阅读说明：本技术 传输线结构 (Transmission line structure ) 是由 萧富仁 于 2020-06-30 设计创作，主要内容包括：本发明为一种传输线结构,包括一介电层结构、一第一外接地层、一第一接垫、一传输线路及一导电通孔。介电层结构具有一顶面,第一外接地层配置于顶面上,第一外接地层的一边缘具有一第一凹口。第一接垫配置于顶面上且适于连接于一电性接头。第一接垫部分地位于第一凹口内,第一凹口的一内缘与第一接垫之间具有间隙。传输线路配置于介电层结构内。导电通孔配置于介电层结构内且连接于第一接垫及传输线路。(The invention relates to a transmission line structure, which comprises a dielectric layer structure, a first external ground layer, a first connecting pad, a transmission line and a conductive through hole. The dielectric layer structure is provided with a top surface, the first external ground layer is arranged on the top surface, and one edge of the first external ground layer is provided with a first notch. The first pad is disposed on the top surface and adapted to be connected to an electrical connector. The first pad is partially located in the first recess, and a gap is formed between an inner edge of the first recess and the first pad. The transmission line is disposed in the dielectric layer structure. The conductive through hole is arranged in the dielectric layer structure and connected to the first connecting pad and the transmission line.)

1. A transmission line structure characterized by:

a dielectric layer structure having a top surface;

a first external ground layer disposed on the top surface, wherein an edge of the first external ground layer has a first notch;

a first pad disposed on the top surface and adapted to be connected to an electrical connector, wherein the first pad is partially located in the first recess, and a gap is formed between an inner edge of the first recess and the first pad;

a transmission line configured in the dielectric layer structure; and

and the conductive through hole is arranged in the dielectric layer structure and is connected with the first connecting pad and the transmission line.

2. The transmission line structure of claim 1, characterized in that: the transmission line structure has a first section, a second section and a third section, the second section is located between the first section and the third section, the first pad is located in the first section and extends toward the second section, the transmission line is located in the third section and extends toward the second section, and the conductive via is located in the second section.

3. The transmission line structure of claim 1, characterized in that: the inner edge of the first notch is arc-shaped, and part of the outer edge of the first pad is arc-shaped and corresponds to the inner edge of the first notch.

4. The transmission line structure of claim 1, characterized in that: the dielectric layer structure has at least one side surface adjacent to the top surface, and the transmission line structure further includes at least one conductive layer disposed on the at least one side surface and connected to the first external ground layer.

5. The transmission line structure of claim 4, wherein: the at least one conductive layer has an extension portion extending from the at least one side surface into the dielectric layer structure, and a gap is formed between the extension portion and the transmission line.

6. The transmission line structure of claim 5, wherein: the dielectric layer structure comprises two dielectric layers which are mutually overlapped, and the transmission line and the extension part are arranged between the two dielectric layers.

7. The transmission line structure of claim 4, wherein: the at least one side surface comprises two opposite side surfaces, the at least one conducting layer comprises two conducting layers, and the two conducting layers are respectively arranged on the two side surfaces and are respectively connected to two opposite ends of the first external stratum.

8. The transmission line structure of claim 4, wherein: the dielectric layer structure further comprises an internal ground layer which is configured in the dielectric layer structure and connected with the at least one conductive layer, one edge of the internal ground layer is provided with a second notch, one end part of the transmission line is partially positioned in the second notch, and a gap is arranged between one inner edge of the second notch and the end part of the transmission line.

9. The transmission line structure of claim 8, wherein: the inner edge of the second notch is arc-shaped, and the outer edge of the end of the transmission line is arc-shaped and corresponds to the inner edge of the second notch.

10. The transmission line structure of claim 4, wherein: the dielectric layer structure has a bottom surface opposite to the top surface, the transmission line structure further includes a second external ground layer disposed on the bottom surface, and the at least one conductive layer is connected to the second external ground layer.

11. A transmission line structure comprising:

a dielectric layer structure having a top surface and a bottom surface opposite to each other;

a first external ground layer disposed on the top surface, wherein an edge of the first external ground layer has a first notch;

a second external grounding layer configured on the bottom surface and provided with an opening;

a first pad disposed on the top surface and adapted to be connected to an electrical connector, wherein the first pad is partially located in the first recess, and a gap is formed between an inner edge of the first recess and the first pad;

a second pad disposed on the bottom surface and located in the opening, wherein a gap is formed between an inner edge of the opening and the second pad;

a transmission line configured in the dielectric layer structure; and

and the conductive through hole is arranged in the dielectric layer structure and is connected with the first connecting pad, the transmission line and the second connecting pad.

12. The transmission line structure of claim 11, characterized in that: the transmission line structure has a first section, a second section and a third section, the second section is located between the first section and the third section, the first pad is located in the first section and extends toward the second section, the transmission line is located in the third section and extends toward the second section, and the conductive via and the second pad are located in the second section.

13. The transmission line structure of claim 11, characterized in that: the inner edge of the first notch is arc-shaped, and part of the outer edge of the first pad is arc-shaped and corresponds to the inner edge of the first notch.

14. The transmission line structure of claim 11, characterized in that: the inner edge of the opening is arc-shaped, and the outer edge of the second pad is arc-shaped and corresponds to the inner edge of the opening.

15. The transmission line structure of claim 11, characterized in that: the dielectric layer structure has at least one side surface adjacent to the top surface and the bottom surface, and the transmission line structure further includes at least one conductive layer disposed on the at least one side surface and connected to the first external ground layer and the second external ground layer.

16. The transmission line structure of claim 15, characterized in that: the at least one conductive layer has an extension portion extending from the at least one side surface into the dielectric layer structure, and a gap is formed between the extension portion and the transmission line.

17. The transmission line structure of claim 16, wherein: the dielectric layer structure comprises two dielectric layers which are mutually overlapped, and the transmission line and the extension part are arranged between the two dielectric layers.

18. The transmission line structure of claim 15, characterized in that: the at least one side surface comprises two opposite side surfaces, the at least one conducting layer comprises two conducting layers, the two conducting layers are respectively arranged on the two side surfaces, and the two conducting layers are respectively connected to two opposite ends of the first external ground layer and two opposite ends of the second external ground layer.

19. The transmission line structure of claim 15, characterized in that: the dielectric layer structure further comprises an internal ground layer, wherein the internal ground layer is arranged in the dielectric layer structure and connected with the at least one conductive layer, one edge of the internal ground layer is provided with a second notch, one end part of the transmission line is partially positioned in the second notch, and a gap is arranged between one inner edge of the second notch and the end part of the transmission line.

20. The transmission line structure of claim 19, wherein: the inner edge of the second notch is arc-shaped, and the outer edge of the end of the transmission line is arc-shaped and corresponds to the inner edge of the second notch.

Technical Field

The present invention relates to an electronic component, and more particularly, to a transmission line structure.

Background

In order to provide a good communication effect for the notebook computer, the antenna is mostly disposed in the frame area around the screen, and the connection between the antenna and the communication module is usually performed by a mini cable (mini cable). The mini-cable has a small wire diameter (about 0.8 mm) and is easy to configure in a limited routing space. However, with the trend of slim design of notebook computers, the gap between the screen and the back plate of the housing is very small, and even a mini cable is not easily disposed in the way of directly passing through the gap between the screen and the back plate of the housing, and needs to be routed along the frame region around the screen. This arrangement makes the transmission path too long and greatly increases the transmission loss and signal interference. In addition, with respect to the wiring space of the pivot structure of the notebook computer, the bus path of the large number of mini cables is too large to reach the host end from the monitor end through the pivot structure.

Disclosure of Invention

The invention provides a transmission line structure which has the characteristics of thinness and high transmission quality.

The transmission line structure of the invention comprises a dielectric layer structure, a first external ground layer, a first connecting pad, a transmission line and a conductive through hole. The dielectric layer structure is provided with a top surface, the first external ground layer is arranged on the top surface, and one edge of the first external ground layer is provided with a first notch. The first pad is disposed on the top surface and adapted to be connected to an electrical connector. The first pad is partially located in the first recess, and a gap is formed between an inner edge of the first recess and the first pad. The transmission line is disposed in the dielectric layer structure. The conductive through hole is arranged in the dielectric layer structure and connected to the first connecting pad and the transmission line.

In an embodiment of the invention, the transmission line structure has a first section, a second section and a third section, the second section is located between the first section and the third section, the first pad is located in the first section and extends toward the second section, the transmission line is located in the third section and extends toward the second section, and the conductive via is located in the second section.

In an embodiment of the invention, an inner edge of the first recess is arc-shaped, and a portion of an outer edge of the first pad is arc-shaped and corresponds to the inner edge of the first recess.

In an embodiment of the invention, the dielectric layer structure has at least one side surface adjacent to the top surface, and the transmission line structure further includes at least one conductive layer disposed on the at least one side surface and connected to the first external ground layer.

In an embodiment of the invention, the at least one conductive layer has an extension portion extending from at least one side surface into the dielectric layer structure, and a gap is formed between the extension portion and the transmission line.

In an embodiment of the invention, the dielectric layer structure includes two dielectric layers stacked on each other, and the transmission line and the extension portion are disposed between the two dielectric layers.

In an embodiment of the invention, the at least one side surface includes two opposite side surfaces, and the at least one conductive layer includes two conductive layers, and the two conductive layers are respectively disposed on the two side surfaces and respectively connected to two opposite ends of the first external ground layer.

In an embodiment of the invention, the transmission line structure further includes an inner ground layer, wherein the inner ground layer is disposed in the dielectric layer structure and connected to the at least one conductive layer, an edge of the inner ground layer has a second recess, an end portion of the transmission line is partially located in the second recess, and a gap is formed between an inner edge of the second recess and the end portion of the transmission line.

In an embodiment of the invention, an inner edge of the second recess is circular arc-shaped, and an outer edge of the end of the transmission line is circular arc-shaped and corresponds to the inner edge of the second recess.

In an embodiment of the invention, the dielectric layer structure has a bottom surface opposite to the top surface, the transmission line structure further includes a second external ground layer disposed on the bottom surface, and the at least one conductive layer is connected to the second external ground layer.

The transmission line structure of the invention comprises a dielectric layer structure, a first external ground layer, a second external ground layer, a first connecting pad, a second connecting pad, a transmission line and a conductive through hole. The dielectric layer structure has a top surface and a bottom surface opposite to each other. The first external ground layer is configured on the top surface. One edge of the first external ground layer is provided with a first notch. The second external grounding layer is arranged on the bottom surface and is provided with an opening. The first connecting pad is arranged on the top surface and is suitable for being connected with an electrical connector, the first connecting pad is partially positioned in the first notch, and a gap is formed between the inner edge of the first notch and the first connecting pad. The second connecting pad is arranged on the bottom surface and is positioned in the opening, and a gap is formed between an inner edge of the opening and the second connecting pad. The transmission line is disposed in the dielectric layer structure. The conductive through hole is arranged in the dielectric layer structure and connected to the first pad, the transmission line and the second pad.

In an embodiment of the invention, the transmission line structure has a first section, a second section and a third section, the second section is located between the first section and the third section, the first pad is located in the first section and extends toward the second section, the transmission line is located in the third section and extends toward the second section, and the conductive via and the second pad are located in the second section.

In an embodiment of the invention, an inner edge of the first recess is arc-shaped, and a portion of an outer edge of the first pad is arc-shaped and corresponds to the inner edge of the first recess.

In an embodiment of the invention, an inner edge of the opening is arc-shaped, and an outer edge of the second pad is arc-shaped and corresponds to the inner edge of the opening.

In an embodiment of the invention, the dielectric layer structure has at least one side surface adjacent to the top surface and the bottom surface, and the transmission line structure further includes at least one conductive layer disposed on the at least one side surface and connected to the first external ground layer and the second external ground layer.

In an embodiment of the invention, the at least one conductive layer has an extension portion extending from at least one side surface into the dielectric layer structure, and a gap is formed between the extension portion and the transmission line.

In an embodiment of the invention, the dielectric layer structure includes two dielectric layers stacked on each other, and the transmission line and the extension portion are disposed between the two dielectric layers.

In an embodiment of the invention, the at least one side surface includes two opposite side surfaces, the at least one conductive layer includes two conductive layers, the two conductive layers are respectively disposed on the two side surfaces, and the two conductive layers are respectively connected to two opposite ends of the first external ground layer and two opposite ends of the second external ground layer.

In an embodiment of the invention, the transmission line structure further includes an inner ground layer, wherein the inner ground layer is disposed in the dielectric layer structure and connected to the at least one conductive layer, an edge of the inner ground layer has a second recess, an end portion of the transmission line is partially located in the second recess, and a gap is formed between an inner edge of the second recess and the end portion of the transmission line.

In an embodiment of the invention, an inner edge of the second recess is circular arc-shaped, and an outer edge of the end of the transmission line is circular arc-shaped and corresponds to the inner edge of the second recess.

In view of the above, in the transmission line structure of the present invention, the first pad for connecting the electrical connector is disposed on the top surface of the dielectric layer structure and is connected to the transmission line inside the dielectric layer structure through the conductive via. Compared with the coaxial arrangement of a common coaxial cable (such as a mini cable), the first pads and the corresponding electrical connectors are arranged on the top surface of the dielectric layer structure as described above, so that the transmission line structure is not axisymmetric in structure and becomes a flat structure, which is beneficial to thinning of the transmission line structure. On the other hand, the first external ground layer and the second external ground layer respectively disposed on the top surface and the bottom surface of the dielectric layer structure can isolate the signal interference from the transmission line in the dielectric layer structure. And the edge of the first external ground layer arranged on the top surface of the dielectric layer structure is provided with a first notch corresponding to the first connecting pad, and a gap is arranged between the first connecting pad and the first notch. Similarly, the second external ground layer disposed on the bottom surface of the dielectric layer structure has an opening corresponding to the second pad, and a gap is formed between the second pad and the opening. Therefore, the equivalent capacitance between the first connecting pad and the first external ground layer and the equivalent capacitance between the second connecting pad and the second external ground layer can be changed by adjusting the size of the gap, so that the impedance matching between the joint structure (the section where the first connecting pad and the electric joint are located) and the sandwich strip line structure (the section where the transmission line is located) is optimized, and the transmission loss degree of the joint structure and the sandwich strip line structure caused by the asymmetric configuration mode is reduced. In addition, the equivalent inductance value of the conductive through hole can be changed by adjusting the outer diameter of the conductive through hole, so that the impedance matching between the joint section and the sandwich strip line section is optimized, and the transmission loss degree is further reduced. Therefore, the transmission line structure of the invention has the characteristics of thinning and high transmission quality.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a schematic diagram of a transmission line structure according to an embodiment of the present invention.

Fig. 2 is an enlarged view of the transmission line structure of fig. 1 in area a.

Fig. 3 is an enlarged view of the transmission line structure of fig. 1 in region B.

Fig. 4 is an exploded view of the transmission line structure of fig. 2.

Fig. 5 is a schematic side view of the transmission line structure of fig. 2.

FIG. 6 shows the transmission line structure of FIG. 1 applied to a notebook computer.

Fig. 7 is a cross-sectional view of the transmission line structure of fig. 2 taken along line I-I.

Fig. 8 is a cross-sectional view of the transmission line structure of fig. 3 along line II-II.

Description of the symbols

50: an electrical connector, 62: a display, 62a: a frame, 62b: a screen, 64: a host, 66: an antenna, 100: a transmission line structure, 110: a dielectric layer structure, 110a: a top surface, 110b: a bottom surface, 110c: a side surface, 110d: a front end, 112, 114: a dielectric layer, 113: a glue layer, 120: a first external ground layer, 120a: a first recess, 125, 180: a conductive layer, 130: a second external ground layer, 130a: an opening, 140: a first pad, 150: a second pad, 160: a transmission line, 162: a terminal, 170: a conductive via, 182: an extension, 190: an internal ground layer, 190a: a second recess, d1, d2 outer diameter, G: a gap, H1, H2, H3: a thickness, L: a length, S1: a first section, S2: a second section, S3: a third section, W1, W2, W3: a width.

Detailed Description

Fig. 1 is a schematic diagram of a transmission line structure according to an embodiment of the present invention. Fig. 2 is an enlarged view of the transmission line structure of fig. 1 in area a. Fig. 3 is an enlarged view of the transmission line structure of fig. 1 in region B. Fig. 4 is an exploded view of the transmission line structure of fig. 2. Referring to fig. 1 to 4, the transmission line structure 100 of the present embodiment includes a dielectric layer structure 110, a first external ground layer 120, a second external ground layer 130, a first pad 140, a second pad 150, a transmission line 160, and a conductive via 170.

The dielectric layer structure 110 has a top surface 110a (labeled in fig. 4) and a bottom surface 110b (labeled in fig. 4) opposite to each other. The first external ground layer 120 and the second external ground layer 130 are disposed on the top surface 110a and the bottom surface 110b of the dielectric layer structure 110, respectively. The edge of the first circumscribed ground layer 120 has a first notch 120 a. The first pads 140 are disposed on the top surface 110a of the dielectric layer structure 110 and partially located in the first recesses 120a of the first external ground layer 120, and a gap is formed between inner edges of the first recesses 120a and the first pads 140. The second external ground layer 130 has an opening 130 a. The second pads 150 are disposed on the bottom surface 110b of the dielectric layer structure 110 and located in the openings 130a of the second outer ground layer 130, and a gap is formed between the inner edges of the openings 130a and the second pads 150. The transmission line 160 is disposed in the dielectric layer structure 110, and the conductive via 170 is disposed in the dielectric layer structure 110 and connected to the first pad 140, the transmission line 160 and the second pad 150.

Fig. 5 is a schematic side view of the transmission line structure of fig. 2, and for clarity of the drawing, fig. 5 only illustrates a portion of the conductive structures in the transmission line structure 100, i.e., the first pads 140, the second pads 150, the conductive vias 170, and the transmission lines 160. As shown in fig. 5, according to the above configuration, the transmission line structure 100 of the present embodiment can be divided into a first section S1 (tab structure), a second section S2 (mode conversion coupling structure) and a third section S3 (sandwich strip line structure), wherein the second section S2 is located between the first section S1 and the third section S3.

Specifically, the first pads 140 located at the first section S1 are suitable for being connected to an electrical connector 50, so as to form the connector structure. The electrical connector 50 is, for example, an I-PEX connector or other type of connector, but the invention is not limited thereto. The conductive via 170 and the second pad 150 are located at the second segment S2. The first pad 140 extends from the first segment S1 to the second segment S2 to connect to the conductive via 170. The transmission line 160 is located in the third section S3 and forms the above-mentioned sandwich strip line structure together with the dielectric structure layer 110, and the transmission line 160 extends toward the second section S2 to connect to the conductive via 170.

The first pads 140 for connecting the electrical connectors 50 are disposed on the top surface 110a of the dielectric layer structure 110 and are connected to the transmission lines 160 inside the dielectric layer structure 110 through the conductive vias 170. Compared with the coaxial arrangement of a common coaxial cable (e.g., a mini cable), the arrangement of the first pads 140 and the corresponding electrical connectors 50 on the top surface 110a of the dielectric layer structure 110 as described above can make the transmission line structure 100 not axisymmetric in structure but a flat structure, which is beneficial to the thinning of the transmission line structure 100. Specifically, the maximum outer diameter of the mini cable is about 0.81 mm, and the maximum outer diameter of the transmission line 160 of the present embodiment can be reduced to 0.4 mm or less. On the other hand, the first external ground layer 120 and the second external ground layer 130 respectively disposed on the top surface 110a and the bottom surface 110b of the dielectric layer structure 110 can perform a shielding function for isolating signal interference to the transmission line 160 in the dielectric layer structure 110.

As described above, the first external ground layer 120 disposed on the top surface 110a of the dielectric layer structure 110 has a first recess 120a corresponding to the first pad 140 at its edge, and a gap is formed between the first pad 140 and the first recess 120 a. Similarly, the second external ground layer 130 disposed on the bottom surface 110b of the dielectric layer structure 110 has an opening 130a corresponding to the second pad 150, and a gap is formed between the second pad 150 and the opening 130 a. Accordingly, the equivalent capacitance between the first pad 140 and the first external ground layer 120 and the equivalent capacitance between the second pad 150 and the second external ground layer 130 can be changed by adjusting the size of the gap, so as to optimize the impedance matching between the first section S1 and the third section S3, and reduce the transmission loss degree of the first section S1 and the third section S3 caused by the asymmetric arrangement manner. In addition, the equivalent inductance of the conductive via 170 can be changed by adjusting the outer diameter of the conductive via 170, so as to optimize the impedance matching between the first pad 140 and the transmission line 160, and further reduce the transmission loss. This is the Mode conversion coupling effect provided by the Mode conversion coupling structure, so as to achieve the impedance conversion and transmission Mode matching between the transmission line unbalanced Mode (Quasi-TEM Mode) of the connector structure and the balanced Mode (TEM Mode) of the sandwich strip line structure.

As shown in fig. 2 and 4, the inner edge of the first recess 120a of the first external ground layer 120 is, for example, circular arc, a portion of the outer edge of the first pad 140 is, for example, circular arc and corresponds to the circular arc inner edge of the first recess 120a, and the gap between the first pad 140 and the inner edge of the first recess 120a is, for example, uniformly equidistant. Similarly, the inner edge of the opening 130a of the second outer ground layer 130 is circular arc-shaped, the outer edge of the second pad 150 is circular arc-shaped and corresponds to the circular arc-shaped inner edge of the opening 130a, and the gap between the second pad 150 and the inner edge of the opening 130a is uniform and equidistant. However, the present invention is not limited thereto, and in other embodiments, the inner edge of the first recess 120a and the corresponding outer edge of the first pad 140 may be square or other non-circular arc shapes, and the gap between the first pad 140 and the inner edge of the first recess 120a may not be equidistant, so as to improve the flexibility of impedance matching as required. Similarly, the inner edge of the opening 130a and the corresponding outer edge of the second pad 150 may be square or other non-circular arc shapes, and the gap between the second pad 150 and the inner edge of the opening 130a may not be equidistant, so as to improve the flexibility of impedance matching as required.

Referring to fig. 2 to 4, the dielectric layer structure 110 of the present embodiment has two side surfaces 110c (labeled in fig. 4) adjacent to the top surface 110a and the bottom surface 110b, the dielectric layer structure 110 includes two dielectric layers 112 and 114 stacked on each other, the two dielectric layers 112 and 114 can be glued to each other by a glue layer 113 (labeled in fig. 4), and each side surface 110c is formed by side surfaces of the two dielectric layers 112 and 114. The dielectric constant (Dk) of the two dielectric layers 112, 114 may be 2.5, and the loss tangent (Df) of the two dielectric layers 112, 114 may be 0.003. The transmission line structure 100 further includes two conductive layers 180, the two conductive layers 180 are respectively disposed on the two side surfaces 110c, the two conductive layers 180 are respectively connected to the two opposite ends of the first external ground layer 120 and the two opposite ends of the second external ground layer 130, so as to jointly play a shielding role of isolating signal interference with the first external ground layer 120 and the second external ground layer 130 for the transmission line 160 in the dielectric layer structure 110. The two conductive layers 180 may extend to the front end 110d of the dielectric layer structure 110 as shown in fig. 2, and connect with the conductive layer 125 (shown in fig. 2) on the top surface 110a (labeled in fig. 4) of the dielectric layer structure 110. The electrical connector 50 shown in fig. 5 is connected to the transmission line 160 through the first pad 140, and is also connected to the first external ground layer 120 and the second external ground layer 130 through the conductive layer 125 and the conductive layer 180. Each conductive layer 180 is electroplated on the corresponding side 110c, for example, by a laser-induced metallization process. Compared with the conventional method in which a plurality of conductive vias are sequentially arranged on both sides of the conductive line as the shielding structure, the present embodiment uses the continuous and complete conductive layer 180 as the shielding structure as described above, thereby achieving a better shielding effect.

Furthermore, each conductive layer 180 of the present embodiment has an extending portion 182, and each extending portion 182 extends from the corresponding side surface 110c into the dielectric layer structure 110 and is located between the two dielectric layers 112 and 114, so as to enhance the adhesion between each conductive layer 180 and the dielectric layer structure 110. Moreover, a gap is formed between each extension 182 and the transmission line 160, and by adjusting the size of the gap, the equivalent distance between each conductive layer 180 and the transmission line 160 can be optimized, thereby achieving the effect of reducing the transmission loss.

In addition, the transmission line structure 100 of the present embodiment may further include an inner ground layer 190 as shown in fig. 2 and 4. The inner ground layer 190 is disposed in the dielectric layer structure 110 and located between the two dielectric layers 112 and 114, and connected to the two conductive layers 180, so as to be connected to the first outer ground layer 120 and the second outer ground layer 130 through the two conductive layers 180. The edge of the inner ground layer 190 has a second recess 190a, an end 162 of the transmission line 160 is partially located within the second recess 190a, and a gap is provided between the inner edge of the second recess 190a and the end 162 of the transmission line 160. Accordingly, the equivalent capacitance between the end 162 of the transmission line 160 and the internal ground layer 190 can be changed by adjusting the size of the gap, so as to optimize the impedance matching between the first section S1 and the third section S3, and reduce the degree of transmission loss generated by the first section S1 and the third section S3 due to the asymmetric arrangement.

As shown in fig. 2 and 4, the inner edge of the second recess 190a of the inner ground layer 190 is, for example, circular arc-shaped, a portion of the outer edge of the end 162 of the transmission line 160 is, for example, circular arc-shaped and corresponds to the circular arc-shaped inner edge of the second recess 190a, and the gap between the end 162 of the transmission line 160 and the inner edge of the second recess 190a is, for example, uniformly equidistant. However, the present invention is not limited thereto, and in other embodiments, the inner edge of the second recess 190a and the corresponding outer edge of the end 162 of the transmission line 160 may be square or other non-circular arc shapes, and the gap between the end 162 of the transmission line 160 and the inner edge of the second recess 190a may not be equidistant, so as to improve the flexibility of impedance matching as required.

According to the above configuration of the present embodiment, the Voltage Standing Wave Ratio (VSWR) of the transmission line structure 100 in the operating frequency band range of 1 GHz to 6 GHz can be less than 1.3. Also, the transmission loss at the operating frequency of 1 GHz and the transmission length of 1 m may be 3.1 dB/m or less, and the transmission loss at the operating frequency of 6 GHz and the transmission length of 1 m may be 8.0 dB/m or less.

FIG. 6 shows the transmission line structure of FIG. 1 applied to a notebook computer. As shown in fig. 6, the antenna 66 at the frame 62a of the display 62 of the notebook computer can be connected to the signal processing module in the host 64 through the transmission line structure 100 of the above embodiment. Since the transmission line structure 100 has a flat structure and a small thickness as described above, it can be directly connected to the host 64 across the back of the screen 62b of the display 62 as shown in fig. 6. This arrangement has a shorter routing distance and can reduce the transmission loss and signal interference. Also, since the transmission line structure 100 has a small thickness, even if the number of the transmission line structures 100 is multiple, it can reach the end of the main body 64 through the pivot structure between the main body 64 and the display 62. Therefore, the design of the antenna system can be conformed to the Multi-input Multi-output (MIMO) antenna system.

The following illustrates a specific dimensional design of the transmission line structure 100 of the present embodiment. Fig. 7 is a cross-sectional view of the transmission line structure of fig. 2 taken along line I-I. Fig. 8 is a cross-sectional view of the transmission line structure of fig. 3 along line II-II. Referring to fig. 7 and 8, in the present embodiment, the total width W1 of the transmission line structure 100 may be 3.02 mm, and the total thickness H1 of the transmission line structure 100 may be 0.4 mm. The thickness H2, H3 of each dielectric layer 112, 114 may be 0.18 millimeters. The outer diameter d1 of the conductive via 170 may be 0.2 millimeters. Width W2 of extension 182 of conductive layer 180 may be 0.4 millimeters. The width W3 of the transmission line 160 may be 0.27 millimeters. The outer diameters of the first pads 140, the ends 162 of the transmission lines 160, and the second pads 150 are the same (fig. 7 shows an outer diameter d2), and the outer diameter d2 may be 0.4 mm to 0.6 mm. The gap between the inner edge of the first recess 120a and the first pad 140, the gap between the inner edge of the opening 130a and the second pad 150, and the gap between the inner edge of the second recess 190a and the end 162 of the transmission line 160 are, for example, the same (labeled as gap G in fig. 7), and the gap G may be 0.1 mm. In addition, the total length L (labeled in fig. 1) of the transmission line structure 100 may be 100 mm. In other embodiments, the above dimensions may be changed as required, and the invention is not limited to the actual values.

In summary, in the transmission line structure of the present invention, the first pads for connecting the electrical connectors are disposed on the top surface of the dielectric layer structure and connected to the transmission line inside the dielectric layer structure through the conductive vias. Compared with the coaxial arrangement of a common coaxial cable (such as a mini cable), the first pads and the corresponding electrical connectors are arranged on the top surface of the dielectric layer structure as described above, so that the transmission line structure is not axisymmetric in structure and becomes a flat structure, which is beneficial to thinning of the transmission line structure. On the other hand, the first external ground layer and the second external ground layer respectively disposed on the top surface and the bottom surface of the dielectric layer structure can isolate the signal interference from the transmission line in the dielectric layer structure. And the edge of the first external ground layer arranged on the top surface of the dielectric layer structure is provided with a first notch corresponding to the first connecting pad, and a gap is arranged between the first connecting pad and the first notch. Similarly, the second external ground layer disposed on the bottom surface of the dielectric layer structure has an opening corresponding to the second pad, and a gap is formed between the second pad and the opening. Therefore, the equivalent capacitance between the first connecting pad and the first external ground layer and the equivalent capacitance between the second connecting pad and the second external ground layer can be changed by adjusting the size of the gap, so that the impedance matching between the joint structure (the section where the first connecting pad and the joint are located) and the sandwich strip line structure (the section where the transmission line is located) is optimized, and the transmission loss degree of the joint structure and the sandwich strip line structure caused by the asymmetric configuration mode is reduced. In addition, the equivalent inductance value of the conductive through hole can be changed by adjusting the outer diameter of the conductive through hole, so that the impedance matching between the joint section and the sandwich strip line section is optimized, and the transmission loss degree is further reduced. Therefore, the transmission line structure of the invention has the characteristics of thinning and high transmission quality.