Abstract
Disclosed is a transmission line-waveguide transition device including side surfaces and a top surface having a size and shape corresponding to a waveguide to which a signal of a transmission line is transmitted, the side surfaces and top surface having a plate shape; and a plate-shaped ridge formed in an inner space defined by the side surfaces and the top surface, the ridge being provided with a slope having one end connected to the transmission line and an opposite end contacting the top surface.
Claims
1. A transmission line-waveguide transition device comprising: side surfaces and a top surface having a size and shape corresponding to a waveguide to which a signal of a transmission line is transmitted, the side surfaces and top surface having a plate shape; and a plate-shaped ridge formed in an inner space defined by the side surfaces and the top surface, the ridge being provided with a slope having one end connected to the transmission line and an opposite end contacting the top surface, wherein the transmission line-waveguide transition device is fixedly mounted on a substrate having the transmission line, wherein a ground surface is formed on the substrate at least at a position where the transition device is mounted, wherein a ground transition area is formed on the ground surface at a position corresponding to the ridge, and wherein the ground transition area is formed to have a width that is reduced starting from a contact point between the ridge and the transmission line.
2. The transmission line-waveguide transition device of claim 1, wherein the ridge has a curve shape as a whole.
3. The transmission line-waveguide transition device of claim 2, wherein the curve shape of the ridge is approximately an “S” shape.
4. The transmission line-waveguide transition device of claim 1, wherein a portion of the ridge contacting the transmission line is connected to the transmission line by soldering, application of a conductive resin, or contact.
5. The transmission line-waveguide transition device of claim 1, wherein the transmission line has a strip line structure, and the ridge is connected to the transmission line by a via hole formed in the substrate of the transmission line.
6. The transmission line-waveguide transition device of claim 1, wherein the ground transition area is formed on the ground surface at a position corresponding to the ridge by removing a part of the ground surface.
7. The transmission line-waveguide transition device of claim 6, wherein a plurality of via holes is formed around the ground transition area.
8. The transmission line-waveguide transition device of claim 1, wherein the transmission line has a coplanar waveguide (CPW) structure, a CPW with Ground (CPWG) structure, or a microstrip line structure.
9. The transmission line-waveguide transition device of claim 1, further comprising: a flange for coupling with a flange of the waveguide.
10. The transmission line-waveguide transition device of claim 1, wherein the reduced width of the ground transition area has a shape of a triangle, and one edge of the triangle is in contact with a contact point between the ridge and the transmission line.
11. The transmission line-waveguide transition device of claim 10, wherein the triangle shape of the ground transition area has a shape of an isosceles triangle.
12. A transmission line-waveguide transition device comprising: side surfaces and a top surface having a size and shape corresponding to a waveguide to which a signal of a transmission line is transmitted, the side surfaces and top surface having a plate shape; and a plate-shaped ridge formed in an inner space defined by the side surfaces and the top surface, the ridge being provided with a slope having one end connected to the transmission line and an opposite end contacting the top surface, wherein the transmission line-waveguide transition device is fixedly mounted on a substrate having the transmission line, wherein a ground surface is formed on the substrate at least at a position where the transition device is mounted, wherein a ground transition area is formed on the ground surface at a position corresponding to the ridge by removing a part of the ground surface, and wherein the inner space is open to the substrate.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) FIGS. 1A, 1B, 1C, and 1D illustrate examples of conventional transmission line-waveguide transition devices.
(2) FIGS. 2A, 2B, and 2C are schematic diagrams illustrating the characteristics of a transmission line-waveguide transition device of the present disclosure.
(3) FIG. 3 is an exploded perspective view of a transmission line-waveguide transition device and a substrate on which a transmission line is formed according to a first embodiment of the present disclosure.
(4) FIG. 4 is a cross-sectional view taken along line A-A′ in FIG. 3.
(5) FIG. 5 is a plan view of the substrate of FIG. 3.
(6) FIGS. 6A and 6B are enlarged perspective views of the transmission line-waveguide transition device of FIG. 3.
(7) FIG. 7 is an exploded perspective view of a transmission line-waveguide transition device and a substrate on which a transmission line is formed according to a second embodiment of the present disclosure.
(8) FIG. 8 is an exploded perspective view of a transmission line-waveguide transition device and a substrate on which a transmission line is formed according to a third embodiment of the present disclosure.
(9) FIG. 9 is a cross-sectional view taken along line A-A′ in FIG. 8.
(10) FIG. 10 is an exploded perspective view of a transmission line-waveguide transition device and a substrate on which a transmission line is formed according to a fourth embodiment of the present disclosure.
(11) FIGS. 11A, 11B, 11C, and 11D are graphs depicting characteristics of transmission line-waveguide transition devices according to various embodiments of the present disclosure.
(12) FIGS. 12A, 12B, and 12C illustrate variations of a ridge structure that is applicable to transition devices according to various embodiments of the present disclosure.
(13) FIG. 13 is a graph of a function model applied in designing slopes of the ridge structures of FIGS. 12A, 12B and 12C.
BEST MODE FOR CARRYING OUT THE INVENTION
(14) Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the accompanying drawings, like reference numerals designate like elements. For simplicity, the sizes and shapes of the elements have been simplified or partially exaggerated.
(15) FIG. 3 is an exploded perspective view of a transmission line-waveguide transition device 20 (hereinafter referred to simply as a “transition device”) and a substrate 10 on which a transmission line 101 is formed according to a first embodiment of the present disclosure, where the transmission line 101 is illustrated as being implemented as a CPW structure. FIG. 4 is a cross-sectional view taken along line A-A′ in FIG. 3, showing a cross section of the transition device 20 and the transmission line 101 coupled to each other. FIG. 5 is a plan view of the substrate 10 of FIG. 3. FIGS. 6A and 6B are enlarged perspective views of the transmission line-waveguide transition device 20 of FIG. 3, in which FIG. 6B shows the internal structure of the transition device 20 more clearly by removing the top surface of the transition device 20.
(16) Referring to FIGS. 3, 4, 5, 6A and 6B, the transmission line-waveguide transition device 20 according to the first embodiment basically includes plate-shaped side surfaces 202 and 204 and a top surface 206 as shown in FIGS. 3, 6A and 6B that have sizes and shapes corresponding to a standardized waveguide 30 (see FIG. 4) to which a signal of the transmission line 101 (FIGS. 3-5) is transmitted. That is, the inner space defined by these side surfaces 202 and 204 and top surface 206 has a size and shape corresponding to the standardized waveguide.
(17) A plate-shaped ridge 210 (FIGS. 3, 4, 6A and 6B) having a slope G (see FIG. 4) with one end connected to the transmission line 101 on the substrate 10 and an opposite end contacting the top surface 206 is formed at the center of the inner space defined by the side surfaces 202 and 204 and the top surface 206. The width of the slope G of the ridge 210 may be designed to correspond to the width of the transmission line 101, for example, to be equal to the width of the transmission line 101.
(18) The slope G of the ridge 210 is a main element for transitioning a signal transmitted from the transmission line 101 to the waveguide, and is pre-designed in an appropriate curve shape as a whole. That is, the curve shape of the slope G may be designed by an appropriate combination of multiple trigonometric curves. For example, a portion Gs (see FIG. 4) in contact with the transmission line 101 may be designed in the shape of a curve that starts with at least a gentle gradient. The curve shape of the slope G of the ridge 210 may be designed through multiple tests and analyses so as to be optimized according to the type of the transmission line and the frequency of the transmission signal.
(19) Particularly, the curve shape of the portion Gs (see FIG. 4) of the ridge 210 that contacts the transmission line 101 should be designed so as to contact the transmission line 101 at a gentle angle rather than a steep angle. This is a major feature that enables effective signal transmission including improvement of junction characteristics and minimization of reflection loss at a connection point between the transmission line 101 and the ridge 210. It is found in the present disclosure that the signal transmission characteristics are deteriorated when the transmission line 101 and the ridge 210 are not connected at a gentle angle. Accordingly, in the embodiments of the present disclosure, the curve shape of the ridge 210 at at least the portion Gs where the ridge 210 contacts the transmission line 101 may be designed to have an inclination angle that gradually increases from 0 degrees with respect to the ground surface.
(20) At the connection point, the ridge 210 and the transmission line 101 may be fixedly connected to each other using a technique of soldering or application of a conductive resin (e.g., silver epoxy). In case of connection by soldering, plating treatment for solder may be pre-performed on a corresponding portion of the ridge 210. Alternatively, the ridge 210 and the transmission line 101 may be connected to each other in a simple contact manner.
(21) The transition device 20 embodied by the side surfaces 202 and 204 and the top surface 206 as well as the ridge 210 having the above configuration may be formed of a conductive metal such as, for example, aluminum (alloy) or copper (alloy). In some cases, the transition device 20 may be silver plated to further improve signal transmission characteristics.
(22) The transition device 20 is fixedly mounted on the substrate 10. For example, the transition device may be fixed on the substrate 10 by, for example, soldering. In this case, the lower end portions of the side surfaces 202 and 204 of the transition device 20 may be pre-subjected to plating treatment for soldering. Alternatively, the transition device 20 may be fixedly mounted on the substrate 10 in a screw coupling manner. In this case, screw holes (not shown) may be vertically formed in the side surfaces 202 and 204 of the transition device 20 in a penetrating manner, and corresponding screw holes (grooves) may be formed in the substrate 10, such that the transition device and the substrate are coupled with each other by coupling screws. Of course, a separate flange (not shown) may be additionally formed on the side surfaces 202 and 204 of the transition device 20 for screw connection, and thus the transition device may be coupled to the substrate 10 by the flange in a screw coupling manner.
(23) A ground surface (an area indicated by a dotted line in FIGS. 3 and 5) is formed on the substrate 10 at least at a position where the transition device 20 is mounted. In the embodiments shown in FIGS. 3, 4, 5, 6A and 6B, the transmission line 101 has the CPW structure, and thus the entire top surface of the substrate 10 is the ground surface.
(24) As shown in FIGS. 3 and 5, a ground transition area 102 is formed on the ground surface formed on the top surface of the substrate 10 at a position corresponding to the ridge 210 of the transition device 20 by removing a part of the ground surface. The ground transition area 102 is formed to have a generally elongated triangular shape (e.g., an isosceles triangle) as the width thereof gradually decreases starting from the connection point between the ridge 210 and the transmission line 101. The ground transition area 102 is formed to improve signal transmission characteristics and impedance matching between the transmission line 101 and the waveguide. The two sides of the ground transition area 102 having the shape of an isosceles triangle may have a generally curved line shape for more precise matching of the ground characteristics in consideration of, for example, the distance to the slope G of the ridge 210.
(25) The transition device 20 having the structure described above may further include a flange 250 for coupling with a flange 350 of the waveguide 30 as shown in FIG. 4. The waveguide 30 may be designed according to a standard specification (for example, in the band of 26.5 GHz to 40 GHz, the standard specification defines the inner size of a ‘WR-28’ waveguide as 7.11 mm×3.56 mm), the transition device 20 and the flange 250 are formed correspondingly. In addition to the flange structure, soldering or welding may be performed to attach the transition device 20 to the waveguide 30, or the transition device 20 may be integrated with the waveguide 30 as an end structure of the waveguide 30.
(26) The transmission line-waveguide transition device 20 of the present disclosure, which may be configured as shown in FIGS. 3, 4, 5, 6A and 6B, can be installed in a simple manner of, for example, placing a kind of cover on the PCB substrate 10. Accordingly, it can be seen that stabilization of characteristics, simplification of assembly, and a compact design can be realized. In particular, since the transition device can be connected directly to the waveguide while being arranged parallel to the waveguide, the product may remain thin as a whole.
(27) FIG. 7 is an exploded perspective view of the transmission line-waveguide transition device 20 and a substrate 12 on which a transmission line 121 is formed according to a second embodiment of the present disclosure, where the transmission line 121 is illustrated as being implemented as a CPWG structure. The transmission line 121 and a ground surface are formed on the top surface of the substrate 12 of the CPWG structure, and a ground surface is formed on the bottom surface of the substrate. In the example of FIG. 7, it is illustrated that multiple via holes 124 are formed around the transmission line 121 to improve grounding.
(28) Referring to FIG. 7, the transmission line-waveguide transition device 20 according to the second embodiment includes side surfaces 202 and 204, a top surface 206 and a ridge 210, which are substantially identical to the elements shown in FIGS. 3, 4, 5, 6A and 6B. Herein, one end of the ridge 210 comes into contact with the transmission line 121 of the CPWG structure. Further, the ridge 210 may have an appropriately pre-designed slope of a curve shape, like the structure of the first embodiment.
(29) A ground surface (an area indicated by a dotted line in FIG. 7) is formed on the substrate 12 at least at a position where the transition device 20 is mounted, and a ground transition area 122 is formed at a position corresponding to the ridge 210 of the transition device 20 by removing a part of the ground surface in the same manner as in the structure of the first embodiment.
(30) FIG. 8 is an exploded perspective view of the transmission line-waveguide transition device 20 and a substrate 14 on which a transmission line 141 is formed according to a third embodiment of the present disclosure, wherein the transmission line 141 is illustrated as being implemented as a strip line structure. FIG. 9 is a cross-sectional view taken along line A-A′ in FIG. 8, showing a cross section of the transition device 20 and the substrate 14 coupled to each other. A ground surface is formed on the top and bottom surfaces of the substrate 14 of the strip line structure, and the transmission line 141 is embedded in a non-conductive dielectric layer, which is the inner layer of the substrate.
(31) Referring to FIGS. 8 and 9, the transmission line-waveguide transition device 20 according to the third embodiment is substantially similar to the previous embodiments in that the transition device includes side surfaces 202 and 204, a top surface 206 as shown in FIG. 8, and a ridge 210. A metal via hole 143 is further through the substrate 14 so as to be connected to the end of the transmission line 141 in the inner layer of the substrate in order to connect the ridge 210 and the transmission line 141 of the strip line structure. The ridge 210 contacts the metal via hole 143 and is thus connected to the transmission line 141.
(32) A ground surface (an area indicated by a dotted line in FIG. 8) is formed on the substrate 14 at least at a position where the transition device 20 is mounted, and a ground pattern is removed from the periphery of the via hole 143. A ground transition area 142 (FIG. 8) is formed at a position corresponding to the ridge 210 of the transition device 20 by removing a part of the ground surface in the same manner as in the structures of the previous embodiments. In the structure of the third embodiment shown in FIGS. 8 and 9, multiple via holes 144 may be formed through the substrate 14 such that the top surface ground and bottom surface ground of the substrate are connected to each other to improve grounding around the ground transition area 142.
(33) FIG. 10 is an exploded perspective view of the transmission line-waveguide transition device and a substrate on which a transmission line is formed according to a fourth embodiment of the present disclosure, wherein the transmission line 161 is illustrated as being implemented as a microstrip line structure. A pattern of the transmission line 161 is basically formed on the top surface of the substrate 16 of the microstrip line structure, and a ground surface is formed on the bottom surface of the substrate.
(34) Referring to FIG. 10, the transmission line-waveguide transition device 20 according to a fourth embodiment of the present disclosure includes side surfaces 202 and 204, a top surface 206, and a ridge 210 as in the previous embodiments. Here, the ridge 210 is arranged so as to contact the transmission line 161 of the microstrip line structure.
(35) A separate ground surface is additionally formed on the substrate 16 at a position where at least the transition device 20 is mounted. A ground transition area 162 is formed on the ground surface additionally formed on the top surface of the substrate 16, at a position corresponding to the ridge 210 by removing a part of the ground surface, as in the previous embodiments. In addition, multiple via holes 164 may be formed in the periphery of the ground transition area 162 through the substrate 16 to improve grounding. Thereby, the ground surface additionally formed on the top surface of the substrate may be connected to the ground surface formed on the bottom surface of the substrate.
(36) FIGS. 11A, 11B, 11C, and 11D are graphs depicting characteristics of transmission line-waveguide transition devices according to various embodiments of the present disclosure, showing the characteristics of the transition devices 20 according to the first, second, third and fourth embodiments. As shown in FIG. 11A, it can be seen that the reflection loss S11 is −19.72 dB and the insertion loss S21 is −0.65 dB when the frequency is 27.00 GHz, and, the reflection loss S11 is −24.63 dB and the insertion loss S21 is −0.69 dB when the frequency is 29.00 GHz. As show in FIG. 11B, it can be seen that the reflection loss S11 is −18.06 dB and the insertion loss S21 is −0.47 dB when the frequency is 27.00 GHz, and, the reflection loss S11 is −25.69 dB and the insertion loss S21 is −0.65 dB when the frequency is 29.00 GHz. As show in FIG. 11C, it can be seen that the reflection loss S11 is −20.44 dB and the insertion loss S21 is −0.69 dB when the frequency is 27.00 GHz, and, the reflection loss S11 is −18.85 dB and the insertion loss S21 is −0.74 dB when the frequency is 29.00 GHz. As show in FIG. 11D, it can be seen that the reflection loss S11 is −29.62 dB and the insertion loss S21 is −0.28 dB when the frequency is 27.00 GHz, and, the reflection loss S11 is −24.69 dB and the insertion loss S21 is −0.32 dB when the frequency is 29.00 GHz. As shown in FIGS. 11A to 11D, it can be seen that the reflection loss S11 in each of the transition devices 20 is sufficiently secured as the −15 dB bandwidth with respect to a desired band, for example, a 28 GHz band. It can also be seen that the insertion loss S21 is within about −0.75 dB and can be designed to be very small. Since part of the loss results from the dielectric substrate, it can be inferred that the actual insertion loss of the transition structure is very small, so as to be negligible.
(37) As in the structures of the first to fourth embodiments of the present disclosure, the transmission line-waveguide transition device according to the present disclosure is applicable to a variety of transmission line structures including a CPW (FIG. 11A), a CPWG (FIG. 11B), a strip line (FIG. 11C), and a microstrip line (FIG. 11D) on single-layered and multi-layered substrates of any shape.
(38) FIGS. 12A, 12B, and 12C illustrate variations of a ridge structure that is applicable to transition devices according to various embodiments of the present disclosure, in which the different curve shapes of the slope of the ridge can be designed. That is, the slope of the ridge 210-1 of the transition device 20-1 shown in FIG. 12A is a straight line, and the slope of the ridge 210-2 of the transition device 20-2 shown in FIG. 12B is a curve that has a small degree of inclination at the start point of the slope section and a large degree of inclination at the end point of the section. The slope of the ridge 210-3 of the transition device 20-3 shown in FIG. 12C is an S-shaped curve having a small degree of inclination at the start and end points of the slope section, similar to a logistic function or a part of a trigonometric function.
(39) FIG. 13 is a graph of function models applied in designing slopes of the ridge structures of FIGS. 12A, 12B and 12C. Referring to FIG. 13, the linear shape of the slope of the ridge 210-1 in FIG. 12A may be designed using a first-order function, and the curve shape of the slope of the ridge 210-2 in FIG. 12B may be designed using a second-order function. The “S” shape of the slope of the ridge 210-3 in FIG. 12C may be designed using a trigonometric function. The functions may be set to satisfy, for example, the following equations, respectively. Here, although not limited thereto, L may have a value of 15, and B may have a value of 3.5, as illustrated in FIG. 13.
(40) [Equations]
First-order function: y=B/L*x
Second-order function: y=(B/L{circumflex over ( )}2)*x{circumflex over ( )}2
Trigonometric function y=−0.5*B*cos(π/L*x)+0.5*B
(41) Herein, L denotes the length of a transition structure, and B denotes the height of the transition structure (i.e., height of the waveguide).
(42) The graph of the curves of the respective functions shown in FIG. 13 models the shape of the slope of the ridge by setting the portion of the PCB contacting the transmission line to the origin (0, 0). Thus, a function of a curve passing through the origin and the end point (L, B) (where L is the ridge length in millimeters and B is the ridge height in millimeters) of a slope may be appropriately set, and thus the slope of the ridge may be designed.
(43) In this case, a structure having a smaller loss for a shorter length L of the ridge, that is, a shorter length of the transition structure may be an optimum structure. In this sense, the structure using a trigonometric function having a small degree of inclination at the start point (0, 0) and the end point (L, B) of the transition structure in the above example is an excellent structure. Regarding the ridge structures, other optimization may be applied depending on a structure employed, the thickness of the PCB, the width of the transmission line, and the like. In addition, different function models may be applied to each part of the ridge in designing the whole slope of a ridge.
(44) As described above, in various embodiments of the present disclosure, the shape of the ridge of the transition device may be optimized by modeling curve shapes of various functions. According to the present disclosure, since transition from a PCB type transmission line to a waveguide is performed through a single transition structure, a function model having excellent characteristics among various function models can be derived and adopted.
(45) As described above, the transmission line-waveguide transition device according to various embodiments of the present disclosure may be configured and operated. While specific embodiments of the present invention have been described above, it is to be understood that various other embodiments and modifications may be made in the present invention. For example, the length of the transition device 20, the curve shape of the slope G of the ridge 210 as shown in FIG. 4, and the like may be differently designed in consideration of characteristics required of a product. In addition to the transmission line mentioned in the above embodiments, the transition device 20 of the present disclosure may also be applied to, for example, a coaxial line. In this case, the inner conductor of the coaxial line may be connected to the ridge.
(46) As such, various modifications and variations of the present disclosure may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.
