Multi-frequency slot antenna, terminal device and antenna design method

Abstract

The present disclosure relates to the technical field of electronic devices, and specifically provides a multi-frequency slot antenna, a terminal device, and an antenna design method. The antenna is applied to a terminal device, the terminal device includes a metal housing, and the antenna includes: a slot formed in the metal housing, which has opposite first and second ends in the length direction; a feeding terminal spanning across the slot and located between the first and second ends; and a first capacitor disposed in the slot, with two poles of the first capacitor respectively connected to two sides in the width direction of the slot; the operating frequency of the antenna includes multiple resonant frequencies, and in the length direction, the first capacitor is located at a position where the voltage values of the multiple resonant frequencies are all non-zero. The antenna of the present disclosure can increase the effective electrical length of the slot antenna, and the different resonant frequencies of the slot antenna can be adjusted according to the capacitance value at the position of the first capacitor, so that the adjusted resonant frequencies fall within the required frequency range.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electronic devices, and particularly to a multi-band slot antenna, a terminal device, and an antenna design method. Background Art

[0002] With the development of electronic devices, more and more functions can be realized by intelligent wearable devices. Taking a smart watch as an example, it has functions such as motion assistance, satellite positioning, wireless connection, and calling, and these functions all need to rely on the antenna built in the watch to be realized.

[0003] In order to pursue the beauty and texture of the device appearance, more and more intelligent wearable devices adopt a full-metal housing, and at the same time use a slot antenna to realize the antenna function. A slot antenna refers to a long strip-shaped slot opened on a metal housing, and electromagnetic waves are radiated outward through a feed straddling the slot. In order to meet the antenna operating frequency requirements, the length of the slot generating electromagnetic wave resonance is generally 1 / 2 of the first-order resonance wavelength. For wearable devices, their volume is often small, and the design space of the slot antenna is limited, making it difficult to meet the antenna functions of multiple frequency bands. Summary of the Invention

[0004] In order to solve the technical problem that the slot antenna in the related art occupies a large space, a multi-band slot antenna, a terminal device, and an antenna design method are provided in the embodiments of the present disclosure.

[0005] In a first aspect, an embodiment of the present disclosure provides a multi-band slot antenna, which is applied to a terminal device. The terminal device includes a metal housing, and the antenna includes:

[0006] A slot opened on the metal housing. In the length direction, the slot has a first end and a second end located on opposite sides respectively;

[0007] A feed terminal straddling the slot and located between the first end and the second end; and

[0008] A first capacitor provided in the slot. Two poles of the first capacitor are respectively connected to two sides in the width direction of the slot; the operating frequency of the antenna includes multi-order resonance frequencies, and in the length direction, the first capacitor is located at a position where the voltage values of the multi-order resonance frequencies are all non-zero; the first capacitor is used to adjust any one of the multi-order resonance frequencies to a target resonance frequency.

[0009] In some embodiments, the feed terminal is located at a position close to the first end or the second end.

[0010] In some embodiments, the multi-order resonance frequencies include a first resonance and a second resonance, and the first resonance and the second resonance represent any two resonance frequencies among the multi-order resonance frequencies;

[0011] The frequency difference between the first resonance and its corresponding first original resonance is a first difference, and the frequency difference between the second resonance and its corresponding second original resonance is a second difference;

[0012] When the first difference is greater than the second difference, the first capacitor is located in a region where the voltage value of the first resonance is greater than the voltage value of the second resonance;

[0013] When the second difference is greater than the first difference, the first capacitor is located in a region where the voltage value of the first resonance is less than the voltage value of the second resonance.

[0014] In a second aspect, an embodiment of the present disclosure provides a terminal device, including a metal housing, and a first slot antenna and a second slot antenna disposed on the metal housing, where at least one of the first slot antenna and the second slot antenna is a multi-band slot antenna according to any one of the embodiments of the first aspect.

[0015] In some embodiments, the metal housing includes a bottom case and a frame, the first slot antenna and the second slot antenna are disposed on the frame, and the slot length directions of the first slot antenna and the second slot antenna are parallel to the bottom case.

[0016] In some embodiments, the first slot antenna and the second slot antenna are arranged end to end on the frame.

[0017] In some embodiments, the first slot antenna is a Global Positioning System (GPS) L1 antenna, and the second slot antenna is a multi-band slot antenna including a Global Positioning System (GPS) L5 antenna and a Bluetooth antenna.

[0018] In some embodiments, the terminal device is a smart watch, and the shape of the frame is one of the following: circular ring, rectangle, rounded rectangle, or rhombus.

[0019] In a third aspect, an embodiment of the present disclosure provides a design method for a slot antenna, where the slot antenna includes a first slot opened on a metal conductor, and the method includes:

[0020] Obtain the original resonance frequency of the slot antenna;

[0021] Obtain the difference between the original resonance frequency and the target resonance frequency;

[0022] A first capacitor is disposed in the first slot, and two poles of the first capacitor are respectively connected to two sides in the width direction of the first slot; and in the length direction of the first slot, the position of the first capacitor is adjusted according to the difference; or, the capacitance value of the first capacitor is adjusted according to the difference; or, the position and capacitance value of the first capacitor are adjusted according to the difference, so that the operating frequency of the slot antenna is equal to the target resonance frequency.

[0023] In some embodiments, the slot antenna is a multi-band slot antenna, and the operating frequency thereof includes multiple-order resonance frequencies;

[0024] Adjusting the position of the first capacitor according to the difference so that the operating frequency of the slot antenna is equal to the target resonance frequency includes:

[0025] Adjusting the position of the first capacitor according to the difference between each-order target resonance frequency and the corresponding original resonance frequency, so that each-order resonance frequency of the slot antenna is equal to the target resonance frequency.

[0026] The multi-band slot antenna provided by the embodiments of the present disclosure is applied to a terminal device. The terminal device includes a metal housing. The antenna includes a slot opened on the metal housing. The operating frequency of the antenna includes multiple-order resonance frequencies. A feeding terminal is disposed in the slot as an antenna excitation source. A first capacitor also spans across the slot. In the length direction, the first capacitor is located at a position where the voltage values of multiple-order resonance frequencies are all non-zero. By setting a capacitor at a position where the radio wave voltage distribution is non-zero, the effective electrical length of the slot is increased. That is, at the same operating frequency, the required slot length of the antenna is shorter, and the space occupied by the antenna structure is reduced. And the adjustment of the multiple-frequency relationship of multiple-order resonance can be realized by adjusting the position of the first capacitor, and the original multiple-order resonance frequencies are all adjusted to available operating frequencies, and the working requirements of multiple frequencies can be realized by using one antenna structure. Moreover, when adjusting the multiple-order resonance frequencies, by adjusting the regional position of the voltage distribution relationship of the first capacitor in the first resonance and the second resonance, the frequency adjustment of the first resonance and the second resonance can be realized.

[0027] For the multi-band slot antenna provided by the embodiments of the present disclosure, the feeding terminal is located at a position close to the first end or the second end of the slot, that is, the feeding is disposed at a position close to one of the grounding ends of the slot, so as to most effectively utilize the slot length, and it is convenient to optimize the return loss of the antenna and improve the antenna performance. In addition, when the feeding terminal is located close to the grounding end, more-order mode resonance frequencies can be excited by the antenna, which is convenient for adjusting and optimizing the multi-band antenna, such as optimizing and adjusting the input impedance of each mode of the antenna.

[0028] The terminal device provided by the embodiments of the present disclosure includes an annular metal housing. The first slot antenna and the second slot antenna are annularly arranged on the metal housing, and at least one of them is the multi-band slot antenna described above, so as to increase the effective electrical length of the slot antenna. At the same working frequency, the length of the slot is greatly shortened. And through the capacitance adjustment of the multiple-order resonance frequency doubling, a multi-band antenna can be realized by using one antenna structure, so that more antenna frequencies can be added to the wearable device with limited volume. For example, a dual-band GPS positioning antenna, Bluetooth, and multi-band 4G and 5G antennas can be realized on the wearable device, which cannot be achieved on a smart watch with traditional dimensions. Taking a smart watch as an example, the first slot antenna of the smart watch is a GPS L1 antenna, and the second slot antenna is a multi-band slot antenna including GPS L5 and a Bluetooth antenna. By using the slot antenna of the present disclosure, a multi-band antenna for GPS L5 and Bluetooth is realized, so that a dual-band GPS and Bluetooth antenna that was originally impossible can be designed on a smart watch with limited volume, enriching the device functions and improving the user experience.

[0029] The design method of the slot antenna provided by the embodiments of the present disclosure includes obtaining the original resonance frequency of the slot antenna without capacitance, arranging the first capacitor in the slot, and adjusting the position and / or capacitance value of the first capacitor so that the working frequency of the slot antenna is equal to the target resonance frequency. Thus, in the case of limited slot length, a lower-frequency antenna structure can be realized by using capacitance, and the frequency doubling relationship between multiple-order resonances can also be adjusted by using capacitance to realize the optimized design of the multi-band antenna. Description of the Drawings

[0030] In order to more clearly illustrate the specific embodiments of the present disclosure or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic diagram of the antenna structure according to some embodiments of the present disclosure.

[0032] Figure 2 is Figure 1 The current and voltage distribution curves of the working resonance of the antenna structure in

[0033] Figure 3 It is the echo loss curve of the antenna when the first capacitor is located at point A and point B respectively.

[0034] Figure 4 It is the echo loss curve of the antenna when the first capacitor with different capacitance values is located at point A.

[0035] Figure 5 It is a schematic diagram of an antenna structure according to a specific embodiment of the present disclosure.

[0036] Figure 6 It is the echo loss curve before and after the bridging capacitor in the slot antenna.

[0037] Figure 7 It is the efficiency curve of the antenna structure in the embodiment of the present disclosure.

[0038] Figure 8 It is a schematic diagram of a smart watch according to a specific embodiment of the present disclosure.

[0039] Figure 9 It is a schematic structural diagram of the antenna structure of a smart watch in the prior art.

[0040] Figure 10 It is the echo loss curve of the first three resonance modes of the slot antenna.

[0041] Figure 11 It is the current and voltage distribution curves of the first three resonance modes of the slot antenna.

[0042] Figure 12 It is the echo loss curve of the first three resonance modes when the capacitor is bridged at point A.

[0043] Figure 13 It is the echo loss curve of the first three resonance modes when the capacitor is bridged at point B.

[0044] Figure 14 It is the echo loss curve of the first three resonance modes when the capacitor is bridged at point C

[0045] Figure 15 It is the echo loss curve of the antenna when the capacitor with a fixed capacitance value is located at points A, B, and C respectively.

[0046] Figure 16 It is Figure 8 a structural example diagram of the antenna structure of the smart watch in

[0047] Figure 17 It is the echo loss curve of the antenna before and after bridging the capacitor.

[0048] Figure 18 It is the curve of the change in isolation between antennas.

[0049] Figure 19 It is another structural example diagram of the antenna structure of the smart watch.

[0050] Figure 20 It is yet another structural example diagram of the antenna structure of the smart watch.

[0051] Figure 21 This is another structural example diagram of the antenna structure of a smart watch.

[0052] Figure 22 This is another structural example diagram of the antenna structure of a smart watch.

[0053] Figure 23 This is another example of the structure of the antenna structure of a smart watch. DETAILED DESCRIPTION

[0054] The technical solution of the present disclosure will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described implementation is a part of the implementation of the present disclosure, rather than all the implementations. Based on the implementation in the present disclosure, all other implementations obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure. In addition, the technical features involved in the different implementations of the present disclosure described below can be combined with each other as long as they do not conflict with each other.

[0055] A slot antenna is an antenna formed by opening a slot on a conductor surface. The slot is typically in the shape of a long strip, and the feed across the slot serves as the excitation source of the antenna. The working principle of a slot antenna is similar to that of a dipole antenna. Generally, the length of the slot is 1 / 2 of the wavelength of the first-order resonant frequency of the antenna, that is, the slot length L of the slot antenna and the wavelength λ of the antenna operating frequency have the following relationship:

[0056]

[0057] In formula (1), C is the speed of light, and f is the first-order resonant frequency. It can be seen from formula (1) that the length L of the slot is inversely proportional to the operating frequency f of the antenna, that is, the lower the operating frequency of the antenna, the longer the slot length required.

[0058] Taking the L1 band of the GPS satellite positioning antenna as an example, its operating center frequency is 1.575GHz, and its 1 / 2 wavelength in free space is approximately 95mm. Although the wavelength can be reduced to a certain extent by filling the gap with injection molding material, the gap length of nearly 100 millimeters is still unacceptable for most wearable devices.

[0059] It should also be noted that in order to achieve connection with mobile terminals, wearable devices must also have a Bluetooth antenna, and some devices even have communication antennas such as 4G LTE or 5G. Therefore, the numerous antennas make the antenna design of wearable devices more difficult. Therefore, how to increase the effective electrical length of the slot antenna and reduce the opening length of the slot is a technical problem that needs to be solved urgently.

[0060] In a first aspect, to solve the above technical problems, an embodiment of the present disclosure provides an antenna structure. The antenna structure is applicable to a terminal device, which can be any device with a slot antenna structure, such as a smart phone, a smart watch, a smart bracelet, etc. The antenna structure of the embodiment of the present disclosure aims to increase the effective electrical length of the slot antenna, thereby reducing the length of the slot. Therefore, it has better effects on terminal devices with smaller volumes, such as wearable devices, etc. However, the antenna structure of the present disclosure is also applicable to any other device with a slot antenna and can achieve the same effect. The present disclosure does not limit this.

[0061] In some embodiments, the antenna structure of the present disclosure includes a slot opened on a metal housing of a terminal device. In the length direction, the slot has opposite first and second ends. A feeding terminal is bridged across the slot and is located between the first end and the second end. A first capacitor is also bridged across the slot, that is, the two poles of the first capacitor are respectively connected to both sides in the width direction of the slot. In the length direction of the slot, the first capacitor is located at a position where the voltage value of the radio wave at the operating frequency of the antenna structure is not zero.

[0062] The core inventive concept of the antenna structure of the present disclosure is: by adding a capacitor in the slot antenna, the effective electrical length of the antenna slot can be increased under the same slot length, and the operating frequency of the antenna can be reduced; that is, in the case of achieving the same operating frequency, the antenna structure of the present disclosure can reduce the length of the slot.

[0063] For ease of understanding, a qualitative description of the solution of the present disclosure is first given here. The generation of resonance in a slot antenna is essentially similar to that of a resonant circuit. Connecting a capacitor across the slot antenna is equivalent to increasing the capacitance value of the resonant circuit, thereby correspondingly reducing the resonant frequency of the slot antenna. The reduction of the resonant frequency is equivalent to increasing the effective electrical length of the slot antenna. That is, at the same resonant frequency, the slot length of the antenna structure of the present disclosure can be smaller.

[0064] The following Figure 1 shows an embodiment to further illustrate how the antenna structure of the present disclosure improves the effective length of the slot. For ease of understanding, in this embodiment, the antenna structure takes a single-frequency antenna as an example, that is, only the first-order resonant frequency of the antenna can be utilized.

[0065] As Figure 1 shown, in this embodiment, the antenna structure includes a slot 200 opened on a metal housing 100. The left and right grounding ends of the slot are the first end 201 and the second end 202 respectively. A feeding terminal 300 is bridged across the slot 200 and serves as the excitation source of the antenna.

[0066] When the first capacitor 400 is not provided, the feeding terminal 300 can form a common slot antenna with the slot 200. Figure 2 The schematic diagrams of the voltage distribution and current distribution of the first-order resonant frequency of the slot antenna are shown. Since the length L of the slot 200 is 1 / 2 wavelength of the first-order resonant frequency, the current of the first-order resonance of the slot antenna reaches the maximum at both ends of the slot 200, and the current value is zero at the middle position of the slot 200. The voltage distribution is opposite to the current distribution, that is, the voltage is zero at both ends of the slot 200, and the voltage reaches the maximum at the middle position of the slot 200.

[0067] According to the working principle of the capacitor, when the voltage difference applied to the two poles of the capacitor is larger, the effect generated by the capacitor is stronger. Accordingly, it can be known that if the first capacitor 400 is arranged at the position where the voltage value of the first-order resonance is 0, the effect of frequency reduction will not be generated. And the position of the first capacitor 400 should satisfy that the stronger the voltage value at the position of the first capacitor 400, the greater the degree of the antenna shifting to the low frequency, that is, the higher the effective electrical length of the antenna.

[0068] Continue to refer to Figure 2 , point A is the midpoint of the slot 200, and point B is the quarter point of the slot 200. It can be seen that the voltage value of the first-order resonance at point A is the highest, and the voltage value at point B is lower than that at point A. In the following examples, the first capacitor 400 is respectively arranged at points A and B to explore Figure 1 the change of the effective electrical length of the antenna structure in the embodiment.

[0069] Figure 3 The change curves of the S parameter (return loss) of the antenna when the first capacitor 400 is respectively located at points A and B are shown. Through Figure 3 it can be seen that when the same capacitor (0.6 pF) is applied at different positions A and B, the frequency shift effect at point A is better than that at point B. This can also confirm the above rule, that is, when the capacitance value is the same, the stronger the voltage value at the position where the first capacitor 400 is arranged, the greater the degree of the antenna shifting to the low frequency, that is, the higher the effective electrical length of the antenna.

[0070] On this basis, the influence of different capacitance values on the antenna performance can be further explored. Figure 4 The change curves of the S parameter (return loss) of the antenna when the first capacitor 400 with different capacitance values is respectively at point A are shown. Through Figure 4As a result, it can be seen that when the first capacitor 400 is at the same position (point A), the greater the applied capacitance value, the stronger the effect of the first resonant frequency shifting towards the low frequency. From this, it can be known that when designing a slot antenna, in the case of insufficient slot length, a large capacitor can also be applied to increase the effective electrical length of the slot antenna. However, it should be noted that the magnitude of the applied capacitance value is inversely proportional to the efficiency of the antenna, so as small a capacitance value as possible should be used to ensure the antenna performance.

[0071] From the above example, it can be seen that when maximizing the antenna efficiency (or when the capacitance value of the first capacitor 400 is fixed), the closer the position of the first capacitor 400 is to the position with the maximum voltage value of the operating resonance, the greater the effective electrical length of the slot antenna. For example, in Figure 1 the shown embodiment, when the first capacitor 400 is set at the midpoint position, the effect of the antenna shifting towards the low frequency is the best.

[0072] Still taking the Figure 1 embodiment as an example, according to the above, when designing the antenna structure, two ideas can be considered:

[0073] 1) When the length of the slot 200 is fixed, by adjusting the position of the first capacitor 400 in the slot, the operating frequency of the antenna structure can be shifted towards the low frequency, so that without changing the length of the slot 200, the frequency of the antenna structure can be reduced to the target frequency. Moreover, when the position of the capacitor is fixed, the greater the capacitance value of the first capacitor used, the stronger the effect of reducing the frequency of the antenna structure. The principle will be described in detail below.

[0074] 2) Always set the first capacitor 400 at the midpoint of the slot 200. By adjusting the length L of the slot 200, the frequency of the antenna structure can be made equal to the target frequency. At this time, the length of the slot 200 is the shortest slot length at this target frequency, thus reducing the occupied space of the antenna.

[0075] Next, a specific example of a wearable device will be combined to further illustrate the design idea of the antenna structure of the present disclosure.

[0076] Taking the intelligent bracelet with a full-metal shell as an example of the wearable device, the intelligent bracelet is mainly used for physiological parameter monitoring and sports assistance. To achieve connection with the mobile phone, a Bluetooth antenna must be included in the bracelet. To achieve motion trajectory detection, a satellite positioning antenna is generally also included in the bracelet. In this embodiment, taking the intelligent bracelet including a Bluetooth antenna (2.4 GHz) and a GPS satellite positioning antenna (1.575 GHz) as an example for illustration.

[0077] As Figure 5 shown, Figure 5The metal housing 10 of the smart bracelet is shown. The metal housing 10 includes a horizontally arranged bottom shell and a frame perpendicular to the bottom shell and surrounding the edge of the bottom shell for one week. In the embodiment of the present disclosure, the slot antenna is arranged on the frame. For the bracelet, a heart rate window needs to be arranged on its lower surface, and the two wide sides are used to connect the metal wristbands, and the metal wristbands will form shielding for the antenna. Therefore, the Bluetooth antenna 11 and the satellite positioning antenna 12 of the bracelet can only be arranged on the two long sides of the metal housing 10. Taking a conventional bracelet as an example, the length of the metal housing 10 is about 58 mm, and the width is about 20 mm.

[0078] When designing the Bluetooth antenna and the satellite positioning antenna, since the length dimension of the bracelet is 58 mm. Considering the structural strength and the placement of internal components, the maximum length L of the slot that can be opened is 50 mm. As can be seen from the foregoing, the 1 / 2 wavelength of the first-order resonance frequency of the satellite positioning antenna (1.575 GHz) is about 95 mm. Although the effective length of the slot can be increased by filling the slot with a nano-injection molding material (dielectric constant of 3.0), it still cannot meet the working frequency requirements of the satellite positioning antenna.

[0079] Figure 6 The curve graph of the return loss of the bracelet antenna before and after bridging a capacitor in the slot is shown. It can be seen that without applying a capacitor in the slot, the resonance frequency of the antenna is 2.16 GHz, which obviously cannot meet the requirements of the GPS antenna. However, when a 0.9 pF capacitor is applied in the middle of the slot, the resonance frequency of the antenna shifts down to 1.575 GHz of the GPS satellite positioning antenna, meeting the design requirements of the satellite positioning antenna. From the above two frequencies, it can be calculated that when a 0.9 pF capacitor is used, the length of the slot is equivalently extended by about 37%, greatly increasing the effective length of the slot.

[0080] Figure 7 The efficiency curve of the GPS satellite positioning antenna 12 is shown. The efficiency of the antenna is greater than 20% at the working frequency of GPS, which can meet the requirements for the performance of the GPS satellite positioning antenna. From the above results, it can be seen that by opening a slot in the metal housing 10 of the all-metal bracelet and applying a capacitor in the slot, it is possible to design the GPS satellite positioning antenna of the all-metal bracelet in this embodiment. In addition, the simulation results show that when the bracelet is worn on the arm, the radiation efficiency of the GPS satellite positioning antenna is still better than 12%, which means that the antenna structure proposed in this case also has good antenna performance in actual use.

[0081] The above design of the satellite positioning antenna 12 has been described in detail. The Bluetooth antenna 11 can also adopt the above antenna structure to reduce the slot length. Of course, due to the relatively high operating frequency of the Bluetooth antenna 11, the slot length of the Bluetooth antenna 11 is much smaller than that of the satellite positioning antenna 12. Therefore, the Bluetooth antenna may not adopt the above antenna structure, and it can also be designed directly in the side space of the bracelet housing. The present disclosure does not limit this.

[0082] As can be seen from the above, the antenna structure of the embodiment of the present disclosure greatly improves the effective electrical length of the slot antenna, reduces the slot length of the antenna structure, and makes it possible to design multiple antennas in a full-metal terminal device with a small volume, enriching the device performance.

[0083] After understanding the principle of the antenna structure in the embodiment of the present disclosure, based on this inventive concept, the design of a multi-band antenna can be further realized.

[0084] Based on the principle of the slot antenna, when the slot antenna is fed through the feeding terminal, multiple-order resonant frequencies can be generated in the slot antenna, and there is a multiple-frequency relationship between the multiple-order resonant frequencies. For a single-band antenna, usually only the first-order resonant mode (fundamental mode) among the multiple-order resonances can be utilized. The "multi-band antenna" described in the present disclosure means that for the same antenna structure, multiple resonant frequencies can be utilized simultaneously. For example, for the same slot antenna, if its first-order resonant frequency is 1.176 GHz and the second-order resonant frequency is 2.4 GHz, then this slot antenna can be used as both the L5 antenna for GPS satellite positioning and the Bluetooth antenna at the same time, greatly simplifying the antenna structure of the device.

[0085] However, according to the foregoing, there is a multiple-frequency relationship between the multiple-order resonances of the slot antenna, and in most cases, the multiple-order resonant frequencies cannot be directly utilized. For example, when the multiple-frequency relationship of the slot antenna is an odd multiple, assuming the first-order resonant frequency is 1.176 GHz, the second-order resonant frequency reaches 3.5 GHz, which has exceeded the available frequency band.

[0086] Based on this, on the basis of the foregoing principle, the embodiment of the present disclosure further utilizes a bridging capacitor in the slot antenna to realize the design of a multi-band antenna, which will make it possible to implement an antenna structure that could not be achieved on a device with a small volume before.

[0087] First, it is worth noting that a slot antenna is composed of grounding points at both ends of the slot and a feeding terminal in the middle of the slot. In theory, the feeding terminal can be located at any position between the two grounding points to achieve the antenna function. However, in related technologies, the feeding terminal is generally set at a position close to one of the grounding points. This is because when the feeding terminal is located close to one side of the grounding point, the slot length can be utilized most effectively, and it is convenient to optimize the return loss of the antenna and improve the antenna performance.

[0088] After further research by the inventors of this case, it is found that the position of the feeding terminal in the slot will also affect the multi-order resonance of the antenna. This is because for the multi-order resonance frequencies of the antenna, the current distribution at the position of the feeding terminal is not zero. If the feeding terminal is located in the middle of the slot antenna, only odd multiples of the resonance frequencies can be excited. If the feeding terminal is located close to one side of the grounding end, more orders of resonance frequencies can be excited, and the resonance frequencies of the first few order multiples are ensured to exist, which is convenient to adjust and optimize the first two or the first three resonance frequencies of the multi-frequency antenna. Therefore, in the following embodiments of the present disclosure, the antenna structure still takes Figure 1 as shown, the feeding terminal 300 is arranged at a position close to the first end 201 or the second end 202 of the slot 200.

[0089] To facilitate an intuitive understanding of the present disclosure solution, the present disclosure solution will be described below in conjunction with a specific embodiment. In this embodiment, the terminal device takes a smart watch with a full-metal shell as an example.

[0090] Figure 8An intelligent watch with an all-metal housing is shown. The all-metal housing means that the frame and the bottom case of the watch are integrally connected metal, and the metal housing will shield the antenna radiation. To implement the antenna structure for the all-metal housing, a circular gap 804 is opened in the metal housing of the watch, that is, the metal housing is divided into an independent metal middle frame 801 and a metal bezel 802. The circular gap 804 between the metal middle frame 801 and the metal bezel 802 serves as the gap of the antenna structure and is sealed and formed through a nano-filling material. Multiple antennas of the intelligent watch can be arranged in sequence end to end at the position of the gap 804. That is, multiple slot antennas respectively use gaps with different arc lengths to implement their antenna structures. It can be seen from this that the maximum space available for the intelligent watch to form an antenna is the entire circumferential arc length space of the gap 804 parallel to the bottom case, and the gap openings of multiple antennas are arranged end to end at the position of the gap 804. It should be noted that the "end to end" described in this disclosure means that when there are multiple antennas, the multiple antennas are arranged in sequence in the circumferential direction of the gap 804. In actual implementation, the length of the antenna opening can be specifically set according to the antenna performance. The entire circumference of the gap 804 can be used, or only a part of the circumferential arc length of the gap 804 can be used. Those skilled in the art should understand this. The metal bezel 802 refers to the circular metal frame provided on the outer periphery of the watch screen 803.

[0091] An intelligent watch generally includes a Bluetooth antenna and a GPS satellite positioning antenna. The center operating frequency of the Bluetooth antenna is 2.44 GHz. The civilian frequency bands of the GPS satellite positioning antenna include the L1 band and the L5 band. The center frequency of L1 is 1.575 GHz, and the center frequency of L5 is 1.176 GHz. Through calculation, it can be known that the 1 / 2 wavelength of the Bluetooth antenna in free space is about 60 mm, and the 1 / 2 wavelength of the L1 wave of the GPS satellite positioning antenna in free space is about 95 mm. For a typical intelligent watch, the diameter of its housing does not exceed 50 mm. By filling the gap with a dielectric material, the entire circumferential space can be used to just make the Bluetooth antenna and the L1 antenna of GPS.

[0092] As Figure 9 shown, in the related art, the antenna structure of the watch can be referred to as shown in the figure. In the entire circular gap, the gap is divided into a left Bluetooth antenna and a right GPS L1 antenna by two ground points, ground 1 and ground 2. That is, the "ground 1 - feed 1 - ground 2" arc segment serves as the Bluetooth antenna, and the "ground 2 - feed 2 - ground 1" arc segment serves as the GPS L1 antenna.

[0093] As can be seen, in the related art, the housing space of a watch can only accommodate a Bluetooth antenna and a GPS L1 antenna, leaving no space for a dual-frequency GPS antenna. The civilian frequency bands of GPS satellite positioning antennas include L1 and L5. Since the satellite coverage of the L1 band is relatively large, L1 is usually used as the basic GPS operating frequency band. A single-frequency GPS antenna is an antenna that only supports the L1 band. Dual-frequency GPS means supporting both the L1 and L5 bands simultaneously. The L1 band is used as the basic band, and L5 is used as an auxiliary band for L1, thereby eliminating the ionospheric error and greatly improving the positioning accuracy.

[0094] From the foregoing calculations, it can be seen that if one wants to design a Bluetooth antenna, a GPS L1 antenna, and a GPS L5 antenna on the smartwatch shown in Figure 8 , the diameter of the watch needs to be increased by more than 80%, which is obviously impossible for a watch.

[0095] Based on the above problems, in the embodiments of the present disclosure, through the aforementioned inventive concept, a Bluetooth antenna and a dual-frequency GPS antenna can be designed simultaneously without increasing the size of the watch (even with a smaller watch size).

[0096] The main inventive concept of the embodiments of the present disclosure is: by bridging a capacitor in a slot antenna to adjust the frequencies of multiple-order resonances, so that the first-order resonance frequency and the second-order resonance frequency of the same slot antenna are both available frequencies. For example, using the same slot antenna to implement GPS L5 and a Bluetooth antenna. The principle of the embodiments of the present disclosure will be described below.

[0097] First, define a reference antenna with a slot length of L. The reference antenna is a common slot antenna, and its structure can be seen in Figure 1 shown, but no capacitor is bridged in the slot. Since in this embodiment, the feeding terminal is close to one of the grounding points, the resonance frequencies generated by this reference antenna follow the following rules: the slot length of the antenna is 1 / 2 wavelength of the first-order resonance frequency f 0 of the antenna; and the operating frequencies of the second-order and third-order resonances of this slot antenna are approximately 2f 0 and 3f 0 respectively. That is, the resonance of the antenna has the characteristic of frequency doubling. Figure 10 shows the echo loss curves of the first three-order resonances of the reference antenna. Figure 11 shows the current and voltage distribution curves of the first three-order resonances of the reference antenna.

[0098] Referring to Figure 11From the voltage and current distributions shown, at the same slot length position, the voltage is maximum at the position where the current is minimum, and vice versa. Based on the aforementioned inventive concept, in order to adjust the original resonance of the reference antenna, a capacitor will be connected across the slot. To better understand how the resonance frequency of the slot antenna is adjusted according to the position of the capacitor, the capacitor is respectively set at Figure 11 the points A, B, and C shown. Point A is the position where the current value of the first-order resonance frequency of the reference antenna is zero (i.e., the voltage value is maximum); Point C is the position of the current zero (i.e., the voltage is maximum) near the right side of the second-order resonance of the reference antenna; Point B is the midpoint position of AC.

[0099] Figures 12 to 14 shows the echo loss curves of the antenna when capacitors with different capacitance values are respectively set at points A, B, and C. From Figure 12 it can be seen that when the capacitor is set at point A, the first-order resonance and the third-order resonance of the antenna shift significantly to lower frequencies with different capacitance values, but the change in the second-order resonance shifting to lower frequencies is not obvious.

[0100] Combined with Figure 11 it can be seen that at point A, the voltage values of the first-order and third-order resonances of the antenna are maximum, while the voltage value of the second-order resonance is zero. According to the aforementioned influence law of the capacitor on the resonance frequency, the greater the voltage value, the stronger the effect of the capacitor, and the more obvious the effect of the corresponding resonance frequency shifting to lower frequencies, which also explains Figure 11 the principle of the results. For example, the third-order resonance frequency changes from 4.28 GHz without a capacitor to 3.20 GHz (capacitance value 0.3 pF) and 2.76 GHz (capacitance value 0.6 pF), while the frequency change of the second-order resonance caused by the change of the capacitance value is not large, always about 2.86 GHz.

[0101] Comparing Figure 13 and Figure 14 results, when the capacitor is set at point B, the proportion of the first-order resonance and the second-order resonance of the antenna shifting to lower frequencies is not much different, but when the capacitor is set at point C, the amplitude of the first-order resonance of the antenna shifting to lower frequencies is significantly smaller than the amplitude of the second-order resonance shift. This result can also be explained by the voltage difference applied across the capacitor: as Figure 11 shown, when the capacitor is at point C, the influence of the capacitor on the second-order resonance of the antenna is greater than that on the first-order resonance. Similarly, through Figure 11 the voltage value at point B in Figure 13 the results can be explained, that is, the adjustment degree or proportion of the capacitor to the first-order resonance and the second-order resonance is almost the same.

[0102] To better understand Figures 12 to 14 the results, Figure 15The echo loss curves of the first-order resonance and the second-order resonance are shown when the capacitance value remains unchanged (0.3 pF) and the capacitors are located at points A, B, and C respectively. From Figure 15 the results, it can be seen that the frequency of the second-order resonance shifts to the low frequency with the following rule: when the capacitor is at point A, the proportion of frequency shift is the smallest; when the capacitor is at point B, the proportion of frequency shift is the second; when the capacitor is at point C, the proportion of frequency shift is the largest. This is because during the process of the capacitor's position changing from A to C, the voltage value of the second resonance of the antenna has been increasing.

[0103] It should be noted that through Figures 12 to 14 the results, it can be known that the capacitance value of the capacitor will also affect the proportion of the result of the antenna shifting to the low frequency. However, the larger the capacitance value of the capacitor, the greater the impact on the efficiency of the antenna. Therefore, a capacitor as small as possible should be selected to ensure the antenna efficiency.

[0104] The exploration of the above frequency adjustment rule of the capacitance position on the multi-order resonance can be used as the guidance for the present disclosure to adjust the first and second-order resonances with a frequency doubling relationship to two target resonances with a non-frequency doubling relationship.

[0105] Specifically, taking the Figure 8 、 Figure 9 shown smartwatch as an example, the idea of designing a dual-frequency GPS satellite positioning antenna in the original antenna structure is: by connecting a capacitor across the original Bluetooth antenna and reasonably adjusting the position of the capacitor using the above rule, so that the first-order resonance frequency of the antenna is about 1.176 GHz of the GPS L5 antenna, and the second-order resonance frequency is about 2.4 GHz of the Bluetooth antenna. Combining with the original GPS L1 antenna, a dual-frequency GPS satellite positioning antenna can be designed in the limited space of the watch housing.

[0106] In one example, the antenna design of the smartwatch in the embodiment of the present disclosure is as shown in Figure 16 . In this example, the shorter arc length on the left is the GPS L1 antenna, that is, the slot antenna formed by "ground 1 - feed 1 - capacitor 1 - ground 2" is used as the GPS L1 antenna, and its center resonance frequency is 1.575 GHz. And the longer arc length on the right is the GPS L5 and Bluetooth antennas, that is, the slot antenna formed by "ground 2 - feed 2 - capacitor 2 - ground 1" is used as the GPS L5 and Bluetooth antennas, and its first-order resonance frequency is 1.176 GHz, and the second-order resonance frequency is 2.4 GHz.

[0107] It should be noted that in this example, for the GPS L1 antenna, a capacitor 1 is also connected across the slot, thereby reducing the slot length of the GPS L1 antenna. And the position of the capacitor 1 is preferably the position where the antenna resonance voltage value is the largest. The principle can be referred to the above and will not be elaborated here.

[0108] For the GPS L5 and Bluetooth antennas, the function of the bridging capacitor 2 in the gap is not only to increase the effective length of the gap by using capacitor 2, but also to reasonably adjust the position of capacitor 2 so that the frequencies of the first-order resonance and the second-order resonance with a frequency doubling relationship are both available target frequencies. The following will combine Figure 17 to illustrate how to adjust the position of capacitor 2.

[0109] Figure 17 shows the antenna echo loss curves of the watch antenna without bridging capacitors and with bridging capacitors 1 and 2. From Figure 17 the results, it can be seen that when no capacitors are bridged, especially for the antenna with a shorter arc length on the left side, the first-order resonance frequency is 2.1 GHz (see the dotted line S11), and for the antenna with a longer arc length on the right side, the first-order resonance and second-order resonance frequencies are 1.408 GHz and 2.821 GHz respectively (see the dotted line S22). Obviously, the resonances of the slot antennas generated by the two different arc lengths are much larger than their target resonance frequencies. By applying capacitor 1 (0.65 pF) and capacitor 2 (0.68 pF), the antenna can be adjusted to the resonance frequencies of the GPS L1 (see the solid line S11), GPS L5, and Bluetooth BT (see the solid line S22) antennas.

[0110] For the antenna with a shorter arc length on the left side, the target of tuning it with capacitor 1 is only a GPS L1 antenna with a working frequency of 1.575 GHz. Therefore, according to the aforementioned principle, the position of capacitor 1 can be preferably the current zero point or the position with the maximum voltage of the first-order resonance of the antenna, that is, the midpoint position of the slot length.

[0111] For the adjustment of the position of capacitor 2, guided by the above principle, the following rules can be referred to during antenna design: calculate the first difference between the original frequency of the first-order resonance of the antenna and the target frequency, calculate the second difference between the original frequency of the second-order resonance and the target frequency, and compare the first difference and the second difference. If the first difference is greater than the second difference, it means that the frequency modulation amplitude of the first-order resonance is larger, and the capacitor position should be located in the region where the first-order resonance voltage value is greater than the second-order resonance. On the contrary, if the second difference is greater than the first difference, it means that the frequency modulation amplitude of the second-order resonance is larger, and the capacitor position should be located in the region where the second-order resonance voltage value is greater than the first-order resonance. For example, in this example, the frequency modulation amplitude of the second-order resonance is larger, and the position of capacitor 2 can be adjusted between BC.

[0112] Figure 18 shows the variation curve of the isolation (S21) between the above-mentioned smart watch antenna structures. From Figure 18It can be seen that the isolation between the two slot antennas is better than -14.5 dB. Such good isolation indicates that the two antennas can be debugged and optimized relatively independently. That is, when the capacitance used in one slot antenna changes, the influence on the resonance of the other slot antenna can be ignored. Thus, the antenna structure of the present disclosure can independently adjust and optimize the two slot antennas. In addition, in the disclosed embodiments, by using Capacitor 1 and Capacitor 2, it is equivalent to reducing the diameter of the watch by about 53%, making it possible to design a dual-frequency GPS satellite positioning antenna in the watch size.

[0113] The above examples are only used to explain and illustrate the antenna structure and its design method of the present disclosure, and are not used to limit the present disclosure. Based on the above examples, there may be other alternative embodiments for the antenna structure of the smart watch of the present disclosure.

[0114] In an alternative example, as Figure 19 shown, the position of the feeding terminal can also be adjusted according to the design requirements. For example, in this example, relative to Figure 16 the example, the two feeding terminals Feed 1 and Feed 2 are arranged in a close position, and the above scheme can also be realized. There is no difference in the formation of the antenna, and those skilled in the art can set it according to the requirements.

[0115] In another alternative example, as Figure 20 shown, it can be seen that there is no capacitor set in the GPS L1 antenna. From the above, since the GPS L1 antenna is only a single-frequency antenna, the main function of the capacitor is to increase the effective electrical length of the slot. Therefore, when the watch size permits, the GPS L1 antenna can adopt a common slot antenna without crossing a capacitor.

[0116] In another alternative example, as Figure 21 shown, it can be seen that there is a capacitor 1 connected across the GPS L1 antenna, while there is no capacitor connected across the GPS L5 and Bluetooth antenna slots. This is because the operating frequency of the GPS L5 antenna, 1.176 GHz, and the operating frequency of the Bluetooth antenna, 2.4 GHz, are in a relatively close multiple relationship. Therefore, in some slot antennas with special sizes or antennas with low requirements for antenna accuracy, the GPS L5 and Bluetooth functions can be realized by using the first two-order resonances of the antenna without connecting a capacitor across it. It is particularly worth noting that in this example, if no capacitor 1 is connected across the GPS L1 antenna, the slot length of the GPS L1 antenna has occupied most of the space of the watch, and there will be no space to set a GPS L5 antenna with a longer slot length. Therefore, in the full-metal watches in the related art, without adopting the antenna structure of the present disclosure, it is still impossible to design a dual-frequency GPS antenna in the full-metal watch.

[0117] In yet another alternative example, asFigure 22 As shown, the difference from Figure 16 the example is that the two slot antennas radiate using the same feeding point, and its overall concept is the same as Figure 16 the example, only in reducing the number of feeding points and optimizing the internal circuit structure.

[0118] In another alternative example, as Figure 23 shown, the difference from Figure 16 the example is that, when the size of the watch permits, by increasing the number of grounding points, better isolation can be achieved between the two slot antennas. That is, "Ground 3 - Feed 1 - Capacitor 1 - Ground 2" forms a slot antenna as the GPS L1 antenna, and the slot antenna formed by "Ground 4 - Feed 2 - Capacitor 2 - Ground 1" serves as the GPS L5 and Bluetooth antennas.

[0119] The above describes the watch antenna structure in the embodiments of the present disclosure. Based on the above disclosure, those skilled in the art should also be able to understand the following points:

[0120] 1) The antenna structure of the present disclosure is not limited to smart watches, but can also be any other terminal device with a full - metal housing suitable for implementation, such as mobile phones, bracelets, etc., and will not be enumerated here.

[0121] 2) The antenna structure of the present disclosure is not limited to the above - mentioned antenna types either. It can be applied to any type of slot antenna, such as 4G LTE antennas, 5G antennas, etc., and the present disclosure does not limit this.

[0122] 3) The multi - frequency antenna structure is not only limited to the above - mentioned GPS L5 and Bluetooth antennas. Any antennas with a high - low frequency relationship can theoretically be adjusted using the antenna structure of the present disclosure. For example, the GPS L1 and Bluetooth antennas can also be designed in the same slot antenna; or, the GPS L1 and GPS L5 antennas can be designed in the same slot antenna; furthermore, the low - frequency and high - frequency bands of 4G or 5G antennas can also be designed in the same slot antenna; etc. The present disclosure does not limit this.

[0123] 4) Regarding the utilization of the resonant frequencies of the antenna structure, it is not limited to the first two - order resonant frequencies either. It can also be any available resonant frequencies suitable for adjustment, such as the first three - order resonance, any two - order or three - order resonance, etc., and the present disclosure does not limit this.

[0124] 5) For the parts not detailed in the present disclosure, such as filling the slot of the slot antenna with a dielectric material, on the one hand, it can increase the effective length of the slot, and on the other hand, it can seal the slot; etc. Those skilled in the art can set it according to specific implementations and will not be elaborated here.

[0125] In addition, it is worth noting that, in addition to the above effects, the antenna structure of the present disclosure can also improve the resonant frequency bandwidth by adjusting the position of the capacitor. This is also one of the inventive concepts of the present disclosure, and a brief description is provided herein.

[0126] As Figure 12 shown, when the capacitor is connected across point A, since the voltage value of the second-order resonance at point A is zero, the second-order resonance does not change significantly. Referring to Figure 12 , it can be seen that when the capacitance value is 0.6 pF, the third-order resonance frequency drops to a frequency very close to the second-order resonance. By adjusting the capacitance value, the third-order resonance frequency can be dropped to the same frequency as the second-order resonance. At this time, it is equivalent to widening the bandwidth of the second-order resonance frequency, greatly improving the antenna efficiency of the second-order resonance frequency. Thus, it can be seen that the antenna structure of the present disclosure can also improve the resonant frequency bandwidth by adjusting the position of the capacitor.

[0127] The above provides a detailed description of the structure and principle of the antenna structure of the embodiments of the present disclosure. In the second aspect, the embodiments of the present disclosure also provide a method for designing the above antenna structure, including: disposing a first capacitor in a first slot, with the two poles of the first capacitor respectively connected to both sides in the width direction of the first slot; and in the length direction of the first slot, the first capacitor is located at the position where the voltage value of the radio wave of the operating frequency of the slot antenna is the largest; obtaining the first original resonant frequency of the slot antenna; obtaining the difference between the first original resonant frequency and the target resonant frequency; and adjusting the length of the first slot according to the difference so that the operating frequency of the slot antenna is equal to the target resonant frequency.

[0128] Specifically, when designing the antenna structure, the first capacitor is always disposed at the midpoint of the slot. By adjusting the length of the slot, the frequency of the antenna structure can be made equal to the target frequency. At this time, the length of the slot is the shortest slot length at this target frequency, thereby reducing the occupied space of the antenna. This design method is applicable to scenarios where there is a need to minimize the opening length of the slot antenna as much as possible, and it also enables the realization of an antenna structure that cannot be achieved on a device with a smaller volume.

[0129] In the third aspect, the embodiments of the present disclosure provide a method for designing the above antenna structure, including: obtaining the second original resonant frequency of the slot antenna; obtaining the difference between the second original resonant frequency and the target resonant frequency; disposing a second capacitor in a second slot, with the two poles of the second capacitor respectively connected to both sides in the width direction of the second slot; and in the length direction of the second slot, adjusting the position of the second capacitor according to the difference so that the operating frequency of the slot antenna is equal to the target resonant frequency.

[0130] Specifically, when designing the antenna structure, with a certain slot length, the operating frequency of the antenna structure can be shifted towards the low frequency by adjusting the position of the first capacitor in the slot, so that the frequency of the antenna structure can be reduced to the target frequency without changing the slot length. This design method is applicable when the slot length is limited, thereby increasing the effective electrical length of the slot and realizing an antenna structure that could not be achieved at this length originally.

[0131] Moreover, this design method is applicable to the design of multi-band antennas. When the operating frequency of the slot antenna includes multiple resonant frequencies, the position of the second capacitor is adjusted according to the difference to make the operating frequency of the slot antenna equal to the target resonant frequency, including: adjusting the position of the second capacitor according to the difference between each target resonant frequency and the second original resonant frequency, so that each resonant frequency of the slot antenna is equal to the target resonant frequency. For the adjustment of the position of the second capacitor, refer to the above for details and will not be elaborated here.

[0132] In a fourth aspect, the present disclosure also provides a wearable device, which includes the antenna structure in any of the above embodiments. The wearable device can be any device type suitable for implementation, such as a smart phone, a smart watch, a smart bracelet, etc. Since the antenna structure of the embodiment of the present disclosure is to reduce the slot length of the metal housing, it has a better effect on devices with a smaller volume. For example, in a preferred example, the wearable device is a smart watch or a smart bracelet, thereby increasing the effective length of the slot of the antenna structure and making it possible to design an antenna that could not be designed on a watch or bracelet with a fully metal housing originally.

[0133] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the embodiments. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the embodiments here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present disclosure.

Claims

1. A multi - frequency slot antenna, characterized in that, it is applied to a wearable device, the wearable device includes a metal housing, the metal housing includes a bottom shell and a frame, and the antenna includes: a slot opened on the frame, and the length direction of the slot is parallel to the bottom shell. In the length direction of the slot, the slot has a first end and a second end opposite to the first end, and both the first end and the second end are closed ends; a feeding terminal, spanning across the slot and located between the first end and the second end; and a first capacitor, arranged in the slot, and two poles of the first capacitor are respectively connected to two sides in the width direction of the slot; wherein, the operating frequencies of the antenna include multi - order resonant frequencies, the multi - order resonant frequencies include a first resonance and a second resonance. In the length direction of the slot, the first capacitor is located at a position where the voltage values of both the first resonance and the second resonance are not zero; the first capacitor is used to adjust the order resonant frequencies of the first resonance and the second resonance to corresponding target resonant frequencies respectively, wherein the target resonant frequency of the first resonance corresponds to the GPS L5 frequency band, and the target resonant frequency of the second resonance corresponds to the 2.4 GHz frequency band.

2. The multi - frequency slot antenna according to claim 1, characterized in that, the feeding terminal is located near the first end or the second end.

3. The multi - frequency slot antenna according to claim 1, characterized in that, the difference between the original resonant frequency and the corresponding target resonant frequency of the first resonance is a first difference, and the difference between the original resonant frequency and the corresponding target resonant frequency of the second resonance is a second difference; when the first difference is greater than the second difference, the first capacitor is located in the region where the voltage value of the first resonance is greater than the voltage value of the second resonance; when the second difference is greater than the first difference, the first capacitor is located in the region where the voltage value of the first resonance is less than the voltage value of the second resonance.

4. A wearable device, characterized in that, it includes a metal housing, the metal housing includes a bottom shell and a frame; a first slot antenna and a second slot antenna arranged on the metal housing, at least one of the first slot antenna and the second slot antenna is a multi - frequency slot antenna, and the length directions of the slots of the first slot antenna and the second slot antenna are parallel to the bottom shell; the multi - frequency slot antenna includes: a slot opened on the frame, in the length direction of the slot, the slot has a first end and a second end opposite to the first end, and both the first end and the second end are closed ends; a feeding terminal, spanning across the slot and located between the first end and the second end; and a first capacitor, arranged in the slot, and two poles of the first capacitor are respectively connected to two sides in the width direction of the slot; Among them, the operating frequency of the antenna includes multiple resonant frequencies, and the multiple resonant frequencies include a first resonance and a second resonance. In the length direction of the slot, the first capacitor is located at a position where the voltage values of the first resonance and the second resonance are both non-zero; the first capacitor is used to adjust the order resonant frequencies of the first resonance and the second resonance to corresponding target resonant frequencies respectively. Among them, the target resonant frequency of the first resonance corresponds to the GPS L5 frequency band, and the target resonant frequency of the second resonance corresponds to the 2.4 GHz frequency band.

5. The wearable device according to claim 4, wherein, the first slot antenna and the second slot antenna are arranged end to end on the frame.

6. The wearable device according to claim 4, wherein, the first slot antenna is a global positioning system (GPS) L1 antenna, and the second slot antenna is a multi-band slot antenna including a global positioning system (GPS) L5 antenna and a Bluetooth antenna.

7. The wearable device according to claim 4, wherein, the wearable device is a smart watch.

8. A manufacturing method of a multi-band slot antenna, wherein, applied to a wearable device including a metal housing, the metal housing includes a bottom case and a frame, and the method includes: opening a first slot on the frame, wherein the first slot has a first end and a second end opposite to the first end, both the first end and the second end are closed ends, and the length direction of the first slot is parallel to the bottom case; arranging a feeding terminal across the first slot, and the feeding terminal is located between the first end and the second end; disposing a first capacitor in the first slot, and two poles of the first capacitor are respectively connected to two sides in the width direction of the first slot; among them, the operating frequency of the antenna includes multiple resonant frequencies, and the multiple resonant frequencies include a first resonance and a second resonance. Among them, the target resonant frequency of the first resonance corresponds to the GPS L5 frequency band, and the target resonant frequency of the second resonance corresponds to the 2.4 GHz frequency band. In the length direction of the slot, the first capacitor is located at a position where the voltage values of the first resonance and the second resonance are both non-zero; the first capacitor is used to adjust the order resonant frequencies of the first resonance and the second resonance to corresponding target resonant frequencies respectively.

9. The method according to claim 8, wherein, the position of the first capacitor is adjusted according to a first difference between the target resonant frequency and the corresponding original resonant frequency of the first resonance and a second difference between the target resonant frequency and the corresponding original resonant frequency of the second resonance.

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