A low-profile electromagnetic dipole antenna with near-full space coverage

Abstract

The present invention provides a low-profile electromagnetic dipole antenna with approximate full-space coverage, which belongs to the field of wireless energy collection and antenna technology, and is composed of two antenna units symmetrically combined about a metal plate 14. Each antenna unit is divided into a four-layer rectangular dielectric structure, which includes, from top to bottom, a top dielectric block with a high dielectric constant, an intermediate upper dielectric plate with a low dielectric constant, an intermediate lower dielectric plate with a low dielectric constant, and a bottom dielectric plate with a low dielectric constant, and each layer is bonded by glue or fixed by insulating screws. The present invention can achieve approximate full-space coverage by using two antenna units. On the basis of a wide coverage range, it not only achieves broadband performance, but also has a high front-to-back ratio. In general, the present invention can collect energy from all directions in the environment within the 3.4-3.6GHz frequency band, and has a low profile and small size, which is conducive to integration with a rectifier circuit for use in a WEH system, thereby providing wireless power supply for tens of thousands of sensors in the Internet of Things.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless energy collection and antennas, and relates to an electromagnetic dipole antenna with approximately full space coverage. Background Art

[0002] The rectenna is the core component of the wireless energy harvesting (WEH) system. The goal of the rectenna is to receive as much RF energy as possible and pass it to the rectifier. The rectifier converts the RF energy into DC for use by the wireless node. For the WEH scenario, since the direction of the incident wave is unknown, the antenna unit is usually omnidirectional. However, the omnidirectional antenna can only collect energy in different directions in a complete plane (such as the XY plane), and the radiation angle of the antenna in another plane (such as the XZ plane) is limited. Therefore, the antenna with full space coverage is more suitable for the WEH system, because it can collect RF energy incident from any direction on two planes (such as the XY plane and the XZ plane), which greatly improves the energy utilization. In the existing research on full space coverage antennas, due to the limited coverage range of each antenna unit, it is necessary to use more units, such as 6, 8 or even 12 units together to form full space coverage radiation, which often leads to complex antenna structure and large antenna size, which is not conducive to the subsequent cascading of other circuit structures and further practical applications. It can be seen that using a small number of antennas, designing an antenna with a compact structure and achieving approximate full space radiation coverage is of great application value.

[0003] In order to achieve radiation coverage of nearly the entire space with a small number of antennas, the antenna must have a wide half-power beamwidth. Electromagnetic dipole antennas use the superposition principle of electric dipole and magnetic dipole patterns to generate wide radiation beams. When the ideal electric dipole and magnetic dipole are excited at the same time and the phase difference is 90 degrees, radiation with nearly full space coverage can be generated, but its operating bandwidth is narrow and the gain is usually small (<0dbi). When the ideal electric dipole and magnetic dipole are excited at the same time and the phase difference is 180 degrees, a unidirectional radiation pattern with a half-power beamwidth of about 130 degrees can be obtained. However, if the half-power beamwidth of the electromagnetic dipole antenna in two planes (such as the XY plane and the XZ plane) is extended to about 180 degrees, on the one hand, the combination of two antenna units that radiate laterally and in opposite directions can achieve nearly full space coverage, which is used in WEH scenarios, thereby collecting as much RF energy in space as possible. On the other hand, a single antenna can outperform an antenna with a zenith radiation pattern in some applications, such as office and home WiFi routers, where the antenna is usually placed away from the center of the room, such as against a wall.

[0004] In order to achieve a low profile and compact design of electromagnetic dipole antennas, dielectric resonator (DR) antennas (DRA) have been widely studied in recent years due to their compact structure, high efficiency, wide bandwidth, flexible design, and diverse radiation patterns. However, most of the current DRAs are either designed as electric dipole antennas to achieve omnidirectional radiation patterns, or as magnetic dipole antennas to achieve zenith radiation patterns, while lateral radiation is relatively rare. The existing lateral radiation DRAs generally have a radiation beam of only about 120 degrees, making it difficult to achieve near-full-space radiation coverage. Therefore, based on the working principle of electromagnetic dipoles, designing a low-profile and wide half-power beamwidth DRA for lateral radiation is the key to achieving a compact structure with near-full-space radiation coverage. This technology can meet a variety of application scenarios and has great market potential. Summary of the invention

[0005] The purpose of the present invention is to achieve full space coverage with a small number of antenna units, and proposes a low-profile electromagnetic dipole dielectric resonator antenna with approximate full space coverage, which can collect radio frequency energy in all directions of space and is suitable for WEH systems. The antenna features are as follows: two antenna units are placed symmetrically about the isolation metal plate axis, and the two ports are well isolated. When in use, they are fed separately, and their radiation patterns have the same shape, but different directions, thereby achieving approximate full space radiation coverage. The following is an explanation of the antenna unit structure, and the results given are also simulation results of feeding one of the ports. The effect of feeding the other port is the same, but the radiation direction is different. By designing the antenna medium as a rectangular block, the radiation pattern of the electric dipole in the Z direction is changed, so that its gain in the Y direction is greater than that in the X direction, and then combined with the magnetic dipole in the Y direction, unilateral radiation in the X direction is formed, which effectively expands the half-power beam width. The antenna is designed at a center frequency of 3.5 GHz. The results show that the half-power beam width in the XY plane is ~220°, the half-power beam width in the XZ plane is ~165°, and the antenna has a high front-to-back ratio, at 3.5 GHz, the front-to-back ratio is ~24.3 dB. The impedance bandwidth of the antenna can cover 3.14-3.88 GHz (~21.1%), and the bandwidth with wide beam and high front-to-back ratio is 3.4-3.6 GHz (5.7%). The antenna gain is ~1.47 dBi. In addition, the profile height of the antenna is ~0.13λ0 (λ0 represents the wavelength corresponding to the center frequency).

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A low-profile electromagnetic dipole antenna with approximately full space coverage is composed of two antenna units symmetrically combined about a metal plate 14. Each antenna unit is divided into four layers of rectangular dielectric structure, which include, from top to bottom, a top dielectric block 1 (first layer) with a high dielectric constant, an intermediate upper dielectric plate 4 (second layer) with a low dielectric constant, an intermediate lower dielectric plate 6 (third layer) with a low dielectric constant, and a bottom dielectric plate 9 (fourth layer) with a low dielectric constant. The layers can be glued together or holes can be punched around the dielectric and fixed with insulating screws (which can be made of plastic). A spatial rectangular coordinate system is established with the center of the antenna unit as the origin, the short side direction of each layer of rectangular dielectric as the X-axis, the long side direction of the rectangle as the Y-axis, and the direction of the dielectric height as the Z-axis.

[0008] The first layer is a top dielectric block 1 with a high dielectric constant. The top dielectric block 1 is provided with an air hole 2 for inserting a metal probe 3, that is, the air hole 2 is at the same height as the top dielectric block 1, and the center of the air hole 2 is located on the X-axis but does not coincide with the origin of the coordinate axis.

[0009] The second layer is a low dielectric constant intermediate upper dielectric plate 4. The intermediate upper dielectric plate 4 is placed as a low dielectric constant dielectric resonator on the lower layer of the top dielectric block 1 as a high dielectric constant dielectric resonator, forming a structure of multiple dielectric resonators (multi-stage DR structure), which can obtain a wider impedance bandwidth. The cross-shaped metal patch 5 with a circular center is located at the center of the lower surface of the intermediate upper dielectric plate 4, that is, the cross-shaped metal patch 5 is located between the second layer and the third layer.

[0010] The third layer is a low dielectric constant intermediate lower dielectric plate 6. A short metallized through hole 7 is provided at a position corresponding to the center of the central circle of the metal patch 5 on the intermediate lower dielectric plate 6. The center of the short metallized through hole 7 is located at the rectangular center of the intermediate lower dielectric plate 6. The short metallized through hole 7 is connected to the circular center of the cross-shaped metal patch 5 with a circular center.

[0011] Air holes 8 penetrating the dielectric plates are provided at positions corresponding to the air holes 2 of the top dielectric block 1 on the intermediate upper dielectric plate 4 and the intermediate lower dielectric plate 6. The air holes 8 of the dielectric plate are aligned with the center of the air holes 2 of the top dielectric block and penetrate the intermediate upper dielectric plate 4 and the intermediate lower dielectric plate 6. The metal probe 3 passes through the air holes 8 of the dielectric plate and is inserted into the air holes 2 of the dielectric block.

[0012] The fourth layer is a bottom dielectric plate 9 with a low dielectric constant. A rectangular metal microstrip 10 is provided in the middle of the upper surface of the bottom dielectric plate 9. The two ends of the metal microstrip 10 are connected to the metal probe 3 and the short metallized through hole 7 respectively. The distance from the center of the metal microstrip 10 to the center of the metal probe 3 and the center of the short metallized through hole 7 is the same. A through hole is provided at a position corresponding to the center of the metal microstrip 10 on the bottom dielectric plate 9. A metal floor 11 is provided on the lower surface of the bottom dielectric plate 9. A through hole is also provided at a position corresponding to the center of the metal microstrip 10 on the metal floor 11. The inner core of the SMA connector 12 passes through the metal floor 11 and is inserted into the bottom dielectric plate 9 and connected to the center of the metal microstrip 10. Energy is fed from the SMA connector 12 and simultaneously excites the metal probe 3 and the cross-shaped metal patch 5 with a circular center connected to the short metallized through hole 7 in phase through the metal microstrip 10. The diameter of the hole on the metal floor 11 is larger than the inner core diameter of the SMA connector 12 to avoid short circuit. The flange of the SMA connector 12 is attached to the metal floor 11.

[0013] One end of the four long metallized through holes 13 is connected to the cross end of the cross-shaped metal patch 5 with a circular center and vertically penetrates the middle lower dielectric plate 6 and the bottom dielectric plate 9 downward, and the other end is connected to the metal floor 11.

[0014] The two antenna units are axially symmetrical about the metal plate 14 to form a binary array. The metal plate 14 is placed on the side of the long side of each layer of rectangular dielectric away from the metal probe 3. Except for the top dielectric block 1, the remaining dielectric layers of the two units are connected to form a whole. One end of the metal plate 14 is connected to the metal floor 11, and the other end passes through the bottom dielectric plate 9, the middle lower dielectric plate 6 and the middle upper dielectric plate 4, and is at the same height as the upper surface of the top dielectric block 1. Accordingly, an air cavity 15 is reserved on the bottom dielectric plate 9, the middle lower dielectric plate 6 and the middle upper dielectric plate 4 for inserting the metal plate 14. The metal plate 14 has an isolation function.

[0015] The cross-shaped metal patch 5 with a circular center located at the center of the lower surface of the second layer of medium acts as an electric dipole in the Z direction, and has far-field patterns of "O" (circle) and "∞" on the XY and XZ planes, respectively. The four layers of medium are designed as rectangular blocks, rather than cylinders or cubes, and their length in the Y direction is greater than the length in the X direction. At this time, the radiation of the electric dipole in the XY plane is slightly inclined toward the Y direction (elliptical mode), rather than omnidirectional (circular mode), that is, it has far-field patterns of "0" (ellipse) and "∞" on the XY and XZ planes. Next, the metal probe 3 located on the positive half axis of the X axis, which passes through the third layer of medium, the second layer of medium in turn and has a certain height in the first layer of medium, acts as a magnetic dipole in the Y direction, and has far-field patterns of "∞" and "O" on the XY and XZ planes, respectively. According to the theory of electromagnetic dipole combination, the electric dipole in the Z direction and the magnetic dipole in the Y direction can form lateral radiation in the X direction by combining. Since the gain of the electric dipole in the Y direction is greater than that in the X direction, the gain from the X direction to the Y direction decreases slowly with the change of angle after combination, thereby expanding the half-power beam width. The expansion angle is related to the side length of the rectangle.

[0016] Furthermore, as required, gaps and grooves can be processed in the rectangular dielectric layer to further improve matching and isolation without affecting the wide beam of the antenna.

[0017] Furthermore, the present application makes the radiation of the electric dipole asymmetric by changing each layer of the medium into a rectangle, thereby widening the beam in combination with the magnetic dipole.

[0018] Furthermore, the middle lower dielectric plate 6 can be removed and replaced with an air gap, in which case the second and fourth layers can be fixed in position using plastic distance screws, and the short metallized through-holes 7 and the long metallized through-holes 13 are replaced with metal column structures.

[0019] Furthermore, the metal probe 3 is not limited to a cylindrical metal probe, and can be deformed, such as using a metal column with a T-shaped upper end, a metal column with a disc at the upper end, etc. It is also not limited to a metal probe, and a metal strip can be used for feeding.

[0020] Furthermore, the dielectric constant of the top dielectric block 1 is not less than 5.

[0021] Furthermore, the dielectric constant of the intermediate upper dielectric plate 4 is not greater than 10.

[0022] Furthermore, the dielectric constant of the middle lower dielectric plate 6 is not greater than 10.

[0023] Furthermore, the bottom dielectric plate 9 has a dielectric constant not greater than 10.

[0024] Furthermore, the dielectric constant of the top dielectric block 1 should be greater than the dielectric constants of the middle upper dielectric plate 4 , the middle lower dielectric plate 6 and the bottom dielectric plate 9 .

[0025] The low-profile electromagnetic dipole antenna with near full space coverage provided by the present invention can collect radio frequency energy in all directions in space, and has a relatively wide impedance bandwidth of 3.16-3.91GHz (21.4%), wherein the bandwidth with wide beam and high front-to-back ratio is 3.4-3.6GHz (5.7%), which can cover the 5G test frequency bands of China Telecom (3.4GHz-3.5GHz) and China Unicom (3.5GHz-3.6GHz), and the isolation of the two ports of the antenna in this frequency band is less than -16dB. It is worth mentioning that in a unit structure, the reason for using a cross-shaped metal patch 5 with a circular center as an electric dipole instead of using a second metal probe other than the metal probe 3 is that the metal patch 5 can avoid drilling holes in the top dielectric block 1, and also avoid the problem of excessive coupling between the two metal probes (in a unit, structure 5 can actually use a metal probe, which is the same as structure 3, but in a different position, but if structure 5 is also a metal probe, it will be more seriously coupled with structure 3, and there is a problem of excessive coupling between the two metal probes in the unit). In addition, this design can also change the middle lower dielectric plate 6 into an air gap. At this time, the short metallized through-hole 7 and the long metallized through-hole 13 should be changed into metal pillars. By adjusting the size of the air gap, the middle upper dielectric plate 4 and the top dielectric block 1, a similar result can be obtained while reducing costs.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention can achieve nearly full space coverage by using two antenna units. On the basis of wide coverage, it not only achieves broadband performance, but also has a high front-to-back ratio. In general, the low-profile electromagnetic dipole dielectric resonator antenna with nearly full space coverage proposed by the present invention can collect energy from all directions in the environment within the 3.4-3.6GHz frequency band, and has a low profile and small size, which is conducive to integration with a rectifier circuit for use in a WEH system, thereby providing wireless power supply for tens of thousands of sensors in the Internet of Things. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a cross-sectional schematic diagram of the overall structure of the electromagnetic dipole antenna with approximately full space coverage proposed by the present invention;

[0029] FIG2( a ) is a schematic cross-sectional view of a top layer high dielectric constant dielectric block in the present invention;

[0030] FIG2( b ) is a cross-sectional schematic diagram of the second layer of low dielectric constant dielectric plate in the present invention;

[0031] FIG2( c ) is a schematic cross-sectional view of the third low dielectric constant dielectric plate of the present invention;

[0032] FIG2(d) is a schematic cross-sectional view of the bottom low dielectric constant dielectric plate of the present invention;

[0033] FIG2( e ) is a bottom view schematically showing the structure of the lower layer of the bottom low dielectric constant dielectric plate in the present invention;

[0034] Figure 3 is a graph of S-parameters simulated when one port is stimulated in Embodiment 1 of the present invention;

[0035] FIG4(a) is a radiation pattern in the xy-plane (left figure) and xz-plane (right figure) when a port is excited at a frequency of 3.4 GHz in Example 1 of the present invention;

[0036] FIG4( b ) is a radiation pattern in the xy- (left) and xz- (right) planes when a port is excited at a frequency of 3.5 GHz in Example 1 of the present invention;

[0037] FIG4( c ) is a radiation pattern in the xy- (left) and xz- (right) planes when a port is excited at a frequency of 3.6 GHz in Example 1 of the present invention;

[0038] Figure 5 This is a structural diagram of embodiment 2 of the present invention.

[0039] In the figure: 1 top dielectric block; 2 air holes of dielectric block; 3 metal probe; 4 middle upper dielectric plate; 5 cross-shaped metal patch with circular center; 6 middle lower dielectric plate / air gap; 7 short metallized via / short metal column; 8 air hole of dielectric plate; 9 bottom dielectric plate; 10 metal microstrip; 11 metal floor; 12 SMA connector; 13 long metallized via / long metal column; 14 metal plate; 15 air cavity. DETAILED DESCRIPTION

[0040] The specific implementation scheme of the present invention is described in detail below in conjunction with the accompanying drawings and technical solutions of the specification.

[0041] Example 1

[0042] See also Figure 1The overall structural cross-sectional view of the binary array composed of electromagnetic dipole antennas, the antenna as a whole is composed of a top dielectric block 1 with a high dielectric constant, an intermediate upper dielectric plate 4 with a low dielectric constant, an intermediate lower dielectric plate 6 with a low dielectric constant, and a bottom dielectric plate 9 with a low dielectric constant. The two antenna units are axially symmetrical about the metal plate 14. Except for the top dielectric block, the remaining dielectric layers of the two units are connected to form a whole, and the unit center distance is 0.29λ0. One end of the metal plate 14 is connected to the metal floor 11, and the other side passes through the bottom dielectric plate 9, the intermediate lower dielectric plate 6 and the intermediate upper dielectric plate 4, and is at the same height as the upper surface of the top dielectric block 1. Accordingly, an air cavity 15 is reserved on the bottom dielectric plate 9, the intermediate lower dielectric plate 6 and the intermediate upper dielectric plate 4 for inserting the metal plate 14. One end of the metal probe 3 contacts the metal microstrip 10, and the other end passes through the air through hole 8 of the dielectric plate and is inserted into the air through hole 2 of the dielectric block for a certain length. Preferably, the metal plate 13 is 30 mm long, 11.259 mm wide, and 1 mm thick. The radius of the metal probe 3 is 0.4 mm. The length of the metal probe 3 inserted into the dielectric block 1 is 4.8 mm. The center of the metal probe 3 is located in the middle of the long side of the top dielectric block 1, 5.9 mm away from the short side 14.

[0043] Referring to the dielectric structure of the top layer with a high dielectric constant in FIG2(a), the top dielectric block 1 is provided with an air hole 2 for inserting a metal probe 3. Preferably, the dielectric constant of the top dielectric block 1 is 10.2, the length is 37 mm, the width is 21 mm, and the thickness is 6.5 mm. The radius of the air hole 2 is 0.5 mm, and the center of the air hole 2 is located in the middle of the long side of the top dielectric block 1, 5.9 mm away from its short side. The radius of the air hole 2 is slightly larger than the radius of the metal probe 3. The reason is that considering the actual processing, if the two radii are the same, it will have a certain impact on the result.

[0044] Referring to FIG. 2( b ), the dielectric plate 4 of the middle upper layer with low dielectric constant is connected as a whole. The cross-shaped metal patch 5 with a circular center is located at the center of the lower surface of the middle upper layer dielectric plate 4. Preferably, the dielectric plate 4 is made of a material with a dielectric constant of 3, with a length of 49 mm, a width of 48 mm, and a thickness of 0.762 mm. The radius of the circular center of the cross-shaped metal patch 5 with a circular center is 2 mm, and the length of the four rectangular arms is 5 mm and the thickness is 0.02 mm.

[0045] Referring to FIG2(c), the dielectric plate 6 of the middle lower layer with a low dielectric constant is connected as a whole by the middle lower dielectric plates 6 of the two units. A short metallized through hole 7 is provided at a position corresponding to the center of the circle of the center circle of the metal patch 5 on the middle lower dielectric plate 6. The center of the short metallized through hole 7 is located at the rectangular center of the middle lower dielectric plate 6. The short metallized through hole 7 is connected to the circular center of the cross-shaped metal patch 5 with the circular center. Preferably, the dielectric plate 6 is made of a material with a dielectric constant of 3, with a length of 49 mm, a width of 48 mm, and a thickness of 3.175 mm. The radius of the short metallized through hole 7 is 0.5 mm.

[0046] refer to Figure 1 , Figure 2(b) and Figure 2(c). Air holes 8 penetrating the dielectric plates are provided at positions corresponding to the air holes 2 of the top dielectric block 1 on the middle upper dielectric plate 4 and the middle lower dielectric plate 6. The air holes 8 of the dielectric plates are aligned with the center of the air holes 2 of the top dielectric block and penetrate the middle upper dielectric plate 4 and the middle lower dielectric plate 6. The metal probe 3 passes through the air holes 8 of the dielectric plates and is inserted into the air holes 2 of the dielectric block. The radius of the air holes 8 of the dielectric plates is 0.4 mm.

[0047] Referring to FIG2(d), the bottom dielectric plate 9 with low dielectric constant is connected to form a whole. A rectangular metal microstrip 10 is provided in the middle of the upper surface of the bottom dielectric plate 9. Figure 1 As shown in FIG2(c), the two ends of the metal microstrip 10 are connected to the metal probe 3 and the short metallized through hole 7 respectively, and the distance from the center of the metal microstrip 10 to the center of the metal probe 3 and to the center of the short metallized through hole 7 is the same. A through hole is provided on the bottom dielectric plate 9 at a position corresponding to the center of the metal microstrip 10. In conjunction with FIG2(e), a metal floor 11 is provided on the lower surface of the bottom dielectric plate 9, and a through hole is also provided at a position corresponding to the center of the metal microstrip 10. The inner core of the SMA connector 12 passes through the metal floor 11 and is inserted into the bottom dielectric plate 9 and connected to the center of the metal microstrip 10. Energy is fed from the SMA connector 12 and simultaneously excites the metal probe 3 and the cross-shaped metal patch 5 with a circular center connected to the short metallized through hole 7 in phase through the metal microstrip 10. The diameter of the hole on the metal floor 11 is larger than the inner core diameter of the SMA connector 12 to avoid short circuit, and the flange of the SMA connector 12 is attached to the metal floor 11. Preferably, the dielectric plate 9 is made of a material with a dielectric constant of 3, and has a length of 49 mm, a width of 48 mm, and a thickness of 0.762 mm. The metal microstrip 10 has a length of 7.2 mm, a width of 2.2 mm, and a thickness of 0.02 mm. The metal floor 11 has a length of 49 mm, a width of 48 mm, and a thickness of 0.02 mm. The inner core radius of the SMA connector 12 is 0.635 mm.

[0048] refer to Figure 12(b), 2(c), 2(d) and 2(e), each unit has four long metallized through holes 13, one end of the long metallized through hole 13 is connected to the cross end of the cross-shaped metal patch 5 with a circular center and vertically penetrates the middle lower dielectric plate 6 and the bottom dielectric plate 9 downward, and the other end is connected to the metal floor 11. Preferably, the radius of the long metallized through hole is 0.4 mm.

[0049] refer to Figure 3 This is a simulated S parameter curve diagram of the electromagnetic dipole antenna proposed in the present invention when one port is excited. It can be seen from the figure that the antenna resonates at two frequency points of 3.2GHz and 3.72GHz, which are the modes of magnetic dipole and electric dipole respectively. The combination of the two modes improves the impedance bandwidth to 3.14-3.88GHz (21.1%). At the same time, in the middle frequency band (3.4-3.6GHz) where the electric dipole and the magnetic dipole are combined, the combination effect of the directional pattern is the best, with a very wide half-power beam width and a very high front-to-back ratio. At the same time, the isolation of the two ports is less than -16dB.

[0050] Refer to Figure 4 (a)-(c) for the radiation patterns at 3.4 GHz, 3.5 GHz and 3.6 GHz when the antenna excites one port. It can be seen from the figure that lateral radiation in the +X direction can be achieved at each frequency point, and the pattern is stable. The slight asymmetry in the XZ plane is caused by the ground plane affecting the radiation of the magnetic dipole. At 3.4 GHz, 3.5 GHz and 3.6 GHz, the gain is 2.13 dBi, 1.47 dBi and 0.86 dBi respectively, the half-power beamwidth in the XY plane is 188°, 220° and 244° respectively, the half-power beamwidth in the XZ plane is 160°, 165° and 172° respectively, and the front-to-back ratio is 20.9 dB, 24.3 dB and 15.9 dB respectively, that is, within the frequency range, the front-to-back ratio is greater than 15 dB. From the above results, it can be seen that when the two antenna units work independently, full space coverage can be achieved approximately. The XY plane is completely covered, and the XZ plane covers an angle of ~262°, with directions of the upper, left and right spaces. The space of ~34 degrees to the left and right of the positive direction of the Z axis, totaling ~68 degrees, is the intersection of the radiation ranges of the two antenna units. The RF energy within this range can be collected by the two antenna units at the same time. Within the frequency range, there is an uncovered area of ​​~98° on the underside of the floor. In actual applications, when the rectenna is integrated with electronic equipment or placed on a platform, part of the radiation of the antenna is usually blocked, and this part of the radiation is wasted. If the radiation of the antenna can be concentrated in the unblocked space, this can achieve the expansion of the effective antenna area when used in the WEH scenario. Therefore, the floor side of this antenna can be integrated with other electronic devices or used for placement, while more energy is collected on the upper, left and right sides of the space.

[0051] Example 2

[0052] In this embodiment, the middle lower dielectric plate 6 in Embodiment 1 is removed and adjusted to an air gap (the Z-direction dimension of the air gap is 3.6 mm), and the short metallized through hole 7 and the long metallized through hole 13 are replaced by metal pillars. Figure 5 , you can punch holes around the dielectric, use plastic spacing screws to fix the relative position of the middle upper dielectric plate 4 and the bottom dielectric plate 9, and leave a 3.6mm air gap between them. Similarly, the relative position of the top dielectric block 1 and the middle upper dielectric plate 4 can also be fixed by plastic screws. The other structures of Example 2 are the same as those of Example 1, but the dimensions of each layer are adjusted as needed. In order to prove the general principle of dielectric materials, this example uses a different dielectric material from that in Example 1, which also requires further adjustment of the dimensions. The adjusted dimensions are as follows:

[0053] The dielectric constant of the middle upper dielectric plate 4 is 3.66, and the dimensions are 49mm×49mm×1.016mm. The dielectric constant of the top dielectric block 1 is 16.9, and the dimensions are 21mm×36mm×5.8mm. The dielectric constant of the bottom dielectric plate 9 is 2.94, and the dimensions are 49mm×49mm×0.762mm. In Example 2, an SMA connector with an inner core radius of 0.435mm was used, and Example 1 was 0.635mm. SMA can be simulated according to the size based on the specific model. The inner core radius has a certain influence on the antenna performance, but it can be optimized by adjusting other parameters.

[0054] The innovation of the present invention is analyzed as follows: The key point of the present invention is to expand the half-power beam width of the electromagnetic dipole antenna unit, and achieve nearly full-space coverage with only two units. A wide half-power beam width and a very high front-to-back ratio can be maintained in the 3.4-3.6GHz frequency range, making it very suitable for WEH systems. In addition, the antenna has a low profile (profile height is 0.13λ0) and a small size (the floor size of the two units is 0.56λ0*0.57λ0). Protection points:

[0055] (1) The invented antenna tilts the radiation of the electric dipole toward the Y direction so that the gain in the Y direction is greater than that in the X direction. Thus, after the electromagnetic dipoles are combined, the gain from the X direction to the Y direction decreases slowly with the change of the angle, thereby expanding the half-power beam width. However, the invention is not limited to changing the radiation of the electric dipole, and the radiation of the magnetic dipole can also be changed. The invention is also not limited to the tilt direction and the combination direction of the directional pattern. The electric dipole or the magnetic dipole can be tilted and radiated in the desired direction.

[0056] (2) The metal plate of the invented antenna is used as isolation, but is not limited to metal plates, and metal columns, etc. may be used.

[0057] (3) The intermediate lower structure of the invented antenna is not limited to a dielectric plate with a low dielectric constant, but may also be an air gap, as long as the metal through holes in the design are replaced with metal pillars.

[0058] (4) The invented antenna can be applied as a binary array or individually. For example, in office and home WiFi routers, the antenna is placed next to the wall. In this case, a unidirectional antenna with a lateral radiation pattern is superior to a unidirectional antenna with a zenith radiation pattern. Not limited to energy harvesting, the antenna is suitable for a variety of wireless communication systems because it has a wide half-power beamwidth, low back radiation, symmetrical radiation pattern, and stable gain over the operating frequency band.

[0059] (5) The antenna design uses the 3.4-3.6 GHz 5G test frequency band of China Telecom and China Unicom as an example, but is not limited to this frequency band. The design technology can be extended to any frequency band.

[0060] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A low-profile electromagnetic dipole antenna with approximately full space coverage, with the center of the antenna unit as the origin, the short side direction of each layer of rectangular medium as the X-axis, the long side direction of the rectangle as the Y-axis, and the direction of the medium height as the Z-axis to establish a spatial rectangular coordinate system; characterized in that: The antenna is composed of two antenna units symmetrically combined about a metal plate (14); each antenna unit is divided into four layers of rectangular dielectric structure, which include, from top to bottom, a top dielectric block (1) with a high dielectric constant, an intermediate upper dielectric plate (4) with a low dielectric constant, an intermediate lower dielectric plate (6) with a low dielectric constant, and a bottom dielectric plate (9) with a low dielectric constant, and each layer is fixed by bonding or insulating screws; each layer of dielectric becomes rectangular, so that the radiation of the electric dipole is asymmetric, thereby combining with the magnetic dipole to broaden the beam; The first layer is a top dielectric block (1) with a high dielectric constant, on which is provided an air hole (2) for inserting a metal probe (3), the center of which is located on the X-axis but does not coincide with the origin of the coordinate axis; The second layer is a middle upper dielectric plate (4) with a low dielectric constant, which serves as a dielectric resonator with a low dielectric constant and forms a structure of multiple dielectric resonators with the top dielectric block (1); a cross-shaped metal patch (5) with a circular center is located at the center of the lower surface of the middle upper dielectric plate (4), that is, the cross-shaped metal patch (5) is located between the second layer and the third layer; The third layer is a middle lower dielectric plate (6) with a low dielectric constant, on which a short metallized through hole (7) is provided, the center of the short metallized through hole (7) is located at the rectangular center of the middle lower dielectric plate (6), and the short metallized through hole (7) is connected to the circular center of the cross-shaped metal patch (5); An air through hole (8) penetrating the dielectric plate is provided on the intermediate upper dielectric plate (4) and the intermediate lower dielectric plate (6) at a position corresponding to the air through hole (2) of the top dielectric block (1); the air through hole (8) of the dielectric plate is aligned with the center position of the air through hole (2) and penetrates the intermediate upper dielectric plate (4) and the intermediate lower dielectric plate (6); the metal probe (3) passes through the air through hole (8) of the dielectric plate and is inserted into the air through hole (2); The fourth layer is a bottom dielectric plate (9) with a low dielectric constant, a rectangular metal microstrip (10) is provided in the middle of the upper surface of the bottom dielectric plate, the two ends of the metal microstrip (10) are respectively connected to the metal probe (3) and the short metallized through hole (7), and the distance from the center of the metal microstrip (10) to the center of the metal probe (3) and to the center of the short metallized through hole (7) is the same; a through hole is provided at a position corresponding to the center of the metal microstrip (10) on the bottom dielectric plate (9), and a metal floor (11) is provided on the lower surface of the bottom dielectric plate (9), and the metal floor ( 11) a through hole is also provided at a position corresponding to the center of the metal microstrip (10); the inner core of the SMA connector (12) passes through the metal floor (11) and is inserted into the bottom dielectric plate (9) and connected to the center of the metal microstrip (10); energy is fed from the SMA connector (12) and simultaneously stimulates the metal probe (3) and the cross-shaped metal patch (5) with a circular center connected to the short metalized through hole (7) in phase through the metal microstrip (10); the diameter of the hole of the metal floor (11) is larger than the inner core diameter of the SMA connector (12); One end of the four long metallized through holes (13) is connected to the cross end of the cross-shaped metal patch (5) and vertically penetrates the middle lower dielectric plate (6) and the bottom dielectric plate (9) downward, and the other end is connected to the metal floor (11); The two antenna units are axially symmetrical about the metal plate (14) to form a binary array; the metal plate (14) has an isolation function and is placed on the side of the long side of each layer of rectangular medium away from the metal probe (3); except for the top layer medium block (1), the remaining layers of medium of the two units are connected to form a whole; one end of the metal plate (14) is connected to the metal floor (11), and the other end passes through the bottom layer medium plate (9), the middle lower layer medium plate (6) and the middle upper layer medium plate (4), and is at the same height as the upper surface of the top layer medium block (1); accordingly, an air cavity (15) for inserting the metal plate (14) is reserved on the bottom layer medium plate (9), the middle lower layer medium plate (6) and the middle upper layer medium plate (4); The cross-shaped metal patch (5) located at the center of the lower surface of the second layer of medium acts as an electric dipole in the Z direction, and has far-field patterns of "O" and "∞" on the XY and XZ planes respectively; the metal probe (3) acts as a magnetic dipole in the Y direction, and has far-field patterns of "∞" and "O" on the XY and XZ planes respectively; the electric dipole in the Z direction and the magnetic dipole in the Y direction are combined to form lateral radiation in the X direction.

2. A low-profile electromagnetic dipole antenna with nearly full space coverage according to claim 1, characterized in that: As needed, gaps and grooves can be processed in the rectangular dielectric layer to further improve matching and isolation without affecting the wide beam of the antenna.

3. The low-profile electromagnetic dipole antenna with nearly full space coverage according to claim 1, characterized in that: The intermediate lower dielectric plate (6) can be replaced by an air gap, and at the same time, the short metallized through hole (7) and the long metallized through hole (13) are replaced by a metal column structure, and the second layer and the fourth layer are fixed with insulating screws.

4. The low-profile electromagnetic dipole antenna with approximately full space coverage according to claim 1, characterized in that: The metal probe (3) is not limited to a cylindrical metal probe, and can be deformed or replaced with a metal strip for power feeding.

5. The low-profile electromagnetic dipole antenna with nearly full space coverage according to claim 1, characterized in that: The dielectric constant of the top dielectric block (1) is greater than the dielectric constants of the middle upper dielectric plate (4), the middle lower dielectric plate (6), and the bottom dielectric plate (9).

6. A low-profile electromagnetic dipole antenna with nearly full space coverage according to claim 5, characterized in that: The top dielectric block (1) has a dielectric constant of not less than 5.

7. The low-profile electromagnetic dipole antenna with nearly full space coverage according to claim 5, characterized in that: The dielectric constant of the intermediate upper dielectric plate (4) is selected to be no greater than 10.

8. The low-profile electromagnetic dipole antenna with nearly full space coverage according to claim 5, characterized in that: The dielectric constant of the middle lower layer dielectric plate (6) is selected to be no greater than 10.

9. The low-profile electromagnetic dipole antenna with nearly full space coverage according to claim 5, characterized in that: The bottom dielectric plate (9) has a dielectric constant not greater than 10.

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