Antenna system and communication terminal

Abstract

The utility model provides an antenna system and a communication terminal. The antenna system comprises a dielectric plate, a first antenna and a second antenna. The working frequency band of the first antenna is a first frequency band, the working frequency band of the second antenna is a second frequency band, and the first frequency band is different from the second frequency band. The first antenna comprises a first unit floor and a first radiator which are arranged on the first surface of the dielectric plate, and the second antenna comprises a second unit floor and a second radiator which are arranged on the second surface of the dielectric plate. The end, adjacent to the first unit floor, of the coplanar waveguide transmission line of the first antenna is a first feed point, the end, facing the first feed point, of the coplanar waveguide transmission line is connected with a first branch knot, the first branch knot is located on the side, facing the first unit floor, of the first radiator, one end of the first branch knot is electrically connected with the coplanar waveguide transmission line, and the other end of the first branch knot is an open end. The first branch inhibits the pilot frequency signal, improves the isolation between the first antenna and the second antenna, improves the gain of the antenna system, and improves the coexistence performance of the first antenna and the second antenna.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to an antenna system and a communication terminal. Background Technology

[0002] With the rapid development of communication technology, people's demand for signal transmission rate during communication is gradually increasing. The coverage and throughput performance of communication terminals have an important impact on the user's communication quality.

[0003] Taking the aforementioned communication terminal as a router as an example, the number of antennas in routers has evolved from 2×2 multiple-input multiple-output (MIMO) technology to 4×4 MIMO. Increasing the number of antennas leads to larger router size and higher cost. Therefore, dual-band common-port duplex antennas have become an important development. However, dual-band common-port duplex antennas are limited by isolation, and their performance is restricted when multiple duplex antennas coexist. Utility Model Content

[0004] This application provides an antenna system and a communication terminal. The first and second antennas have high isolation and good coexistence characteristics. This improves the radiation efficiency of the antenna system and the throughput rate of the antenna terminal.

[0005] In a first aspect, this application provides an antenna system for implementing communication functions. The antenna system includes a dielectric substrate, a first antenna, and a second antenna. The first antenna operates in a first frequency band, and the second antenna operates in a second frequency band. The first and second frequency bands are different, allowing the antenna system to operate in at least two frequency bands. The dielectric substrate includes two opposing surfaces, a first surface and a second surface. Specifically, the first antenna is primarily disposed on the first surface of the dielectric substrate, and the second antenna is primarily disposed on the second surface of the dielectric substrate; in short, the first and second antennas are disposed on the same dielectric substrate. The first antenna includes a first ground plane and a first radiator arranged adjacent to each other along a first direction, and the first ground plane and the first radiator are disposed on the first surface. The second antenna includes a second ground plane and a second radiator arranged adjacent to each other along the first direction, and the second ground plane and the second radiator are disposed on the second surface. This ensures that the first and second antennas share the same aperture. The aforementioned first antenna also includes a coplanar waveguide transmission line. The end of the coplanar waveguide transmission line adjacent to the first unit ground plane is a first feed point. A first stub is connected to the end of the coplanar waveguide transmission line facing the first feed point. The first stub is located on the side of the first radiator facing the first unit ground plane. One end of the first stub is electrically connected to the coplanar waveguide transmission line, and the other end is an open end. This first stub serves as a filter and decoupler, suppressing inter-frequency signals and improving the isolation between the first and second antennas. Therefore, it helps to improve the gain of the antenna system and the coexistence performance of the first and second antennas. This, in turn, improves the radiation efficiency of the first and second antennas and increases the throughput rate of the mobile terminal. Furthermore, the first stub in this scheme has a simple structure and is integrated with the antenna structure, eliminating the need for additional filter designs and reducing the cost of the antenna system.

[0006] In a further technical solution, a second stub is connected to one end of the coplanar waveguide transmission line facing the feed point. The second stub is arranged adjacent to the first stub, and one end of the second stub is electrically connected to the coplanar waveguide transmission line, while the other end is an open end. This double-stub connection to the coplanar waveguide transmission line can further suppress harmonics in the second frequency band, improving the suppression effect.

[0007] When specifically configuring the first and second branches, the second branch can be arranged parallel to the first branch. This helps reduce the space occupied by the first and second branches and facilitates the formation of reverse current between them, thereby improving the suppression of the first antenna.

[0008] The electrical length of the first stub is less than or equal to one-quarter of the dielectric wavelength. Therefore, this first stub can be equivalent to a series inductor and capacitor, forming a low-pass filter circuit. This creates a mismatch in the second frequency band, which helps suppress harmonics of the second antenna, reduces the impact of the second antenna on the first antenna, and improves the isolation between the first and second antennas.

[0009] Similarly, the electrical length of the second stub is less than or equal to one-quarter of the dielectric wavelength. This second stub can then be equivalent to a series inductor and capacitor, forming a low-pass filter circuit. This creates a mismatch in the second frequency band, which helps suppress harmonics of the second antenna, reduces the impact of the second antenna on the first antenna, and improves the isolation between the first and second antennas.

[0010] This application also offers a variety of options for the shape of the first and second branches.

[0011] For example, if the first stub is a straight strip, its structure is relatively simple. Alternatively, the first stub may have a bend near its open end to increase its electrical length, which is beneficial for setting a longer first stub in a small space, thereby improving its suppression performance. Alternatively, the first stub may include a first sub-stub and a second sub-stub. One end of the first sub-stub is connected to the coplanar waveguide transmission line, and the other end forms an interdigital capacitor with the second sub-stub. The end of the second sub-stub facing away from the first sub-stub is an open end. The interdigital capacitance of the first stub itself can provide a certain capacitance value, thereby improving filtering performance and the isolation between the first and second antennas.

[0012] Similarly, if the second stub is a straight strip, its structure is relatively simple. Alternatively, the second stub may have a bend near its open end to increase its electrical length, which is beneficial for placing a longer electrical stub in a small space, thereby improving its suppression performance. Alternatively, the second stub may include a fifth sub-stub and a sixth sub-stub. One end of the fifth sub-stub is connected to the coplanar waveguide transmission line, and the other end forms an interdigital capacitor with the sixth sub-stub. The end of the sixth sub-stub facing away from the fifth sub-stub is an open end. The interdigital capacitance of the second stub itself can provide a certain capacitance value, thereby improving filtering performance and the isolation between the first and second antennas.

[0013] In the embodiments of this application, the first branch and the second branch can be the same or different.

[0014] In this application's technical solution, the first unit floor is connected to a third branch. One end of the third branch is electrically connected to the first feed line, and the other end is an open end. The third branch is located within the first unit floor. Setting the third branch allows adjustment of the antenna balun, thereby reducing the influence of the first feed line on the radiation pattern of the first antenna.

[0015] In this embodiment, the shape of the third branch can be chosen in various ways. For example, the third branch includes a third sub-branch and a fourth sub-branch, with one end of the third sub-branch electrically connected to the first feeder line and the other end electrically connected to the fourth sub-branch. The third and fourth sub-branches are arranged perpendicularly. This allows for a longer third branch within a smaller space, thus improving its effectiveness. For example, the third and fourth sub-branches can form a T-shaped branch, or they can form an L-shaped branch.

[0016] For the second antenna, a first slot is provided on the side of the second radiator facing the second unit floor. The second antenna also includes a second coaxial line, the second feed point of which is close to the second unit floor. When the first antenna is working, the current coupled from the first antenna to the second antenna is more concentrated near the first slot, thereby avoiding the second feed point of the second antenna and further improving the isolation between the first and second antennas.

[0017] In a further technical solution, a second slot is provided on the side of the second unit floor facing the second radiator. This helps to further improve the isolation between the first antenna and the second antenna.

[0018] Specifically, when setting the first and second slots, the first and second slots are arranged symmetrically along the first direction. This helps to improve the symmetry of the second antenna, thereby improving the roundness of the second antenna's direction pattern.

[0019] In one technical solution, the first groove is an L-shaped groove. The first groove can be made relatively long and has a simple shape, which facilitates the simplification of the design process.

[0020] In the specific technical solution, the first frequency band is lower than the second frequency band. This is beneficial for improving the coexistence characteristics of the first and second antennas.

[0021] Secondly, this application also provides a communication terminal, which includes a housing and the antenna system provided in the first aspect, wherein the antenna system is disposed in the housing. In this solution, the antenna system can achieve communication in different frequency bands, and the first and second antennas share the same aperture, which helps to reduce the size of the communication terminal. Furthermore, the first and second antennas have high isolation and good coexistence characteristics. This solution can improve the radiation efficiency of the first and second antennas, thereby increasing the throughput rate of the antenna terminal. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a communication terminal in an embodiment of this application;

[0023] Figure 2 This is a schematic diagram of the side structure of an antenna system in an embodiment of this application;

[0024] Figure 3 This is a schematic diagram of the structure of the first surface of the antenna system in an embodiment of this application;

[0025] Figure 4 This is a schematic diagram of the structure of the second surface of the antenna system in an embodiment of this application;

[0026] Figure 5 This is a partially enlarged schematic diagram of the first antenna in an embodiment of this application;

[0027] Figure 6 This is a schematic diagram of the standing wave (SWR) and impedance characteristics of an open circuit.

[0028] Figure 7 This is an equivalent circuit diagram of the first branch in the embodiments of this application;

[0029] Figure 8 This is a schematic diagram of the structure of the first surface of the antenna system in an embodiment of this application;

[0030] Figure 9 This is a partially enlarged schematic diagram of the antenna system in an embodiment of this application;

[0031] Figure 10 This is a Smith chart comparison diagram of the first antenna in the embodiments of this application;

[0032] Figure 11 This is a schematic diagram comparing the return loss of the first antenna in the embodiments of this application;

[0033] Figure 12 This is a schematic diagram comparing the radiation efficiency of the first antenna in an embodiment of this application;

[0034] Figure 13 This is a schematic diagram of a local coupling current of the first antenna in an embodiment of this application;

[0035] Figure 14 This is a partially enlarged schematic diagram of the first antenna in an embodiment of this application;

[0036] Figure 15 This is a partially enlarged schematic diagram of the first antenna in an embodiment of this application;

[0037] Figure 16 This is a partially enlarged schematic diagram of the second antenna in an embodiment of this application;

[0038] Figure 17 This is a schematic diagram comparing the isolation of the first antenna and the second antenna in an embodiment of this application;

[0039] Figure 18 This is a partially enlarged schematic diagram of the second antenna in an embodiment of this application;

[0040] Figure 19 This is a partially enlarged schematic diagram of the second antenna in an embodiment of this application;

[0041] Figure 20 This is a partially enlarged schematic diagram of the first antenna in an embodiment of this application;

[0042] Figure 21 This is an efficiency comparison chart of the first antenna in an embodiment of this application;

[0043] Figure 22 This is an efficiency comparison chart of the second antenna in an embodiment of this application;

[0044] Figure 23 This is a schematic diagram of the isolation between the first antenna and the second antenna in an embodiment of this application;

[0045] Figure 24 This is a comparative diagram of the radiation pattern of an antenna system in an embodiment of this application.

[0046] Figure label:

[0047] 100 - Antenna system; 200 - Housing;

[0048] 300 - RF chip; 400 - Feeder cable;

[0049] 1-Dielectric plate; 11-First surface;

[0050] 12 - Second surface; 2 - First antenna;

[0051] 21-First unit floor; 211-Third branch;

[0052] 2111 - Third sub-node; 2112 - Fourth sub-node;

[0053] 22 - First radiator; 23 - Third radiator;

[0054] 24 - Coplanar waveguide transmission line; 25 - First feed point;

[0055] 26 - First feeder line; 27 - First stub;

[0056] 271 - Bend; 272 - First sub-node;

[0057] 273 - Second sub-node; 28 - Second sub-node;

[0058] 3-Second daytime rail; 31-Second unit floor;

[0059] 311 - Second slot; 32 - Second radiator;

[0060] 321 - First slot; 33 - Fourth radiator;

[0061] 34 - Fifth radiator; 35 - Second coaxial line;

[0062] 36 - Second feed point; 37 - Second feed line;

[0063] Z - First direction. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0065] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more” unless the context clearly indicates otherwise.

[0066] References to “an embodiment” or “a specific embodiment” as used in this specification mean that one or more embodiments of this application include a particular feature, structure, or characteristic described in connection with that embodiment. The terms “comprising,” “including,” “having,” and variations thereof mean “including, but not limited to,” unless otherwise specifically emphasized.

[0067] The following explains the terminology that may appear in the embodiments of this application.

[0068] Radiator: In an antenna, this is the device used to receive / transmit electromagnetic wave radiation. In some cases, the term "antenna" is narrowly defined as a radiator, which converts guided wave energy from the transmitter into radio waves, or converts radio waves into guided wave energy, for radiating and receiving radio waves. The modulated high-frequency current energy (or guided wave energy) generated by the transmitter is transmitted to the transmitting radiator via a feed line, where it is converted into electromagnetic wave energy of a specific polarization and radiated in the desired direction. The receiving radiator converts the electromagnetic wave energy of a specific polarization from a specific direction in space back into modulated high-frequency current energy, which is then transmitted to the receiver input via a feed line.

[0069] Radio frequency (RF) chip: This is the combination of all components of an antenna used for receiving and transmitting radio frequency waves. In the case of a receiving antenna, the RF chip can be considered as the antenna section from the first amplifier to the front-end transmitter. In a transmitting antenna, the RF chip can be seen as the section after the last power amplifier. In some cases, the RF chip can also be understood as the feed unit. The RF chip has the function of converting radio waves into electrical signals and sending them to the receiver components. Generally, it is considered part of the antenna system for converting radio waves into electrical signals and vice versa. Maximum power transfer capability and efficiency should be considered when designing an antenna. For this purpose, the antenna feed impedance must be matched with the load resistance. The antenna feed impedance is a combination of resistance, capacitance, and inductance. To ensure maximum power transfer conditions, the two impedances (load resistance and feed impedance) should be matched. Matching can be achieved by considering frequency requirements and antenna design parameters such as gain, directivity, and radiation efficiency.

[0070] Feed line: Also called a transmission line, it refers to the connection line between the antenna's radio frequency chip and the radiator. Depending on the frequency and form, the transmission line can directly transmit current waves or electromagnetic waves. The connection point on the radiator where it connects to the transmission line is usually called the feed point. Transmission lines include conductive transmission lines, coaxial transmission lines, waveguides, or microstrip lines. Depending on the implementation, transmission lines can include bracket antenna bodies or glass antenna bodies. Depending on the carrier, transmission lines can be implemented using LCP (Liquid Crystal Polymer), FPC (Flexible Printed Circuit), or PCB (Printed Circuit Board), etc.

[0071] Communication / Operating Frequency Band: Regardless of the type of antenna, it always operates within a certain frequency range (bandwidth). For example, an antenna supporting the B40 band operates within the frequency range of 2300MHz to 2400MHz, or in other words, its operating frequency band includes the B40 band. The frequency range that meets the specifications can be considered the antenna's operating frequency band. The width of the operating frequency band is called the operating bandwidth. The operating bandwidth of an omnidirectional antenna may reach 3-5% of the center frequency. The operating bandwidth of a directional antenna may reach 5-10% of the center frequency. Bandwidth can be considered as a frequency range on both sides of the center frequency (e.g., the resonant frequency of a dipole), where the antenna characteristics are within the acceptable range of the center frequency.

[0072] The resonant frequency band and the operating frequency band can be the same or different, or their frequency ranges can partially overlap. In one embodiment, the resonant frequency band of the antenna can cover multiple operating frequency bands of the antenna.

[0073] Medium wavelength: refers to the wavelength of electromagnetic waves propagating in a medium at the operating frequency band. For example, if the operating frequency band is [f1, f2], the corresponding medium wavelength is also the range [w1, w2]. Alternatively, to simplify calculations, the above-mentioned medium wavelength can also refer to the wavelength of electromagnetic waves propagating in the medium at the center frequency f0 of the operating frequency band. In this case, the medium wavelength is a specific value w0.

[0074] Antenna return loss: This can be understood as the ratio of the signal power reflected back to the antenna port after passing through the antenna circuit to the transmit power at the antenna port. The smaller the reflected signal, the larger the signal radiated into space through the antenna, and the higher the antenna's radiation efficiency. Conversely, the larger the reflected signal, the smaller the signal radiated into space through the antenna, and the lower the antenna's radiation efficiency.

[0075] Antenna return loss can be represented by the S11 parameter, which is one of the S-parameters. S11 represents the reflection coefficient, and this parameter characterizes the antenna's transmission efficiency.

[0076] In one embodiment, the S11 diagram can be understood as a schematic diagram representing the resonance generated by the antenna. In one embodiment, the resonance shown in the S11 diagram within the range of -6dB can be understood as the resonant frequency / frequency range / operating frequency band generated by the antenna. The S11 parameter is usually negative. The smaller the S11 parameter, the smaller the antenna return loss, the less energy reflected back by the antenna itself, which means more energy actually enters the antenna, and the higher the antenna radiation efficiency; the larger the S11 parameter, the greater the antenna return loss, and the lower the antenna radiation efficiency.

[0077] It should be noted that in engineering, an S11 value of -6dB is generally used as the standard. When the S11 value of an antenna is less than -6dB, the antenna can be considered to be working normally, or the antenna can be considered to have good transmission efficiency.

[0078] Radiation efficiency refers to the ratio of the power radiated by an antenna into space (i.e., the power effectively converted into electromagnetic waves) to the active power input to the antenna. The active power input to the antenna equals the antenna's input power minus the power loss. Power loss mainly includes return loss power, ohmic loss power of the metal, and / or dielectric loss power. Both metal loss and dielectric loss are factors affecting radiation efficiency.

[0079] Those skilled in the art will understand that radiation efficiency is generally expressed as a percentage, and there is a corresponding conversion relationship between it and dB. The closer the radiation efficiency is to 0 dB, the better the radiation efficiency of the antenna.

[0080] dB: This stands for decibel, a logarithmic concept with base 10. Decibels are used to evaluate the proportional relationship between two physical quantities; they themselves have no physical dimensions. For every 10-fold increase in the ratio between two quantities, their difference can be expressed as 10 decibels. For example: A = 100, B = 10, C = 5, D = 1, then A / D = 20 dB; B / D = 10 dB; C / D = 7 dB; B / C = 3 dB. In other words, a 10-decibel difference between two quantities is a 10-fold difference, a 20-decibel difference is a 100-fold difference, and so on. A 3-decibel difference is a 2-fold difference between the two quantities.

[0081] The term "end" in the context of the main radiator's first / second / third / fourth / grounded / open ends should not be narrowly interpreted as a point or end physically disconnected from other radiators. It can also refer to a segment of the main radiator including the first endpoint, which is the endpoint of the main radiator at the gap. For example, the first end of the main radiator can be considered a segment of the main radiator within a range of one-eighth of a first wavelength from the first endpoint. The first wavelength can be the wavelength corresponding to the operating frequency band of the main radiator, the wavelength corresponding to the center frequency of the operating frequency band, or the wavelength corresponding to the resonant point. In one embodiment, "end / point" can include a connection / coupling region on the radiator that is coupled to other conductive structures. For example, a feed end / feed point can be a coupling region on the antenna radiator that is coupled to a feed structure (e.g., a region facing a part of the feed structure). Similarly, a ground end / grounding point can be a connection / coupling region on the antenna radiator that is coupled to a ground structure.

[0082] Open and Closed Terminals: In some embodiments, open and closed terminals are defined relative to whether or not they are grounded; the closed terminal is grounded, and the open terminal is not grounded. In one embodiment, the open terminal may also be referred to as a floating terminal, a free terminal, an open terminal, or an open-circuit terminal. In one embodiment, the closed terminal may also be referred to as a grounded terminal or a short-circuit terminal. It should be understood that in some embodiments, other conductors can be coupled through the open terminal to transfer coupled energy (which can be understood as transferring current).

[0083] In some embodiments, the open end and the closed end are, for example, relative to other conductors, with the closed end electrically connected to other conductors and the open end not electrically connected to other conductors.

[0084] To put it simply, the "open end" of a radiator can be defined as one end of the radiator that is spaced apart from the floor or coupled to the floor through a capacitive device.

[0085] To put it simply, the "grounding terminal" of a radiator can be understood as: if one end of the radiator is directly connected to the floor or coupled to the floor through an inductive device, it can be regarded as the grounding terminal of the radiator.

[0086] In some embodiments, the understanding of "closed end" can also be from the perspective of current distribution. A closed end or ground end can be understood as a point of high current or low electric field on a radiator. In one embodiment, coupling electronic devices (e.g., inductive devices) through a closed end can maintain the current distribution characteristics of the point of high current / low electric field. In one embodiment, opening a slit at or near the closed end (e.g., filling the slit with insulating material) can maintain the current distribution characteristics of the point of high current / low electric field.

[0087] In some embodiments, the understanding of "open terminal" can also be from the perspective of current distribution. An open terminal or a floating terminal can be understood as a point with a small current or a point with a large electric field on the radiator. In one embodiment, coupling electronic devices (e.g., capacitive devices) through an open terminal can maintain the current distribution characteristics of the point with a small current or a large electric field.

[0088] It should be understood that when an electronic device (e.g., capacitor, inductor, etc.) is coupled at the radiator end of a gap (which, from the perspective of the radiator's structure, resembles a radiator at the opening of an open or suspended end), the radiator end can be a point with a large current / small electric field. In this case, it should be understood that the radiator end at the gap is actually a closed end or a grounded end, etc.

[0089] Electrical length: Electrical length can be expressed as the ratio of physical length (i.e., mechanical length or geometric length) multiplied by the time it takes for an electrical or electromagnetic signal to travel in a medium to the time required for that signal to travel a distance in free space equal to the physical length of the medium. Electrical length can be expressed by the following formula:

[0090]

[0091] Where L is the physical length, a is the transmission time of the electrical or electromagnetic signal in the medium, and b is the transmission time in free space.

[0092] Alternatively, electrical length can also refer to the ratio of physical length (i.e., mechanical length or geometric length) to the wavelength of the transmitted electromagnetic wave, and electrical length can satisfy the following formula:

[0093]

[0094] Where L is the physical length and λ is the wavelength of the electromagnetic wave.

[0095] In some embodiments of this application, the physical length of the radiator can be understood as within ±20% of the electrical length of the radiator, for example, within ±10% or within ±5%.

[0096] In the embodiments of this application, the wavelength in a certain wavelength mode of the antenna (such as half-wavelength mode, etc.) can refer to the wavelength of the signal radiated by the antenna. It should be understood that the wavelength of the radiated signal in air can be calculated as follows: wavelength = speed of light / frequency, where the frequency is the frequency of the radiated signal. The wavelength of the radiated signal in a medium can be calculated as follows: wavelength = (speed of light / √ε) / frequency, where ε is the relative permittivity of the medium, and the frequency is the frequency of the radiated signal.

[0097] To facilitate understanding of the communication terminal provided in this application embodiment, its application scenario is first introduced below. The communication terminal in this application embodiment refers to a terminal with communication functions. Specifically, it can refer to a communication terminal employing one or more of the following communication technologies: Bluetooth (BT) communication technology, Global Positioning System (GPS) communication technology, Wireless Fidelity (WiFi) communication technology, Global System for Mobile Communications (GSM) communication technology, Wideband Code Division Multiple Access (WCDMA) communication technology, Long Term Evolution (LTE) communication technology, 5G communication technology, and other future communication technologies. The communication terminal in this application embodiment can include a fixed terminal or a mobile terminal. For example, a mobile terminal can be a mobile phone, tablet computer, laptop computer, smart bracelet, smartwatch, smart helmet, and smart glasses; a fixed terminal can be a router, smart TV, smart home device, smart speaker, and desktop computer. In addition, the aforementioned communication terminal may also be a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a communication terminal in a 5G network, or a communication terminal in a future evolved public land mobile network (PLMN), etc., and the embodiments of this application are not limited to this.

[0098] Figure 1 This is a schematic diagram of the structure of a communication terminal in an embodiment of this application. Figure 1 Taking a router as an example in Sino-Singapore communication terminals, such as Figure 1 As shown, the communication terminal in this embodiment includes an antenna system 100 and a housing 200. The antenna system 100 is mounted on the housing 200 and is used to realize the communication capability of the communication terminal. The communication terminal also includes a radio frequency (RF) chip 300, which is electrically connected to the antenna system 100 via a feed line 400 to realize signal transmission. Furthermore, the communication terminal in this embodiment may also include an RF front-end module, which is connected between the RF chip 300 and the antenna system 100.

[0099] Figure 2 This is a schematic diagram of a side structure of the antenna system 100 in an embodiment of this application, as shown below. Figure 2As shown, the antenna system 100 in this embodiment includes a dielectric substrate 1, a first antenna 2, and a second antenna 3. The first antenna 2 operates in a first frequency band, and the second antenna 3 operates in a second frequency band. The first and second frequency bands are different. In this embodiment, the antenna system 100 can operate in at least two frequency bands, which is beneficial for improving the coverage and throughput performance of the communication terminal. The first antenna 2 and the second antenna 3 are respectively disposed on two sides of the dielectric substrate 1, which is beneficial for improving the integration of the antenna system 100. The first antenna 2 and the second antenna 3 share the same aperture, which is beneficial for miniaturizing the communication terminal. For ease of description, the two opposing surfaces of the dielectric substrate 1 are considered to be the first surface 11 and the second surface 12, that is, the dielectric substrate 1 includes the opposing first surface 11 and the second surface 12. The first antenna 2 is disposed on the first surface 11 of the dielectric substrate 1, and the second antenna 3 is mainly disposed on the second surface 12 of the dielectric substrate 1.

[0100] Figure 3 This is a schematic diagram of the structure of the first surface 11 of the antenna system 100 in this embodiment of the application. Figure 4 This is a schematic diagram of the structure of the second surface 12 of the antenna system 100 in an embodiment of this application. Figures 2-4 As shown, specifically, the first antenna 2 includes a first unit ground plane 21 and a first radiator 22 arranged adjacently along the first direction Z, which are disposed on the first surface 11 of the dielectric substrate 1. The second antenna 3 includes a second unit ground plane 31 and a second radiator 32 arranged adjacently along the first direction Z, which are disposed on the second surface 12. It is worth noting that, in addition to the first radiator 22, the first antenna 2 may also include a third radiator 23, which can be arranged with the first radiator 22 along the first direction Z. Furthermore, in addition to the second radiator 32, the second antenna 3 may also include a fourth radiator 33 disposed on the second surface 12, which can be arranged with the second radiator 32 along the first direction Z; the second antenna 3 may also include a fifth radiator 34 disposed on the first surface 11 to fully utilize the space of the first surface 11 of the dielectric substrate 1 and improve the communication performance of the second antenna 3.

[0101] In one embodiment, the orthographic projection of the fifth radiator 34 onto the dielectric plate 1 is located within the orthographic projection of the fourth radiator 33 onto the dielectric plate 1.

[0102] Figure 5 This is a partially enlarged schematic diagram of the first antenna 2 in an embodiment of this application. Figure 5 Specifically, it can be Figure 3 A magnified view of point A in the diagram. (See diagram below.) Figure 3 and Figure 5As shown, the first antenna 2 also includes a coplanar waveguide transmission line 24 (CPW), which is a high-performance and easy-to-fabricate microwave planar transmission line. The CPW can be directly formed on the first surface 11 of the dielectric substrate 1 and can be fabricated in the same process as the first radiator 22 and various radiators on the first surface 11. The end of the CPW adjacent to the first unit ground plane 21 is a first feed point 25. The first feed point 25 is connected to a first feed wire 26 to receive the feed signal and feed the first radiator 22 and other radiators of the first antenna 2. In a specific embodiment, the first feed wire 26 can be a first coaxial line. A first stub 27 is connected to the end of the CPW facing the first feed point 25. The first stub 27 is located on the side of the first radiator 22 facing the first unit ground plane 21. One end of the first stub 27 is electrically connected to the CPW 24, and the other end is an open end.

[0103] In this embodiment, the first antenna 2 and the second antenna 3 of the antenna system 100 are integrated on both sides of the dielectric substrate 1, forming a dual-frequency common-port wireless network communication technology (Wi-Fi) high-gain duplex antenna. This solution overcomes the problem of increased product space and material costs caused by designing separate antennas. In other words, this solution helps reduce the space occupied by the antenna system 100 and lowers its cost. Since the first antenna 2 and the second antenna 3 share the same aperture, isolation issues can easily arise, limiting the performance of the antenna system 100. Therefore, this application connects a first stub 27 to the coplanar waveguide transmission line 24 near the first feed point 25. This first stub 27 acts as a filter and decoupler, suppressing inter-frequency signals and improving the isolation between the first antenna 2 and the second antenna 3. This, in turn, helps improve the gain of the antenna system 100 and enhances the coexistence performance of the first antenna 2 and the second antenna 3. Furthermore, the first stub 27 in this solution has a simple structure and is integrated with the antenna structure, eliminating the need for additional filter designs and other structures, thus helping to reduce the cost of the antenna system 100. This improves the radiation efficiency of the first antenna 2 and the second antenna 3, thereby increasing the throughput rate of the antenna terminal.

[0104] In one embodiment, the first frequency band is lower than the second frequency band. For example, the first frequency band is 2.400 GHz to 2.4835 GHz, and the second frequency band is 5.150 GHz to 5.850 GHz. The first antenna 2 is a 2.4 GHz antenna, and the second antenna 3 is a 5 GHz antenna. Figures 2 to 4In the illustrated embodiment, the first antenna 2 includes two radiators, and the second antenna 3 includes four radiators, with some of the radiators of the second antenna 3 located on the first surface 11. In this embodiment, by connecting the first stub 27 to the coplanar waveguide transmission line 24, not only can the first antenna 2 generate a filtering response to suppress the harmonic signals of the second frequency band of the second antenna 3, but the distribution of the mutual coupling current between the common-aperture antennas can also be changed, causing the mutual coupling current to avoid the position of the first feed point 25, thereby achieving decoupling of the two antennas and improving the isolation between the first antenna 2 and the second antenna 3.

[0105] Specifically, Figure 6 This is a schematic diagram of the standing wave (SWR) and impedance characteristics of an open circuit. Figure 7 This is an equivalent circuit diagram of the first branch 27 in one embodiment of this application. In one embodiment of this application, the electrical length of the first branch 27 is equal to one-quarter of the dielectric wavelength. Figure 6 As shown, the standing wave (SWR) characteristic of the first stub 27 is equivalent to that of an inductor and a capacitor connected in series, and the first stub 27 itself can also be considered an inductor. Therefore, the equivalent circuit diagram of the first stub 27 is as follows. Figure 7 As shown, the first stub 27 can be equivalent to a low-pass filter circuit, which generates mismatch in the second frequency band, thereby helping to suppress the harmonics of the second antenna 3, reduce the influence of the second antenna 3 on the first antenna 2, and improve the isolation between the first antenna 2 and the second antenna 3.

[0106] In another embodiment of this application, the electrical length of the first branch 27 can also be less than one-quarter of the dielectric wavelength. For example... Figure 5 As shown, the standing wave (SWR) characteristic of the first branch 27 is equivalent to that of a capacitor, and the first branch 27 itself can also be considered as an inductor. Therefore, the equivalent circuit diagram of the first branch 27 is also as shown. Figure 7 As shown, the first stub 27 can also be equivalent to a low-pass filter circuit, generating mismatch in the second frequency band, which helps suppress the harmonics of the second antenna 3, reduces the impact of the second antenna 3 on the first antenna 2, and improves the isolation between the first antenna 2 and the second antenna 3. In addition, the electrical length of the first stub 27 in this scheme can be designed to be smaller, which helps to reduce the space occupied by the first stub 27 and improves the miniaturization requirements of the antenna system 100.

[0107] Figure 8 This is a schematic diagram of the structure of the first surface 11 of the antenna system 100 in an embodiment of this application. Figure 9 This is a partially enlarged schematic diagram of the antenna system 100 in an embodiment of this application. Specifically, Figure 9 for Figure 8 A magnified view of a section at point B. (See image below.) Figure 8 and Figure 9As shown, in another embodiment, the coplanar waveguide transmission line 24 is further connected to a second stub 28 at one end facing the feed point. This second stub 28 is adjacent to the first stub 27, and one end of the second stub 28 is electrically connected to the coplanar waveguide transmission line 24, while the other end is an open end. In this scheme, the coplanar waveguide transmission line 24 is connected with two stubs, which can further suppress harmonics in the second frequency band and improve the suppression degree.

[0108] Similar to the first branch 27, the electrical length of the second branch 28 is less than or equal to one-quarter of the dielectric wavelength. For a related description, please refer to the description of the first branch 27, which will not be repeated here.

[0109] Figure 10 This is a Smith chart comparison diagram of the first antenna 2 in an embodiment of this application. Figure 11 This is a schematic diagram comparing the return loss of the first antenna 2 in an embodiment of this application. Figure 12 This is a schematic diagram comparing the radiation efficiency of the first antenna 2 in an embodiment of this application. Figures 10-12 The medium-thickness lines represent the curves of the first antenna 2 without the first stub 27 and the second stub 28, the thinnest lines represent the curves of the first antenna 2 with the first stub 27, and the thickest lines represent the curves of the first antenna 2 with both the first stub 27 and the second stub 28. For example... Figure 10 and Figure 11 As shown, the matching of the first antenna 2 with only the first stub 27 deteriorates in the second frequency band, thus improving the suppression performance; the matching of the first antenna 2 with both the first stub 27 and the second stub 28 deteriorates further in the second frequency band, thus further improving the suppression performance. Figure 12 As shown, the first antenna 2 with only the first stub 27 improves the radiation efficiency in the first frequency band, but reduces the radiator efficiency in the second frequency band. The first antenna 2 with both the first stub 27 and the second stub 28 further improves the radiation efficiency in the first frequency band, but further reduces the radiator efficiency in the second frequency band.

[0110] In addition to filtering the target frequency band, the settings of the first branch 27 and the second branch 28 can also be combined with same-frequency decoupling. Figure 13 This is a schematic diagram of a partial coupling current of the first antenna 2 in an embodiment of this application, as shown below. Figure 13 As shown, when the second antenna 3 is working, the currents of the second antenna 3 coupled to the first stub 27 and the second stub 28 of the first antenna 2 are reverse currents. That is, the direction of the current of the second antenna 3 coupled to the first stub 27 is opposite to the direction of the current of the second antenna 3 coupled to the second stub 28. The currents of the two stubs cancel each other out, reducing the current of the second antenna 3 coupled to the feed point of the first antenna 2, thereby further improving the isolation.

[0111] like Figure 13 As shown, in one embodiment, the second stub 28 is arranged parallel to the first stub 27. This arrangement helps reduce the space occupied by the first stub 27 and the second stub 28, and also helps to generate reverse current in the first stub 27 and the second stub 28, thereby improving the suppression of the first antenna 2.

[0112] In this embodiment, the specific shapes of the first branch 27 and the second branch 28 can be varied. For example, in one embodiment, such as... Figure 13 As shown, the first branch 27 are all straight branches, and the second branch 28 can also be a straight branch. Figure 14 This is a partially enlarged schematic diagram of the first antenna 2 in an embodiment of this application, as shown below. Figure 14 As shown, in one embodiment, the first branch 27 has a bend 271 on the side near the open end. This design can increase the electrical length of the first branch 27, which is beneficial for setting a first branch 27 with a longer electrical length in a small space, thereby improving the suppression of the first branch 27. Similarly, the second branch 28 can also have a bend 271 on the side near the open end, which will not be described in detail here.

[0113] Figure 15 This is a partially enlarged schematic diagram of the first antenna 2 in an embodiment of this application, as shown below. Figure 15 As shown, in one embodiment, the first stub 27 includes a first sub-stub 272 and a second sub-stub 273. One end of the first sub-stub 272 is connected to the coplanar waveguide transmission line 24, and the other end forms an interdigital capacitor with the second sub-stub 273. The end of the second sub-stub 273 facing away from the first sub-stub 272 is an open end. In this scheme, the interdigital capacitor of the first stub 27 itself can provide a certain capacitance value, thereby improving the filtering performance and the isolation between the first antenna 2 and the second antenna 3. Similarly, the second stub 28 can also be an interdigital capacitor.

[0114] In the embodiments of this application, the first branch 27 and the second branch 28 may be the same or different, and this application does not impose any restrictions on this. In some embodiments, the second branch 28 is not completely identical to the first branch 27, but it can still satisfy the description of the first branch 27 in the embodiments of this application, that is, the second branch 28 can also satisfy the characteristics of the first branch 27 to produce the corresponding technical effects, which will not be elaborated here.

[0115] Figure 16 This is a partially enlarged schematic diagram of the second antenna 3 in an embodiment of this application. Specifically, Figure 16 It can be Figure 4 A magnified view of a section at point C. (See image below.) Figure 4 and Figure 16As shown, in one embodiment, a first slot 321 is provided on the side of the second radiator 32 of the second antenna 3 facing the second unit floor 31. The second antenna 3 also includes a second coaxial line 35, the second feed point 36 of which is close to the second unit floor 31. The second feed point 36 of the second coaxial line 35 is connected to a second feed wire 37 to feed the second antenna 3. In a specific example, the second feed wire 37 can be a third coaxial line. In this embodiment, by providing the first slot 321 on the side of the second radiator 32 facing the second unit floor 31, when the first antenna 2 is working, the current coupled from the first antenna 2 to the second antenna 3 is more concentrated near the first slot 321, thereby avoiding the second feed point 36 of the second antenna 3, which is beneficial to further improve the isolation between the first antenna 2 and the second antenna 3.

[0116] Figure 17 This is a schematic diagram comparing the isolation of the first antenna 2 and the second antenna 3 in an embodiment of this application, as shown below. Figure 17 As shown in the figure, the lines respectively represent the S-parameter curves of the second antenna 3 without the first stub 27, the second stub 28, and the first slot 321; the S-parameter curves of the second antenna 3 with the first stub 27 but without the second stub 28 and the first slot 321; the S-parameter curves of the second antenna 3 with the first stub 27 and the second stub 28 but without the first slot 321; and the S-parameter curves of the second antenna 3 with the first stub 27, the second stub 28, and the first slot 321. Figure 17 As shown, this scheme helps to improve the isolation between the second antenna 3 and the first antenna 2, and improves the coexistence performance of the first antenna 2 and the second antenna 3.

[0117] Figure 18 This is a partially enlarged schematic diagram of the second antenna 3 in an embodiment of this application. Please refer to... Figure 18 In one embodiment, a second slot 311 is provided on the side of the second unit floor 31 facing the second radiator 32. This design helps to further improve the isolation between the first antenna 2 and the second antenna 3.

[0118] Please continue to refer to this. Figure 18 In some embodiments, the first groove 321 and the second groove 311 can be arranged symmetrically along the first direction Z, and the axis of symmetry of the first groove 321 and the second groove 311 is perpendicular to the first direction Z. This arrangement is beneficial for improving the symmetry of the second antenna 3, thereby improving the roundness of the orientation pattern of the second antenna 3.

[0119] In this application, the specific shapes of the first groove 321 and the second groove 311 can be selected in various ways, for example, Figure 18 In the embodiment shown, the first slot 321 and the second slot 311 are elongated. Figure 19This is a partially enlarged schematic diagram of the second antenna 3 in an embodiment of this application, as shown below. Figure 19 As shown, in one specific embodiment, the first groove 321 is an L-shaped groove. In this design, the first groove 321 can be made relatively long and has a simple shape, which simplifies the design process.

[0120] Figure 20 This is a partially enlarged schematic diagram of the first antenna 2 in an embodiment of this application, as shown below. Figure 20 As shown, in one embodiment, a third branch 211 is connected to the first unit floor 21. One end of the third branch 211 is electrically connected to the first feed line 26, and the other end is an open end. The third branch 211 is located within the first unit floor 21. Along the second direction, the third branch 211 is located between the first unit floor 21 and the first feed line 26. In this scheme, the third branch 211 can adjust the balun of the antenna, thereby reducing the influence of the first feed line 26 on the radiation pattern of the first antenna 2.

[0121] Figure 21 This is an efficiency comparison diagram of the first antenna 2 in an embodiment of this application. The thick line in the diagram represents the antenna efficiency curve of the first antenna 2 in the antenna system 100 without any branches or slots, and the thin line represents the antenna efficiency curve of the first antenna 2 in the antenna system 100 with the first branch 27, the second branch 28, the third branch 211, the first slot 321, and the second slot 311. Figure 21 As shown, in one embodiment, the first antenna 2 has comparable efficiency in the first frequency band, while its suppression of the second frequency band is improved.

[0122] Figure 22 This is an efficiency comparison diagram of the second antenna 3 in an embodiment of this application. The solid line in the diagram represents the antenna efficiency curve of the second antenna 3 in the antenna system 100 without any branches or slots, and the thin line represents the antenna efficiency curve of the second antenna 3 in the antenna system 100 with the first branch 27, the second branch 28, the third branch 211, the first slot 321, and the second slot 311. Figure 22 As shown, in one embodiment, the second antenna 3 has comparable efficiency in the second frequency band, while its suppression of the first frequency band is improved.

[0123] Figure 23 This is a schematic diagram of the isolation between the first antenna and the second antenna in an embodiment of this application, as shown below. Figure 23 As shown in the embodiment of this application, two decoupling pits can be generated, which significantly improves the isolation and enhances the coexistence performance of the first antenna and the second antenna.

[0124] In specific embodiments, at least one of the structures mentioned in the various embodiments of this application, such as the first branch 27, the second branch 28, the third branch 211, the first slot 321, and the second slot 311, is symmetrical about the first direction Z, that is, the axis of symmetry is parallel to the first direction Z. Alternatively, any structure among the first branch 27, the second branch 28, the third branch 211, the first slot 321, and the second slot 311 can be symmetrical about the first direction Z. This scheme is beneficial for improving the roundness of the radiation pattern of the antenna system 100.

[0125] Figure 24 This is a radiation pattern comparison diagram of the antenna system 100 in the embodiments of this application, such as... Figure 24 As shown in the embodiment of this application, the antenna system 100 maintains good radiation pattern performance in various operating frequency bands, and the main beam of the antenna is located in the horizontal plane. Compared with the original antenna, the horizontal plane radiation pattern gain is comparable to that of the original antenna.

[0126] In this embodiment, the shape of the third branch 211 can also be selected in various ways, which will not be described in detail here. For example Figure 20 As shown, in one embodiment, the third branch 211 includes a third sub-branch 2111 and a fourth sub-branch 2112. One end of the third sub-branch 2111 is electrically connected to the first feeder line 26, and the other end is electrically connected to the fourth sub-branch 2112. The third sub-branch 2111 and the fourth sub-branch 2112 are arranged vertically. This design is advantageous for setting a longer third branch 211 in a smaller space, thereby improving the effectiveness of the third branch 211. For example, the third branch 211 can be formed as a T-shaped branch, or it can also be formed as an L-shaped branch.

[0127] In the technical solution of this application, the addition of a first branch 27, a second branch 28, a third branch 211, or the opening of a first slot 321 and a second slot 311, etc., all make the structure of the antenna system 100 simpler. In addition to improving the isolation between the first antenna 2 and the second antenna 3, the size and cost of the antenna system 100 are not increased, and no additional insertion loss is introduced.

[0128] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An antenna system, characterized in that, It includes a dielectric substrate, a first antenna, and a second antenna. The first antenna operates in a first frequency band, and the second antenna operates in a second frequency band. The first frequency band and the second frequency band are different. The first antenna includes a first unit ground plane and a first radiator arranged adjacent to each other along a first direction, and the second antenna includes a second unit ground plane and a second radiator arranged adjacent to each other along the first direction. The dielectric substrate includes a first surface and a second surface that are opposite to each other. The first unit ground plane and the first radiator are disposed on the first surface, and the second unit ground plane and the second radiator are disposed on the second surface. The first antenna further includes a coplanar waveguide transmission line. One end of the coplanar waveguide transmission line adjacent to the first unit floor is a first feed point. The end of the coplanar waveguide transmission line facing the first feed point is connected to a first stub. The first stub is located on the side of the first radiator facing the first unit floor. One end of the first stub is electrically connected to the coplanar waveguide transmission line, and the other end is an open end.

2. The antenna system as described in claim 1, characterized in that, The coplanar waveguide transmission line is also connected to a second branch at one end facing the feed point. The second branch is arranged adjacent to the first branch, and one end of the second branch is electrically connected to the coplanar waveguide transmission line, while the other end is an open end.

3. The antenna system as described in claim 2, characterized in that, The second branch is arranged parallel to the first branch.

4. The antenna system according to any one of claims 1 to 3, characterized in that, The electrical length of the first branch is less than or equal to one-quarter of the dielectric wavelength.

5. The antenna system according to any one of claims 1 to 4, characterized in that, The first branch is a straight branch, or the first branch has a bend on the side near the open end.

6. The antenna system according to any one of claims 1 to 5, characterized in that, The first stub includes a first sub-stub and a second sub-stub. One end of the first sub-stub is connected to the coplanar waveguide transmission line, and the other end forms an interdigital capacitance with the second sub-stub. The end of the second sub-stub away from the first sub-stub is an open end.

7. The antenna system according to any one of claims 1 to 6, characterized in that, The first unit floor is connected to a third branch, one end of which is electrically connected to the first feeder line, and the other end is an open end. The third branch is located inside the first unit floor.

8. The antenna system as described in claim 7, characterized in that, The third branch includes a third sub-branch and a fourth sub-branch. One end of the third sub-branch is electrically connected to the first feeder line, and the other end is electrically connected to the fourth sub-branch. The third sub-branch and the fourth sub-branch are arranged perpendicularly.

9. The antenna system according to any one of claims 1 to 8, characterized in that, The second radiator has a first groove on the side facing the second unit floor.

10. The antenna system as claimed in claim 9, characterized in that, The second unit floor has a second groove on the side facing the second radiator.

11. The antenna system as claimed in claim 10, characterized in that, The first groove and the second groove are arranged symmetrically along the first direction.

12. The antenna system according to any one of claims 9 to 11, characterized in that, The first groove is an L-shaped groove.

13. The antenna system according to any one of claims 1 to 12, characterized in that, The first frequency band is lower than the second frequency band.

14. A communication terminal, characterized in that, It includes a housing and an antenna system as described in any one of claims 1 to 13, wherein the antenna system is disposed in the housing.

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