T-shaped ultra-wideband transparent antenna based on coplanar waveguide feed and design method thereof

Abstract

The invention discloses a coplanar waveguide feed-based T-shaped ultra-wideband transparent antenna and a design method thereof, and belongs to the technical field of ultra-wideband transparent antennae, the coplanar waveguide feed-based T-shaped ultra-wideband transparent antenna comprises a transparent dielectric substrate, and a coplanar waveguide feed structure, a radiation unit and a grounding plate structure are integrated on the same surface of the transparent dielectric substrate; the radiation unit is a T-shaped composite radiation patch; the grounding plate structure comprises two L-shaped windows, and the L-shaped windows are formed in the large-area grounding plane; and the two L-shaped windows are symmetrically distributed about the central longitudinal axis of the antenna and form partial projection overlapping with the T-shaped composite radiation patch. Through the collaborative design of the specific T-shaped composite radiation patch and the symmetrical L-shaped window, a plurality of resonant modes are effectively excited and deeply fused, so that the bandwidth limitation of the transparent antenna is overcome, and a key component is provided for a transparent integrated communication terminal; the whole structure is compact, the transparency is high, and stable and efficient ultra-wideband work can be achieved within the frequency band ranging from 4.7 GHz to 7.45 GHz.

Description

Technical Field

[0001] This invention belongs to the technical field of ultra-wideband transparent antennas, specifically relating to a T-shaped ultra-wideband transparent antenna based on coplanar waveguide feeding and its design method. Background Technology

[0002] With the rapid development of 5G, IoT, and smart display technologies, wireless communication devices are evolving towards higher frequencies, wider bandwidth, smaller size, and seamless visual integration. Integrating antennas with the device's physical form (such as smart glass windows, transparent displays, and car windows) is an ideal way to achieve both a simple appearance and integrated functionality. Transparent antennas are a key technology for achieving this seamless visual integration.

[0003] Currently, transparent antennas are mainly achieved by fabricating radiating structures made of transparent conductive materials such as indium tin oxide (ITO) or metal meshes on transparent dielectric substrates. However, the sheet resistance of transparent conductive materials is much higher than that of traditional metals, leading to a severe deterioration in antenna efficiency, especially high-frequency performance. Traditional microstrip antenna structures, with their ground plane located on the back of the dielectric substrate, are more sensitive to the resistance of the conductive layer and have narrow bandwidths, making them difficult to meet the demands of modern ultra-wideband communication. Coplanar waveguide (CPW) feeding structures, because all conductors are located on the same plane of the dielectric substrate, are easily compatible with transparent conductive processes, and offer advantages such as low dispersion and ease of integration, have become the preferred solution for transparent antennas.

[0004] Existing transparent antenna designs using coplanar waveguides typically employ simple patch modifications (such as adding slots or stubs) or conventional slotting on the ground plane to extend bandwidth. However, these methods often only introduce limited additional resonances, resulting in poor bandwidth extension and making it difficult to achieve continuous ultra-wideband coverage exceeding 2 GHz. For example, simply adjusting the patch shape usually results in a narrow impedance matching bandwidth; while simple ground plane slotting can introduce new resonances, impedance mismatch regions often exist between the resonant modes, preventing smooth fusion into a wide and deep frequency band. Therefore, designing an innovative coplanar waveguide antenna structure that can effectively coordinate and fuse multiple resonant modes while maintaining high transparency, thereby completely overcoming the bandwidth bottleneck of transparent antennas, has become a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings of the prior art by providing a T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding, thereby solving the following problems: (1) Coplanar waveguide antennas using transparent conductive materials are difficult to achieve a wide and flat impedance matching bandwidth in high-frequency bands (such as C-band), which cannot meet the needs of ultra-wideband communication systems such as 5G New Radio (NR) high-frequency band and Wi-Fi 6E (6GHz band).

[0006] (2) Traditional structural improvement methods (such as single patch deformation or ground plane slotting) have limited effect on bandwidth improvement, and the coupling and matching between each resonant mode are not easy to control, resulting in a dip in the S11 curve or discontinuous bandwidth.

[0007] (3) The technical challenges of achieving ultra-wideband performance, good radiation efficiency and high transparency simultaneously under compact size constraints are enormous.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, a T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding includes a transparent dielectric substrate, wherein a coplanar waveguide feeding structure, a radiating element and a ground plane structure are integrated on the same surface of the transparent dielectric substrate. The coplanar waveguide feeding structure includes a central signal line arranged along the longitudinal axis of the antenna center, and large-area ground planes are respectively arranged on both sides of the central signal line at intervals. The radiating element is a T-shaped composite radiating patch, which includes a central main branch arranged along the longitudinal axis of the antenna center, the central main branch being connected to the central signal line; horizontal branches extend symmetrically from the upper two sides of the central main branch in the horizontal direction, and multiple bandwidth enhancement holes are opened on each side of the horizontal branch. The ground plane structure includes two L-shaped windows, which are opened on the large-area ground plane; the two L-shaped windows are symmetrically distributed about the longitudinal axis of the antenna center and partially overlap with the T-shaped composite radiating patch.

[0009] Furthermore, the transparent dielectric substrate has a rectangular structure with a length a=45mm, a width b=25mm, and a thickness of 1mm, and its material is resin glass.

[0010] Furthermore, the coplanar waveguide feeding structure is located in the lower half of the central region of one side of the transparent dielectric substrate, and the central signal line on the coplanar waveguide feeding structure is separated from the large-area ground planes on both sides by a gap; and the end of the central signal line is connected to the lower end of the central main branch of the radiating unit through an impedance matching section.

[0011] Furthermore, the T-shaped composite radiating patch is located in the upper half of the central region of one side of the transparent dielectric substrate; the central main branch on the T-shaped composite radiating patch is a rectangular conductive patch arranged in a vertical direction with a width of c=6mm, and its lower end is connected to the coplanar waveguide feeding structure as a feed point.

[0012] Furthermore, the horizontal supports on both sides are two rectangular conductive arms, which together with the central main branch form an inverted "T" shape. The width of the rectangular conductive arms is h=3mm.

[0013] Furthermore, the bandwidth enhancement hole is a rectangular hole, and six rectangular holes are uniformly etched on each of the horizontal branches. The spacing between the rectangular holes is d=1mm, the width of the rectangular hole is f=1.7mm, and the length is g=10mm.

[0014] Furthermore, the L-shaped window includes a short, vertically extending slot and a long, horizontally extending slot, which are connected and form an "L" shape.

[0015] Furthermore, the length of the elongated groove in the L-shaped window is i=19mm and the width is j=1.5mm; the distance between the elongated groove and the rectangular hole located on the same side is e=2.5mm.

[0016] Secondly, a design method for a T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding includes the following steps: S1. Select resin glass as the transparent dielectric substrate material, and divide the same surface of the transparent dielectric substrate into a coplanar waveguide feeding structure region, a radiating unit region and a ground plane structure region; wherein, the coplanar waveguide feeding structure region is located at the center of the lower half of the transparent dielectric substrate, and the radiating unit region is located at the center of the upper half of the transparent dielectric substrate. S2. Design a coplanar waveguide feeding structure in the coplanar waveguide feeding structure region, including setting a center signal line along the longitudinal axis of the antenna center and setting large-area ground planes at intervals on both sides of the center signal line; S3. Design a T-shaped composite radiating patch in the radiating unit area, including a central main branch arranged along the longitudinal axis of the antenna center, with the lower end of the central main branch serving as a feed point and connected to a coplanar waveguide feed structure; horizontal branches extend symmetrically in the horizontal direction on both sides of the upper part of the central main branch, and six rectangular holes are uniformly etched on each side of the horizontal branch. S4. Design a ground plane structure in the ground plane structure area, including opening an L-shaped window on each of the two large-area ground planes, ensuring that the two L-shaped windows are symmetrically distributed about the longitudinal axis of the antenna center, and partially overlap with the T-shaped composite radiating patch in projection; S5. An impedance matching section is used to connect the center signal line of the coplanar waveguide feed structure to the central main branch of the T-shaped composite radiating patch. Through simulation optimization and adjustment of various structural parameters, the low-frequency, mid-frequency and high-frequency resonant modes are smoothly integrated to form an ultra-wideband impedance matching characteristic of 4.72GHz-7.44GHz.

[0017] Furthermore, by adjusting the length of the vertical short strip and the width of the horizontal long strip of the L-shaped window, the low-frequency extension effect is optimized; by adjusting the size and spacing of the rectangular holes, the high-frequency resonance characteristics are controlled, so that the low-frequency, mid-frequency and high-frequency resonance modes can be smoothly integrated.

[0018] The T-shaped ultrawideband transparent antenna and its design method based on coplanar waveguide feeding provided by this invention have the following beneficial effects: 1. This invention effectively excites and deeply integrates multiple resonant modes through the synergistic design of a specific "T-shaped composite radiating patch" and a "symmetrical L-shaped ground plane window," thereby overcoming the bandwidth limitation of transparent antennas and providing key components for transparent integrated communication terminals. The overall structure is compact and highly transparent, enabling stable and efficient ultra-wideband operation in the 4.7GHz to 7.45GHz frequency band.

[0019] 2. Excellent transparency and process compatibility; This invention adopts a fully coplanar structure, eliminating the need for vias. All conductive patterns are located on the same side of the substrate, making it particularly suitable for one-time molding of metal mesh patterns using processes such as laser etching. While ensuring radio frequency performance, it achieves high light transmittance (>80%), perfectly meeting the "invisibility" requirements of applications such as smart glass windows.

[0020] 3. The design mechanism is clear and the adjustability is good; The performance improvement of this invention has a clear physical mechanism. The correspondence between each structural unit and the resonant mode is clear (e.g., the L-shaped window dominates low-frequency extension and coupling), which allows engineers to easily optimize through simulation and adjust it for different needs. It has good repeatability and is conducive to productization. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural schematic diagram of the T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding in Example 1; Figure 2 This is a front view of the antenna in Example 1, showing the longitudinal cross-sectional structure of the antenna. Figure 3 The top view (core planar structure diagram) of the antenna in Example 1 reveals the specific shape, size, and positional relationship of the T-shaped radiating patch, coplanar waveguide feed line, symmetrical L-shaped window, and rectangular aperture; Figure 4 The image shows the simulation curve of the antenna reflection coefficient (S11) in Example 1. The S11 curve clearly demonstrates the ultra-wideband characteristics (4.72-7.44GHz) below -10dB. Figure 5 The graph shows the maximum gain of the antenna in Example 1 as a function of frequency, used to demonstrate its stable radiation performance within the operating frequency band.

[0022] Among them, 1. transparent dielectric substrate; 2. coplanar waveguide feeding structure; 3. large area ground plane; 4. L-shaped window. Detailed Implementation

[0023] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0024] Example 1 This embodiment provides a T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding, reference... Figure 1 and Figure 2 Specifically, it includes a transparent dielectric substrate 1, on which a coplanar waveguide feeding structure 2, a radiating unit, and a ground plane structure are integrated on the same surface.

[0025] In some embodiments, the transparent dielectric substrate 1 has a rectangular structure, as referenced. Figure 3 The preferred dimensions are: length a=45mm, width b=25mm, and thickness 1mm; the material is resin glass to ensure good microwave performance and optical transparency.

[0026] In some embodiments, the coplanar waveguide feeding structure 2 includes a central signal line arranged along the longitudinal axis of the antenna center, and large-area ground planes 3 arranged at intervals on both sides of the central signal line; In one specific embodiment, the coplanar waveguide feeding structure 2 is located in the lower half of the central region of one side of the transparent dielectric substrate 1. The center signal line on the coplanar waveguide feeding structure 2 is separated from the large-area ground planes 3 on both sides by a gap; and the end of the center signal line is connected to the lower end of the central main branch of the radiating unit through an impedance matching section.

[0027] In some embodiments, the radiating element is a T-shaped composite radiating patch, which includes a central main branch arranged along the longitudinal axis of the antenna center, the central main branch being connected to the central signal line; and also includes horizontal branches extending symmetrically in the horizontal direction on both sides of the upper part of the central main branch, wherein each horizontal branch has a plurality of bandwidth enhancement holes.

[0028] In one specific embodiment, the T-shaped composite radiating patch is located in the upper half of the central region of one side of the transparent dielectric substrate 1; the central main branch on the T-shaped composite radiating patch is a rectangular conductive patch arranged in a vertical direction with a width of c=6mm, and its lower end is connected to the coplanar waveguide feeding structure 2 as a feed point.

[0029] In one specific embodiment, reference is made to Figure 3 The horizontal branches on both sides are two rectangular conductive arms. The two rectangular conductive arms and the central main branch together form an inverted "T" shape. The width of the rectangular conductive arms is h=3mm.

[0030] In one specific embodiment, reference is made to Figure 3 The bandwidth enhancement holes are rectangular holes, and six rectangular holes are uniformly etched on each horizontal branch. The rectangular holes are used to disturb the high-frequency current path and precisely control the high-frequency resonance characteristics. The spacing between the rectangular holes is d=1mm, the width of the rectangular hole is f=1.7mm, and the length is g=10mm.

[0031] In some embodiments, for grounding plate structures; The two large-area ground planes 3 of the coplanar waveguide feeding structure 2 form L-shaped windows 4 of the same size with the T-shaped radiating patch. The L-shaped windows 4 are opened on the large-area ground planes 3. The two L-shaped windows 4 are symmetrically distributed about the longitudinal axis of the antenna center and partially overlap with the T-shaped composite radiating patch.

[0032] In one specific embodiment, the L-shaped window 4 includes a short, vertically extending slot and a long, horizontally extending slot, which are connected and form an "L" shape.

[0033] refer to Figure 3 The length of the long strip in the L-shaped window 4 is i=19mm and the width is j=1.5mm; the distance between the long strip and the rectangular hole on the same side is e=2.5mm.

[0034] The structural coordination relationship and working principle of this embodiment are as follows: The T-shaped composite radiating patch, the symmetrical L-shaped window 4, and the coplanar waveguide feeder are all located on the same plane and work together through direct electrical connection and indirect electromagnetic field coupling.

[0035] like Figure 4 As shown, after the signal is fed through the CPW, it excites the T-shaped composite radiating patch to resonate. The central main branch dominates the generation of a low-frequency resonant mode (approximately 5.0 GHz); the horizontal branches on both sides and the rectangular holes on them work together to generate two closely adjacent high-frequency resonant modes (approximately 6.1 GHz and 7.1 GHz). At the same time, the symmetrical L-shaped window 4 on the ground plane strongly alters the current distribution and electric field structure near the feed point, effectively introducing parallel inductance and series capacitance. This "window effect" not only effectively lowers the antenna's lowest operating frequency to below 4.7 GHz, but more importantly, it acts as an impedance transformation and matching network, smoothly connecting the low-frequency, mid-frequency, and high-frequency resonant modes, so that the antenna's input impedance remains close to 50 Ω throughout the wide bandwidth from 4.72 GHz to 7.42 GHz, thus forming a deep and flat ultra-wideband impedance matching characteristic.

[0036] This invention exhibits superior ultra-wideband performance; existing transparent antennas, especially those based on CPW structures, typically have a narrow -10dB bandwidth (<2GHz). This invention, through an innovative combination of a "T-shaped patch + rectangular aperture" and a "symmetrical L-shaped grounding window," successfully excites and deeply integrates multiple resonant modes. Figure 4 As shown, this invention achieves an absolute bandwidth of 2.72 GHz (4.72-7.44 GHz) and a relative bandwidth of over 44%, fully covering the core frequency band of Wi-Fi 6E. This performance is far superior to the comparative example using only T-shaped patches or simple ground plane slots, demonstrating the powerful bandwidth expansion capability of the combined design.

[0037] This invention features a compact structure and excellent radiation performance. It achieves ultra-wideband characteristics within an extremely small size (45mm × 25mm), with a compact and efficient structural layout. The ground plane window design significantly improves performance without increasing any physical dimensions. Furthermore, as... Figure 5 As shown, the antenna's maximum gain remains stable throughout the entire operating frequency band, reaching and exceeding 3 dBi in the core frequency band, demonstrating its excellent energy radiation capability.

[0038] Example 2 This embodiment, based on the antenna structure in Embodiment 1, provides a design method for a T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding, including the following steps: S1. Select resin glass as the material of transparent dielectric substrate 1, and divide the same surface of transparent dielectric substrate 1 into a coplanar waveguide feeding structure 2 region, a radiating unit region and a ground plane structure region; wherein, the coplanar waveguide feeding structure 2 region is located at the center of the lower half of transparent dielectric substrate 1, and the radiating unit region is located at the center of the upper half of transparent dielectric substrate 1. S2. Design a coplanar waveguide feeding structure 2 in the region of the coplanar waveguide feeding structure 2, including setting a center signal line along the longitudinal axis of the antenna center, and setting large-area ground planes 3 at intervals on both sides of the center signal line; S3. Design a T-shaped composite radiating patch in the radiating unit area, including a central main branch arranged along the longitudinal axis of the antenna center, with the lower end of the central main branch as the feed point and connected to the coplanar waveguide feed structure 2; horizontal branches extend symmetrically in the horizontal direction on both sides of the upper part of the central main branch, and six rectangular holes are uniformly etched on each side of the horizontal branch. S4. Design a ground plane structure in the ground plane structure area, including opening an L-shaped window 4 on each of the two large-area ground planes 3, ensuring that the two L-shaped windows 4 are symmetrically distributed about the longitudinal axis of the antenna center, and partially overlap with the T-shaped composite radiating patch in projection; S5. An impedance matching section is used to connect the center signal line of the coplanar waveguide feed structure 2 with the central main branch of the T-shaped composite radiating patch. Through simulation optimization, the structural parameters are adjusted to smoothly integrate the low-frequency, mid-frequency and high-frequency resonant modes, forming an ultra-wideband impedance matching characteristic of 4.72GHz-7.44GHz. Specifically, in this embodiment S5, the low-frequency extension effect can be optimized by adjusting the length of the vertical short strip and the width of the horizontal long strip of the L-shaped window 4; and the high-frequency resonance characteristics can be controlled by adjusting the size and spacing of the rectangular holes, so that the low-frequency, mid-frequency and high-frequency resonance modes can be smoothly integrated.

[0039] Although specific embodiments of the invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by a person skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding, characterized in that: The substrate includes a transparent dielectric substrate, on which a coplanar waveguide feed structure, a radiating element, and a ground plane structure are integrated on the same surface. The coplanar waveguide feeding structure includes a central signal line arranged along the longitudinal axis of the antenna center, and large-area ground planes are respectively arranged on both sides of the central signal line at intervals. The radiating element is a T-shaped composite radiating patch, which includes a central main branch arranged along the longitudinal axis of the antenna center, the central main branch being connected to the central signal line; horizontal branches extend symmetrically from the upper two sides of the central main branch in the horizontal direction, and multiple bandwidth enhancement holes are opened on each side of the horizontal branch. The ground plane structure includes two L-shaped windows, which are opened on the large-area ground plane; the two L-shaped windows are symmetrically distributed about the longitudinal axis of the antenna center and partially overlap with the T-shaped composite radiating patch.

2. The T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 1, characterized in that: The transparent dielectric substrate has a rectangular structure with a length a=45mm, a width b=25mm, and a thickness of 1mm. Its material is resin glass.

3. The T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 1, characterized in that: The coplanar waveguide feeding structure is located in the lower half of the central region of one side of the transparent dielectric substrate. The central signal line on the coplanar waveguide feeding structure is separated from the large-area ground planes on both sides by a gap. The end of the central signal line is connected to the lower end of the central main branch of the radiating unit through an impedance matching section.

4. The T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 1, characterized in that: The T-shaped composite radiating patch is located in the upper half of the central region of one side of the transparent dielectric substrate; the central main branch on the T-shaped composite radiating patch is a rectangular conductive patch arranged vertically with a width of c=6mm, and its lower end is connected to the coplanar waveguide feeding structure as a feed point.

5. The T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 1, characterized in that: The horizontal supports on both sides are two rectangular conductive arms. The two rectangular conductive arms and the central main branch together form an inverted "T" shape. The width of the rectangular conductive arms is h=3mm.

6. The T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 1, characterized in that: The bandwidth enhancement hole is a rectangular hole, and six rectangular holes are uniformly etched on each of the horizontal branches. The spacing between the rectangular holes is d=1mm, the width of the rectangular hole is f=1.7mm, and the length is g=10mm.

7. The T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 1, characterized in that: The L-shaped window includes a short, vertically extending slot and a long, horizontally extending slot, which are connected and form an "L" shape.

8. The T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 1, characterized in that: The length of the elongated slot in the L-shaped window is i=19mm and the width is j=1.5mm; the distance between the elongated slot and the rectangular hole on the same side is e=2.5mm.

9. A design method for a T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Select resin glass as the transparent dielectric substrate material, and divide the same surface of the transparent dielectric substrate into a coplanar waveguide feeding structure region, a radiating unit region and a ground plane structure region; wherein, the coplanar waveguide feeding structure region is located at the center of the lower half of the transparent dielectric substrate, and the radiating unit region is located at the center of the upper half of the transparent dielectric substrate. S2. Design a coplanar waveguide feeding structure in the coplanar waveguide feeding structure region, including setting a center signal line along the longitudinal axis of the antenna center and setting large-area ground planes at intervals on both sides of the center signal line. S3. Design a T-shaped composite radiating patch in the radiating unit area, including a central main branch arranged along the longitudinal axis of the antenna center, with the lower end of the central main branch serving as a feed point and connected to a coplanar waveguide feed structure; horizontal branches extend symmetrically in the horizontal direction on both sides of the upper part of the central main branch, and six rectangular holes are uniformly etched on each side of the horizontal branch. S4. Design a ground plane structure in the ground plane structure area, including opening an L-shaped window on each of the two large-area ground planes, ensuring that the two L-shaped windows are symmetrically distributed about the longitudinal axis of the antenna center, and partially overlap with the T-shaped composite radiating patch in projection; S5. An impedance matching section is used to connect the center signal line of the coplanar waveguide feed structure to the central main branch of the T-shaped composite radiating patch. Through simulation optimization and adjustment of various structural parameters, the low-frequency, mid-frequency and high-frequency resonant modes are smoothly integrated to form an ultra-wideband impedance matching characteristic of 4.72GHz-7.44GHz.

10. The design method of a T-shaped ultrawideband transparent antenna based on coplanar waveguide feeding according to claim 9, characterized in that, By adjusting the length of the vertical short slots and the width of the horizontal long slots of the L-shaped window, the low-frequency extension effect is optimized; by adjusting the size and spacing of the rectangular holes, the high-frequency resonance characteristics are controlled, so that the low-frequency, mid-frequency and high-frequency resonance modes can be smoothly integrated.

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