Metal frame smart watch antenna based on double-fed technology

Abstract

The application relates to the technical field of wearable antennas, in particular to a metal frame smart watch antenna based on a double-feed technology, which comprises a metal frame, a metal ground plate, a parasitic metal, a first feed port, a second feed port, a feed source, a power divider and a phase shifter; the feed source forms two feed paths through the power divider, one of which feeds into the first feed port, and the other feeds into the second feed port through the phase shifter. The antenna can be configured to connect a slot antenna to the first feed port and connect a patch antenna to the second feed port so that the two antennas work simultaneously, or configured to connect the two feed ports to the same patch antenna so that the patch antenna generates a double mode. The scheme is favorable for improving the low-frequency antenna efficiency, improving the bandwidth performance, and realizing double-feed work under the condition of a single excitation source.

Description

Technical Field

[0001] This invention relates to the field of wearable antenna technology, specifically a metal-framed smartwatch antenna based on dual-feed technology. Background Technology

[0002] With the continuous evolution of wireless communication technology, the LTE band has long been regarded as an important low-frequency resource in mobile communication due to its low propagation loss, wide coverage, strong penetration, and relatively low network construction cost. However, in the application scenario of smartwatches, low-frequency antenna design has always faced significant technical constraints. First, the overall height of a smartwatch is limited, and the coupling relationship between the metal casing, strap, and internal floor is complex. The low-frequency current distribution is easily affected by the nearby metal environment, resulting in low-frequency radiation efficiency. Second, due to the size limitations of the installation area, smartwatch low-frequency antennas usually have a narrow operating bandwidth, making it difficult to meet the performance requirements of multi-band, wideband communication systems for terminal antennas. In existing technologies, the metal casing or motherboard floor is usually used as an antenna radiator, but its low-frequency radiation potential is still not fully utilized. Although traditional single-feed methods can drive the floor to generate some radiation, it is still difficult to balance radiation efficiency and bandwidth performance, often resulting in low efficiency or insufficient bandwidth. Some solutions have attempted to improve floor radiation performance by optimizing impedance matching networks or adjusting electromagnetic coupling structures. However, these solutions generally require the introduction of complex circuit structures or additional radiation components, which not only contradicts the trend of miniaturization and thinning of smartwatches, but also increases design difficulty and manufacturing costs. They may even adversely affect the original radiation characteristics due to the addition of parasitic structures.

[0003] In view of this, how to achieve efficient low-frequency radiation within the limited space of a smartwatch while simultaneously improving the operating bandwidth remains a key technical problem that urgently needs to be solved in this field. To address this problem, this study proposes two innovative parallel feeding schemes: First, by simultaneously exciting the slot antenna and the patch antenna using a parallel dual-feed method, the equivalent radiation aperture of the antenna is expanded, thereby improving antenna efficiency and operating bandwidth; second, by simultaneously exciting the patch antenna in two modes, namely the same-direction electric field mode and the opposite-direction electric field mode, using a parallel dual-feed method, both antenna efficiency and operating bandwidth are improved. Both of these technical approaches provide new implementation ideas for the design of next-generation compact low-frequency smartwatch antennas. It should be noted that the parallel feeding technology based on phase difference has been proposed in the invention patent "A Mobile Phone Antenna and Electronic Device Based on Common-Mode and Differential-Mode" (Publication No.: CN117748173A). This patent mainly eliminates the local minimum radiation efficiency points generated by the inverted-F antenna with parasitic branches through a parallel feeding method with phase difference, thereby achieving common-mode operation of the slot antenna in a wide frequency band. However, this existing technology is mainly aimed at mobile phone antenna scenarios, and does not involve the specific application of parallel feeding technology in low-frequency antennas of smartwatches to improve efficiency and bandwidth, nor does it propose corresponding solutions for the structural constraints, coupling characteristics and low-frequency radiation requirements under the compact space conditions of smartwatches. Summary of the Invention

[0004] The purpose of this invention is to provide a metal frame smartwatch antenna based on dual-fed technology to solve the technical problems mentioned in the background art.

[0005] Based on the above ideas, the present invention provides the following technical solution: A metal-frame smartwatch antenna based on dual-feed technology, comprising: It includes a metal frame, a metal floor, parasitic metal, a first feed port, a second feed port, a feed source, a power divider, and a phase shifter; The feed source forms two feeds via the power divider, one of which is fed into the first feed port, and the other is fed into the second feed port after passing through the phase shifter; The antenna is configured in any of the following structures: In the first structure, the first feed port is connected to the slot antenna, and the second feed port is connected to the patch antenna, so that the slot antenna and the patch antenna can work simultaneously. In the second configuration, the first feed port and the second feed port are connected to the same patch antenna, enabling the patch antenna to generate dual modes.

[0006] The doubly-fed structure provides a foundation for reconstructing the low-frequency radiation path, enabling the metal frame, ground plane, parasitic metal, and related radiating elements within a limited volume to operate under more controllable feeding conditions, thereby improving the overall radiation performance in the low-frequency band. For the first type of structure, this overall concept facilitates the formation of a cooperative radiation mechanism between two different radiating elements; for the second type of structure, this overall concept facilitates the formation of a dual-mode operating mechanism based on the same patch antenna. Therefore, the beneficial effects of claim 1 can be summarized as follows: without departing from the constraints of the compact structure of a watch, the doubly-fed concept provides a unified technical basis for improving low-frequency radiation efficiency, target frequency band coverage, and bandwidth optimization.

[0007] Preferably, it also includes four circular dielectric substrates and an ITO conductive film; The dielectric substrate and the ITO conductive film constitute the screen. The dielectric substrate and the metal ground plane constitute the main circuit board; The dielectric substrate, parasitic metal, and dielectric substrate constitute the back cover.

[0008] It helps reduce the need to introduce additional large independent radiating components to achieve the doubly fed effect. On the other hand, it also helps to build the coupling relationship between the metal frame, ground plane and parasitic metal within the existing overall boundary, thereby providing a physical support basis for the subsequent formation of slot antennas, patch antennas or dual-mode patch antennas.

[0009] Preferably, the dielectric substrate, ITO conductive film, metal ground plane, parasitic metal, and metal frame are center-aligned; The lower surface of the dielectric substrate is flush with the top of the metal frame, the lower surface of the metal floor is flush with the top of the dielectric substrate, the upper surface of the dielectric substrate is flush with the bottom of the metal frame, and the upper surface of the dielectric substrate is flush with the bottom of the parasitic metal.

[0010] Standardized control of the overall spatial configuration is crucial. For low-frequency small wearable antennas, the relative positions of the metal components and dielectric layers directly affect the feed path, current distribution, coupling gap, and equivalent radiation boundary. Significant offsets, misalignments, or irregularities in the structural arrangement can easily lead to unstable resonance states, mode coupling shifts, or insufficient performance consistency between prototypes. Center alignment and flush mounting allow for a more regular three-dimensional spatial relationship between the metal frame, metal ground plane, parasitic metal, and screen-related conductive layers. This helps reduce the impact of assembly deviations on antenna performance, enhances repeatability and consistency between different prototypes, and provides more stable geometric boundary conditions for effective transmission and mode establishment of dual-fed signals within a given structure.

[0011] Preferably, the energy provided by the feed is first transmitted to the input of the power divider via a matching network, and then distributed to the output ports. The energy from the output port is directly fed into the first feed port, and the energy from the output port is fed into the second feed port after passing through a phase shifter.

[0012] The feed energy is further specified to first be transmitted to the input of the power divider via a matching network, and then distributed to two output ports by the power divider. One output port is directly fed into the first feed port, and the other is fed into the second feed port after passing through a phase shifter. The beneficial effect of this technical feature is mainly reflected in the controllability and engineering implementation of the dual-feed process. It should be noted that for low-frequency small antennas, simply setting two feed ports does not necessarily mean that better antenna performance can be obtained. The key is whether a suitable energy distribution relationship, phase relationship, and impedance matching relationship can be formed between the two feed branches. The combination of matching network, power divider, and phase shifter as defined in claim 4 provides a clear implementation method for controlled excitation of dual branches under a single feed source. It is beneficial to coordinate the distribution and phase adjustment of the two feed signals without increasing the number of independent excitation sources, thereby reducing the adverse effects caused by feed imbalance, impedance mismatch, and branch coupling uncontrolled effects. In other words, the value of this technical feature lies in providing a more stable, more adjustable, and more terminal integration-compliant feed network implementation path for dual-feed schemes.

[0013] Preferably, when the antenna has the first structure, the metal ground plane and the parasitic metal are separated only by a dielectric substrate; The slot antenna consists of a metal ground plane, a metal frame, a gap between the two, and a first feed port. The patch antenna consists of a metal ground plane, a dielectric substrate, parasitic metal, and a second feed port.

[0014] With only a dielectric substrate separating the metal ground plane and the parasitic metal, a slot antenna is constructed from the metal ground plane, the metal frame, and the gap between them; a patch antenna is constructed from the metal ground plane, the dielectric substrate, the parasitic metal, and the second feed port. Two types of radiating elements with different operating mechanisms, yet capable of coexisting in the same terminal space, are clearly constructed, thus providing a clear structural object for the first dual-fed scheme. Specifically, the slot antenna primarily relies on the gap between the metal frame and the metal ground plane to form the radiation path, which is more conducive to manipulating the frame-related current; the patch antenna primarily relies on the interlayer structure between the metal ground plane, the dielectric layer, and the parasitic metal to form another type of radiation path. Through these limitations, different types of radiators are no longer in a state of ambiguity but are clearly defined as structural units that can be separately controlled and can work collaboratively in a dual-fed state. Based on this, when both are simultaneously excited by dual feeding, a clearer basis for collaborative radiation can be formed within the limited space of the watch, rather than relying solely on a single radiator to undertake all low-frequency radiation tasks.

[0015] Preferably, the first power supply port is connected to the metal floor and the metal frame, and the second power supply port is connected to the metal floor and the parasitic metal. The first power supply port has an angle of 0° with the positive x-axis, the second power supply port has an angle of 0° with the positive x-axis, and both are 17mm away from the center point of the metal floor.

[0016] The effectiveness of a doubly fed structure depends not only on the presence of two ports, but also on the optimal positional relationship between these ports within the overall geometry for optimal current distribution, mode coupling, and impedance response. By defining the connection positions and geometric references of the two feed ports, the interaction between the two feed signals and the metal frame, metal ground plane, and parasitic metal can be more clearly defined. This helps reduce resonance drift, mode imbalance, and inter-prototype dispersion caused by random or asymmetrical arrangements.

[0017] Preferably, the slot antenna radiates when there is one and only the first feed port. The patch antenna radiates when fed by only the second feed port; When the first feed port and the second feed port are simultaneously fed, the slot antenna and the patch antenna participate in radiation simultaneously to expand the radiation aperture and improve radiation efficiency.

[0018] The actual effect of the dual-fed antenna scheme on radiation behavior is clarified, thus providing a clear technical mechanism and implementation logic for coordinated radiation. Based on this limitation, the first scheme in dual-fed mode is no longer an enhanced version of a single radiating element, but rather forms a larger equivalent radiation aperture through the simultaneous operation of two radiating elements. As can be seen from the embodiments in the specification, this scheme can achieve complete coverage in the LTE B8 band, and the in-band average radiation efficiency and in-band average system efficiency in dual-fed mode are superior to those of single ring slot antennas and single patch antenna schemes.

[0019] Preferably, when the antenna has the second structure, a dielectric substrate, a dielectric substrate, and air are spaced between the metal ground and the parasitic metal; The first feed port and the second feed port are respectively connected to the feed metal post and the feed metal post, and are connected to the same patch antenna through the feed metal post; When the first feed port and the second feed port are fed simultaneously, the patch antenna generates dual modes to improve radiation efficiency and broaden the antenna bandwidth.

[0020] By employing dual-point excitation on the same patch antenna, more usable low-frequency operating modes can be explored within a limited space. For small-sized watch patch antennas, using only a single-feed method often results in limitations in size, making it difficult to balance bandwidth and efficiency. By introducing dual-point feeding and a dual-mode operating mechanism, the same patch antenna can have a wider range of operating states without significantly increasing the overall structural complexity. This solution exhibits a wider impedance bandwidth and improved efficiency compared to single-feed patch antennas in the LTE B8 band.

[0021] Preferably, the two ends of the power supply metal column are in direct contact with the metal floor and the parasitic metal, respectively; The feed metal column and the feed metal column have a radius of 1 mm and a height of 7.5 mm; The patch antenna radiates when fed by one and only the first feed port.

[0022] One end of the feeding metal post contacts the metal ground plane, and the other end contacts the parasitic metal, forming a clear and compact energy transmission path between the two feeding ports and the same patch antenna. This helps to avoid the additional uncertainties caused by too many intermediate transition structures. At the same time, limiting the size of the feeding metal post helps to make this dual-point feeding connection method have clearer implementation boundaries and fabrication feasibility within the limited space of the terminal. Furthermore, claim 9 also states that the patch antenna itself can form basic radiation when fed only by the first feeding port. This indicates that the second structure does not exist independently of the single-port operation, but rather extends the existing basic radiation capability to dual-point excitation and dual-mode operation.

[0023] The technical solution of the present invention may include the following beneficial effects: To address the issue of low radiation efficiency of low-frequency antennas in smartwatches within limited space, this application proposes two dual-fed implementation paths. For the first dual-fed smartwatch antenna with a metal frame, a parallel feeding method is used to simultaneously excite both the slot antenna and the patch antenna. This allows the two radiating elements, which were originally operating separately, to work collaboratively in the dual-fed state, thereby expanding the equivalent radiation aperture and improving low-frequency radiation efficiency. The embodiments in the specification also state that, within the LTE B8 band, this scheme outperforms both the single loop slot antenna and the single patch antenna schemes in terms of in-band average radiation efficiency and in-band average system efficiency. For the second dual-fed smartwatch antenna with a metal frame, a parallel feeding method is used to simultaneously excite two modes of the same patch antenna, allowing the small-sized patch antenna to achieve more efficient mode utilization in the low-frequency band. Therefore, overall, this application enhances the utilization of low-frequency radiation resources through the dual-fed design, which is beneficial for improving the efficiency performance of low-frequency antennas in smartwatches.

[0024] To address the issue of limited bandwidth in low-frequency antennas, this application does not simply rely on adjusting the size of a single radiator, but rather reconstructs the antenna's operating state through a dual-feed method. For the first approach, simultaneously exciting both the slot antenna and the patch antenna with a dual-feed system creates a cooperative radiation relationship, which is beneficial for improving coverage and bandwidth performance within the target low-frequency band. As described in the embodiments, this approach can fully cover the LTE B8 band; therefore, it is appropriate to conservatively state that it improves target band coverage and low-frequency bandwidth performance. For the second approach, by simultaneously exciting the patch antenna in both unidirectional and reverse electric field modes with a dual-feed system, the same patch antenna can operate in dual modes, thereby achieving bandwidth expansion.

[0025] Although this application employs doubly-fed technology, it does not require two independent external excitation sources. Instead, it uses a power divider to distribute the energy of the same feed source into two paths, and then uses a phase shifter to regulate one of these paths, enabling controlled doubly-fed operation at both feed ports under a single excitation source. The advantages of this approach are twofold: firstly, it achieves dual-branch excitation without significantly increasing the number of input ports, avoiding higher system complexity introduced by an additional independent excitation source; secondly, it makes the doubly-fed scheme more suitable for smartwatch terminals with limited space and high integration requirements. The abstract, claims, and embodiments clearly describe that the feed source is distributed by a power divider and fed into two ports, and a doubly-fed relationship is established through a phase shifter. Therefore, the main advantage of the third aspect of this application can be summarized as follows: while maintaining terminal integration requirements and the simplicity of feed implementation, it can drive doubly-fed operation using only a single excitation source, thus providing an feasible engineering implementation path for improving low-frequency performance. Attached Figure Description

[0026] Figure 1 The diagram shows the technical schematics of the loop slot antenna and patch antenna schemes in this invention (a) and the doubly fed patch antenna scheme (b).

[0027] Figure 2 The diagram shows the structure of the loop slot antenna and patch antenna based on the dual-fed technology of the present invention (a), the structure of the dual-fed patch antenna scheme (b), and the wearing diagram (c).

[0028] Figure 3 The diagram shows a single loop antenna (a), a single patch antenna (b), and a schematic diagram (c) of the first metal frame smartwatch antenna structure based on dual-fed technology of the present invention.

[0029] Figure 4 S11 comparison diagram of a single loop slot antenna, a single patch antenna, and the first metal frame smartwatch antenna based on dual-fed technology of the present invention.

[0030] Figure 5 The graph shows a comparison of the radiation efficiency (a) and system efficiency (b) of a single loop antenna, a single patch antenna, and the metal frame smartwatch antenna based on the first dual-feed technology of this invention.

[0031] Figure 6 The first image shows a single-fed patch antenna (a), the second type of metal frame smartwatch antenna structure based on dual-fed technology (b), and the second type of dual-antenna modes (c) and (d) generated by the metal frame smartwatch antenna based on dual-fed technology (c) and (d) (co-directional electric field mode and reverse electric field mode).

[0032] Figure 7 The image shows a comparison of S11 between a single-fed patch antenna and a metal-framed smartwatch antenna based on dual-fed technology, as described in the second invention.

[0033] Figure 8 The diagram shows a comparison of the radiation efficiency and system efficiency of a single-fed patch antenna and a metal-framed smartwatch antenna based on dual-fed technology, as described in this invention. Detailed Implementation Example

[0034] like Figure 1 As shown in (a), the technical concept of the first scheme is to simultaneously construct a slot antenna radiation path and a patch antenna radiation path within the limited internal space of a metal-framed smartwatch, and to excite both of them to work separately through a doubly-fed method, so that the two types of radiating elements cooperate in radiation within the target low-frequency band. The focus of this scheme is not simply to increase the number of radiators, but to form a larger equivalent radiation aperture by using a parallel doubly-fed method so that the slot antenna and patch antenna, which could originally work separately, can form under the same working state. This is beneficial to improving low-frequency radiation efficiency and ensuring coverage of the target frequency band.

[0035] like Figure 2 As shown in (a), the metal-framed smartwatch antenna in this embodiment includes four circular FR-4 dielectric substrates 1a, 2a, 3a, and 4, an ITO conductive film 1b, a metal ground plane 2b, a parasitic metal 3b, a metal frame 5, a feed source, a power divider, a phase shifter, a first feed port 6, and a second feed port 7. Dielectric substrate 1a and the ITO conductive film 1b constitute the screen portion, dielectric substrate 2a and the metal ground plane 2b constitute the main circuit board portion, and dielectric substrate 3a, the parasitic metal 3b, and dielectric substrate 4 constitute the back cover portion. All the above components are aligned at their centers, and the lower surface of dielectric substrate 1a is flush with the top of the metal frame 5, the lower surface of the metal ground plane 2b is flush with the top of dielectric substrate 3a, the upper surface of dielectric substrate 3a is flush with the bottom of the metal frame 5, and the upper surface of dielectric substrate 4 is flush with the bottom of the parasitic metal 3b, forming a relatively regular spatial stacking relationship. The dielectric substrate material has a dielectric constant of 4.3 and a loss tangent of 0.025°. The dielectric substrate 1a has a radius of 23 mm and a thickness of 0.5 mm, and its lower surface is coated with an ITO conductive film 1b with a radius of 20.3 mm and a thickness of 0.02 mm. The dielectric substrate 2a has a radius of 21.3 mm and a thickness of 0.5 mm, and its lower surface is etched with a metal ground plane 2b with a radius of 18.8 mm and a thickness of 0.02 mm. The dielectric substrate 3a has a radius of 23 mm and a thickness of 2 mm, and its lower surface is etched with a parasitic metal 3b with a radius of 22 mm and a thickness of 0.02 mm. The dielectric substrate 4 has a radius of 23 mm and a thickness of 0.5 mm. The metal frame 5 is annular, with an outer radius of 23 mm, an inner radius of 21.3 mm, a thickness of 1.7 mm, and a height of 7 mm. The clearance between the metal frame 5 and the ITO conductive film 1b is 1 mm, and the clearance between the metal frame 5 and the metal ground plane 2b is 2.5 mm.

[0036] In this embodiment, the metal ground plane 2b and the parasitic metal 3b are separated only by the dielectric substrate 3a. Under this structural condition, the first feed port 6 connects the metal ground plane 2b and the metal frame 5, and the second feed port 7 connects the metal ground plane 2b and the parasitic metal 3b. This forms two types of radiating elements: first, a slot antenna consisting of the metal ground plane 2b, the metal frame 5, the gap between them, and the first feed port 6; second, a patch antenna consisting of the metal ground plane 2b, the dielectric substrate 3a, the parasitic metal 3b, and the second feed port 7. The angle between the first feed port 6 and the positive x-axis is 0°, and the angle between the second feed port 7 and the positive x-axis is also 0°, with both ports 17mm away from the center point of the metal ground plane. This arrangement allows the two feed branches to act on different radiating elements, thus providing a clear structural basis for subsequent coordinated excitation.

[0037] In terms of the feeding network, the energy provided by the feed source is first transmitted to the input terminal a of the power divider via a matching network, and then distributed by the power divider to the output ports b and c. The energy at output port b is directly fed into the first feed port 6, and the energy at output port c is fed into the second feed port 7 after passing through a phase shifter. This feeding method allows a controlled dual-feed relationship to be established between the two ports with only a single feed source, enabling the slot antenna and patch antenna to operate simultaneously under the target conditions. Its working mechanism is as follows: when only the first feed port 6 is fed, the slot antenna mainly undertakes the radiation; when only the second feed port 7 is fed, the patch antenna mainly undertakes the radiation; when both the first and second feed ports 6 and 7 are fed simultaneously, both the slot antenna and the patch antenna participate in radiation. Due to the combined effect of the two types of radiating elements, the overall equivalent radiating aperture is increased, thus improving the radiation efficiency in the low-frequency band. (See attached illustration for wearing scenario.) Figure 2 As can be seen from c, this solution still maintains good compatibility with the structure of smartwatch terminals.

[0038] like Figure 3 As shown, Figure 3 (a) is a schematic diagram of a single ring slot antenna structure. Figure 3 (b) is a schematic diagram of a single patch antenna structure. Figure 3 (c) is a schematic diagram of the cooperative working structure of the slot antenna and patch antenna based on doubly-fed technology in this embodiment. This diagram more intuitively shows that this embodiment does not simply add a radiating component to the original watch structure, but rather establishes slot antenna paths and patch antenna paths separately within the same terminal space, and enables both to participate in radiation simultaneously under the target operating state through a doubly-fed relationship. In other words, the core of this embodiment is not in "adding two ports" itself, but in using two ports to correspond to different radiating elements, ultimately realizing the doubly-fed behavior as cooperative radiation behavior.

[0039] like Figure 4 The diagram shown is a comparison of step S11 for a single ring slot antenna, a single patch antenna, and the dual-fed ring slot antenna and patch antenna schemes in this embodiment. Figure 4It can be seen that the -6dB impedance bandwidth of a single ring slot antenna is 108MHz (868MHz-975MHz), which can completely cover the LTE B8 band; the -6dB impedance bandwidth of a single patch antenna is 54MHz (892MHz-946MHz), which is narrow and cannot completely cover the LTE B8 band; while the -6dB impedance bandwidth of the dual-fed ring slot antenna and patch antenna scheme in this embodiment is 98MHz (870MHz-968MHz), which can also completely cover the LTE B8 band. Therefore, this embodiment achieves the structural objective of dual-radiating element cooperation while maintaining complete coverage of the target low-frequency band. For this embodiment, it is more appropriate to emphasize its improved coverage and efficiency within the target frequency band, rather than simply summarizing it as achieving bandwidth expansion compared to all single-fed schemes.

[0040] like Figure 5 As shown in (a), this is a comparison of the radiation efficiency of a single-loop slot antenna, a single-patch antenna, and the dual-fed scheme of this embodiment. In the LTE B8 band (880MHz-960MHz), the average in-band radiation efficiency of the single-loop slot antenna is -9.0dB, the average in-band radiation efficiency of the single-patch antenna is -9.2dB, while the average in-band radiation efficiency of the dual-fed loop slot antenna and patch antenna scheme of this embodiment is -6.7dB, representing an improvement of more than 2dB compared to any of the aforementioned single-fed schemes. Figure 5 As shown in (b), the corresponding system efficiency comparison chart is presented. Within the LTE B8 band, the average in-band system efficiency of a single slot antenna is -9.2 dB, and that of a single patch antenna is -11.1 dB. In contrast, the average in-band system efficiency of the dual-fed scheme in this embodiment is -6.9 dB, representing an improvement of over 2 dB compared to any single-fed scheme. These results demonstrate that this embodiment, by simultaneously exciting both the slot antenna and the patch antenna with a dual-fed system, enables the two radiating elements to form cooperative radiation within the target frequency band, thereby making fuller use of the low-frequency radiation resources in the limited terminal space and exhibiting a significant efficiency improvement.

[0041] In summary, the first metal frame smartwatch antenna based on dual-feed technology establishes two types of radiation paths—slot antenna and patch antenna—within the same watch space. It uses a dual-feed network composed of a single feed source, a power divider, and a phase shifter to excite two radiating elements respectively, enabling the two radiating elements to participate in radiation in the target low-frequency band. This helps to expand the equivalent radiation aperture, improve radiation efficiency, and ensure complete coverage of the LTE B8 band. Example

[0042] like Figure 1As shown in (b), the technical concept of the second scheme is to improve low-frequency performance by not relying on the collaborative operation of two different radiating elements, but by simultaneously exciting two operating modes of the same patch antenna—the same-direction electric field mode and the opposite-direction electric field mode—through parallel dual-feed technology. This allows the small-sized patch antenna to achieve a richer range of low-frequency operating states within the limited space of a smartwatch. The main problem addressed by this scheme is that single-feed patch antennas are prone to insufficient bandwidth, inadequate mode utilization, and limited efficiency in the low-frequency band. By establishing a dual-mode operating mechanism, the utilization of the low-frequency band by the same patch antenna can be improved without significantly increasing the overall structural complexity.

[0043] like Figure 2 As shown in (b), the metal-framed smartwatch antenna in this embodiment also includes four circular FR-4 dielectric substrates 1a, 2a, 3a, and 4, an ITO conductive film 1b, a metal ground plane 2b, a parasitic metal 3b, a metal frame 5, and a feed source, a power divider, a phase shifter, a first feed port 6, and a second feed port 7. Unlike embodiment 1, this embodiment also includes feed metal pillars 8a and 8b. The two ends of the feed metal pillars 8a and 8b are in direct contact with the metal ground plane 2b and the parasitic metal 3b, respectively, with a radius of 1 mm and a height of 7.5 mm. This arrangement allows the two feed ports to be connected to the same patch antenna through the two feed metal pillars, thereby forming a dual-point excitation structure. The remaining stacked structure and overall configuration are consistent with embodiment 1, and can still maintain a good structural compatibility with the smartwatch terminal.

[0044] In this embodiment, a dielectric substrate 2a, a dielectric substrate 3a, and air are spaced between the metal ground plane 2b and the parasitic metal 3b. The first feed port 6 and the second feed port 7 are respectively connected to feed metal posts 8a and 8b, and are connected to the same patch antenna through the two feed metal posts. The energy provided by the feed source is first transmitted to the input terminal a of the power divider via a matching network, and then distributed by the power divider to the output ports b and c; wherein, the energy of output port b is directly fed into the first feed port 6, and the energy of output port c is fed into the second feed port 7 after passing through a phase shifter. Thus, a dual-point feeding relationship can be established for the same patch antenna under a single feed source condition. The mechanism is as follows: when only the first feed port 6 is fed, the patch antenna is in a single-feed working state; when the first feed port 6 and the second feed port 7 are fed simultaneously, under the action of power division and phase shifting, the same patch antenna forms a dual-mode working state, i.e. Figure 6 (c) and Figure 6 (d) shows the same-direction electric field mode and the opposite-direction electric field mode. Compared with single-feed antennas that only excite one main operating state, this embodiment excites two modes of the same patch antenna by dual-feed antennas, which is beneficial to improve the bandwidth performance in the target low-frequency band and is accompanied by efficiency improvement.

[0045] like Figure 6 As shown, Figure 6 (a) is a single-fed patch antenna. Figure 6 (b) is a schematic diagram of the second type of metal frame smartwatch antenna structure based on dual-fed technology in this embodiment. Figure 6 (c) and Figure 6 (d) is a schematic diagram of the two operating modes formed in the dual-fed state in this embodiment, namely the same-direction electric field mode and the opposite-direction electric field mode. This figure clearly shows that this embodiment does not improve performance by adding another type of independent radiating element, but rather establishes a dual-mode operating mechanism on the same patch antenna by using two feed ports and phase modulation.

[0046] like Figure 7 The image shown is a comparison diagram of S11 between a single-fed patch antenna and a metal-frame smartwatch antenna based on dual-fed technology, as described in this embodiment. Figure 7 It can be seen that the -6dB impedance bandwidth of the single-fed patch antenna is 100MHz (870MHz-970MHz), which can fully cover the LTE B8 band; while the -6dB impedance bandwidth of the dual-fed patch antenna scheme in this embodiment is 170MHz (800MHz-970MHz), increasing the bandwidth by 70MHz while still covering the LTE B8 band. This result demonstrates that this embodiment, by simultaneously exciting two modes of the same patch antenna with dual feed, can significantly improve the bandwidth performance of the patch antenna in the target low-frequency band.

[0047] like Figure 8 The image shows a comparison of the efficiency of a single-fed patch antenna and a metal-frame smartwatch antenna based on dual-fed technology, as described in this embodiment. According to the specification, in the LTE B8 band (880MHz-960MHz), the average in-band system efficiency of a single-fed antenna is -6.3dB, while the average in-band system efficiency of the dual-fed patch antenna solution in this embodiment is -5.0dB, representing an improvement of 1.3dB in average in-band efficiency. Combined with... Figure 6 The dual-mode working mechanism shown and Figure 7 The bandwidth improvement results shown indicate that this embodiment, by exciting the same patch antenna with a dual-point feed method to achieve dual-mode operation, allows the small-sized patch antenna to achieve more full mode utilization in the low-frequency band while maintaining the conditions for a single feed source. This demonstrates a comprehensive effect of improved bandwidth accompanied by improved efficiency. For this embodiment, the efficiency comparison in the specification uses in-band average system efficiency data as a more reliable performance basis.

[0048] In summary, the second type of metal-frame smartwatch antenna based on dual-feed technology establishes a dual-point feeding relationship on the same patch antenna and uses a power divider and phase shifter to enable dual-mode operation, thereby improving the utilization of the low-frequency band within the limited space of the smartwatch. This solution demonstrates a significant bandwidth expansion effect in the embodiments, accompanied by improved efficiency, while still maintaining the integrated advantages of a single-feed input.

Claims

1. A metal-framed smartwatch antenna based on dual-fed technology, characterized in that, include: Includes a metal frame (5), a metal floor (2b), parasitic metal (3b), a first feed port (6), a second feed port (7), a feed source, a power divider, and a phase shifter; The feed source forms two feeds via the power divider, one of which is fed into the first feed port (6), and the other is fed into the second feed port (7) via the phase shifter. The antenna is configured in any of the following structures: In the first structure, the first feed port (6) is connected to the slot antenna, and the second feed port (7) is connected to the patch antenna, so that the slot antenna and the patch antenna work simultaneously; In the second structure, the first feed port (6) and the second feed port (7) are connected to the same patch antenna so that the patch antenna can generate dual modes.

2. The metal frame smartwatch antenna based on dual-fed technology according to claim 1, characterized in that, It also includes four circular dielectric substrates (1a), (2a), (3a), (4) and an ITO conductive film (1b); The dielectric substrate (1a) and the ITO conductive film (1b) constitute a screen; The dielectric substrate (2a) and the metal ground plane (2b) constitute the main circuit board; The dielectric substrate (3a), parasitic metal (3b) and dielectric substrate (4) constitute the back shell.

3. The metal frame smartwatch antenna based on dual-fed technology according to claim 2, characterized in that, The dielectric substrates (1a), (2a), (3a), (4), ITO conductive film (1b), metal ground plane (2b), parasitic metal (3b) and metal frame (5) are aligned at the center; The lower surface of the dielectric substrate (1a) is flush with the top of the metal frame (5), the lower surface of the metal floor (2b) is flush with the top of the dielectric substrate (3a), the upper surface of the dielectric substrate (3a) is flush with the bottom of the metal frame (5), and the upper surface of the dielectric substrate (4) is flush with the bottom of the parasitic metal (3b).

4. The metal frame smartwatch antenna based on dual-feed technology according to claim 3, characterized in that, The energy provided by the feed is first transmitted to the input terminal (a) of the power divider via a matching network, and then distributed to the output port (b) and the output port (c). Among them, the energy of the output port (b) is directly fed into the first feed port (6), and the energy of the output port (c) is fed into the second feed port (7) after passing through the phase shifter.

5. A metal frame smartwatch antenna based on dual-fed technology according to claim 2, characterized in that, When the antenna is of the first type, the metal ground plane (2b) and the parasitic metal (3b) are separated only by a dielectric substrate (3a). The slot antenna consists of a metal ground plane (2b), a metal frame (5), a gap between the two, and a first feed port (6); The patch antenna consists of a metal ground plane (2b), a dielectric substrate (3a), a parasitic metal (3b), and a second feed port (7).

6. A metal frame smartwatch antenna based on dual-fed technology according to claim 2, characterized in that, The first power supply port (6) is connected to the metal floor (2b) and the metal frame (5), and the second power supply port (7) is connected to the metal floor (2b) and the parasitic metal (3b). The first power supply port (6) has an angle of 0° with the positive x-axis, the second power supply port (7) has an angle of 0° with the positive x-axis, and both are 17mm away from the center point of the metal floor (2b).

7. A metal frame smartwatch antenna based on dual-fed technology according to claim 2, characterized in that, The slot antenna radiates when only the first feed port (6) is fed; When the patch antenna is fed by only the second feed port (7), it radiates; When the first feed port (6) and the second feed port (7) are fed simultaneously, the slot antenna and the patch antenna participate in radiation at the same time to expand the radiation aperture and improve the radiation efficiency.

8. A metal frame smartwatch antenna based on dual-feed technology according to claim 2, characterized in that, When the antenna is of the second type, the metal ground plane (2b) and the parasitic metal (3b) are separated by a dielectric substrate (2a), a dielectric substrate (3a) and air; The first feed port (6) and the second feed port (7) are respectively connected to the feed metal post (8a) and the feed metal post (8b), and are connected to the same patch antenna through the feed metal post; When the first feed port (6) and the second feed port (7) are fed simultaneously, the patch antenna generates dual modes to improve radiation efficiency and broaden the antenna bandwidth.

9. A metal frame smartwatch antenna based on dual-fed technology according to claim 2, characterized in that, The two ends of the power-feeding metal column (8a) and the power-feeding metal column (8b) are in direct contact with the metal floor (2b) and the parasitic metal (3b), respectively. The radius of the feeding metal column (8a) and the feeding metal column (8b) is 1 mm and the height is 7.5 mm. The patch antenna radiates when it is fed by only the first feed port (6).

Images