Miniaturized microstrip antennas for smart grid wireless sensors

Abstract

The present invention discloses a miniaturized microstrip antenna applied to a smart grid wireless sensor, comprising: a dielectric substrate, a metal grounding plate located below the dielectric substrate, and a rectangular antenna patch located above the dielectric substrate; wherein two cutouts are symmetrically introduced on two non-radiating sides of the rectangular antenna patch, and two groups of slots are introduced in the center of the rectangular antenna patch; a complementary open resonant ring CSRR defect ground structure is introduced on the metal grounding plate, wherein the complementary open resonant ring CSRR defect ground structure is a group of concentric, mutually oppositely placed open resonant rings, and the point on the metal grounding plate that intersects with the coaxial feeder is set as the geometric center of the CSRR defect ground structure. Compared with the existing antennas applied to smart grid wireless sensors, the present invention utilizes defect ground structures and meandering technology to achieve miniaturized design of the antenna while ensuring the radiation performance of the antenna.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a miniaturized microstrip antenna applied to a smart grid wireless sensor. Background Art

[0002] This section is intended to provide a background or context for the embodiments of the invention recited in the claims. No description herein is admitted to be prior art by inclusion in this section.

[0003] With the rapid development of integration technology, electronic components are required to be integrated into various devices with smaller sizes. Therefore, how to reduce the physical size of microstrip antennas (to achieve antenna miniaturization) has become a hot issue in the field of electronics. The so-called miniaturization of microstrip antennas is to reduce the size of the antenna while keeping the antenna resonant frequency unchanged; equivalently, it can also be considered as reducing the antenna resonant frequency while keeping the overall size of the antenna unchanged.

[0004] Traditional smart grid wireless sensors usually use miniaturized omnidirectional antennas such as dipoles, monopoles and helical antennas to achieve miniaturized design of the equipment. However, for smart grid application scenarios with a large number of metal cabinets, the application space is small and the surroundings are all good conductors. If ordinary dipole-type omnidirectional antennas (dipole, monopole and helical antennas) are used, the antenna's transceiver performance will be greatly reduced due to the influence of metal conductors. In order to solve this problem, it is necessary to design antennas that are directional and less affected by conductors. Microstrip antennas have attracted widespread attention because they have a ground plane and can significantly reduce the influence of surrounding metal. Compared with miniaturized dipole-type omnidirectional antennas, traditional microstrip antennas have the disadvantage of being larger in size. Summary of the invention

[0005] The embodiment of the present invention provides a miniaturized microstrip antenna applied to a smart grid wireless sensor, comprising: a dielectric substrate, a metal ground plate located below the dielectric substrate, and a rectangular antenna patch located above the dielectric substrate;

[0006] Among them, two cuts are symmetrically introduced on two non-radiating sides of the rectangular antenna patch, and two groups of slots are introduced in the center of the rectangular antenna patch;

[0007] A complementary open resonant ring CSRR defect ground structure is introduced on the metal ground plane. The complementary open resonant ring CSRR defect ground structure is a group of concentric open resonant rings placed opposite to each other. The point on the metal ground plane that intersects with the coaxial feed line is set as the geometric center of the CSRR defect ground structure.

[0008] The present invention designs a defective ground structure of a complementary open ring resonator (CSRR). After loading the structure, the size of the antenna is reduced. By using meander technology, the shape of the rectangular radiation patch is designed as an irregular slotted patch, the antenna resonant frequency is reduced, and a miniaturized design is achieved. By combining the loaded defective ground structure with the meander technology, the physical size of the antenna is miniaturized while the radiation gain of the antenna remains almost unchanged. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0010] Figure 1 Schematic diagram of the structure of a miniaturized microstrip antenna applied to a smart grid wireless sensor in an embodiment of the present invention;

[0011] Figure 2 A structural diagram of a conventional rectangular microstrip antenna proposed in an embodiment of the present invention;

[0012] Figure 3 A schematic diagram of the structure of an antenna defect proposed in an embodiment of the present invention;

[0013] Figure 4 S is the difference between the rectangular microstrip antenna proposed in the embodiment of the present invention and the traditional rectangular microstrip antenna 11 Comparison diagram;

[0014] Figure 5 A comparison diagram of the radiation patterns of the rectangular microstrip antenna with a defective ground structure in an embodiment of the present invention and the traditional rectangular microstrip antenna;

[0015] Figure 6 1 is a current vector distribution diagram on three shapes of patches in an embodiment of the present invention;

[0016] Figure 7 The structure diagram of the antenna using the irregular slotted patch in the embodiment of the present invention;

[0017] Figure 8 The irregular slotted patch antenna in the embodiment of the present invention and the traditional patch antenna S 11 Comparison chart;

[0018] Fig. 9 A comparison diagram of the radiation patterns of the irregular slotted patch antenna and the traditional patch antenna in an embodiment of the present invention;

[0019] Fig.10The defective and irregular slotted patch antenna and the traditional antenna S are simultaneously introduced in the embodiment of the present invention. 11 Comparison chart;

[0020] Fig.11 A comparison diagram of the radiation patterns of the defective and irregular slotted patch antennas and the traditional antennas in the embodiment of the present invention;

[0021] Fig.12 S of the three miniaturized antennas in the embodiment of the present invention and the traditional patch antenna 11 Comparison chart. DETAILED DESCRIPTION

[0022] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0023] In view of the fact that microstrip antennas in the prior art are larger in size than dipole antennas, the present invention proposes to use meander technology to design both the antenna's radiation patch and the floor to maximize the miniaturization of the antenna. On the radiation patch, meander technology is used to effectively extend the surface current path. On the antenna floor, a defective ground structure is loaded to change the current distribution of the floor.

[0024] The present invention proposes a miniaturized microstrip antenna for use in smart grid wireless sensors, such as Figure 1 As shown, the structure includes: a dielectric substrate, a metal ground plate located below the dielectric substrate, and a rectangular antenna patch located above the dielectric substrate;

[0025] Among them, two cuts are symmetrically introduced on two non-radiating sides of the rectangular antenna patch, and two groups of slots are introduced in the center of the rectangular antenna patch;

[0026] A complementary open resonant ring CSRR defect ground structure is introduced on the metal ground plane. The complementary open resonant ring CSRR defect ground structure is a group of concentric open resonant rings placed opposite to each other. The point on the metal ground plane that intersects with the coaxial feed line is set as the geometric center of the CSRR defect ground structure.

[0027] Specifically, Figure 1 The left side of the figure is a bottom view of the antenna structure loaded with defective ground and irregular slotted patch at the same time, from which the metal ground plane (printed on the dielectric substrate) can be seen, wherein the open resonant ring introduced on the metal ground plane is a square open resonant ring. The open resonant ring can also be a circular open resonant ring or a regular hexagonal open resonant ring.

[0028] Specifically, the incision may be a triangular incision, a rectangular incision or a semicircular incision. Figure 1 The right side figure is a top view of the antenna structure loaded with defective ground and irregular slotted patches at the same time. The rectangular antenna patch and the dielectric substrate can be seen from the figure, wherein the two triangular cutouts of the rectangular antenna patch are symmetrical. And this triangle is an isosceles triangle, one of the bottom corner points is located on a radiating edge of the rectangular antenna patch, and the other bottom corner point is located on the upper or lower non-radiating edge. Among them, the two groups of slots are symmetrical. The slot is composed of a rectangular and a semicircular slot. The diameter of the semicircular slot in the slot coincides with one of the long sides of the rectangular slot, and the semicircular slot is located at the center of the long side of the rectangular slot.

[0029] The specific plan is described as follows.

[0030] In order to compare the performance parameters of the miniaturized microstrip antenna proposed in the present invention, the present invention designs a traditional rectangular microstrip antenna as a control group, such as Figure 2 As shown, Figure 2 (a) is the top view of the rectangular microstrip antenna. Figure 2 (b) is a side view of a rectangular microstrip antenna. The material used is Roger RO4350(tm) dielectric substrate with a thickness of H = 2mm. The side length of the square ground plane is a = 45mm, the length of the patch parallel to the y direction is L = 23.26mm, and the width of the patch parallel to the x direction is W = 45mm. In order to avoid additional interference radiation, the antenna adopts a coaxial feeding method, and the feeding point deviates from the center axis of the patch in the x direction y0 = 5.9mm. Through ANSYS HFSS simulation, the resonant frequency of the antenna is 3.05GHz, S 11 The frequency band range of <10dB is 3.02-3.09GHz.

[0031] Metal ground plane is introduced as Figure 3 The complementary split ring resonator (CSRR) defective ground structure shown is a group of concentric, mutually oppositely placed positive direction split resonant rings, and the point on the metal ground plate that intersects with the coaxial feed line is set as the geometric center of the CSRR defective ground structure. This defective ground structure can effectively increase the effective dielectric constant and change the patch current distribution, so the resonant frequency of the antenna is reduced, and a good miniaturization effect is obtained.

[0032] like Figure 3 As shown, the side length of the outer side of the defective ground structure is w1, the distance between the inner side of the outer ring and the outer side of the inner ring is p1, the width of the ring is g1, and the opening width of the ring is k1. After optimization, the dimensions of the antenna are confirmed to be w1 = 12 mm, g1 = 0.3 mm, p1 = 1.25 mm, and k1 = 1 mm.

[0033] The S of this antenna is different from that of the traditional rectangular antenna.11 For example Figure 4 As shown, the radiation patterns of the two are Figure 5 shown.

[0034] Then, the microstrip antenna design using irregular slotted patches is used. The meander technology is an antenna miniaturization technology that uses irregular patches and slots to make the current detour and extend the current path. To make the current path on the patch longer, we must first observe the patch current vector distribution on the original traditional rectangular antenna, such as Figure 6 (a) As shown. According to the current flow distribution, the shape contour and slot position of the special patch are further designed. Figure 6 As shown in (a), the current of the rectangular patch flows from the left radiating edge to the right edge. Therefore, two triangular cuts are introduced on the two non-radiating edges of the antenna. The current flows along the cuts, which will increase the current path, as shown in Figure 6 (b) In order to make the current path growth effect more significant, two sets of symmetrical slots are introduced in the center of the patch, and each set of slots is composed of a rectangular and a semicircular slot. Figure 6 As shown in (c), after the introduction of the cuts on the non-radiating edge and two sets of slots, the current is forced to detour and the effective current length is significantly increased.

[0035] In addition, the purpose of adding cutouts is to increase the current path that originally runs along the two sides of the patch. A triangular cutout is the simplest and most effective way to increase the path. The cutout can also be in other shapes, for example, a cutout that aligns the two sides can be added, but the antenna gain and other indicators obtained by simulation are not as good as the triangular cutout.

[0036] Of course, the principles of slots and adding cutouts on the sides are both meandering technologies, except that slots lengthen the current flow path inside the patch, while cutouts on the sides lengthen the path along the edge of the patch. The slots can be in other shapes, but the slots in the above shapes are more preferred.

[0037] Figure 7 The structure diagram of the antenna using an irregular slotted patch. hs is the distance between the vertex of the triangular cut and the edge of the patch parallel to the y direction, rs is the radius of the two inner semicircular slots, gs is the width of the inner rectangular slot parallel to the x direction, ps is the spacing between the two rectangular slots, ls is the length of the rectangular slot parallel to the y direction, ts is the distance between the vertex of the triangular cut and the central axis of the patch in the x direction, and ds is the length of the side of the triangular cut parallel to the y direction.

[0038] Through optimization simulation, the size parameters of the patch are determined as rs=2.5mm, ps=12mm, gs=3mm, ls=18mm, ts=1mm, hs=2.7mm, and ds=20mm respectively.

[0039] The S of this antenna is different from that of the traditional rectangular antenna. 11 For example Figure 8 As shown, the radiation patterns of the two are Fig. 9 The above-mentioned antenna miniaturization effects of loading defects alone and using irregular slotted patches are limited. It is envisaged that the two miniaturization technologies will be integrated to achieve a more significant miniaturization effect. Figure 1 The schematic diagram of the antenna structure with defective ground and irregular slotted patch loaded at the same time is shown in Table 1.

[0040] Table 1 Antenna dimensions for simultaneously loading defective ground and irregular slotted patches (unit: mm)

[0041] a L W H <![CDATA[y0]]> rs 45.00 23.29 29.78 1.52 5.10 2.50 gs ls ts hs ds ps 3.00 18.00 1.00 2.70 20.00 12.00

[0042] Among them, a is the side length of the square metal ground plate, L is the length of the patch parallel to the y direction, W is the width of the patch parallel to the x direction, y0 is the distance that the feeding point deviates from the center axis of the patch in the x direction, the side length of the outer side of the outer ring of the defective ground structure is w1, the distance between the inner side of the outer ring and the outer side of the inner ring is p1, the width of the ring is g1, the opening width of the ring is k1, hs is the distance between the vertex of the triangular cut and the edge of the patch parallel to the y direction, rs is the radius of the two inner semicircular slots, gs is the width of the inner rectangular slot parallel to the x direction, ps is the spacing between the two rectangular slots, ls is the length of the rectangular slot parallel to the y direction, ts is the distance between the vertex of the triangular cut and the center axis of the patch in the x direction, and ds is the side length of the triangular cut parallel to the y direction.

[0043] The S of this antenna is different from that of the traditional rectangular antenna. 11 For example Fig.10 As shown, the radiation patterns of the two are Fig.11 shown.

[0044] The following is a comparison of antenna performance:

[0045] Fig.12 S of three miniaturized antennas and traditional rectangular antennas 11 From the comparison chart, it can be seen that the three miniaturized antennas can reduce the resonant frequency. Among them, the resonant frequencies of the structure with defect loading alone and the irregular slotted patch alone are similar; the antenna with two miniaturization methods superimposed can further reduce the resonant frequency. A more comprehensive performance comparison of the traditional rectangular antenna and the three miniaturized microstrip antennas proposed in this invention is shown in Table 2.

[0046] Table 2 Performance comparison of three miniaturized antennas and rectangular antenna

[0047] Traditional patch antenna Antenna introduced into defective ground Slotted antenna Slotted antenna with defective ground introduced Resonance frequency(GHz) 3.05 2.75 2.69 2.4 <![CDATA[S 11 <10dB(GHz)]]> 3.02-3.09 2.72-2.78 2.67-2.71 2.38-2.42 bandwidth 2.29％ 2.18％ 1.49％ 1.67％ <![CDATA[S 11 (dB)]]> -36.09 -42.2 -47.93 -35.98 Maximum gain (dBi) 5 3.5 3.4 2.2 Minimum gain (dBi) -13.5 -17.4 -12.1 -14.8 Front-to-back ratio (dB) 18.5 20.9 15.5 17 Area reduction ratio / 30.78％ 34.11％ 47.51％

[0048] As can be seen from Table 2, the resonant frequency of the traditional microstrip antenna is 3.05GHz, and the resonant frequencies of the antennas loaded with defective ground alone and with irregular slotted patches alone are reduced to 2.75GHz and 2.69GHz, respectively. The areas of these two antennas are reduced by 30.78% and 34.11%, respectively, compared with the traditional rectangular antenna. The resonant frequency of the antenna loaded with defective ground and irregular slotted patches at the same time is greatly reduced to 2.4GHz, which is 47.51% smaller than the rectangular antenna area. The miniaturization design has achieved a satisfactory effect. At the same time, it is observed that other electrical properties remain at an excellent level, so this miniaturized antenna is reasonably designed. Antenna S that combines two miniaturization technologies 11 The <10dB frequency band ranges from 2.38 to 2.42 GHz, which is in line with the Wi-Fi frequency band commonly used in smart grids and has the potential to be integrated into smart grid wireless sensor nodes.

[0049] In summary, the present invention proposes a miniaturized microstrip antenna for use in smart grid wireless sensors, which achieves the following beneficial effects:

[0050] (1) A square complementary split ring resonator (CSRR) defective ground structure was designed. After loading this structure, the size of the antenna was reduced.

[0051] (2) By using meander technology, the shape of the rectangular radiating patch is designed to be an irregular slotted patch, thereby reducing the antenna resonant frequency and achieving miniaturization.

[0052] (3) By combining the defect-loaded ground structure with the meander technology, the physical size of the antenna is reduced by 47.51% without significantly reducing the radiation gain of the antenna. Compared with the 30.87% size reduction of the defect-loaded ground structure alone and the 34.11% size reduction of the meander technology, the miniaturization effect of combining the two miniaturization technologies is greatly improved, and all performance indicators of the antenna are maintained at a good level.

[0053] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0054] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0057] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A miniaturized microstrip antenna for use in smart grid wireless sensors, characterized in that: include: A dielectric substrate, a metal ground plate located below the dielectric substrate, and a rectangular antenna patch located above the dielectric substrate; Among them, two cuts are symmetrically introduced on two non-radiating sides of the rectangular antenna patch, and two groups of slots are introduced in the center of the rectangular antenna patch; A complementary open resonant ring CSRR defect ground structure is introduced on the metal ground plane, wherein the complementary open resonant ring CSRR defect ground structure is a group of concentric open resonant rings placed opposite to each other, and the point on the metal ground plane that intersects with the coaxial feed line is set as the geometric center of the CSRR defect ground structure; The cutout is a triangular cutout, a rectangular cutout or a semicircular cutout; the triangle is an isosceles triangle, one of the base angle points is located on a radiating edge of the rectangular antenna patch, and the other base angle point is located on the upper or lower non-radiating edge; The slot is composed of a combination of a rectangular and a semicircular slot, or a combination of a rectangular and a trapezoidal slot, or a combination of a rectangular and a rectangular slot; the diameter of the semicircular slot in the slot coincides with a long side of the rectangular slot, and the semicircular slot is located at the center of the long side of the rectangular slot; The open resonant ring is a square open resonant ring, a circular open resonant ring or a regular hexagonal open resonant ring; the side length of the outer side of the outer ring of the defective ground structure determined by the optimization simulation is 12 mm, the distance between the inner side of the outer ring and the outer side of the inner ring is 0.3 mm, the width of the ring is 0.3 mm, and the opening width of the ring is 1 mm; The distance between the vertex of the triangular cut and the edge of the patch parallel to the y direction determined by the optimization simulation is 2.7mm, the radius of the two inner semicircular slots is 2.5mm, the width of the inner rectangular slot parallel to the x direction is 3mm, the spacing between the two rectangular slots is 12mm, the length of the rectangular slot parallel to the y direction is 18mm, the distance between the vertex of the triangular cut and the central axis of the patch in the x direction is 1mm, and the side length of the triangular cut parallel to the y direction is 20mm.

2. The miniaturized microstrip antenna for smart grid wireless sensors according to claim 1, characterized in that: The two groups of slots are symmetrical.

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