupling structure |
| CN101728620B (en) * | 2010-01-28 | 2013-02-13 | 大连海事大学 | Asymmetric coplanar waveguide directional coupler |
| CN206697587U (en) * | 2017-04-26 | 2017-12-01 | 成都市克莱微波科技有限公司 | Multilayer stripline high-power broadband directional coupler |
| CN111048879A (en) * | 2019-12-31 | 2020-04-21 | 广东盛路通信科技股份有限公司 | Broadband constant-amplitude conversion structure from rectangular waveguide to double-end strip line |
| CN218677535U (en) * | 2022-07-07 | 2023-03-21 | 广州司南技术有限公司 | Strong coupling stripline structure of passive element |
| CN115207591A (en) * | 2022-07-07 | 2022-10-18 | 广州司南技术有限公司 | Strong coupling strip line and microwave element containing same |
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2022
- 2022-07-07 CN CN202210794218.3A patent/CN115207591A/en active Pending
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2023
- 2023-05-06 WO PCT/CN2023/092498 patent/WO2024007717A1/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024007717A1 (en) * | 2022-07-07 | 2024-01-11 | 广州司南技术有限公司 | Strong coupling striplines and microwave element comprising same |
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| WO2024007717A1 (en) | 2024-01-11 |
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