Low-cost miniaturized LET-CAT.1 PCB printed antenna

Abstract

The utility model provides a low-cost miniaturized LET-CAT.1 PCB (printed circuit board) antenna, which is used for solving the technical problem that the existing PCB antenna is not suitable for miniaturization and built-in standardization of an Internet of Things equipment antenna. The antenna comprises a ground plane and a clearance zone, the ground plane and the clearance zone are both printed on a PCB, an antenna main body structure is arranged in the clearance zone, and the antenna main body structure is electrically connected with the ground plane; the antenna main body structure comprises a feeder line and an inverted U-shaped structure, one end of the feeder line is electrically connected with the ground plane, and the other end of the feeder line is electrically connected with the inverted U-shaped structure. The utility model provides a low-cost miniaturized LET-CAT.1 PCB printed antenna, which is a built-in antenna of an LTE-CAT.1 Internet of Things communication device, is ultra-miniaturized in structure and ultra-low in cost, supports a plurality of frequency bands, such as Telecom B1, Unicom B3 and Mobile B38-41, and realizes whole network communication.

Description

Technical Field

[0001] The utility model relates to the technical field of PCB printed antennas, in particular to a low-cost miniaturized LET-CAT.1 PCB printed antenna. Background Art

[0002] The current IoT device market is expanding rapidly, and has formed a market size of over one trillion US dollars. Among them, IoT devices involving wireless communications account for an increasingly high proportion. The development of its supporting key component antenna has matured and improved, and is gradually moving towards low cost, miniaturization and standardization.

[0003] Antennas need to match dedicated working frequency bands to work. The mainstream wireless standard for LTE IoT devices is LTE-CAT.1. According to the frequency band division of the 3GPP protocol, it includes B1, B3, B5, B8 of FDD standard and B38, B39, B40, B41 of TDD standard. The involved frequencies include low frequency 824~960MHz and high frequency 1.71~2.69GHz. The low frequency 824~960MHz is used as the blind frequency band of the operator's 4G base station, and the connection priority is lower than the high frequency 1.71~2.69GHz.

[0004] PCB printed antenna is an extremely low-cost antenna. It is a combined trace on the PCB. It can be drawn as a straight trace, an inverted F-shaped trace, a serpentine or circular trace, etc. The electromagnetic wave simulation software HFSS is used to design the antenna shape and size that meet the bandwidth requirements. The actual object is proof-made and tested on a vector network analyzer to verify whether it meets the design requirements.

[0005] PCB antenna refers to the part on the PCB used for wireless reception and transmission. Its structure usually includes radiators, feed points and ground planes. According to different design requirements and application scenarios, PCB antennas can have a variety of different shapes and structures, the most common of which are inverted F-shaped, serpentine, straight, etc. Its length is usually one-quarter of the signal wavelength. The main advantages include low cost, high space utilization, easy manufacturing and integration, stable performance, etc., but there are also some limitations, such as narrow bandwidth, low efficiency, complex design and limited antenna directivity.

[0006] The invention patent with application number 202310446290.1 ​​discloses a PCB antenna for LTE band, including a substrate, which is divided into a clearance area and a functional area. In the clearance area, a first antenna structure is arranged on the top surface of the substrate, and a second antenna structure is arranged on the bottom surface of the substrate; the first antenna structure is an inverted L antenna or a PIFA antenna, and the second antenna structure is a line segment; a ground plane is arranged in the functional area; the first antenna structure includes a feed end, a radiator and a tuning segment connected in sequence, and the feed end is arranged adjacent to the ground plane; the radiator adopts a serpentine routing, including multiple parallel line segments connected end to end; the second antenna structure corresponds to the tuning line segment, and is symmetrically arranged on the top and bottom surfaces of the substrate, and the two ends of the two are connected by vias to form a ring circuit. The above invention optimizes the antenna performance of the first antenna structure by adding a second antenna structure located on the bottom surface of the substrate, so that it can achieve the corresponding antenna performance requirements in the target working band with a very small antenna size. However, after the antenna of the above invention is miniaturized, there are problems such as performance degradation at the beginning and end of the working frequency band and no support for LTE frequency bands below 1GHz. However, it will not affect the acquisition of network access licenses for LTE devices using this antenna and the actual networking effect. Utility Model Content

[0007] In view of the technical problem that existing PCB printed antennas are not suitable for miniaturization and built-in standardization of antennas for Internet of Things devices, the utility model proposes a low-cost miniaturized LTE-CAT.1 PCB printed antenna, which is a built-in antenna for LTE-CAT.1 Internet of Things communication equipment, and has an ultra-miniaturized structure and ultra-low cost, and supports multiple frequency bands, such as Telecom B1, Unicom B3 and Mobile B38~41, to achieve full network access.

[0008] In order to achieve the above-mentioned purpose, the technical solution of the utility model is implemented as follows: a low-cost miniaturized LET-CAT.1 PCB printed antenna, including a ground plane and a clearance area, both of which are printed on a PCB circuit board, an antenna main structure is arranged in the clearance area, and the antenna main structure is electrically connected to the ground plane; the antenna main structure includes a feeder line and an inverted U-shaped structure, one end of the feeder line is electrically connected to the ground plane, and the other end of the feeder line is electrically connected to the inverted U-shaped structure.

[0009] Preferably, the inverted U-shaped structure includes an inverted U-shaped part I and an inverted U-shaped part II, the lower end of one end of the inverted U-shaped part I is electrically connected to the other end of the feeder line, and a section of wiring is shared between the other end of the inverted U-shaped part I and the inverted U-shaped part II.

[0010] Preferably, the length of the vertical section of the inverted U-shaped member II away from the feeder is smaller than the length of the vertical section of the inverted U-shaped member I; the length of the horizontal section of the inverted U-shaped member II is smaller than the length of the horizontal section of the inverted U-shaped member I.

[0011] Preferably, the widths of the horizontal sections and the vertical sections of the inverted U-shaped member I and the inverted U-shaped member II are the same.

[0012] Preferably, the inverted U-shaped part I and the feeder line form an inverted spoon structure, and the inverted U-shaped part II, the inverted U-shaped part I and the feeder line form an inverted spoon structure, and the two inverted spoon structures cover different communication frequency bands.

[0013] Preferably, a feeding point is provided on the ground plane, and the feeding point is electrically connected to one end of the feeding line.

[0014] Preferably, the basic structure of the feed line is a 50Ω microstrip line, one end of the 50Ω microstrip line is connected to the feed point, and the other end is electrically connected to the lower end of one end of the inverted U-shaped piece I.

[0015] Preferably, the size of the PCB circuit board is 80*80 mm, and the size of the clearance area is 20*20 mm.

[0016] Preferably, the length of the feed line is 8 mm, and the width of the inverted U-shaped part I and the inverted U-shaped part II are both 1.5 mm.

[0017] Preferably, the size of the inverted U-shaped part I is 5*11mm, and the inverted U-shaped part I is connected to the feeder line to form an inverted spoon structure, so that the antenna covers the frequency band of 2.3~2.69GHz; the width of the inverted U-shaped part II is 4.5mm, and the length of the vertical section of the inverted U-shaped part II away from the feeder line is 4.5mm. The inverted U-shaped part II, the feeder line and the inverted U-shaped part I form an inverted spoon structure, so that the antenna covers the frequency band of 1.71~2.3GHz; the length of the wiring shared by the other end of the inverted U-shaped part I and the inverted U-shaped part II is 11mm.

[0018] Compared with the prior art, the utility model has the following beneficial effects: it is composed of a three-part structure consisting of an antenna main structure, a feeder line and a ground plane, with the antenna main structure being designed and improved, and a bypass inverted U-shaped structure being added to form a new radiator. In this way, the induced current on the radiator has multiple paths, and the resulting coupling effect can effectively broaden the coverage frequency band of the antenna, while improving the performance of the head and tail of the frequency band, thereby achieving the design goal of covering the mainstream LTE IoT frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic diagram of the structure of the utility model (unit: mm).

[0021] Figure 2 It is the standing wave ratio diagram of the antenna of the present invention.

[0022] Figure 3 It is the directional diagram of the main radiation plane of the antenna of the present invention.

[0023] In the figure, 1 is the ground plane, 11 is the feeding point, 2 is the clearance area, 3 is the feeder line, 4 is the inverted U-shaped structure, 41 is the inverted U-shaped part I, and 42 is the inverted U-shaped part II. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] like Figure 1 As shown, a low-cost miniaturized LET-CAT.1 PCB printed antenna includes a ground plane 1 and a clearance area 2, both of which are printed on a PCB circuit board. An antenna main structure is provided in the clearance area 2, and the antenna main structure is electrically connected to the ground plane 1; the antenna main structure is a main structure used to radiate electromagnetic waves. The antenna main structure includes a feeder 3 and an inverted U-shaped structure 4, one end of the feeder 3 is electrically connected to the ground plane 1, and the other end of the feeder 3 is electrically connected to the inverted U-shaped structure 4. The function of the feeder 3 is to connect the feeding point 11 and the inverted U-shaped structure 4, and it is also a part of the antenna radiator. The inverted U-shaped structure 4 is the main radiator, and its main function is to radiate the LTE frequency band electromagnetic waves required by the design.

[0026] The PCB antenna of the utility model is printed on the circuit board, and includes three parts: the ground plane, the clearance, and the antenna main structure in the clearance area. The utility model is a combined PCB printed antenna, a PCB antenna of the LTE-CAT.1 frequency band commonly used in IoT devices, printed on an FR4 PCB circuit board, the PCB circuit board is a two-layer structure, with a size of 80*80mm and a thickness of 1.6mm. The upper and lower layers of the antenna part are completely clear (no components and wiring are placed), with an area of ​​20*20mm, and the rest of the copper is used as the ground plane of the antenna.

[0027] Preferably, the inverted U-shaped structure 4 includes an inverted U-shaped part I 41 and an inverted U-shaped part II 42, the lower end of one end of the inverted U-shaped part I 41 is electrically connected to the other end of the feeder line 3, and a section of wiring is shared between the other end of the inverted U-shaped part I 41 and the inverted U-shaped part II 42. The antenna main body structure is composed of a section of feeder line 3 and two inverted U-shaped structures, the feeder line 3 connects the feed point 11 located on the ground plane and the left end of the inverted U-shaped structure, and the two inverted U-shaped structures are combined together, and a section of wiring is shared in the middle. The combination increases the induced current path flowing through the antenna, enhances its coupling effect, and greatly broadens the coverage bandwidth of the antenna.

[0028] The basic structure of the feed line 3 is a 50Ω microstrip line, one end of which is connected to the feed point 11, and the other end is electrically connected to the lower end of one end of the inverted U-shaped piece I 41, as shown in FIG. Figure 1 As shown, the left side of the 50Ω microstrip line is connected to the feed point on the ground plane, and extends to the right into the clearance area as a part of the antenna body, ensuring the connectivity of the signal transmitted from the feed point 11 to the antenna body in the clearance area and radiated out.

[0029] The overall size of the PCB circuit board is about 80*80mm, and the clearance area is about 20*20mm. The larger the size, the better the antenna performance. This size is the minimum size to ensure that the antenna has good radiation performance.

[0030] Based on the electromagnetic field principle that the lower the frequency, the larger the antenna size, in order to reduce the size, its communication bandwidth does not consider supporting the 824~960MHz frequency band with lower networking priority, but is only designed to support high frequencies covering 1.71~2.69GHz. It not only meets the full network LTE communication needs of IoT devices, but also realizes the ultra-miniaturized design requirements.

[0031] The widths of the horizontal and vertical sections of the inverted U-shaped member I 41 and the inverted U-shaped member II 42 are the same. The routing width of the antenna main structure is 1.5 mm, that is, the routing width of the inverted U-shaped member I 41 and the inverted U-shaped member II 42 is 1.5 mm. The line width is generally set to 1 mm. Increasing the line width here is conducive to enhancing the radiation signal of the antenna.

[0032] A feeding point 11 is provided on the ground plane 1, and the feeding point 11 is electrically connected to one end of the feeder line 3. The connection point between the feeder line 3 of the antenna main structure and the ground plane is the feeder point 11 of the antenna, and the feeder point 11 is not directly connected to the ground plane to avoid the antenna radiator connecting to the ground plane and causing a significant attenuation of the signal. The feeder line 3 of the antenna main structure is 8 mm long and is connected to the lower left end of the inverted U-shaped member I 41.

[0033] The length of the vertical section of the inverted U-shaped member II 42 away from the feeder 3 is shorter than the length of the vertical section of the inverted U-shaped member I 41; the length of the horizontal section of the inverted U-shaped member II 42 is shorter than the length of the horizontal section of the inverted U-shaped member I 41. The difference in the length of the two inverted U-shaped members is mainly affected by the overall length of the antenna. This length is the optimal solution after debugging and optimization, and the main effect is to improve the radiation performance and communication bandwidth of the relatively poor head and tail frequency parts of the LTE frequency band.

[0034] The inverted U-shaped part I 41 and the feeder line 3 form an inverted spoon structure. The inverted U-shaped part II 42, the inverted U-shaped part I 41 and the feeder line 3 form an inverted spoon structure. The two inverted spoon structures cover different communication frequency bands. By covering different frequency bands, the communication bandwidth of the antenna can be broadened.

[0035] The size of the inverted U-shaped part I 41 is 5*11mm, and it is connected to the feed line 3 to form an inverted spoon shape, so that the antenna can cover the 2.3~2.69GHz frequency band. The inverted U-shaped part II 42 of the antenna main structure is 4.5mm wide, 11mm high on the left, and 4.5mm high on the right. In the antenna main structure composed of the feed line 3 and the inverted U-shaped part I 41, from the feed point, feed line 3, the vertical section at the left end of the inverted U-shaped part I 41, the horizontal section, the inverted U-shaped part II 42 to the inverted spoon shape at the end of the antenna, the antenna can cover the 1.71~2.3GHz frequency band.

[0036] The overlapping part of the inverted U-shaped part I 41 and the inverted U-shaped part II 42 of the antenna main structure has a height of 11 mm, which forms an electromagnetic coupling effect with the right sides of the inverted U-shaped part I 41 and the inverted U-shaped part II 42, respectively, reduces the antenna standing wave ratio, increases the frequency band coverage, and ultimately meets the design requirement of 1.71 GHz ~ 2.69 GHz bandwidth.

[0037] Figure 2 The standing wave ratio curve of the antenna on the vector network analyzer is shown. The horizontal axis is the frequency, ranging from 1000 to 3000MHz, and the vertical axis is the standing wave ratio. The design requires that the standing wave ratio at 1.71 to 2.69GHz is less than 4. Figure 2 The maximum standing wave ratio of the antenna of the present invention is 3.65@2.5MHz, which meets the design requirements.

[0038] Figure 3 The figure shows the radiation pattern of the main radiation plane of the antenna measured in a microwave OTA darkroom. The radiation pattern is roughly circular as a whole, indicating that the antenna has omnidirectional radiation characteristics.

[0039] Table 1 shows the passive efficiency and gain data of the PCB printed antenna of the present invention measured in a microwave OTA darkroom. The design requires that the efficiency is higher than 40% and the gain is greater than 1. It can be seen from Table 1 that the measured data of the antenna of the present invention meets the design requirements.

[0040] Table 1 Passive efficiency and gain data of the present invention

[0041]

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-cost miniaturized LET-CAT.1 PCB printed antenna, comprising a ground plane (1) and a clearance area (2), wherein the ground plane (1) and the clearance area (2) are both printed on a PCB circuit board, characterized in that: An antenna main body structure is provided in the clearance area (2), and the antenna main body structure is electrically connected to the ground plane (1); the antenna main body structure comprises a feeder line (3) and an inverted U-shaped structure (4), one end of the feeder line (3) is electrically connected to the ground plane (1), and the other end of the feeder line (3) is electrically connected to the inverted U-shaped structure (4).

2. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 1, characterized in that: The inverted U-shaped structure (4) comprises an inverted U-shaped part I (41) and an inverted U-shaped part II (42), wherein the lower end of one end of the inverted U-shaped part I (41) is electrically connected to the other end of the feeder line (3), and a section of wiring is shared between the other end of the inverted U-shaped part I (41) and the inverted U-shaped part II (42).

3. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 2, characterized in that: The length of the vertical section of the inverted U-shaped member II (42) away from the feeder (3) is shorter than the length of the vertical section of the inverted U-shaped member I (41); the length of the horizontal section of the inverted U-shaped member II (42) is shorter than the length of the horizontal section of the inverted U-shaped member I (41).

4. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 3, characterized in that: The widths of the horizontal sections and vertical sections of the inverted U-shaped member I (41) and the inverted U-shaped member II (42) are the same.

5. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to any one of claims 2 to 4, characterized in that: The inverted U-shaped member I (41) and the feeder (3) form an inverted spoon structure, and the inverted U-shaped member II (42), the inverted U-shaped member I (41) and the feeder (3) form an inverted spoon structure, and the two inverted spoon structures cover different communication frequency bands.

6. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 5, characterized in that: A feeding point (11) is provided on the ground plane (1), and the feeding point (11) is electrically connected to one end of the feeder line (3).

7. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 5, characterized in that: The basic structure of the feed line (3) is a 50Ω microstrip line, one end of the 50Ω microstrip line is connected to the feed point (11), and the other end is electrically connected to the lower end of one end of the inverted U-shaped piece I (41).

8. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 6 or 7, characterized in that: The size of the PCB circuit board is 80*80 mm, and the size of the clearance area (2) is 20*20 mm.

9. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 8, characterized in that: The length of the feed line (3) is 8 mm, and the width of the inverted U-shaped part I (41) and the inverted U-shaped part II (42) are both 1.5 mm.

10. The low-cost miniaturized LET-CAT.1 PCB printed antenna according to claim 9, characterized in that: The size of the inverted U-shaped part I (41) is 5*11 mm. The inverted U-shaped part I (41) is connected to the feeder (3) to form an inverted spoon structure, thereby achieving coverage of the antenna in the 2.3~2.69 GHz frequency band. The width of the inverted U-shaped part II (42) is 4.5 mm. The length of the vertical section of the inverted U-shaped part II (42) away from the feeder (3) is 4.5 mm. The inverted U-shaped part II (42) and the feeder (3) and the inverted U-shaped part I (41) form an inverted spoon structure, thereby achieving coverage of the antenna in the 1.71~2.3 GHz frequency band. The length of the wiring shared by the other end of the inverted U-shaped part I (41) and the inverted U-shaped part II (42) is 11 mm.

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