An antenna loaded with impedance

Abstract

This invention discloses an antenna with applied impedance, belonging to the field of wireless communication technology. The antenna has a long, flat structure with a slot inside, forming a slot opening. The slot opening is a semi-circular structure, which constitutes the main part of the antenna's radiating surface. The semi-circular structure has a gap, and the applied impedance is placed in the gap of the slot opening. The antenna is flat and can be printed on a single-sided PCB, facilitating its assembly in compact wireless device environments. It also provides a tunable and easy-to-operate antenna radiating surface. By placing the applied impedance in the gap of the slot, a reasonable traveling and standing wave distribution of the antenna current is ensured, resulting in a wide antenna impedance bandwidth while maintaining high radiation efficiency. Therefore, the antenna of this invention can be built into compact and complex wireless communication device environments and maintain high performance.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to an antenna with applied impedance. Background Technology

[0002] Wireless communication devices play a vital role in our daily lives and work. Consequently, many consumer electronics wireless communication devices increasingly consider individual consumer needs, striving for both high performance and novel, compact designs. Antennas, as crucial components of wireless communication devices, require ultra-small size, easy integration, high performance, and a compact, conformal design to meet the demands of these new devices. Common antenna types used in wireless communication devices, especially frequently used WiFi devices such as routers and mobile terminals, include dipole antennas, monopole antennas, and inverted-F antennas.

[0003] Dipole and monopole antennas are simple in structure and theoretically sound, making them easy to design as individual antenna components and thus widely used. However, due to their relatively fixed radiation direction, they typically require vertical placement, making it difficult to integrate them with the low-profile, conformal designs of modern wireless devices. Dipole and monopole antennas also have narrow bandwidths, and a single antenna cannot adapt to multi-frequency WiFi protocol standards. When antennas need to be designed according to the requirements of wireless devices, their size further decreases, resulting in an even narrower impedance bandwidth. Therefore, dipole and monopole solutions are generally not directly applicable to new devices.

[0004] The inverted-F antenna has a small structure, meeting the requirement of a low profile, and is usually printed on the edge of the RF board. It overcomes the narrow bandwidth shortcomings of the dipole and monopole antennas mentioned above, but it still has its drawbacks. For example, in practical applications, a specific clearance area needs to be reserved, and components and metal parts need to be avoided near the antenna structure. Otherwise, the antenna will be subjected to severe environmental loading, and the antenna's radiation impedance will usually change drastically, making it difficult to match with the impedance of the environment, resulting in low radiation efficiency of the antenna in that environment.

[0005] Using impedance loading can alleviate the problem of impedance mismatch between antenna and environment. According to antenna theory, loading an integrated resistor can broaden the impedance variation range of the antenna, providing more matching possibilities during design. When the loaded impedance flattens the antenna's impedance over a wide bandwidth, the antenna exhibits wider bandwidth characteristics. Currently, existing loaded antennas are mostly loaded onto specific types of antennas, limiting their shape and making it difficult to integrate them into devices for conformal design. For example, Patent Document 1 (Publication No. CN10227077A) loads an impedance onto a bowtie antenna; Patent Document 2 (Publication No. CN108461910A) uses a Vivaldi antenna as a design prototype. Although these antennas can be printed on circuit boards to form a low-profile structure in terms of height, their planar area is still relatively large.

[0006] Secondly, using the impedance loading method may result in very low antenna efficiency. Reference 3 (SVHum, JZChu, RHJohnston and M.Okoniewski, "Efficiency of a resistively loaded microstrip patch antenna," in IEEE Antennas and Wireless Propagation Letters, vol.2, pp.22-25, 2003, doi:10.1109 / LAWP.2003.810777.) confirms from multiple perspectives that although the bandwidth of the impedance-loaded microstrip patch antenna is improved, its efficiency is unacceptably low. How to rationally use the impedance loading method to maintain both small antenna size and high radiation efficiency is of significant academic importance and economic value. Summary of the Invention

[0007] The purpose of this invention is to overcome the problem in the prior art of how to reasonably use the applied impedance to keep the antenna small in size while maintaining high radiation efficiency, and to provide an antenna with applied impedance.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] An antenna with applied impedance, the antenna having a long, flat structure, a slot inside the antenna forming a slot opening, and the slot opening having a semi-circular structure, the semi-circular structure forming the main part of the antenna's radiating surface, the semi-circular structure having a gap, and the applied impedance being placed in the gap of the slot opening.

[0010] The antenna is also provided with a feed point and at least one ground point at its bottom, and the feed point is the beginning of the semi-circular structure, and the ground point is the end of the semi-circular structure.

[0011] The antenna radiating surface and the loading impedance are used to form the current of the antenna in the form of a traveling and standing wave.

[0012] By adopting the above technical solution, the antenna is flat and can be printed on a single-sided PCB, making it easy to assemble in a compact wireless device environment; it also provides a tunable and easy-to-operate antenna radiating surface; by setting the loading impedance at the slot, a reasonable traveling wave distribution of the antenna current is ensured, resulting in a wide antenna impedance bandwidth while ensuring high radiation efficiency. Therefore, the antenna of the present invention can be built into a compact and complex wireless communication device environment and maintain high performance.

[0013] As a preferred embodiment of the present invention, the semi-circular structure can be bent once or multiple times. When bending, the angle is a right angle, a chamfer, or a rounded corner. The chamfer or rounded corner is set according to the current reflection and impedance matching conditions.

[0014] As a preferred embodiment of the present invention, the semi-circular structure has at least one of the gaps, each gap having a different width, the gaps dividing the semi-circular structure into a plurality of resonant units with different lengths and widths, the resonant units being connected to each other by a loaded impedance.

[0015] As a preferred embodiment of the present invention, a metal branch structure is formed around the resonant unit by cutting part of the antenna or adding metal branches. The metal branches are fixedly connected to the semi-circular structure, or coupled to the semi-circular structure through the gap.

[0016] As a preferred embodiment of the present invention, each pair of grounding points is connected by the metal branch.

[0017] As a preferred embodiment of the present invention, the number of loading impedances is less than or equal to the number of gaps, and the loading impedance is at least one.

[0018] As a preferred embodiment of the present invention, the loading impedance is one of a resistor, a capacitor, or an inductor, or a combination of the resistor, capacitor, or inductor.

[0019] As a preferred embodiment of the present invention, the antenna has dimensions of 0.344λ0 × 0.04λ0 (length × width), where λ0 is the wavelength at a working frequency of 2.4 GHz.

[0020] On the other hand, a wireless device RF board with applied impedance is disclosed, wherein an antenna with applied impedance as described above is integrated on the wireless device RF board, the wireless device RF board is grounded, and the feed point and ground point of the antenna are connected to the feed point and ground point of the wireless device RF board respectively.

[0021] As a preferred embodiment of the present invention, the bottom of the antenna is provided with at least one fixing foot without a metal layer, and the radio frequency board of the wireless device is provided with at least one slot for mounting the antenna.

[0022] Compared with the prior art, the advantages of the present invention are as follows: the antenna is flat and can be printed on a single-sided PCB, making it easy to assemble in a compact wireless device environment; it also provides a tunable and easy-to-operate antenna radiating surface; by setting the loading impedance at the slot, a reasonable traveling wave distribution of the antenna current is ensured, resulting in a wide antenna impedance bandwidth while ensuring high radiation efficiency. Therefore, the antenna of the present invention can be built into a compact and complex wireless communication device environment and maintain high performance. Attached Figure Description

[0023] Figure 1 This is an example diagram of the shape of an antenna with applied impedance as described in Embodiment 1 of the present invention;

[0024] Figure 2 This is a diagram showing the current distribution of an impedance-loaded antenna as described in Embodiment 1 of the present invention at 5.9 GHz.

[0025] Figure 3 This is an example diagram of a semi-circular antenna formed by bending a metal strip, as described in Embodiment 1 of the present invention.

[0026] Figure 4 This is an example diagram of an antenna with loaded impedance and metal stubs, as described in Embodiment 1 of the present invention.

[0027] Figure 5 This is an example diagram of the feed point and ground point of an antenna with applied impedance as described in Embodiment 2 of the present invention;

[0028] Figure 6 This is an assembly example diagram of an antenna with applied impedance as described in Embodiment 2 of the present invention;

[0029] Figure 7 This is a schematic diagram of a specific embodiment of an antenna with applied impedance as described in Embodiment 3 of the present invention;

[0030] Figure 8 The 3D radiation pattern of an impedance-loaded antenna as described in Embodiment 3 of the present invention at a frequency of 2.420 GHz;

[0031] Figure 9 The 3D radiation pattern of an impedance-loaded antenna as described in Embodiment 3 of the present invention at a frequency of 5.320 GHz;

[0032] Figure 10 This is diagram S11 of an antenna with applied impedance as described in Embodiment 3 of the present invention;

[0033] Figure 11 This is a position indicator diagram in the model of the radiation pattern of an antenna with applied impedance as described in Embodiment 3 of the present invention;

[0034] Figure 12 The planar radiation pattern and gain of an impedance-loaded antenna as described in Embodiment 3 of the present invention at a frequency of 2.45 GHz;

[0035] Figure 13 The planar radiation pattern and gain of an impedance-loaded antenna as described in Embodiment 3 of the present invention at a frequency of 5.5 GHz;

[0036] Figure 14 This is an efficiency-frequency relationship diagram of an antenna with applied impedance as described in Embodiment 3 of the present invention;

[0037] The markings in the diagram are: 1-semi-circular structure, 2-loaded impedance, 3-gap, 4-feed point, 5-grounding point, 6-metal branch. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0039] Example 1

[0040] An antenna with applied impedance, such as Figure 1 and Figure 5 As shown, the antenna has a long, flat structure with a slot inside, forming a slot opening. The slot opening is a semi-circular structure 1 made of metal. The semi-circular structure 1 constitutes the main part of the antenna's radiating surface. The semi-circular structure 1 has a gap 3, and the applied impedance 2 is placed at the gap 3 of the slot opening.

[0041] The antenna is also provided with a feed point 4 and at least one ground point 5 at its bottom, and the feed point 4 is the beginning of the semi-circular structure 1, and the ground point 5 is the end of the semi-circular structure 1.

[0042] Feed point 4 is located on the left side of the antenna, and ground point 5 is located on the right side of feed point 4 (since the antenna can be designed with mirror symmetry, the fact that feed point 4 is on the left and ground point 5 is on the right is relative). The number, specific location and width of the grounding metal of ground point 5 are not constant.

[0043] The antenna radiating surface and the loading impedance 2 are used to form the current of the antenna in the form of a traveling and standing wave.

[0044] Specifically, according to antenna theory and transmission theory, an unloaded antenna can be modeled as an open transmission line. The current in the antenna forms a standing wave on the antenna radiating surface. When a resistor is applied to the end of the antenna, if the applied load is equal to the characteristic impedance at the end of the antenna, a transmission line with a matched load at the end is formed. At this time, there is no reflected wave on the antenna radiating surface, forming a wide impedance broadband traveling wave antenna.

[0045] A well-placed loading impedance 2 helps ensure the ratio of traveling wave to standing wave (SWR), allowing the antenna to retain the broadband characteristics of a traveling wave antenna while providing high radiation efficiency in the SWR portion. The loading impedance 2 is located in the middle of the antenna's radiating surface. A traveling wave is formed in the resonant element section from feed point 4 to loading impedance 2. This resonant element should be configured as a high-frequency radiating surface, such as in the 5GHz band where high bandwidth is required.

[0046] When the frequency is 5.9 GHz, the current distribution of the antenna is as follows: Figure 2 As shown, in the 5GHz resonant unit, the minimum position of the current changes with the phase, and the antenna current in the left part exhibits obvious traveling wave characteristics. However, the overall antenna current is not entirely a traveling wave; the right half of the resonant unit provides standing wave characteristics, preventing the current on the antenna from being completely absorbed by the loaded load and improving the antenna's radiation efficiency.

[0047] like Figure 3 As shown, the semi-circular structure 1 can be bent once or multiple times. When bending, the angle is a right angle, a chamfer, or a rounded corner. The chamfer or rounded corner is set according to the current reflection and impedance matching conditions.

[0048] The semi-circular structure 1 has at least one of the slots 3, each slot 3 having a different width. The slots 3 divide the semi-circular structure 1 into several resonant units with different lengths and widths, and the resonant units are connected to each other by a loading impedance 2.

[0049] like Figure 4 As shown, a metal stub structure is formed around the resonant unit by cutting part of the antenna or adding metal stubs 6. The metal stubs 6 are fixedly connected to the semi-circular structure 1, or coupled to the semi-circular structure 1 through the gap 3, forming a parasitic structure of the resonant unit to optimize the impedance characteristics of the antenna.

[0050] Specifically, by simply adjusting the arm length of each resonant element, the resonant center frequency of the antenna resonant element is changed, thereby making the antenna work at different resonant points.

[0051] Each pair of grounding points 5 can be connected via the metal stub 6.

[0052] Specifically, the interconnected grounded metal stubs 6 form parasitic capacitance, which helps improve the antenna's quality factor and matching impedance.

[0053] The number of loading impedances 2 is less than or equal to the number of gaps 3, and the loading impedance 2 is at least one.

[0054] The applied impedance 2 is one of a resistor, a capacitor, or an inductor, or a combination of the resistor, capacitor, or inductor. The package type of the applied impedance 2 is not constant and can be determined according to the size of the gap 3.

[0055] Specifically, the antenna radiating surface includes a feed point 4, at least one ground point 5, multiple resonant units, multiple metal stubs 6 or parasitic capacitances. The antenna's loading impedance 2 and the antenna radiating surface can be printed on one side of a printed circuit board. The dielectric constant and thickness of the printed circuit board are not constant and depend on the specific engineering requirements.

[0056] The antenna has dimensions of 0.344λ0 × 0.04λ0, where λ0 is the wavelength at a working frequency of 2.4 GHz, i.e., 43 × 5 mm. 2 The thickness can be determined by the manufacturing process parameters of the printed circuit board, and can be taken as 0.004λ0, or 0.5mm. A printed circuit board with a dielectric constant of 4.2 can be used for production. The antenna has a small overall volume and a low profile, making it easy to integrate on the RF board.

[0057] By adopting the above technical solution, the antenna is flat and can be printed on a single-sided PCB, making it easy to assemble in a compact wireless device environment; it also provides a tunable and easy-to-operate antenna radiating surface; by setting the loading impedance at the slot, a reasonable traveling wave distribution of the antenna current is ensured, resulting in a wide antenna impedance bandwidth while ensuring high radiation efficiency. Therefore, the antenna of the present invention can be built into a compact and complex wireless communication device environment and maintain high performance.

[0058] Example 2

[0059] A wireless device RF board with applied impedance, such as Figure 5 As shown, the wireless device RF board integrates the antenna with the applied impedance as described in Embodiment 1. The wireless device RF board is grounded, and the antenna's feed point 4 and ground point 5 are connected to the corresponding feed point and ground point of the wireless device RF board.

[0060] Specifically, the flat structure of the antenna allows it to be approximately at the same height as the components on the wireless device's RF board, making it easy to integrate as a component on the RF board. Its assembly feature is that the antenna, printed on the circuit board, is vertically aligned with the grounded RF board. The size and thickness of the RF board are not constant, and the position of the antenna relative to the edge of the RF board is also not constant. Pads are provided at the feed point 4 and ground point 5 of the RF board, allowing for soldering connections between the antenna and the corresponding feed and ground points on the RF board.

[0061] The antenna has at least one mounting foot without a metal layer at its bottom, and the radio frequency board of the wireless device has at least one slot for mounting the antenna.

[0062] Specifically, such as Figure 6 As shown, the antenna does not need to be strictly perpendicular to the RF board of the wireless device during assembly. An angle of ±10° between the antenna and the RF board is considered an acceptable assembly error. To ensure stable assembly of the flat antenna, one or more mounting feet without a metal layer can be provided on the bottom of the printed circuit board where the antenna is located. Correspondingly, one or more slots can be made in the corresponding positions on the RF board of the wireless device to mount the antenna.

[0063] Example 3

[0064] This embodiment is a specific implementation of embodiment 1, such as... Figure 7 As shown, the antenna is used in compact wireless device environments. This embodiment demonstrates the use of the antenna in a router device. The antennas are vertically mounted on an RF board, one on each side, with the two antennas mirror-symmetrical. In actual operation, various electrical components such as surface mount resistors, electrolytic capacitors, connectors, and metal shielding covers are allowed to be closely arranged near the antennas. A heat sink made of aluminum is located under the RF board; its metal structure has minimal impact on antenna performance. The invented antenna is printed on a single-sided PCB. A lumped resistor with a resistance of 402Ω is soldered to the middle of the top of the antenna. This resistor connects the left part of the structure containing the feed point and the right part of the structure containing a ground point, making the overall antenna a wraparound structure. Figure 8 , Figure 9 As shown in the figure, the measured radiation pattern of the above embodiment shows that the antenna can form a hemispherical radiation well in the direction of its top.

[0065] The antenna operates in the 2.4GHz and 5GHz frequency bands, covering both Wi-Fi frequency bands, and has a wide impedance bandwidth. For example, in a certain design, its -10dB impedance bandwidth is 2.24GHz-2.52GHz in the 2.4GHz band and 5.05GHz-5.9GHz in the 5GHz band. Figure 10 As shown.

[0066] like Figure 11 As shown, the antenna's radiation direction is hemispherical, with its normal direction perpendicular to the wireless device's RF board. On planes perpendicular to both the ground plane and the antenna board plane, the antenna's radiation pattern exhibits good half-circularity. Figure 12 and Figure 13 As shown, the antenna can achieve uniform gain in both the 2.4 GHz and 5 GHz bands.

[0067] like Figure 14 As shown, the antenna achieves an efficiency of over -2dB in the 2.4GHz and 5.8GHz bands of the Wi-Fi protocol, while its efficiency is slightly lower in the 5.2GHz band, ranging from -3dB to -2dB. According to antenna theory, the smaller the antenna size, the more difficult it is to match its radiation impedance, resulting in lower radiation efficiency. The antenna of this invention exhibits higher radiation efficiency compared to other antennas of similar size.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An impedance loaded antenna, characterized by, The antenna has a long, flat structure. The antenna has a slot inside to form a slot opening. The slot opening is a semi-circular structure (1). The semi-circular structure (1) constitutes the main part of the antenna's radiating surface. The semi-circular structure (1) has a gap (3). The load impedance (2) is placed at the gap (3) of the slot opening. The antenna is also provided with a feed point (4) and at least one ground point (5) at its bottom, and the feed point (4) is the beginning of the semi-circular structure (1), and the ground point (5) is the end of the semi-circular structure (1). The antenna radiating surface and the loading impedance (2) are used to form the current of the antenna into a traveling standing wave. The semi-circular structure (1) can be bent once or multiple times. When bent, the corner is a right angle, a chamfer, or a rounded corner. The chamfer or rounded corner is set according to the current reflection and impedance matching conditions. The semi-circular structure (1) has at least one of the slots (3), each slot (3) having a different width, the slots (3) dividing the semi-circular structure (1) into a number of resonant units with different lengths and widths, the resonant units being connected by a loading impedance (2); The resonant unit is surrounded by a metal branch structure formed by cutting part of the antenna or adding metal branches (6). The metal branches (6) are fixedly connected to the semi-circular structure (1) or coupled to the semi-circular structure (1) through the gap (3).

2. An impedance loaded antenna according to claim 1, wherein, Each pair of grounding points (5) is connected by the metal stub (6).

3. An impedance loaded antenna according to any one of claims 1-2, characterized in that, The number of loading impedances (2) is less than or equal to the number of gaps (3), and the loading impedance (2) is at least one.

4. An impedance loaded antenna according to claim 3, wherein, The loading impedance (2) is one of a resistor, a capacitor, or an inductor, or a combination of the resistor, capacitor, or inductor.

5. An antenna with applied impedance according to claim 1, characterized in that, The antenna has dimensions of 0.344λ0 × 0.04λ0, where λ0 is the wavelength at a working frequency of 2.4 GHz.

6. A wireless device radio frequency board loaded with impedance, characterized by, The wireless device RF board integrates an antenna with a loading impedance as described in any one of claims 1-5. The wireless device RF board is grounded, and the feed point (4) and ground point (5) of the antenna are connected to the feed point and ground point of the wireless device RF board respectively.

7. The impedance loaded wireless device radio frequency board of claim 6, wherein, The antenna has at least one mounting foot without a metal layer at its bottom, and the radio frequency board of the wireless device has at least one slot for mounting the antenna.

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