A TEM mode based "sandwich" structure broadband quasi-full metallic gap transmission line and slot antenna

Abstract

The application provides a sandwich structure quasi-full intermetallic gap transmission line and slot antenna based on TEM mode, which has no cut-off frequency, extremely low loss and super wide band transmission capacity. The'mushroom' unit structure of the transmission line includes a metal top plate, an upper metal column, a dielectric film, a lower metal column and a metal bottom plate from top to bottom. The transmission line is formed by arranging the unit structure periodically and adding a feed line structure, specifically, the dielectric film is clamped in the metal column, the upper surface center of the dielectric film is printed with a metal feed line, and the coaxial cavity supporting pure TEM mode is co-constructed with the external shielding structure. The slot antenna formed based on the transmission line includes a transmission line feed layer, a middle metal layer with a middle slot and a top metal layer with a top slot from bottom to top, and the size of the top slot is larger than that of the middle slot. The application completely solves the defects of traditional waveguide size and large SIW dielectric loss, and provides an efficient and compact passive device for the millimeter wave frequency band.

Description

Technical Field

[0001] This invention relates to a transmission line structure and an antenna structure based on the transmission line structure, belonging to the field of wireless signal transmission technology applications, specifically a broadband quasi-all-metal gap transmission line and slot antenna based on a TEM mode "sandwich" structure. Background Technology

[0002] As modern wireless communication technology continues to evolve towards microwave and millimeter-wave bands, radio frequency (RF) front-end systems place extremely stringent demands on the transmission efficiency and integration density of microwave passive devices. Conventional planar transmission lines (such as microstrip lines and coplanar waveguides), widely used in lower frequency bands, face severe radiation loss, dielectric loss, and surface wave leakage problems when operating frequencies rise to the microwave band. This not only leads to a sharp decline in transmission efficiency but also easily causes severe electromagnetic crosstalk within the system. Therefore, conventional planar transmission lines are gradually becoming unsuitable for high-efficiency signal transmission tasks at high frequencies. This need for efficient, high-density passive transmission structures is particularly urgent in applications such as modern high-throughput satellite communication systems.

[0003] To overcome the limitations of conventional planar transmission lines at high frequencies, the industry has widely adopted technologies such as enclosed rectangular waveguides, conventional gap waveguides (GW), and substrate integrated waveguides (SIW) based on printed circuit board technology. However, these existing technologies still face insurmountable physical bottlenecks. On the one hand, while SIW structures are easy to integrate, they rely entirely on a solid dielectric substrate as the transmission medium for electromagnetic waves, inevitably resulting in severe dielectric loss in the microwave band, significantly reducing overall transmission efficiency. On the other hand, traditional rectangular waveguide structures and conventional gap waveguides based on parallel plate patterns rely primarily on higher-order modes such as TE or TM for electromagnetic wave transmission. Because these modes have inherent physical cutoff frequencies, the cross-sectional dimensions of the transmission line must be strictly designed according to the operating wavelength, resulting in a bulky and cumbersome overall structure that cannot meet the high-density integration requirements of modern RF front-ends.

[0004] Furthermore, existing high-frequency transmission line structures are often limited by the dispersion characteristics of specific waveguide modes, resulting in extremely limited single-mode transmission bandwidth. In practical engineering, adjusting the single-mode bandwidth is often very difficult and easily leads to impedance mismatch, making it difficult to achieve ultra-wideband transmission while maintaining extremely low loss and compact size. In summary, existing technologies in microwave transmission line and antenna design are deeply mired in the technical dilemma of being unable to simultaneously achieve "compact size," "low transmission loss," and "wideband." There is an urgent need in this field to develop a new transmission line structure that is not limited by the cutoff frequency, has extremely high transmission efficiency, and allows for flexible configuration of the operating frequency band. Based on this need, if a physical transmission mechanism that can completely eliminate dielectric loss can be found, enabling the transmission line itself to have excellent broadband transmission performance (e.g., covering the 10GHz to 40GHz band), and its single-mode transmission bandwidth can be arbitrarily and precisely adjusted simply by changing the size of the internal periodic unit, thus accurately adapting to efficient and compact applications such as Ku-band (10.7-14.5GHz) transceiver slotted antennas, it will have significant engineering application value. Summary of the Invention

[0005] To address the aforementioned problems or shortcomings and to solve the issues of traditional transmission lines, this invention provides a quasi-all-metal gap transmission line based on TEM mode, and designs a slot antenna using this transmission line to demonstrate its significant advantages.

[0006] Technical solution:

[0007] A broadband quasi-all-metal gap transmission line with a "sandwich" structure based on TEM mode is disclosed. Its "mushroom-shaped" unit structure comprises, from top to bottom, a metal top plate 1, an upper metal pillar 2, a dielectric film 3, a lower metal pillar 4, and a metal base plate 5. The metal top plate 1 and the metal base plate 5 are arranged parallel to each other, serving as the upper and lower external metal shielding interfaces of the transmission line structure, respectively. The upper end face of the upper metal pillar 2 is integrally formed with the lower surface of the metal top plate 1, and the lower end face of the lower metal pillar 4 is integrally formed with the upper surface of the metal base plate 5.

[0008] The transmission line structure consists of an upper metal pillar 2 and a lower metal pillar 4 arranged in a periodic array, forming a periodic "mushroom-shaped" structure. The cross-sectional dimensions and arrangement positions of the upper and lower metal pillars correspond one-to-one. A dielectric film 3 is horizontally sandwiched between the lower end face of the upper metal pillar 2 and the upper end face of the lower metal pillar 4, thus vertically dividing the entire transmission line cavity. A metal feed line 9 is printed on the upper surface at the center of this extremely thin dielectric film 3, positioning it at the exact center of the transmission cavity enclosed by the upper and lower metal plates and surrounding metal pillars.

[0009] Through this symmetrical internal structural configuration, the metal top plate 1, the metal bottom plate 5, and the corresponding upper and lower "mushroom-shaped" metal pillar arrays together construct a dispersion bandgap (electromagnetic band gap) capable of blocking the lateral leakage of high-frequency electromagnetic waves. Since the feed line is placed in the center of the cavity, this structure physically forms a novel quasi-coaxial, all-metal transmission mechanism. When the frequency of the radio frequency signal falls within the dispersion bandgap of this periodic metal pillar unit, the electromagnetic energy is completely confined to the central region for propagation. Furthermore, because this quasi-coaxial structure supports pure TEM mode transmission, it fundamentally eliminates the inherent physical cutoff frequency limitation of TE or TM higher-order modes in traditional rectangular waveguides, allowing the cross-section of the transmission line to be designed to be extremely compact.

[0010] More importantly, the transmission line itself possesses excellent broadband transmission performance, and the size design of this invention allows its effective transmission frequency band to cover the ultra-wideband range. In practical design, without changing the overall architecture, only by adjusting the physical dimensions of the upper and lower metal pillars 2 and 4, such as the period, height, or radius, the dispersion bandgap can be shifted, thereby arbitrarily and precisely adjusting the specific operating bandwidth of the transmission line. Furthermore, by using only the extremely thin dielectric film 3, resulting in minimal dielectric loss, extremely high broadband transmission efficiency is achieved.

[0011] Based on the aforementioned superior transmission line structure, this invention further provides a high-efficiency transceiver slot antenna unit. The slot antenna's overall physical architecture, from bottom to top, comprises: a feed layer 6 based on a TEM-mode quasi-all-metal slot transmission line, an intermediate slot 7, and a top slot 8. The feed layer 6, based on a TEM-mode quasi-all-metal slot transmission line, internally employs the aforementioned five-layer transmission line structure, including a metal top plate 1 to a metal bottom plate 5, achieving efficient, low-loss signal transmission and feeding to the upper antenna radiation structure. Above the metal top plate 1 of the feed layer 6, metal layers for radiating electromagnetic waves are sequentially stacked. The intermediate slot 7 is located on an all-metal plate immediately above the feed layer 6, and the top slot 8 is located on the topmost all-metal plate; both are vertically aligned and couple the radio frequency energy transmitted by the feed layer 6. To further extend the antenna's operating bandwidth, the geometry of the top slot 8 is designed to be larger than that of the intermediate slot 7, thus forming a geometrically progressive slot radiation architecture in the vertical radiation direction. Thanks to the efficient, pure TEM-mode feed network provided by the bottom quasi-all-metal gap transmission line feed layer 6, this multi-layer slot antenna achieves extremely high radiation efficiency with almost no dielectric loss. By properly adjusting the structure, the antenna can operate precisely in a wideband frequency band from 10.7 GHz to 14.5 GHz, perfectly covering the standard frequency bands for receiving and transmitting Ku-band satellite communications, achieving high-gain wideband transceiver functionality in an extremely compact size.

[0012] In summary, the present invention can realize a transmission line and antenna with wide bandwidth, high efficiency, low loss, and high compactness. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the "mushroom-shaped" unit of the transmission line of the present invention;

[0014] Figure 2 As an example, the mode dispersion diagram of the "mushroom-shaped" unit of the transmission line of the present invention;

[0015] Figure 3 This is a schematic diagram of the overall structure of the transmission line of the present invention;

[0016] Figure 4 This is a schematic diagram of the surface current on the transmission line of the present invention;

[0017] Figure 5 In this embodiment, the mode dispersion diagram of the transmission line of the present invention within the operating frequency band is shown.

[0018] Figure 6 In this embodiment, the port impedance of the transmission line of the present invention within the operating frequency band is shown.

[0019] Figure 7 In this embodiment, the S of the transmission line port of the present invention 11 picture;

[0020] Figure 8 In this embodiment, the transmission loss of the transmission line of the present invention is described.

[0021] Figure 9 This is a schematic diagram of the overall antenna structure of the present invention;

[0022] Figure 10 This is an exploded view of the antenna structure of the present invention;

[0023] Figure 11 This is a diagram showing the dimensions of the top layer slot 8 of the antenna in this embodiment.

[0024] Figure 12 This is a dimensional diagram of the gap 7 in the middle layer of the antenna of the present invention, as shown in the embodiment.

[0025] Figure 13 As shown in the embodiment, the dimensional diagram of the feed layer 6 of the quasi-all-metal gap transmission line of the antenna of the present invention based on TEM mode is provided.

[0026] Figure 14 In this embodiment, the S-axis of the antenna at the port within the operating frequency band of the present invention... 11 picture;

[0027] Figure 15 In this embodiment, the gain pattern of the antenna of the present invention at the center frequency is shown.

[0028] Figure 16 As shown in the embodiment, the gain curve of the antenna of the present invention varies with frequency;

[0029] Figure 17 As shown in the embodiment, the directivity coefficient curve of the antenna of the present invention varies with frequency. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] Example 1

[0032] This embodiment provides a broadband quasi-all-metal gap transmission line with a "sandwich" structure based on TEM mode, and a slot antenna designed using this transmission line. The unit structure of this gap transmission line is described below. Figure 1 A broadband quasi-all-metal gap transmission line with a "sandwich" structure based on TEM mode is disclosed. Its "mushroom-shaped" unit structure comprises, from top to bottom, a metal top plate 1, an upper metal pillar 2, a dielectric film 3, a lower metal pillar 4, and a metal base plate 5. The metal top plate 1 and the metal base plate 5 are arranged parallel to each other, serving as the upper and lower external metal shielding interfaces of the transmission line structure, respectively. The upper end face of the upper metal pillar 2 is integrally formed with the lower surface of the metal top plate 1, and the lower end face of the lower metal pillar 4 is integrally formed with the upper surface of the metal base plate 5.

[0033] The transmission line structure consists of an upper metal pillar 2 and a lower metal pillar 4 arranged in a periodic array, forming a periodic "mushroom-shaped" structure. The cross-sectional dimensions and arrangement positions of the upper and lower metal pillars correspond one-to-one. A dielectric film 3 is horizontally sandwiched between the lower end face of the upper metal pillar 2 and the upper end face of the lower metal pillar 4, thus vertically dividing the entire transmission line cavity. A metal feed line 9 is printed on the upper surface at the center of this extremely thin dielectric film 3, positioning it at the exact center of the transmission cavity enclosed by the upper and lower metal plates and surrounding metal pillars.

[0034] Through this symmetrical internal structural configuration, the metal top plate 1, the metal bottom plate 5, and the corresponding upper and lower "mushroom-shaped" metal pillar arrays together construct a dispersion bandgap (electromagnetic band gap) capable of blocking the lateral leakage of high-frequency electromagnetic waves. Since the feed line is placed in the center of the cavity, this structure physically forms a novel quasi-coaxial, all-metal transmission mechanism. When the frequency of the radio frequency signal falls within the dispersion bandgap of this periodic metal pillar unit, the electromagnetic energy is completely confined to the central region for propagation. Furthermore, because this quasi-coaxial structure supports pure TEM mode transmission, it fundamentally eliminates the inherent physical cutoff frequency limitation of TE or TM higher-order modes in traditional rectangular waveguides, allowing the cross-section of the transmission line to be designed to be extremely compact.

[0035] In this embodiment, as Figure 1 As shown, the overall size of the "mushroom-shaped" unit of the "sandwich" structure gap transmission line is p = 3 mm. Both the upper metal pillar 2 and the lower metal pillar 4 have a height hdy = 1 mm and a radius r = 1 mm. The dielectric film 3 is made of polyimide material, and its relative permittivity is... = 3.5, loss tangent = 0.0027, thickness h1 = 0.1 mm.

[0036] like Figure 2 As shown, this is the mode dispersion curve supported when the "sandwich" structure gap transmission line unit structure is composed of arrays. It can be seen that in the frequency band range of 10 GHz-40 GHz, this structure does not support the transmission of any mode, which is called the dispersion band gap. Therefore, when the transmission line operates in the frequency band range of 10 GHz-40 GHz, the signal on the transmission line will not leak out of the structure and will be "locked" on the transmission line.

[0037] like Figure 3 The diagram shows the overall structure of the "sandwich" structure gap transmission line of the present invention. The printed feed line is located on the upper surface of the center of the dielectric film 3. The linewidth of the feed line is wx = 1.7 mm.

[0038] like Figure 4 As shown, the distribution of the current on the upper surface of the "sandwich" structure gap transmission line of the present invention can be seen. It can be seen that the current is completely parallel to the signal transmission direction, which is in complete agreement with the current distribution in TEM mode.

[0039] like Figure 5The figure shows the mode dispersion diagram of the "sandwich" structure gap transmission line of the present invention within the operating frequency band. It can be seen that within the dispersion bandgap of the unit structure array, from 10 GHz to 40 GHz, only one mode of transmission is supported, and the curve is a straight line, satisfying the transmission characteristics of the TEM mode, further proving that the signal mode transmitted by this structure is the TEM mode.

[0040] like Figure 6 The figure shows the port impedance of the "sandwich" structure gap transmission line of the present invention within the operating frequency band. When the linewidth is 1.7 mm, the impedance variation is only 1.5 mm across the entire 10 GHz-40 GHz frequency band. .

[0041] from Figure 7 It can be seen that the S of the "sandwich" structure gap transmission line port of the present invention 11 The figure shows that it has excellent matching performance throughout the entire operating frequency band.

[0042] like Figure 8 As shown, the transmission loss of the "sandwich" structure gap transmission line of the present invention is reduced. After using the quasi-all-metal structure, most of the dielectric loss is eliminated, and the transmission loss is less than 0.035dB throughout the entire operating frequency band, which has great advantages over traditional transmission lines (microstrip lines, SIW, etc.).

[0043] Based on the aforementioned superior transmission line structure, this embodiment further provides a slot antenna structure based on a TEM mode "sandwich" structure broadband quasi-all-metal gap transmission line. The slot antenna's overall physical architecture, from bottom to top, includes: a feed layer 6 based on the TEM mode quasi-all-metal gap transmission line, an intermediate slot 7, and a top slot 8. The feed layer 6, based on the TEM mode quasi-all-metal gap transmission line, internally employs the aforementioned five-layer transmission line structure comprising a metal top plate 1 to a metal bottom plate 5, achieving efficient and low-loss signal transmission and feeding to the upper antenna radiating structure. Above the metal top plate 1 of the feed layer 6, metal layers for radiating electromagnetic waves are stacked sequentially. The intermediate slot 7 is located on an all-metal plate immediately above the feed layer 6, and the top slot 8 is located on the topmost all-metal plate; both are vertically aligned and couple the radio frequency energy transmitted by the feed layer 6. To further extend the antenna's operating bandwidth, the geometry of the top-layer slot 8 is designed to be larger than that of the middle-layer slot 7, thus forming a progressively larger slot radiation architecture in the vertical radiation direction. Thanks to the efficient, pure TEM-mode feed network provided by the bottom quasi-all-metallic gap transmission line feed layer 6, this multi-layer slot antenna achieves extremely high radiation efficiency with virtually no dielectric loss. By appropriately adjusting this structure, the antenna can operate precisely in the 10.7 GHz to 14.5 GHz broadband band, perfectly covering the standard frequency bands for Ku-band satellite communication reception and transmission, achieving high-gain broadband transceiver functionality in an extremely compact size.

[0044] from Figure 9 and Figure 10 The diagram shows the structure of a slotted antenna designed using this gap transmission line. The overall antenna length l = 18 mm, width w = 15 mm, height ht1 = 1.5 mm for the middle layer slot 7, and height ht2 = 4 mm for the top layer slot 8. The feed layer 6 of the quasi-all-metal gap transmission line based on the TEM mode adopts the design mentioned in this embodiment, using a progressive structure to form a rectangular space below the antenna slot to facilitate energy radiation.

[0045] like Figure 11 The diagram shows the structural dimensions of the top-layer slot 8 of the slot antenna. The total length of the slot is lt2 = 17 mm, the width of the wider part of the slot is wy2 = 7 mm, the width of the narrower part is wt2 = 5 mm, the length of the wider part of the slot is ly2 = 7 mm, and the radii of the two chamfers of the slot are r3 = 0.5 mm and r4 = 1 mm, respectively.

[0046] like Figure 12The diagram shows the structural dimensions of the slot 7 in the middle layer of the slot antenna. The total length of the slot is lt1 = 12 mm, the width of the wider part of the slot is wy1 = 3.2 mm, the width of the narrower part is wt1 = 1.5 mm, the length of the wider part of the slot is ly1 = 3.5 mm, and the radii of the two chamfers of the slot are r1 = 0.35 mm and r2 = 1 mm, respectively.

[0047] like Figure 13 The figure shows the dimensions of the feed layer 6 of the quasi-all-metal gap transmission line of the slot antenna based on the TEM mode. The feed line used has a width wxt = 1.2 mm and a length lxt = 12 mm.

[0048] like Figure 14 As shown, this is the S-band of this antenna within its operating frequency band. 11 The graph shows that it is less than -10 dB within the required operating frequency band (10.7 GHz-14.5 GHz), indicating good impedance matching performance.

[0049] like Figure 15 The image shows the gain pattern of this antenna at the center frequency, with a maximum gain of 7.04 dBi. It can be seen that the pattern is highly symmetrical, which is due to the highly symmetrical antenna structure.

[0050] like Figure 16 The figure shows the gain curve of this antenna as a function of frequency. It can be seen that the gain increases with increasing frequency. This is because the relative area of ​​the antenna size to the wavelength also increases with increasing frequency. The gain is 5.43 dBi at 10.7 GHz and 7.6 dBi at 14.5 GHz.

[0051] like Figure 17 The figure shows the directivity coefficient curve of this antenna as a function of frequency. Similar to the gain curve, it also has the characteristic of increasing with increasing frequency. The directivity coefficient is 5.62 dBi at 10.7 GHz, 7.89 dBi at 14.5 GHz, and 7.1 dBi at the center frequency.

[0052] according to Figure 16 and Figure 17 The data shows that the antenna's transmission efficiency is greater than 94% across the entire frequency band, and its aperture efficiency is greater than 73% across the entire frequency band. It can be seen that after using a quasi-all-metal structure, the antenna exhibits excellent performance in both transmission and aperture efficiency.

[0053] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A broadband quasi-all-metal gap transmission line with a "sandwich" structure based on TEM mode, characterized in that: "mushroom-shaped" metal pillars are the unit structure of the transmission line, which includes, from top to bottom, a metal top plate (1), an upper metal pillar (2), a dielectric film (3), a lower metal pillar (4), and a metal bottom plate (5). The broadband quasi-all-metal gap transmission line based on the TEM mode is composed of transmission line units arranged periodically and a metal feed line (9) printed at the center. The specific structure includes, from bottom to top, a metal base plate, a lower "mushroom-shaped" metal pillar array, a dielectric film, and an upper "mushroom-shaped" metal pillar array. The dielectric film is horizontally sandwiched between the lower "mushroom-shaped" metal pillar array and the upper "mushroom-shaped" metal pillar array, and a metal feed line 9 is printed at the center of the upper surface of the dielectric film.

2. The broadband quasi-all-metal gap transmission line with a "sandwich" structure based on TEM mode according to claim 1, characterized in that: The upper and lower "mushroom-shaped" metal column arrays are composed of multiple metal column units arranged periodically.

3. The broadband quasi-all-metal gap transmission line with a "sandwich" structure based on TEM mode according to claim 2, characterized in that: The upper "mushroom-shaped" metal pillar array corresponds one-to-one with the lower "mushroom-shaped" metal pillar array, and a metal pillar-free channel is left in the central area of ​​the array. Metal feed lines are printed at the center of the upper surface of the dielectric film in the metal pillar-free channel area to form a transmission cavity extending longitudinally.

4. A slot antenna with a "sandwich" structure based on TEM mode and a broadband quasi-all-metallic gap transmission line, characterized in that, From top to bottom, it includes a feed layer (6) of a quasi-all-metal gap transmission line based on TEM mode, an intermediate layer gap (7) and a top layer gap (8). The feed layer (6) of the TEM-mode-based "sandwich" structure broadband quasi-all-metal gap transmission line used in the slot antenna is made according to any one of claims 1-3. The feed line is printed on the upper surface of the dielectric film and extends along the center line of the metal-free channel. Its shape is a rectangular straight strip.

5. A slot antenna with a "sandwich" structure broadband quasi-all-metal slot transmission line based on TEM mode according to claim 4, characterized in that: Both the intermediate layer gap (7) and the top layer gap (8) are rectangular metal structures.

6. A slot antenna with a "sandwich" structure broadband quasi-all-metal slot transmission line based on TEM mode according to claim 5, characterized in that: The intermediate layer gap (7) opened on the intermediate metal layer has a dumbbell-shaped structure.

7. A slot antenna with a "sandwich" structure broadband quasi-all-metal slot transmission line based on TEM mode according to claim 6, characterized in that: The top layer slot (8) opened on the top metal layer also has a dumbbell-shaped structure and is strictly aligned with the geometric center of the lower middle layer slot (7).

8. A slot antenna with a "sandwich" structure broadband quasi-all-metal slot transmission line based on TEM mode according to claim 7, characterized in that: The geometry of the top layer gap (8) is larger than that of the middle layer gap (7).

9. A broadband quasi-all-metal gap transmission line and slot antenna based on a TEM mode "sandwich" structure according to claim 8, characterized in that: The dielectric film is made of polyimide, and its extremely thin thickness results in negligible dielectric loss in the microwave frequency band.

10. A slot antenna with a "sandwich" structure broadband quasi-all-metal slot transmission line based on TEM mode according to claim 9, characterized in that: The metal base plate, the corresponding upper and lower "mushroom-shaped" metal column arrays, and the lower surface of the middle metal layer together constitute a dispersion bandgap cavity that supports pure TEM mode transmission. Electromagnetic wave energy is transmitted along the metal feed line in the metal-free column channel and is coupled upwards and radiated outwards through the progressively sized intermediate layer gap (7) and top layer gap (8) to cover the broadband operating frequency band of the Ku-band transceiver.

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